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1973 The ffecE t of Thyroxine and Thiourea on Territorial Behavior in Cichlid Fish. Peter Harry Spiliotis Louisiana State University and Agricultural & Mechanical College
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Recommended Citation Spiliotis, Peter Harry, "The Effect of Thyroxine and Thiourea on Territorial Behavior in Cichlid Fish." (1973). LSU Historical Dissertations and Theses. 2573. https://digitalcommons.lsu.edu/gradschool_disstheses/2573
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SPILIOTIS, Peter ferry, 1946- THE EFFECT OF THYROXINE AND THIOUREA ON TERRITORIAL BEHAVIOR IN CICHLID FISH.
The Louisiana State University and Agricultural and Mechanical College, Ph.D., 1973 Psychology, general
University Microfilms, A XEROX Company, Ann Arbor, Michigan
THIS DISSERTATION HAS BEEN MICROFILMED EXACTLY AS RECEIVED. THE EFFECT OF THYROXINE AND THIOUREA ON
TERRITORIAL BEHAVIOR IN CICHLID FISH
A Dissertation
Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy
in
The Department of Psychology
by Peter Harry Spiliotis B .A ., The University of North Carolina, 1969 M .A ., Louisiana State University, 1971 December, 1973 ACKNOWLEDGMENT
The author would like to thank his major professor Dr, Donald
R. Hoffeld for his guidance and assistance during this project. The author would also like to express gratitude to members of his committee,
Dr. Albert H. Meir, Dr, Billy M, Seay, Dr, Arthur J. Riopelle, and
Dr. Nathan W. Gottfried. Special thanks is extended to Dr. Laurence
Siegel, Chairman of the Department of Psychology and Dr. Irwin A. Berg,
Dean of the School of Arts and Sciences who made available funds in support of this dissertation. I am Indeed grateful to the typist, Mrs.
Mary Mevers.
ii TABLE OF CONTENTS
Page
TITLE P A G E ...... i
ACKNOWLEDGMENT...... ii
LIST OF T A B L E S ...... iv
ABSTRACT ...... v
INTRODUCTION ...... I
Functional Considerations of Thyroid Hormones ...... 3 Territorial Behavior and Its Components ...... 8 P u r p o s e ...... 13
METHOD ...... 15
Subjects...... 15 A ppar a t u s ...... 15 Procedure...... 16 Statistical Analysis and Informal Data...... 19
RESULTS...... 21
Reliability...... 21 Quantitative Behavior Measures...... 21 Qualitative Observational Data...... 26 S u m m a r y ...... 30
DISCUSSION...... 33
Hormones and Territoriality ...... 33 Activity and Locomotor Levels ...... 37 Pigmentation and Coloration Displays...... 37 Drug Dosage ...... 39 Rhythmicity ...... 40
REFERENCES...... 41
APPENDIX ...... 51
VITA ...... 55
iii LIST OF TABLES
Table Page
1. Mean Frequency of Behavior Categories for each Defended Territory in Group I ...... 22
2. Mean Frequency of Behavior Categories for each Defended Territory in Group II...... 23
3. Mean Frequency of Behavior Categories for each Defended Territory in Group III ...... 24
iv ABSTRACT
Two species of mature cichlids, Cichlasoma meeki and Cichlasoma biocellatum, exhibited behavioral changes in critical stimuli involved in defense of a territory after prolonged thyroxine treatment. Fish exhibited increased locomotor activity, changes in integument pigmenta tion which corresponded to adopted functional behaviors, and spent con siderably more time on the surface of aquaria. Only C. meeki showed flutter behavior. Dominant territorial fish tended to increase the area of their territory and their dominance over nonterritorial members.
In C. meeki prolonged thyroxine resulted in significant increases in two behavior categories from baseline--territorial mouth fighting
(Tm, p ^.005) and nipping of the subtrate outside the territorial pit
(N, p<.025). Similar increases in the frequency of nipping (p <^.025) occurred in C. biocellatum. These changes suggest that thyroxine may have a role in agonistic behavior during defense of a territory and also effects critical stimuli involved in territorial behavior. The standard aquarium setting and social category system place limitations on the extent that intensification of territorial behavior can be evaluated. Thiourea treated C. meeki abandoned previously defended territories, developed darker integument pigmentation, grouped together and schooled stationary at the bottom of each aquaria. The diminution in activity consisted of uncoordinated jerky movements, persistent beating of pectoral fins, and periodic bouts of agonistic behavior. Within 2 weeks of the thiourea treatment, all behavior categories significantly decreased (p -^.025). Thiourea treatment decreased the number of critical sign stimuli necessary for the execution of territorial behavior. Thiourea dosage level was critical and JJ. meeki are suscep tible to prolonged thiourea treatment.
vi INTRODUCTION
In vertebrate evolution, the forebrain haa attained an increas ing dominate control over certain behavior responses, with the result that they tend to escape hormonal control. In lower vertebrates, the influence of the forebrain may be less marked, and behavior sequences may be increasingly controlled by hormones (Beach, 1947, 1948).
According to Beach, hormones act as chemical sensitizers which alter the responsiveness of the CNS to stimuli from the environment. How ever, there is little evidence for the exact functional role of the fish thyroid (Matty, I960) and the physiological effects and peripheral target of the fish thyroid hormones have been difficult to elucidate definitively (Berg, Gorbman, & Kobayaski, 1959; Gorbman, 1969).
Fish are low in the vertebrate series and therefore may provide insight into the ways in which hormones have gained control over behavior in the course of vertebrate evolution. Moreover, fish possess a repertoire of behaviors which are relatively simple and much more rigid and stereotyped than those of higher vertebrates. In conjunction, territorial behavior exemplifies some adaptive features of fish.
Territorial behavior in fish serves to: (1) regulate the population;*
(2) provide food reserve for adults and young; (3) increase geograph ical range of the species; (4) provide undisturbed areas for pairing and spawning; and (5) provide conditions for obtaining the best suitable mate for reproduction (Lorenz, 1937). Therefore, the thyroid hormone 2 control or influence in territorial behavior in fish may express basic functional relationships in the execution of adaptive behavior.
Ethologists approach the analysis of behavior within the frame work of the "black box." The black box is the machinery inside the animal through which behavior, that is muscular and glandular activity
(the output) is produced, under the influence of sensory stimuli. By observing the output, under different input conditions the experimenter can predict the presence of mechanisms in the black box and define them on the basis of the functions he found them to fulfill. The behavioral unit for the occurrence of which the ethologist investigates the causes of behavior is the Fixed Action Pattern (FAP) (Lorenz, 1937). The FAF or consummatory behavior (Craig, 1918), consists of stereotyped activi ties which are aa typical for a species as morphological structures and therefore can be used as taxonomic features (Whitman, 1899). Holzapfel
(1940) extended the idea of FAP to the attainment of suitable living conditions (right temperature, salinity, _gH, territorial behavior, and familiar environment). The variable behavior sequence or appetitive behavior which precedes the attainment of a FAP encompasses the animal searching for the situation in the environment which releases the FAP.
Moreover, as previously stated by Beach (1947), hormones act as chemi cal sensitizers which alter the responsiveness of the central nervous system to stimuli from the environment. In this manner, the extent of the appetitive behavior, the timing of events, and their intensity of expression may depend on hormones (Beach, 1947). Tinbergen's (1950) hierarchial system of behavior has shown how the change in gonadal 3
hormonal level in the blood activates nervous centers and initiates
generalized appetitive behavior. This in turn is followed by pro
gressively more specialized acts as the appropriate releasers are en
countered, and the innate releasing mechanisms activated until the
final consummatory act is performed. The external environment guides
and directs the different activities involved. Therefore, in order to
investigate fish behavior in a thorough manner, one must incorporate
sophisticated ethological measurements of behavior in connection with
physiological techniques.
Functional Considerations of Thyroid Hormones
Thyroid tissue is present in all vertebrate groups (Gorbman,
1959). In lower vertebrates, thyroid follicles are present but are not
encapsulated and organized into a compact gland. Thus thyroid tissue
in teleost may be scattered in connective tissue throughout from the
pharyngeal region to distant areas such as the ventral aorta, eye,
brain, spleen, and kidney (Baker et al., 1955; Baker, 1958; Chavln,
1956; Frisen & Frisen, 1967; Baker-Cohen, 1959).
In the teleost, four general areas of investigation have been
researched: (1) metabolic actions (2) structural effects (3) reproduc
tion (4) effects on the central nervous system and behavior. The best known property of thyroid hormones in homoiothermic animals is the
control over energy (heat) and oxygen production. The basal metabolic rate (BMR) falls rapidly after thyroidectomy and may be elevated above
the normal level by administering thyroid hormones. In adult poikilotherms or cold blooded animals such action by thyroxine has 4
been inconclusive, indicating that control over respiratory and
calorigenic metabolism may not be a function of thyroxine (Matty, 1957;
Hoar, 1958; Fromm & Reineke, 1957; Pickford & Atz, 1957). However,
thyroid function in poikilotherms has been found associated with phases
of metabolism other than respiratory rate. Hochacka (1962) reported
that thyroxine operates as an activator in carbohydrate metabolism in
the trout, whereas Fontaine and Hatey (1950) reported increased level
of glucose with prolonged thyroxine treatment in the salmon. Thyroxine
has also been shown to effect metabolic processes producing increased ammonia excretion in the goldfish (Hoar, 1958) and nitrogen metabolism
in the brown trout (Thornbum & Matty, 1963). Moreover, observations
on fishes seem to imply that the piscine thyroid is also Involved in the metabolism of salts and water (Fontaine, 1956; Smith, 1956; Gorbman
& Berg, 1955); however more recent evidence (Dharmamba, et aJL., 1967) questions whether thyroxine has an important influence in osmoregulation as was initially expected since other hormones (corticosteriods and neurohypophyseal peptides) play a larger role.
A second group of phenomona is related to structural changes derived from thyroid treatment. Thyroid action has been reported to effect the integument and its derivatives in fish. Numerous authors have observed a common pigmentary response in the skin of fishes
(trout, salmon, and guppy) called "silvering” (Robertson, 1949; Sage,
1967, 1968; Matty & Sheltawy, 1967). This "silvering" effect from pro
longed thyroxine treatment seems to have resulted from changes in integumentary guanin metabolism (Matty & Sheltawy, 1967). Increases in 5 pigmentation in the skin of carp (Sembrat, 1956) and Channa punctalis
(Belsare, 1966) have been reported with antithyroid drug, thiouracil or thiourea and opposite effects were reported for thyroxine treatment.
In contrast, thyroxine treatment also increased black pigmentation in goldfish (Muller, 1953) and in Anquille anquilla (Vilter, 1946). In addition, thiourea treated fish also exhibit melanophore' granule dis persion (Belsare et aj.., 1966). Moreover, LaRoche & Leblund (1952) and
LaRoche e£ a_l. (1966) found that radiothyroidectomized trout showed increased melanin pigmentation and thinning of both epidermal and dermal elements. Morphological changes were corrected with an Increase in the number of pigment cells per surface area after throxine administration
(LaRoche et al.. 1966).
The relation of body growth to thyroid function in teleosts remains uncertain and a conclusive demonstration that thyroid treatment will stimulate overall growth has yet to be reported. Radio- thyroidectomy in the platyfish (Baker-Cohen, 1961) and trout (LaRoche,
1966) markedly retarded the rate of growth and development in each species. Thyroid products have been reported to have growth stimulating properties when administered to guppies (Smith, et al., 1953; Sage,
1965, 1968), trout (Barrington et al.. 1961), sunfish (Gross et al.,
1963), salmon (Piggins, 1962) and goldfish (Bjorklund, 1965). However, thyroid treatment of salmon by some investigators resulted in retarded growth rate (Dales & Hoar, 1954; Honma & Murakawa, 1955; LaRoche &
Leblond, 1952). Two experiments by Sage with guppies (1965, 1968) using the antithyroid agent thiourea resulted in inhibited growth. A 6
treatment group receiving both thiourea and thyroxine showed an inter mediate growth rate. The action of thyroid hormones in growth seems to be secondary in fish as in mammals (Simpson, et a_K , 1950;
Solomon & Greep, 1959), and a more complex analysis of its role is needed in order to explain contradictory results.
The third area of investigations is the relation of the teleost thyroid to reproduction. Circumstantial evidence indicates an influ ence of the thyroid gland upon reproductive behavior. A direct gameto- genic effect of thyroid hormones has not so far been observed, and one is forced to conclude that the thyroid normally plays a synergistic, auxiliary or complementary role (Matty, 1960). Many seasonal changes which appear in the teleost thyroid are however related to reproduction
(Fickford & Atz, 1957; Matty, 1960). Treatment with antithyroid drugs has resulted in inhibited maturation of the gonads of Fundulus heteroclitus (Chambers, 1953), and in regressed gonadal states in the minnow Phoxinus phoxinus (Barrington & Matty, 1952) and Lebistes reticulatus (Smith, Sladek & Kellner, 1953).
A fourth series of actions is the role of the thyroid hormones in the central nervous system and behavior in teleost. Experimental investigations have indicated that thyroid hormones affect the pattern of motor behavior, level of activity, and aggregate behavior. Hoar et al. (1952) and Hoar (1955) reported that goldfish and salmon treated with thyroxine displayed greater locomotor activity, swim closer to the surface of the water, and have less intense groupings. Thiourea
treated subjects were less active, increased intensity of groupings, and 7 schooled near the bottom of the tank. More recently, Sage (1968) re ported similar results with 4 week exposure treatments with thyroxine and thiourea to guppies. Thyroxine treated fish showed increased swimming, higher incidence of jumping behavior (flutter behavior, per sistent swimming against the walls of the aquarium), and more time in the periphery of the tank. Thiourea treated fish exhibited less swimming and an absence of jumping behavior and spent less time in the periphery than controls. In addition, Froselius (1957)reported an increase of appetitive behavior and general locomotor activity in the anabantid fish after injections of thyroxine. Hoar et al. (1952) sug gests that the thyroid hormone in the blood activates nervous centers and initiates generalized appetitive behavior. This in turn will be followed by progressively more specialized acts as the appropriate releasers are encountered and the innate releasing mechanisms activated until the final consummatory act is performed.
In general, thyroid hormones affect behavior by bringing about an increase in activity. This increment may be a result of hormonal influence on metabolism or direct action on neural mechanisms in the
CNS underlying the behavioral responses (increased locomotor and general activity) (Lfley, 1969). Electrophysiologlcal studies have indi cated that thyroid hormones may directly affect the CNS and sense organ states by influencing the responsiveness of the CNS to external stimuli
(Hoar, 1965). Thyroid treated goldfish were more responsive to elec trical stimulation than untreated fish (Hoar et al., 1955) and showed changes in the properties of their electrical potentials for optically 8 generated CNS activity (Hara et al.. 1965; Hara et al., 1966) and olfactory activity (Oshima and Gorbman, 1966a, 1966b, 1965).
In addition, there appears to be a distinct interrelationship between the thyroid gland and the sympathetic nervous system
(Waldstein, 1966; Harrison, 1964). The effects of sympathetic cate cholamines, particularly epinephrine, mimic some of the physiological actions (tachycardia, increased oxygen consumption, and accelerated lipolysis) of thyroid hormones (Gelhorn & Feldman, 1941; Comsa, 1950).
Secondly, the hormones interact synergistically, so that the action of sympathetic catecohlamines is Increased by administration of thyroid hormones (Brewster, Issac, Osgood, & King, 1956; Raab, 1944) or hyperthyroidism (Horstmann, 1954; Swanson, 1956, 1957; Rosenblum, Hahn,
& Levine, 1933), thereby augmenting the effects of epinephrine and norepinephrine. In a like manner, the effects of sympathetic cate cholamines are diminished by spontaneous or experimental hypothyroidism
(Rosenblum et al.. 1933; Brewster et. al., 1956; Raab, 1944). A third line of interrelationship involves the ability of adrenergic blocking agents to reduce the hemodynamic and metabolic effects of thyroid hormones (Brewster et al,, 1956). The locus of the synergistic inter action of these hormones remains to be elucidated.
Territorial Behavior and Its Components
Tinbergen (1936) defined "territory" as an area which is defended by a fish shortly before and during the formation of a sexual alliance. Noble (1939) presented a more general definition indicating that territorial behavior is exhibited when a territory is defended. 9
Among many piscine species, as gonads mature, nuptial coloration and
other secondary sex characteristics become present, shortly thereafter,
the elements of sexual and territorial behavior appear. Territories are established more commonly at the onset of breeding season as a place where sexual bonds are formed (Noble, 1939) and where spawning will occur (Breder, 1936). Territorial behavior facilitates the formation of behavior interrelationships or bonds between partners (Noble, 1939;
Neil, 1964). The territory probably represents an area most suited to the physiological requirements of the individual, who rapidly develops a special attachment to the site (Aronson, 1957). As invaders of the same species as well as members of other species invade the territory, the territorial holding fish will execute aggressive actions (agonistic behavior) in order to defend the territory. With the initiation of sexual pairing, agonistic behavior by the pair gradually changes the social structure of the fish school into a territorial society in which the distances between the members is increased and maintained by some real fighting and a great deal of threatening (Baerends & Baerends Van
Roon, 1950). The method of defense varies with the "weapons of the species" (Aronson, 1959), piscine defenses include threats, biting, chasing, fighting, and tail beating, etc.
In cichlids, one sexually active male becomes dominant over the rest in a restricted area. This male becomes brightly colored and inhibits the development of similar colors in subordinate males. How ever, threat and not color is of greater importance in securing a dominant position in the social hierarchy and establishing a territory (Nobel & Curtis, 1939). There is a hierarchy of displays, their
potency and importance being reflected by form, frequency, and dura
tion (Ruwet & Voss, 1966; Voss & Ruwet, 1966), seeming to express
degrees of intimidation, the milder degree being a harmless warning
and the more severe a direct threat. Serious fighting occurs in which
rival fish grip each others jaws and wrestle by pushing and pulling
each other to and fro, but most belligerent conflicts are resolved
without real damage, with defeated fish showing attitudes of submis
sion. Real fighting has been replaced by symbolic combat (Nobel &
Curtis, 1939; Baerends & Baerends Van Roon, 1950).
Agonistic behavior is considered "reproductive" insofar as it
is an essential preliminary to reproduction, but it may also occur
during territorial behavior at times and places unrelated to breeding,
such as maintenance of individual distance and breeding habits (Breder,
1936; Baerends 6c Baerends Van Roon, 1952; Noble et al.. 1938). Such activities are unlikely to be under the same hormonal control as
seasonly changing reproductive behavior (gonadotropic and gonadal hormones) (Blum 6c Fiedler, 1965; Smith et a l .. 1967). Hoar (1965) and
Baggerman (1966) suggest that during the period before the onset of breeding the level of agonistic or aggressive behavior is controlled by the level of gonadotropic hormone activity (physiologically like
FSH, LH, and prolactin). Gradually the mechanisms controlling this behavior becomes more sensitive to gonadal hormones (androgens, estrogens, and progesterone) with the waning of gonadotropic influence
(Gottfried 6c Van Mullen, 1967). 11
Territorially induced aggressive behaviors have been called
fixed action patterns (Lorenz, 1937; Holzapfel, 1940). In a given
situation, a specific stimulus in the environment releases an inborn reaction or motor pattern. However, in territorial behavior simple stimulus response components fall short of fully explaining the con trolling causal mechanisms. In fact, the optimal external stimulus may consist of a summation of several stimuli simultaneously which normally are separated from each other in time (principle of heterogeneous summation) (Seitz, 1940). Seitz (1940) evaluated a set of stimuli releasing fighting responses in cichlids and concluded that the intensity of a response depended not only on what sign stimuli are present but how many are present. Three sign stimuli presented simultaneously elicited a more intense response than two stimuli.
Furthermore, different responses may be given to the same external stimulus, varying with the endocrine state, experience, fatigue, and fear (Collias, 1944). In defense of a territory, demands are placed on the territorial holding fish to have the abilities to discriminate species, sexes, gravid individuals, partners, movement patterns and territorial boundaries.
Stimulus Factors. Physical stimuli are important factors con trolling the execution of the various aspects of reproductive behavior
(territorial and courtship) but the integration and coordination of the components depend on a continuous interplay of external and internal factors since not only do hormones affect behavior, but also behavior affects the endocrine state (Lehman, 1965; Hinde, 1965). 12
In fish, external visual factors that involve the use of color, color changes, and movement patterns of either the whole body or part of it, are important for processing information for territorial defense (Fruer & lies, 1972). Visual factors involved in movement patterns, integument pigmentation, and other structural specializations have been reported to be very specific for eliciting particular behavior patterns in territorial defense (Tinbergen, 1951; Baerends & Baerends
Van Roon, 1950; Neil, 1964; Tavolga, 1956; Noble & Curtis, 1939), enabling fish to (1) advertise the fact that a particular male has established a territory; (2) designate the position of an individual in the social hierarchy; and (3) coordinate their movements for appro priate displays (Fryer & lies, 1972). The role of visual stimuli in courtship behavior has also been emphasized (Breder & Coates, 1935;
Clark & Aronson, 1951; Baerends et al., 1955; Liley, 1966).
Olfactory stimuli also play a role in intraspecies communica tion. Cichlids employ chemical pheremones in recognizing their young
(Kuhme, 1963), initiating courtship behavior (Tavolga, 1955), species recognition (Noble & Curtis, 1939), and during a fright reaction to impending danger (Pfeiffer, 1962; Noble, 1939). Other nonvisual stimuli are also important means of communication. Sound production in cichlids has been reported to be an integral part of courtship and territorial behavior involving courtship movements, mate location, and fighting between rival males (Kramer, 1965; Bauer, 1963). Character istic sound productions were recorded for particular threat displays and aggressive acts during defense of a territory (Rodman, 1966). 13
Mechanical and tactile stimulation is widespread during territorial
and courtship behavior. The rate of water movement and texture of
bottom (Fabricus, 1950; Winn, 1953) act as stimuli for breeding.
During territorial defense and courtship behavior, biting, butting,
mouthing and other bodily parts have been observed in many species
(Aronson, 1949; Noble & Curtis, 1939; Gottier, 1969; Baerends &
Baerends Van Roon, 1952).
More recently, electrical signals initiated by the central
nervous system and discharged from electric organs have been detected
as sensory signals in agonistic communication (Black-Cleworth, 1970).
Electrical discharge frequency wa3 used in the identification of dis
plays in fighting behavior between rival males and in the expression of
varying degrees of dominance and submission. The agonistic patterns of
the electric fish Gymnotus is clearly related in both form and function
to aggressive displays in other teleost and indicated that sensory mechanisms are involved in agonistic behavior (Black-Cleworth, 1970).
Purpose
The purpose of this study was to Investigate the qualitative
and quantitative effects of thyroxine and the antithyroid drug
thiourea on the factors or stimuli involved in regulating the extent,
timing of events, and intensity of expression of appetitive behaviors
during territorial behavior in cichlid fish. Thyroxine has been
reported to increase the responsiveness of the CNS to external stimuli
(Hoar, 1965, 1967; Oshima & Gorbman, 1966, 1968; Hara et al.. 1967), 14
augment the effects of sympathetic catecholamines (Waldstein, 1966;
Brewster _et al., 1956), affect the pattern of motor behavior, level of
activity, aggregate behavior (Hoar, 1952, 1955, 1958; Sage, 1967, 1968) and integument pigmentation (Malty & Sheltawy, 1967; Belsare, 1966;
Robertson, 1949; Sage, 1968). These behaviors and stimuli (pigmenta
tion, pattern of motor movement, level of activity, aggregate behavior) have been found to be critical sign stimuli during appetitive behavior
in the releasing of consummatory acts during territorial behavior
(Lorenz, 193/, Tinbergen, 1942; Noble, 1939; Breder, 1936; Baerends &
Baerends Van Roon, 1950; Neil, 1964). The present investigation was
specifically designed to provide an evaluation of the extent of terri
torial behavior by cichlids residing in aquaria and to what extent
changes detected by the social category system for cichlids (Costelloe,
1970) can be used to reflect levels of agonistic behavior and terri
toriality after thyroxine and thiourea treatment. In this manner, a
qualitative and quantitative evaluation of several external stimuli
that have been reported to be influenced by thyroid hormones can
be evaluated simultaneously in the context of territorial defense. METHOD
Subjects
Forty-eight mature Cichlasoma meeki (firemouths) and twenty-
four mature Cichlasoma biocellatum (Jack Dempsey) were observed. These
fish were obtained from an aquarium dealer. Additional fish were on
hand for replacement in case of mortalities.
Apparatus
Experimental subjects were contained in 20 gallon standard
(12"x;2”x30") aerated aquariums. Eight firemouths were in each of six
aquaria. Three of the populated tanks connected by syphons were grouped
to a fourth unpopulated tank occupied by a pump (Group I). In this manner, complete circulation and water changes were provided for the
group. The three remaining tanks populated with firemouths were
arranged in a similar manner (Group II). The twenty-four Jack Dempseys
were populated in a like manner composing Group III. Temperature was maintained at 76-80° F by individual heaters. Lighting was provided
by incandescent lamps (30 watts in the overhead tank lids). A
16L:8D photoperiod was regulated electrically by a Tork Control Timer.
This photoperiod has been reported to engender an increase in
agonistic and reproductive behavior in contrast to a much shorter
period, 8L:16D (Hoar, 1962). The additional fish for possible replace ment were contained in a separate tank under the same standard living
15 16 conditions as experimental fish. Twice daily, fish were fed a dry commercial fish food, Tetra-Min.
Procedure
Observational sessions were divided into three phases for Group
I but into two phases for both Groups II and III. During each phase, observations of male/female fish pair or a single dominant fish defending a territory were taken. Phase 1 consisted of establishing a baseline of territorial behavior for each of the three groups.
Phase 2 tested the effect of hormone treatment with either thyroxine
(Groups I and III) or thiourea (Group II) on social behavior of territorial fish. Phase 3 consisted of removing the remaining thyroxine from Group I and reversing the treatment to thiourea. The data collection procedure was similar to that recently developed by
Costelloe (1970) for the social behavior of cichlid fish. Experimental tanks were checked for the number of territories. Each territorial fish or fish pair was observed for 3' 45" or one session, divided Into
15-fifteen second intervals during which each behavioral category that occurred in the interval was recorded only at its first instance, making a maximum total of 15 response categories/session. More com plete details of this procedure can be found elsewhere (Costelloe,
1970; Hoffeld, 1972). Observations were taken twice daily, at 12:00 noon and 6:00 P.M. Five experimental observers participated equally in each phase.
Phase _1. During phase 1, the 3 populated aquaria for Groups I,
II, and III were observed. Social behavior exhibited by each 17 territorial dyad or dominant fish was recorded in order to establish a baseline level for each group. Informal records were taken of size of territorial fish, activity and locomotor levels, pigmentation, aquarium location, and intersubject distance were recorded. During phase 1, two observers recorded at each session in order to provide a measure of interobserver reliability during the baseline phase of the experiment. The social category system for cichlids has been reported to be generally reliable (Costelloe, 1970), correlations ranging from
.76 to .99. Phase 1 lasted one week (5 days - 10 sessions).
Phase 2 . In phase 2, subjects received hormonal treatment.
In Groups I and III, subjects received synthetic thyroxine sodium
(1: 2,000,000 in concentration) added to the water in each of the 4 tanks. All four tanks in Group II received the antithyroid drug thiourea (1: 1,000 in concentration). Additional hormone doBes for replacement were added 3 times weekly; however Group II did not receive additional drug treatment after week 3. A single blind technique was used, concealing the treatment group from observers. Each of the 5 observers observed drug treated groups equally. Phase 2 lasted three weeks (15 days - 30 sessions).
Phase 3. Immediately following the last session of Phase 2, . a Barnstead filter was connected to the pump system in Group I in order to remove residual hormone. This filter remained installed for 3 days. During treatment reversal or Phase 2, Group I received thiourea treatment for 2 weeks but in a lower concentration (1: 2,000) than administered to Group II in Phase 2, Observational procedures 18 were the same as Phase 2, Phase 3 lasted 3 weeks (15 days - 30 sessions).
Behavior Categories. The behavior categories and codings given below are listed on the basis of frequency of appearance by either member of a territorial pair or a dominant territorial fish in the experimental tank (Costelloe, 1970). Other behavior categories occurred but in insufficient number to be considered for analysis.
Territorial Behaviors. Interaction between a member of the
territorial pair or a dominant territorial fish with another
fish.
Territorial Frontal (Tf) - When adversaries approach frontally gill covers become erect broadening the head.
Territorial Chasing (Tc) - Resident fish lays median fins against body and tries to overtake the intruder with quick darting movements.
Territorial Bite-Butt (Tb) - The fish swims rapidly toward adversary and contacts with another fish other than the mate.
Territorial Braking (Too) - Both approach and retreat are seen alternately as distance between fish narrows.
Territorial Mouth-fighting (Tm) - Upon reaching opponent, the mouth is open and both try to grip the other's jaw firmly. They push and pull, beating heavily with tails and pectorals.
Miscellaneous Behaviors. Activity by any territorial fish.
Pit Digging (P) - From the horizontal position the fish turns vertically with head downward in the pit. When it reaches the substrate it opens its mouth, penetrates gravel and closes mouth. Fish swims backward and resumes position. Advances and ejects gravel.
Nipping (N) - The fish bites at the substrate gravel out side of its pit, occasionally taken into the mouth but not carried. 19
Statistical Analysis and Informal Data
The experimental design is shown in the diagram below:
Phase 1 Phase 2 Phase 3
Group I 10 sessions/ three 10 session three 10 session territory Intervals (30) intervals (30) (thyroxine) (thiourea)
Group II 10 sessions/ three 10 session territory intervals (30) (thiourea)
Group III 10 sessions/ three 10 session territory intervals (30) (thyroxine)
The Wilcoxon Matched-Pairs Signed-Ranks Test (1945) was used to assess differences between the baseline level (Phase 1) and subsequent drug treated weeks for behavior categories occurring within each territory in each of the 3 groups. This nonparametric technique is particularly applicable in cases where subjects can be used as their own control.
The test utilizes information about the relative magnitude and direction of differences within pairs. In this manner, for territories defended during each session of Phase I, the frequencies of each behavior category were matched and compared with the behavior frequen cies occurring within the same territories during each of the drug treated weeks. This evaluation would provide a judgment of which member of the pair is "greater than."
Additional data was recorded by observers during each session on an informal basis. Changes in activity (hypoactive-norma1- hyperactive), locomotor level (slow-normal-fast), pigmentation 20
(bright-normal-dark), aquarium pit location, relative size of terri torial holding fish, intersubject distance (intergrouping-dispersion), and location of non-territorial fish were surveilled and recorded on a separate charted data sheet. RESULTS
Reliability
The use of the social category system as a quantitative mea sure of territorial behavior was generally reliable for the seven behavior categories that were consistently observed. The inter observer reliability taken during Phase 1 showed that observers did not differ more than 2 counts (Tf, Tb, Tc) for any behavior category per session. The scores of the additional observers deviated from those of the designated observers within the following percentage ranges, Tf(77-100%), Tb(83-100%), Tc(82-100%). Two categories differed only by one count (N, 86-100%; P, 84-100%), while the re maining two categories, Tea and Too, were recorded consistently (100%) by both observers.
Quantitative Behavior Measures
The number of territories defended and the mean frequencies for each behavioral category in the three groups is shown in Tables 1,
2, and 3. During each session of the baseline phase (week 1), 2 territories in each of the aquaria were defended by either a male/ female pair or by a dominant fish, resulting in 60 territorial observa tions. These established territories were the basis of comparison for the effect of subsequent drug treatment.
During the 3 weeks of Phase 2, the number of territories for the thyroxine treated fish in Group I (Table 1) remained the same for
21 TABLE 1
MEAN FREQUENCY OF BEHAVIOR CATEGORIES FOR EACH DEFENDED TERRITORY IN GROUP I
Week N Tf Tm Too Tc Tb N P
Phase I 1 - 60 1.92 .53 .05 4.38 4.67 6.77 .68
phase 2 2 60 .48* .42 .130 3.57* 4.50 4.73 2.83 (Thyroxine) 3 60 .82 .77 , 02 4.35 4.13 7.20 .85
4 56 1.38 1.36*** .23^ 4.00 4.84 9.27* 1.05
Phase 3 5 25 4.15 1.56 .520 2.52*** 5.24*** 6.04*** 1.60 (Thiourea) TS
6 1 1.83** 1.50* o o .00*** 1.67*** .00*** .00***
7 0 .00*** .00* .000 .00*** .00*** .00*** .00***
* Significant difference at .025 ** Significant difference at .01 *** Significant difference at .005 0 Not amenable to statistical analysis
N> to TABLE 2
MEAN FREQUENCY OF BEHAVIOR CATEGORIES FOR EACH DEFENDED TERRITORY IN GROUP II
Week N Tf Tm Too Tc Tb N P
Phase 1 1 60 2.05 .47 .17 7.42 3.95 3.68 2.43
Phase 2 2 27 .70** .30** .11 4.70*** 3.04** 4.70*** 3.30 (Thiourea) 3 0 .00*** .00*** .00 ,00*** ,00*** .00*** .00***
4 0 .00*** .00*** .00 .00*** .00*** .00*** .00***
* Significant difference at .025
** Significant difference at .01
*** Significant difference at .005
^ Not amenable to statistical analysis TABLE 3
MEAN FREQUENCY OF BEHAVIOR CATEGORIES FOR EACH DEFENDED TERRITORY IN GROUP III
Week N Tf Bn Too Tc Tb N P o o
Phase 1 1 60 .12 .07 • 5.38 .82 6.23 3.55
Phase 2 2 60 .07 .02 .00^ 4.92 .63 6.77 2.67 (Thyroxine) 3 56 .27 .09 .oo0 6.37 1.13 7.14 2.57 o. o o 4 58 .22 .00 5.98 1.02 7.62* 2.13
* Significant difference at .025
0 Not amenable to statistical analysis, 25 weeks 2 and 3 but dropped to 56 during the 4th week. In Group III
(Table 3), the fish treated with thyroxine, also consistently defended their established territories during week 2 but deviated to 56 in week
3 and to 58 in the fourth week. The thiourea treated fish in Group
II (Table 2) however showed a sharp decline in the number of terri tories defended to 27 during week 2. During the third and fourth week, no territories were defended. In Phase 2, the previously thyroxine treated fish of Group I received a lower thiourea doBage during and also showed a sharp decrease in the number of territories from 56 to
25 during the fifth week. During week 6, only 1 territory was observed, while no territories were defended in the seventh week.
The differences between the baseline and subsequent weeks for each behavior category within each territory was evaluated by the Wilcoxon Matched-Pairs Signed-Ranks Test. The probability levels associated with these comparisons for a one-tailed test are given in Table 1 for Group I and Table 2 for Group II. Only one of the com parisons in Group III (Jack Dempseys) attained statistical signifi cance at the .025 level shown in Table 3.
Group I. During phase 2, fish treated with thyroxine showed a significant decrease (p .025) in frequency of 2 categories, Tf and
Tc, after the initial drug administration during week 2 (see Table 1 for mean frequency). However, throughout weeks 3 and 4 both of these behaviors increased in frequency. No significant statistical differ ences between the baseline levels and behaviors observed in week 3 were attained for any categories. In the final week of thyroxine treatment 26
(week 4), a level of statistical significance was attained in two behavior categories, mouth fighting (Tm) (p -^.005) and nipping
(p < .025). In Phase 3, after one week of thiourea treatment, 3 behavior categories decreased significantly from their baseline level-- chasing (p < .005), biting-butting (p <, .005), and nipping (p < .005),
Attention should be given however to the high frequencies of the behavior categories occurring during this period (week 5) in the remain ing defended territories (see Table 1). By the end of week 6, all behavior categories decreased statistically (p < .025) from previous established territorial behavior.
Group II. The firemouths treated with the higher dosage of thiourea in Phase 2 decreased significantly at least at the .01 level from their baseline for all behavior categories except pit digging (p ^ .025), By the end of week 3, this category also attained significance (p ^ .005).
Group III. The only category which changed significantly for the thyroxine-treated Jack Dempseys was nipping. This increase
(p < .025) occurred during the last week of hormone treatment.
Qualitative Observational Data
In each aquarium, the.establishment and maintenance of a terri tory by both Cichlasoma meeki and Cichlasoma biocellatum followed a general pattern. The size of the 20 gallon aquarium limited the number of fish that became dominant and defended territories. Although many of the members were able to assume'territories, the activity of the 27 dominant territorial fish made the establishment of more than two terri tories impossible. In each case, the largest fish in the aquarium secured the largest territory and controlled a large portion of the bottom area. The fish defending the other territory were situated at the other end of the aquarium in smaller areas. Each territorial fish dug one or more pits in its territory soon after the establishment of the territory. The remaining school or nonterritorial fish were located in the surface area or small interspace between territories. These fish often tried to come down to the bottom or encroach on defended territory but were driven away (intraterritorial fighting). Intra territorial fighting occurred when fish entered the territory claimed by another. Boundary fighting also occurred between the owners of the two contiguous territories. In this case, the more dominant fish succeeded in pushing the opponent back, temporarily extending his terri tory while contracting the territory of the less dominant fish.
Threats and fighting were used to attain a dominant position in the social hierarchy and to establish control over a territory. Threat
(Tf) and chasing others away from a territory (Tc) were used to avoid indulging in serious combat. More serious threatening occurred in the face to face confrontation (Too) in which rival males, with mouths open and gill covers erect, both approached and retreated from each other.
This behavior was more frequent in the firemouths than in the Jack
Dempseys. Recourse to more belligerent combat occurred when threat or chasing failed to drive off a rival fish. The more serious fighting consisted of biting (Tb) and mouth fighting (Tm), in which rivals 28 locked jaws and wrestled by pulling each other to and fro. Terri torial biting occurred more frequently in the territorial fish posses sing the smaller territory. These fish resorted to physical contact in the restricted quarters in order to maintain a territory. Actual damage was avoided since defeated fish eventually recognized their plight and gave signs of submission (posture it adopted and coloration) or evacuated the territory.
Group During the thyroxine treatment phase, fish were rated by observers to be generally more active and faster in their movements than before. The dominant territorial fish increased its territorial boundaries resulting in the reduction of the adjoining territory, and, in one aquarium, the abandonment of the territory by the subdominant fish (see Table 1, reduction in number of territories during week 4).
The nonterritorial fish were clustered mainly in the top and center of the periphery of the tank, swimming against the aquarium glass (flutter behavior). These fish appeared skittish and were easily frightened
(extremely sensitive to tap on the glass wall). The principal color of the fish (firemouths) remained light silvery gray but the throat and reproductive marking were judged to be brighter than the pre-hormonal level. Vertical bands located between the eye and caudal fin were more apparent in the nonterritorial fish, exhibiting submission, whereas dominant territorial fish displayed longitudinal black blocks.
The subsequent thiourea treatment to the firemouths during
Phase 2 resulted in dramatic changes in behavior within the 5th week.
There was a decrease in the number of fish defending territories and 29
fish tended to group together (school) at the bottom center of the tank.
There were sporadic bouts of agonistic behavior between fish in the group but no discernible dominant fish after the first session of week
6. During the seventh week, the fiBh were more dispersed but were situated on the bottom. The fish remained hypoactive but often moved
sporadically with fast jerky locomotor movements. The most prevalent behavior was the beating of the pectoral fins. All fish became pre dominantly brownish gray with no visible pigmented vertical bands.
Reproductive markings were judged darker, often being completely masked. There was little feeding during the sixth and seventh week.
Group II. The firemouths receiving the higher dosage of thiourea showed immediate effects to the drug. Only 27 of the previous
60 territories were defended during week 2, none after the third day
of treatment. Fish grouped together and schooled at the bottom of each
tank. There was no apparent dominant fish at this time, but periodical
ly members exhibited diminished agonistic behaviors toward each other while in the group. There was a diminution in locomotor movement and activity, consisting mainly of uncoordinated jerky movements over
short distances and persistent beating of the pectorals. There was a rapid change in pigmentation in contrast to the untreated condition.
All fish were principally brownish gray, with a deep reddish brown
throat and darkened reproductive markings, at times, completely masked.
During this period, there was limited feeding and members appeared
sick. Eight of the fish died before the end of week four.
Group III. In Phase 2, the Jack Dempseys treated with 30 thyroxine became more active in general during week four. One tank housed a dominant territorial fish that became extremely hyperactive, using fast coordinated locomotor movements to drive the other fish into a top corner of the aquarium. The subdominant fish in this aquarium abandoned its territory and entered the nonterritorial group, which often showed postures of submission to this extremely dominant terri torial fish. The nonterritorial fish in the two other tanks alternated their position from the center to the top of the aquarium away from the ensuing territorial fish. In two tanks, fish pairs separated leaving the male defending the territory and unreceptive to entrance into his territory by his former partner. In each aquarium, by the end of the thyroxine treatment period, all remaining territorial fish had in creased their area of control or dominance in the aquarium. No flutter behavior was observed by the Jack Dempseys in any of the aquaria.
In a large ma j orlty of the Jack Dempseys, the vertica1 band formed by the pigmentation in the integument, which represent reactions to aggression or disturbance, became more pronounced while the ventral part of the body became a darker black. The reproductive colors or spots were judged brighter.
Summary
All fish treated with thyroxine for 3 weeks exhibited Increased locomotor activity, changes in integument pigmentation which corres ponded to adopted functional behaviors, and spent considerably more time in the top of the aquaria. Only Cichlasoma meeki showed flutter behavior. During this period, the dominant territorial fish tended to 31 increase the area of the territory and their control or dominance over the nonterritorial members. Quantitative differences in territorial behaviors between the baseline and thyroxine treated periods were not decisive. In Cichlasoma meeki. the two behavior categories (Tc, chasing; Tf, frontal display) decreased and differed significantly
(p •< .025) after the initial administration of thyroxine during week 2.
During the final week of thyroxine treatment, territorial mouth fight ing (Bn) and nipping (N) increased and approached statistical signifi cance (Tm, p < ,005; N, p ^ .025). Only one behavior category, nipping
(N, p <; .025), reflected quantitative changes during week 4 from previous territorial behaviors in Cichlasoma biocellatum.
Fish treated with thiourea exhibited dramatic changes in be havior. Group II, the higher dosage group exhibited the effects imme diately and more dramatically; however the effect of the drug became lethal to 8 of the fish during the last week of observation. Thiourea treated fish abandoned previously defended territories, grouped together and schooled at the bottom of each aquarium. There was a diminution of overt activity, consisting mainly of uncoordinated jerky movements over short distances and persistant beating of the pectoral fins. Integument pigmentation became darker in all fish.
Quantitative statistical differences (at least p <.01) were found in the high dosage group for all categories except pit digging (P) after only one week of thiourea treatment. This behavior approached significance (p < .005) after week 3. In Group I, only 3 categories
(Tc, chasing; Tb, biting-butting; N, nipping) achieved 32 a level of significance (p .005) after one week of thiourea treat ment, but by the end of week 6, all territorial categories differed statistically from their baseline (p .025). DISCUSSION
Hormones and Territoriality
It is well established that intraspecies aggression by threat or fighting is used to attain the dominant position in a hierarchy and to establish control over a territory in cichlids (Baerends & Baerends
Van Roon, 1950; Seitz, 1940; Hoffeld, 1972). Moreover, the importance of an interaction between internal and external factors necessary for activation of a system of territorial behavior patterns has been stressed (Seitz, 1940; Heiligenberg, 1965). In this study, after the initial administration of thyroxine during Phase 2 to Firemouth cichlids, or C. meeki, there was a sudden unexpected statistically significant decrease in agonistic behaviors with two categories--Tc and
Tf. This decrement was accompanied by dominant fish remaining in their pits and digging at the substrate. After this brief diminution how ever, agonistic behavior Increased in all categories with further thyroxine treatment as expected. Prolonged thyroxine treatment sig nificantly increased the frequency of two behavior categories, mouth fighting and nipping during the defense of a territory by Cichlasoma meeki. Under comparable conditions, Cichlasoma biocellatum showed an increase in nipping only. Mouth fighting is considered a more fierce and potent "test of strength" (Fryer & lies, 1972; Ruwet & Voss,
1966) in cichlids and occurs less frequently than other territorially induced agonistic behaviors (Costelloe, 1970). Jack Dempseys form 34 more stable societies and are less excitable than Cichlasoma meeki
(Baerends & Baerends Van Roon, 1950). This attribute may account for the lack of significant increases in mouth fighting among C. biocellatum after thyroxine treatment. Increased nipping or biting off the substrate outside of the pit occurred in both species and accompanied an increase in control over area outside the pit in the aquaria by the dominant fish. Not only are these results suggestive of increased dominance or territorial behavior (Lorenz, 1937) but they can be interpreted as increased displaced aggression. According to a number of modern ethologists (Baerends, 1966; Heiligenberg, 1965; Bastock, et al., 1953) biting of gravel from the substrate is derived from attack behavior through redirection and it is considered a displacement activ ity, Heiligenberg (1965) has shown that as aggressive tendencies increase, but the performance of overt attacks to an adequate object inhibited, Pelmatochromis tended to start biting off the substrate.
Moreover, when opponents became present, the tendency to attack de creased after biting of the substrate. Biting of the substrate or nipping can be considered an alternative for attack behavior in reducing aggression if the environment does not provide external situations to evoke overt aggressive behavior.
The experimental approach to investigate behavior in respect to group structure and organization faces the problem of artificiality.
Most naturalistic observations do not permit a finer analysis of causal relations but the aquarium setting is an artificial setting, restricting the amount and extent of territorial behavior. Casual factors are 35 difficult to isolate in defense of a territory because any one event is accompanied by many others. Moreover, when subjected to experiment, captive fish also meet many situations which they would never encounter in nature and which, if they did, they would try to avoid. However, aquarium observations can provide valuable information related to natural conditions. In the present experiment, there appeared to be an increase in dominance or control over a larger area of the aquarium by the dominant territorial fish after prolonged thyroxine treatment.
Nonterritorial fish were clustered in the top and center of tanks, restricting their ability to execute retaliatory behaviors and thus making it untenable to rely solely on an increase in fighting and threat displays (behavior category system) as an intensification of territorial behavior. The study did however provide reliable evidence for increased mouth fighting, a rather fierce agonistic pattern for cichlids between dominant fish and nonterritorial holding
fish. The extent that other territorial behaviors (chasing, biting,
frontal display, and braking) could have been more feasibly evaluated was restricted by the crowding of the nonterritorial fish. The in crease in mouth fighting and dominance suggests that thyroxine has a role in agonistic behavior during territorial behavior. More direct
control of influence of aggressive behavior in cichlids seems to be
through the gonadotropins of the pituitary and reproductive hormones
(Blum & Fiedler, 1965; Baggerman, 1966. Metuzals, et: ajl., 1968) or
through synergistic effects between reproductive and thyroid hormones
(Matty, 1960). 36
That thiourea treatment has a detrimental effect on clchlid
fish defending territories was clearly demonstrated; however, because
of its toxic effect, a strict evaluation or interpretation cannot be made. Fish progressively abandoned territories and schooled stationary at the bottom of the tank with no discemable dominant fish. Moreover,
sporadic bouts of agonistic behavior occurred periodically between
fish during the early stages of thiourea treatment. Baerends and
Baerends Van Roon (1950) claim that adult cichlids enter schools only when conditions are unfavorable for reproduction, the worse the condi
tions the denser the school becomes. A plausible assumption for the underlying mechanisms controlling schooling behavior is that thiourea
inhibits gonadal hormones which prevent schooling (Barrington & Matty,
1952; Smith, et al., 1953). It is noteworthy that after thiourea treatment, periodic bouts of agonistic behavior occurred, reproductive colors faded, and activity dissipated as the amount of territorial be havior decreased. The course and effect of these stimuli, critical for territorial behavior, appear to adhere to the principle of heterogeneous summation (Seitz, 1940): inasmuch as some stimuli which normally evoke a response are absent, the response may be reduced quantitatively but not qualitatively. The intensity of the response depends on how many of the sign stimuli are present but not on which. This principle may account for the high level of some agonistic behavior shown in Group I by previously thyroxine treated firemouths during the early stages of thiourea treatment before they too abandoned their territory, and pro gressively decreased their number of agonistic displays. Thiourea treatment decreased the number of effective sign stimuli. 37
Activity and Locomotor Levels
This study confirms earlier findings (Hoar, 1955; Sage, 1968;
Fontaine, 1963) that thyroxine treated fish have greater general activity, exhibit flutter behavior, tend to reside in the tank periph ery, and have greater locomotor activity. In contrast, the anti thyroid drug, thiourea, rendered fish motionless for variable periods of time with occasional movement in short erratic bursts, and resulted in fish schooling near the bottom of aquaria. The behavioral effects precipitated by the toxic level of thiourea could be an adaptation to severe stress; however, these results are comparable to previous findings. The changes in territorial behavior may be a result of direct hormonal influence on general metabolism, direct action on neural mechanisms (Hoar, 1952; Liley, 1969) in the CNS underlying the behavior responses, or brought into use by normal evironmental stimuli acting via the endocrine system (Sage, 1968).
Pigmentation and Coloration Displays
The results of this experiment indicate similar effects of thyroid hormones on integument pigmentation. The "silvering effect" or lighting of color (Robertson 1949; Sage, 1967; Matty & Sheltawy,
1967) caused by increased guanine metabolism, was most apparent in the firemouths. On the other hand, an increase in black pigmentation
(melanophores) (Muller, 1953; ViIter, 1946) after thyroxine treatment was observed in the Jack Dempseys, reaffirming an apparent dual role of thyroid hormones in pigmentation (Pickford & Atz, 1957).
In the context of territorial behavior, the concomitant pigment 38 changes associated with defense of a territory became more pronounced following prolonged thyroxine treatment. In Cichlasoma meeki. vertical bands, indicating an emotional state of BubmiBsion and dis turbance (Neil, 1964), were clearly more pronounced in nonterritorial fish. Consistent observations of these crossbands (melanophores) in
Cichlasoma biocellatum were less frequent; but this contrast may corre spond to the fact that meeki behave more "nervously" than Cichlasoma biocellatum which show their cross bands for only a few seconds
(Baerends & Baerends Van Roon, 1950). The accentuation of these behavior patterns, expressing emotional states, could possibly be guided by the synergistic interaction of thyroxine and sympathetic nervous system effects (Waldstein, 1966; Harrison, 1964). Increased sympathetic secretions have been reported to produce "excitement pallor"
(Parker, 1948; Von Firsch, 1911), activation of melanophore granules
(Rasquin, 1958; Odiorne, 1957), and the ease to which emotional dis plays can be released (Marrone, et al., 1966). This evidence supports the view that thyroid hormones may affect integument pigmentation directly or indirectly through the sympathetic nervous system.
The effect of thiourea treatment In Cichlasoma meeki corrobo rates previous reports that thiourea stimulated pigmentation and darkening of colors (Belsare, 1946; Sembrat, 1966). Special emphasis should be given to the fact that the darkening effect of thiourea treatment faded reproductive colors. These changes in sexual colora tion may have been produced by a retarding effect on gonadal hormones
(Barrington & Matty, 1952; Smith, et _al., 1953). Reproductive 39 markings or colors were judged brighter by observers after thyroxine treatment and suggests a complementary role of thyroid hormones with sex hormones (Pickford & Atz, 1957; Matty, 1960).
Drug Dosage
The importance of hormonal dosage levels in Investigating aggressive behavior in cichlids has been reported (Blum & Fiedler,
1965). Moreover, interspecies variation in susceptibility to drugs makes it impossible with certainty that the drug will behave in the same way as it did with other species. The thyroxine dosage level
(1: 2,000,000) was adequate in producing observable behavioral effects in both species of cichlid comparable to effects reported in other species of fish. For the two thiourea treated groups, a relationship did exist between the dosage level and the magnitude of its effects; however one must take into account that Group I had received previous thyroxine treatment. The higher dosage level (1; 1000) resulted in more immediate and dramatic effects than the lower dosage (1: 2,000) level. Toxic signs appeared during the last week of treatment and 8 fish died (below LD-50). Surveillance of the fish of both groups after the termination of the experiment revealed that the effect of thiourea was Irreparable for Cichlasoma meeki; even if replaced in clean water. Other species of fish such as salmon (Hoar, 1952), goldfish (Hoar, 1955), guppies (Sage, 1968) and Phoxlnus phoxinus
(Barrington & Matty, 1955) have been reported to have sustained thiourea treatment under similar conditions without lethal effects. 40
It appears that Cichlasoma meeki are more susceptible to prolonged thiourea treatment and allow a toxic level to accumulate.
Rhythmicity
Recent interest has been directed in how physiological rhythms manifest themselves in overt behavioral rhythms. Investigators have focused on the cyclic pattern of daily activity in bass (Davis, 1963) locomotor levels in salmon (Hoar, 1942, 1958) and swimming activity in the minnow (Muller, 1968). Moreover, differences in photoperiods have affected the daily levels of agonistic and reproductive behavior in salmon (Hoar, 1962). This investigation was not designed specifi cally to detect periodic changes in social behavior in cichlids. The social category system of data collection is not amenable to a thorough evaluation of this problem, however differences were present between the morning and afternoon sessions from composite comparisons across all behavior categories and experimental conditions. A simple sign test distinguished that daily sessions were different (simply + or -) for both Group I (p < ,001) and II (p ^.02). Comparisons of the weekly frequencies of all behavior categories between morning and afternoon sessions for each group are provided in Tables A, B and C of the
Appendix. REFERENCES
Aronson, L. R. Hormones and reproductive behavior: some phylogenetic considerations. In Comparative Endocrinology. ed. by A. Gorbman. New York: John Wiley fie Sons, 1959, 98-120.
Aronson, L. R. Influence of the stimuli provided by the male cichlid fish Tilapia macrocephala on the spawning frequency of the female. Physiol. Zool. 1945, JJ3, 403-415.
Aronson, L. R. Reproductive and parental behavior. In The Physiology of Fish, ed. by M. E. Brown. New York: The Academic Press, 1957, Vol. 2; 271-304.
Baerends, G. P. Les societes et les families de poissons. Colloq. Centre Natl. Rech. Sci. (Paris), 1952, 34, 207-219.
Baerends, G. P. fit Baerends Van Roon, J. M. An introduction to the study of the ethology of cichlid fishes. Behavior. 1950, Supplement 1, 1-242.
Baerends, G. P., Brouwer, R., & Waterbolk, H. Ethological studies on Lebistes reticulatus (Peters). I. An analysis of the male courtship pattern. Behavior, 1955, 8, 249-334.
Baggerraan, B, On the endocrine control of reproductive behavior in the male three-spinned sticleback (Gasterosteus aculeatus) ■ Svmp. Soc. Exptl. Biol.. 1966. 2 0 . 427-456.
Baker, K. F. Heteroptic thyroid tissues in fishes. I. The origin and the development of heterotopic thyroid tissue in platyfiBh. J. Morphol.. 1958, 103, 91-134.
Baker, K. F., Berg, 0., Gorbman, A., Nigrelli, R. F. fit Gordon, M. Functional thyroid tumors in the kidney of platyfish, Cancer Res. _15, 118-123.
Baker-Cohen, K. F. Renal and other heterotopic thyroid tissue in fishes. In Comparative Endocrinology.ed. A, Gorbman. New York: John Wiley fit Sons. 1959, 283-301.
Baker-Cohen, K. F. The role of the thyroid in the development of platyfish. Zoologica.. 1961, 46, 181-196.
Barrington, E. J. W., Barron, N. fit Piggins, D. J. The influence of thyroid powder and thyroxine upon the growth of rainbow trout (Salmo gairdnerii). Gen. Comp. Endocrinol.. 1961. _1, 170-178. 41 42
Barrington, E. J. & Matty, A. J. The identification of thyrotrophis secreting cells in the pituitary gland of the minnow (Phoxinus phoxinus) . Quart. J. Micr. Set., 96, 1955, 193.
Bastock, M., Morris, D. and Moynihan, M. Some comments on conflict and thwarting in animals. Behavior, 1953, 6, 66-84.
Bauer, J. Lautausserungen bei, Tilepia nilotica. Aguer u. Terrar.. 2. lb, 1963, 171-172.
Beach, F. A. A review of physiological and psychological studies of sexual behavior in mammals. Physiol. Rev.. 1947, ,27, 240-307.
Beach, F. A. Hormones and Behavior. New York: Hoeber, Inc., 1948.
Belsare, D. K., Zargar, V. N., & Verma, S. M. The effect of thiourea and thyroxine on the developing larvae of Channa punctatus. Bloch. Zool. Polon., 1966, JL6, 149-154.
Bjorklund, R. 0. The effect of thyroid hormones on the growth of goldfish, Carassius auratus. Trans. Illinois State Acad. Sci. 1965, 58, 64-67.
Black-Cleworth, P. The Role of Electrical Discharges in Nonreproductlve Social Behavior of Gymnotus Canepo (Gymnotidao, Pisus). Animal Behavior Monographs. 3;, 1970, 1-77.
Blum, V. & Fiedler, K. Hormonal control of reproductive behavior in some cichlid fish. Ge n . Comp. Endocrinol.. 1965, 5,, 186-196.
Breder, C. M. The reproductive habits of the North American sunfiBhes (Fam. Centrachidae), Zoologies. 1936, 21, 1-50.
Breder, C. M. & Coates, C. W. Sex recognition in the guppy. Lebistes reticulatus (Peters), Zoologies. 1935, 19, 187-207.
Brewster, W. R . , Isaac, J. P., Osgood, P. F., and King, T. L. The Hemodynamic and metabolic interrelationships in the activity of epinephrine, nonepinephrine, and the thyroid hormones. Circulation. 31. 1956, 1.
Chambers, H. A. Toxic effects of thiourea on the liver of the adult male killfish, Fundalus heteroclltus (Linn.). Bull. Bingham Qceanogr. Coll.. 14. 1953, 69.
Chavin, W. Thyroid distribution and function in the goldfish. J. Exptl. Zool.. 1956, 133, 259-279.
Clark, E. & Aronson, L. R. Sexual behavior in the guppy. Lebistes reticulatus (Peters), Zoologies, 1951, 36, 49-66.
Collias, N. E. Aggressive behavior among vertebrate animals. Physiol. Zoo., 1944, J7, 83-123. 43
Costelloe, C. A. The development of a quantitative scale for the measurement of social behavior of cichlid fish. Unpublished Master's thesis, Louisiana State University, 1970.
Craig, W. Appetities and aversions as constituents of instincts. Biol. Bull.. 1918, 34, 91-107.
Curasa, J. Adrenaline-Thyroxin interaction in Guinea Pigs. American Journal of Physiology. 161. 1950, 550-553.
Dales, S. & Hoar, W. S. Effects of thyroxine and thiourea on the early development of chum salmon (Oncerhynchusketa). Can. J. Zool., 1954, 32, 244-254.
Davis, R. E. Dally "predawn" peak of locomotion in bluegill and large- mouth bass. Animal Behavior, 12, 1963, 272-283.
Dharmamba, M., Handin, R. I., Nandi, J., & Bern, H. A. The effect of prolactin on freshwater survival and on plasma osmotic pressure of hypophysectomized Tilapia mossambica, Gen. Comp. Endocrinol.. 1967, 9, 295-302.
Fabricus, E. Heterogeneous stimulus summation on the release of spawning in fish. Rep. Inst. Freshwater Res. Drottningholm. 1950, 31, 57-99.
Fontaine, M. The hormonal control of water and salt— electrolyte metabolism In fish. Mem. Soc. Endocrinology. London: Cambridge University Press, 1956, 569-82.
Fontaine, M. and Hatey, S. Variations de la tenelu tu foie en glycogene chez le jeune saumon (Salmo Salan L.) au cours de la "smoltification." C. R. Soc. Biol. (Paris), 144, 1950, 953.
Forselius, S. Studies of anabantid fishes. Zoo. Bedr. Uppsala. 1957, 32, 97-597.
Frisen, L. & Frisen, M. Analysis of the topographis distribution of thyroid activity in a teleost fish, Carassius carassius. L. Acta Endocrinol.. 1967, 56, 533-546.
Fromm, P. 0. & Reineke, E. P. Some aspects of thyroid physiology in rainbow trout, J. Cellular Comp. Physiol., 1957, 48, 393-404.
Fryer, G., lies, T. 0. The Cichlid Fishes of the Great Lakes of Africa. Oliver & Boyd, 1972, Edinburgh.
Gellhom, E, and Feldman, J. The influence of the thyroid on the Vago- insulin and sympathetico-adrenal systems. Endocrinology. 29. 1941, 467-74. 44
Gorbman, A. Problems in the comparative morphology and physiology of the vertebrate thyroid gland. In Comparative Endocrinology, ed. A. Gorbman, New York: John Wiley & Sons, 1959, 266-282.
Gorbman, A. Thyroid Function and its Control in Fishes. In "Fish Physiology" (W. S. Hoar & D. S. Randall, eds.) pp. 241-274, Vol. II, 1969. Academic Press, New York.
Gorbman, A. & Berg, 0. Thyroid function in the fishes Fundulus heterocljtus. F. majaljs. and F. diaphanus. Endocrinology. 1955, 56, 86-92.
Gottfried, H, & Van Mullem, P. J. On the histology of the interstitium and the occurrence of steriods in the stickleback (Gasterosteus aculeatus L.) testis. Acta Endocrinol.. 1967, 56, 1-15.
Gottier, R. F. The effect of social disorganization in Cichlasoma biocellatum. Dissertation Abstr., 1969, 29, 3940.
Greenberg, B., Zijlstru, J. J. & Baerends, G, P. A quantitative description of the behavior changes during the reproduction cycle of the cichlid fish Aeguldens portalegrensis Hensel., Koninkl Ned. Akad Welenscha Proc., 1965, c68, 135-149.
Gross, W. L., Fromm, P. 0. & Roelefs, E. W. Relationship between thyroid growth in green sunfish, Lepcxnis cyanelbus. Tran A m . Fisheries Soc., 1963, 92, 401-407.
Hara, T. J. & Gorbman, A. Electrophysiological studies of the olfactory system of the goldfish, Carassius auratus. I. Modification of the electrical activity of the olfactory bulb by other nervous structures. Comp. Blochem. Physiol.. 1967, 21, 185-200.
Hara, T. J., Gorbman, A. & Ueda, K. Influence of thyroid state upon optically evoked potentials in the midbrain of the goldfish. Proc. Soc. Exptl. Biol. Med., 1966, 122. 471-475.
Hara, T. J., Ueda, K. & Gorbman, A. Influence of thyroxine and sex hormones upon optically evoked potentials in the optic tectum of goldfish. Gen. Comp. Endocrinol., 1965, j>, 317-319.
Harrison, T. Adrenal Medullany and Thyroid Relationships, Physiological Review, 44, No. 2, 177-181, 1964.
Heiligenberg, W. A quantitative analysis of digging movements and their relationship to aggressive behavior in cichlids. Animal Behaviour, 1965, JL3, 163-170.
Hinde, R. A. Interaction of internal and external factors in integra tion of canary reproduction. In Sex Behavior, ed. F. A, Beech. New York: Wiley, 1965, 381-415. Hoar, W. S. Comparative physiology: Hormones and reproduction in fishes. An n . Rev. Physiol.. 1965, 27, 51-70. 45
Hoar, W. S. Diurnal variations in feeding of young salmon and trout. J. Fisheries Res. Board Can,, 6, 1942, 90-101.
Hoar, W. S. Effects of synthetic thyroxine and gonadal sterlods on the metabolism of goldfish. Can. J. Zool. 1958, 36, 113-121.
Hoar, W. S. Reproductive behavior of fish. Gen. Comp. Endocrinol. Suppl.,1, 1962 , 206-216.
Hoar, W. S. The endocrine system as a chemical link between the organism and its environment. Trans. Roy. Soc. Can. Sect..II, 1965, 3, 175-200.
Hoar, W. S. The evolution of migratory behavior among juvenile salmon of the genus Onarhynchus J. Fisheries Res. Board Can. 15, 1958, 391-428.
Hoar, W. S. Keenleyside, M. H. A. & Goodall, R. G. Effects of thyroxine and gonadal steriods on the activity of salmon and goldfish. Can. J. Zool..1955, 33, 428-439..
Hoar, W. S., MacKinnen, D. & Redlich, A. Effects of some hormones on the behavior of salmon fry. Can. J. Zool.. 1952, _30, 273-286.
Hochacka, P. W. Thyroidal effects on pathways for carbohydrate metabolism in a teleost, Ge n . Comp. Endocrinol., 1962, _2, 499-505.
Hoffeld, D. R. Population pressure, pollution, and the behavior of cichlid fishes. In R. F. Thompson & J. Voss (eds.), Topics in learning and performance. London: Academic Press, 1972.
Holzapfel, M. Triebbedengte Ruhezustanda aIs Ziel von Appetenzhand- lungen, Naturwissenschaften. 1940, 28, 273-280.
Honma, Y. & Murakawa, S. Effects of thyroxine and thiourea on the development of chum salmon larvae. Japan J. Ichthvol.. 1955. 4, 83-93.
Horstmann, P. The effect on Adrenaline on the Oxygen consumption in Diabetes Mellitus and in Hyperthyroidism. Acta Endocrinologyr 16, 1954, 233-47.
Kraner, E. and Helnecke, P. Sound production by cichlid fishes. Science. New York; 14a. 1965, 555-558.
Kuhme, W. Chemische ausgeloste Brutpflege und Schwam Hemichromis bimaculotus.Z. Tierpsychol.. 20, 1963, 688-704. 46
LaRoche, G, & Leblond, C. P. Effect of thyroid preparations and Iodine on Salmonidae. Endocrinology, 1952, J51, 524-530.
LaRoche, G., Woodall, A. N., Johnson, C . L. & Halner, J. E. Thyroid function in the rainbow trout (Salmo gairdnerii'). II. Effects of thyroidectomy on the development of young fish. Gen. Comp. Endocrinol.. 1966, 6., 249-266.
Lehrman, D. S. Interaction between internal and external environments in the regulation of the reproduction cycle of the ring dove. In Sex and Behavior (F. A. Beach, ed.) New York: Wiley, 1965, 355-380.
Liley, N. R. Ethological isolating mechanisms in four sympatric species of poecillid fishes. Behavior. 1966, 13, Supplement 1-197.
Liley, N. R. Hormones and Reproductive Behavior in Fishes. In Fish Physiology, eds. Hoar & Randall. New York; Academic Press, 1969, Vol. 3, 73-110.
Lorenz, K. Ueber die Bildung des Instinktbegriffs. Naturwissenschaften 1937, 25, 289-300.
Marrone, R. C., Pray, S. L., Bridges, C. C. Norepenephrine and elicilation of aggressive display responses in Belta splenders. Psychonomic Science. 5, 1966, 207-208.
Matty, A. J. Thyroid cycles in Fish. Symposium, Zoological Society of London. 2, 1960, 1-15.
Matty, A. J. Thyroidectomy and its effects upon oxygen consumption of a teleost fish, Pseudoscarus guacamaia. J. Endocrinol.. 1957, 15, 1-8.
Matty, A. J. & Sheltawy, M. J. The relation of thyroxine to skin purines in Salmo irideus. Gen. Comp. Endocrinol.. 1967, 9_, 473 (abstr).
Metuzals, J., Ballintijn de Vries, G., and Baerends, G. P. (1968). The correlation of cytological changes in the adenohypophysis of the cichlid fish Aeguiders partolegrensis (Hersel) with behavior changes during the reproductive cycle. Koninkl Ned. Akad Welenscha Proc. c71» 391-410.
Muller, J. Uber die Wirkung von Thyroxi und Thyeotropen Honnon auf den Stoffwechsel und die farburg der Goldfisches Z. Vergl. Physiol.. 35. 1953, 1-12. 47
Muller, K. Frerlauferde clrcadiane Periodik von Ellritzen am Pokrkrels. Naturwissenschaften,55, 1968, 140.
Neil, E. H. An analysis of color changes and social behavior of Tilapia mossatnbica. Univ. Calif. (Berkeley) Publ. Zool.. 1964, 75, 1-58.
Noble, G. K. Sexual selection among fishes. Biol. Revs. Cambridge Phil. Soc.. 1938, 13, 133.
Noble, G. K. The experimental animal from the Naturalist's point of view. Am. Nat, 73, 1939, 113-126.
Noble, G. K. & Curtis, B. The social behavior of the jewel fish Hemichromis bimaculatus. Bull. A m . Museum Nat. Hist., 1939, 75, 1-46.
Noble, G. K., Kurapf, K. F., & Billings, V. N. The induction of brooding behavior in the jewel fish. Endocrinology, 1938, 23, 353-359.
Odiorne, J. M. Color changes. In "The Physiology of Fishes." (M. C. Brown, ed.), Academic Press, Vol. II, 1957, 387-40.
Oshima, K. & Gorbman, A. Olfactory response in the forebrain of gold fish and their modification by thyroxine treatment. Gen. Comp. Endocrinol., 1966, _7, 398-409.
Oshima, K. & Gorbman, A. Influence of thyroxine and steriod hormones on spontaneous and evoked unitary activity in the olfactory bulb of goldfish. Gen. Comp. Endocrinol.,1966, J7, 482-491.
Oshima, K, 6c Gorbman, A. Modification by sex hormones of the spontaneous and evoked bulbar electrical activity in goldfish. J. Endocrinol. 40, 409-420.
Parker, G. H. "Animal color changes and their neurohumours." Cambridge Universal Press, London and New York: 1948.
Pfeiffer, W. The fright reaction of fish. Biological Review. 37, 1962, 495-511.
Pickford, G. E. 6c Atz, J. W. The Physiology of the Pituitary Gland of Fishes. New York: N. Y. Zool. Soc., 1957.
Piggins, D. J. Thyroid feeding of salmon parr. Nature, 1962, 195, 1017-1018.
Raab, W. Epinephrine tolerance of the heart altered by thyroxine and thiouracil. J. Pharmacology and Experimental Therapy. 82. 1944, 330. 48
Rasquin, P. Studies in the control of pigment cells and light reactions in recent teleost fishes. Bull. A m . Museum Nat. Hist., 115. 1958, 1-68.
Robertson, 0. H. Production of the silvery smolt in rainbow trout by intramuscular injecting of mammalian thyroid extract and thyrotropic hormone. J. Exp. Zool., 1949, 110. 337-355.
Rodman, D. T. Sound production by the African cichlid Tilapia mossambica Ichthyologje. 38. 1966, 279-280.
Rosenblum, H . , Hahn, R. G., and Leuine, S. A. Epinephrine; its effects on the cardiac mechanism in experimental hyperthyroidism and hypothyroidism. Archives of Internal Medicine, 51, 1933, 279.
Ruwet, J. C. & Voss, J. L 1etude des movements d'expression chez lea Tilapic (Poissurs, Cichlids). 35th Ann. Bull. Soc. r. Sci. Liege, 1966, 778-800.
Sage, M. Respiratory and behavioral responses of Poecilia to treat ment with thyroxine and thiourea. Gen. Comp. Endocrinol.. 1968, 10, 304-309.
Sage, M. Response of pituitary cell of Poecilia to changes in growth induced by thyroxine and thiourea. Gen. Comp. Endocrinol.. 1967, 8, 314-319.
Sage, M. The effects of thyroxine and thiourea on the respiration and activity of the teleost Lebistes reticulatus (Peters). Gen. Comp. Endocrinol.. 1965, ,5, 706-707 (abstr.).
Seitz, A. Die Paarbildung bei einigen Clchliden. I. Die paarbildung bei Astatotilapia strigigena Pfeffer. Zeitschrift fur Tierpsychologie. 1940, 40-84,
Sembrat, K. Influence of thyroid gland on the skin of teleosts. Zool. Polo.. 1956, 7, 3-33.
Simpson, M. E., Asling, C. VJ. & Evans, H. M. Some endocrine influence on skeletal growth and differentiation, Yale J. Biol. Med.„ 1950, 23, 1-27.
Solomon, J. & Greep, R. 0. The effects of alterations in thyroid function on the pituitary growth hormone content and acidophil cytology, Endocrinology. 1959, 65, 158-164.
Smith, D. C. W. The role of the endocrine organs in the salinity tolerance of the trout, Mem. Soc. Endocrinol.. 1956, 5, 83-98. 49
Smith, D. C. W., Sladek, S. A. & Kellner, A. W. The effect of mammalian thyroid extract on the growth rate and sexual differentiation in the fish Lebistes reticulatus treated with thiourea. Physiol. Zool.. 1953, 26, 117-124,
Smith, R. j. F. & Hoar, W. S. The effects of prolactin and testosterone on the parental behavior of the male stickleback (Gasterosteus aculeatus. Animal Behavior. 1967, JL5, 342-352,
Swanson, H. E. Interrelations between Thyroxin and Adrenalin on the Regulation of Oxygen Consumption on the Albino Rat. Endocrinology, 59, 1956, 217-25.
Swanson, H. E. The Effect of Temperature on the Potentiation of Adrenalin by Thyroxine in the Albino Rat. Endocrinology. 60. 1957, 205-213.
Tavolga, W. N. Ovarian fluids as stimuli to courtship behavior in the gobiid fish, Bathygobius soporator. Anat. Record. 1955, 122. Suppl. 425.
Tavolga, W. N. Reproductive behavior in the gobiid fish, Bathygobius soporator. Bull. A m . Museum N a t . Hist., 1954, 104. 431-459.
Tavolga, W. N. Visual, chemical, and sound stimuli as cues in the sex discrimination behavior of the gobiid fish. Bathygobius soproator. Zoologica, 1956, 43., 49-65.
Thornburn, C. C. & Matty, A. J. The effect of thyroxine on some aspects of nitrogen metabolism in the goldfish (Carassius auratus) and the trout (Salmo truttat Comp. Biochem. Physiol. 1963, 8, 1-12.
Tinbergen, N. The function of sexual fighting in birds; and problem of the origin of territory; Bird Banding. 1936, I, 1-8.
Tinbergen, N. The hierarchical organization of nervous mechanisms underlying instinctive behavior. Symp. Soc. Exptl. Biol., 1950, 4, 305-312.
Tinbergen, N. The study of Instinct. London: Oxford University Press, 1951. von Frisch, K. Bertrage zur Physiologie der Pigmentzallan in der Fischhant Arch. Ge s . Physol.. 138. 1911, 319-387.
Voss, J. & Ruwet, J. C. Inventaire des movements d'expression chez Tilopia quineensis (Blkr 1863) et T. macroclur (Blkr 1912) (Poissons, cichlids). Annls. Soc. r. Zool. Belg.. 96. 1966, 145-188.
Vi Iter, V. Action de la thyroxine sur la metemorphose Irocive de 1 'arguille. C. P. Soc. Biol. Paris 140, 1946, 783-785. 50
Waldstein, S. Interrelationship of the thyroid gland and sympathetic nervous system. Annual Review of Medicine. 1966, 17, 123-132.
Whitman, C. 0. Animal Behavior. Biol. Lect. Marine Biol. Lab. Wood1a Hole Mass. Boston; 1899, 285-338.
Wilcoron, F. Individual comparisons by ranking methods. Biometrics Bulletin. _1, 1945, 80-83.
Winn, H. E. Breeding habits of the Percid Fish Hadropterus copelandi in Michigan, Copeja. 1953, 26. APPENDIX 52
t a b l e a
COMPARISON OF FREQUENCIES OF BEHAVIOR CATEGORIES BETWEEN
MORNING (AM) AND AFTERNOON (PM) SESSIONS FOR GROUP I
Tf Tm Too Tc Tb N P Week AM PM AM PM a m PMAM PM AMPMAM PM AMPM
Phase 1 1 81 34 18 14 3 0 134 129 156 124 206 200 28 13
Phase 2 2 19 10 16 9 3 5 117 97 173 97 163 135 74 53 (thyroxine) 3 26 23 37 9 1 0 125 136 132 117 213 219 27 24 4 57 20 39 37 12 0 135 89 176 95 271 238 39 20
Phase 3 5 76 27 28 11 11 2 55 8 105 25 106 47 40 0 (thiourea) 6 11 0 9 0 0 0 0 0 10 0 0 0 0 0 7 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Total 270 114 147 80 30 7 566 539 752 458 959 839 208 110 53
TABLE B
COMPARISON OF FREQUENCIES OF BEHAVIOR CATEGORIES BETWEEN
MORNING (AM) AND AFTERNOON (PM) SESSIONS FOR GROUP II
Tf Tta Too Tc Tb N P Week AM PM AM PM AM PM AM PM AM PM AM PM AM PM
Phase 1 1 72 51 14 14 6 4 194 241 120 117 256 265 87 59
Phase 2 2 12 7 5 3 2 1 64 53 53 29 92 35 50 39 (thiourea) 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Total 84 58 19 17 8 5 258 294 173 146 348 300 137 98 54
TABLE C
COMPARISON OF FREQUENCIES OF BEHAVIOR CATEGORIES BETWEEN
MORNING (AM) AND AFTERNOON (PM) SESSIONS FOR GROUP III
Tf Ttn Too Tc Tb N P Week AM PM AM PMAM PM AM PM AM PM AM PM AM PM
Phase I 1 6 1 4 0 0 0 181 142 22 27 169 195 112 101
Phase 2 2 4 0 1 0 0 0 177 118 18 20 223 247 102 97 (thyroxine) 3 11 4 3 1 0 0 195 172 25 38 197 2 03 87 63 4 13 0 0 0 0 0 197 144 22 37 211 231 58 66
Total 34. 5 8 1 0 0 750 576 87 122 800 876 359 327 VITA
Peter Harry SpiliotlG was born November 11, 1946 In Wilmington,
North Carolina. He received his Bachelor of Arts degree from the
University of North Carolina in 1969 and his Master of Arts from
Louisiana State University in 1971. He is presently a candidate for the degree of Doctor of Philosophy at Louisiana State University.
55 EXAMINATION AND THESIS REPORT
Candidate: Peter Harry Spiliotis
Major Field: Psychology
Title of Thesis: The Effect of Thyroxine and Thiourea on Territorial Behavior in Cichlid Pish Approved:
Major professor
ff Dean of the Graduate) School
EXAMINING COMMITTEE:
Date of Examination:
November 14, 1973