DOCSLIB.ORG

Size-Fecundity Relationships and Their Evolutionary Implications in Five Desmognathine Salamanders

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Size-Fecundity Relationships and Their Evolutionary Implications in Five Desmognathine Salamanders SIZE-FECUNDITY RELATIONSHIPS AND THEIR EVOLUTIONARY IMPLICATIONS IN FIVE DESMOGNATHINE SALAMANDERS STEPHEN G. TILLEY Museum of Zoology, University of Michigan, Ann Arbor Received June 5, 1968 The plethodontid salamander genus Des­ genus has been "the gradual transformation mognathus comprises seven species accord­ of a population with a high egg production ing t.o current taxonomy, of which six and low survival into a population with low occur in, and four are endemic to the Ap­ egg production and a high survival to ma­ palachian Mountain system of eastern turity." He found no differences in num­ North America. Over most of the southern ber of clutches per year or age at maturity Blue Ridge Physiographic Province several that might compensate for differences in of these forms may exist sympatrically. An clutch size. apparent maximum of sympatry occurs in This paper attempts to further explore the Balsam Mountains of southwestern Vir­ and compare the relationships between size ginia, where five species, D. quadramacu­ and fecundity among the five sympatric latus, D. monticola, D. fuscus, D. ochro­ species of Desmognathus and to elaborate phaeus, and D. wrighti occur in abundance. on the hypotheses drawn by Organ relative Organ (1961) studied the ecological rela­ to evolutionary trends in reproductive tionships and population dynamics of these habits. In particular I have sought to species at Whitetop Mountain and Mt. determine whether fecundity differences Rogers in the Balsam Mountains. Hairston among the five species are explained simply (1949) compared the ecologies of D. by differences in their sizes, or whether size­ quadramaculatus, D. monticola, D. ochro­ fecundity relationships are more complex. phaeus, and D. wrighti in the Black Moun­ tains of North Carolina where those four MATERIALS AND METHODS forms occur sympatrically. Both authors This study is based mainly on Organ's found that, in the order given above, these series of Desmognathus from the Balsam species form a series in which decreasing Mountains. With regard to the species size is paralleled by an increasing tendency wrighti and quadramaculatus, I restricted toward terrestrial habits. Organ further this study to these series. I have included found that the trend is also paralleled by specimens of D. monticola from western increasing juvenile survivorship. He con­ North Carolina in addition to specimens cluded that heavier juvenile mortality is from the Balsam Mountains in an attempt to associated with aquatic sites, and that D. include more of the total snout-vent length quadramaculatus, D. monticola, D. fuscus, range for that species. Data on series of D. ochrophaeus, and D. wrighti represent D. ochrophaeus from the vicinity of High­ an evolutionary trend in which selection lands, North Carolina and D. fuscus from has favored progressively more terrestrial Licking County, Ohio are included where habits. comparisons with Balsam Mountain ma­ Size and egg production are positively terial of those two species are appropriate. correlated in the genus Desmognathus, as Whenever possible, only females with they are in many animals. Organ (1961) eggs greater than 1 mm in diameter were also emphasized that the larger species lay examined. Otherwise it was difficult to larger clutches than the smaller ones, and distinguish smaller eggs from those to be that the evolutionary trend within the deposited the following year, since in the EVOLUTION 22:806-816. December, 1968 806 SIZE-FECUNDITY RELATIONSHIPS IN FIVE SALAMANDERS 807 early stages of yolk deposition egg sizes Harrison's work indicates that annual egg are so variable as to obscure the differences laying may occur in D. aeneus. The evi­ between the clutches of successive years. dence for bienniality in Leurognatkus is Snout-vent length measures the distance not, in my opinion, compelling. In view of from the tip of the snout to the posterior these arguments it would seem dangerous angle of the vent. The method of covari­ to assume bienniality in D. wrigkti, D. ance analysis was utilized to compare the monticola, and D. quadramaculatus. While slopes and elevations of the regression lines more data on this point are sorely needed, for the five species, using the methods and I shall assume all five species dealt with forms of calculations given in Snedecor here to be annual reproducers. (1956). The squared deviations and cross products of deviations were calculated from Nesting Habits computer calculated raw sums, sums of All five species exhibit parental care, in squares, and sums of cross products. In which the females remain with the eggs the case of D. quadramaculatus rounding until hatching. Pope (1924) found that error prevented the use of computer calcu­ females of D. monticola and D. quadra­ lated raw sums, and hand-calculated sums maculatus attach each egg individually to were used instead. the roof of the nesting cavity so that the eggs form a flat mass one or two eggs thick, SUMMARY OF HABITS AND whereas D. fuscus, D. ochrophaeus, and D. LIFE HISTORIES wrigkti (information on the latter species The following accounts are based pri­ from Organ, 1961) generally deposit their marily on the studies of Hairston and eggs in spherical clusters with only a few Organ, supplemented in certain cases by actually attached to the roof of the nesting my own observations. cavity. Females of the five species utilize some­ Female Reproductive Cycles what different sites for egg deposition. D. Organ concluded that all five of the spe­ quadramaculatus utilizes the most aquatic cies deposit eggs biennially, but Martof sites, depositing eggs on the undersides of and Rose (1963) found evidence for an­ rocks in the beds of streams and beneath nual egg laying in D. ochrophaeus in the small waterfalls. D. monticola, D. ochro­ southern Appalachians. Tilley and Tinkle pkaeus, and D. wrigkti deposit eggs in less (1968) have presented evidence for an an­ aquatic sites than D. quadramaculatus, be­ neath stream banks and, in the case of D. nual or possibly even biannual cycle in D. ochrophaeus in the vicinity of Mt. Mitchell ochrophaeus, beneath moss on rocks and and in the Balsam Mountains. Spight logs in seepage areas. D. fuscus appears to (1967) concluded that D. fuscus deposits lay eggs in situations intermediate between eggs annually in eastern North Carolina those utilized by D. quadramaculatus and and Harrison (1967) found that a sixth those used by the other species. species, D. aeneus, also lays annually. Martof (1962) found evidence for biennial Lengtk of tke Larval Period reproduction in another desmognathine, The length of the larval period varies Leurognathus marmoratus. greatly among the five species, and reflects The same weaknesses which Tilley and the aquatic to terrestrial trend discussed Tinkle found in the arguments for biennial above. In the terrestrial D. wrigkti meta­ egg laying in D. ochrophaeus probably morphosis occurs prior to hatching (one apply as well to D. wrigkti, D. fuscus, wonders, therefore, why it deposits its eggs D. monticola, and D. quadramaculatus. in aquatic sites). Organ gave estimates of Spight's study bears this out for D. fuscus. 26-28 months for D. quadramaculatus, 12- 808 STEPHEN G. TILLEY 4.0 3.5 0 Z ...w U ... 3.0 0 u. o· 0... 2.5 2.0 3.0 3.5 4.0 4.5 LOGe SNOUT -v ENT LENGTH FIG. 1. Relationships between size and fecundity in five species of Desmognathus. Lines represent least squares regression lines of log. follicle number on log. snout-vent length. 13 months for D. monticola, 13-16 months cola prefers the banks of streams, as does for D. fuscus, and 10-11 months for D. D. fuscus. Organ found that both D. ochrophaeus. The estimate for D. ochre­ ochrophaeus and D. wrighti occur in ter­ phaeus is in error (Tilley and Tinkle, 1968); restrial situations. Males of both species the larval period of that species is from 4 are largely terrestrial during the summer to 6 months at Mt. Mitchell, North Caro­ months, moving to aquatic sites such as lina. seepage areas and spring heads during the Age at Maturity winter. His data, as well as Hairston's and Organ estimated that males of all five my own observations, indicate that of the species matured at 3.5 years of age, while two, D. wrighti is the more terrestrial. The Spight (1967) estimated 3 years for males aquatic sites preferred by D. ochrophaeus of D. fuscus. Both authors concluded that are of the seepage area-spring head variety, females require an additional year to pro­ rather than the stream or stream side habi­ duce their first clutch of eggs. tats occupied by D. quadramaculatus and D. monticola. Habitats The species are also segregated altitudi­ D. quadramaculatus occurs chiefly in nally to a certain degree. D. ochrophaeus larger and faster streams, while D. monti- occurs from the lowest to the highest avail- SIZE-FECUNDITY RELATIONSHIPS IN FIVE SALAMANDERS 809 TABLE 1. Summary of regression data. n =sample size, r =correlation coefficient. Equations and correlation coefficients are for regressions of log. foUicle number on log. snout-vent length. v = Balsam Mountains (Virginia), 0 =Ohio. Significance Regression Species " level equation D. wrighti 23 0.458 0.050 Y = 2.4130X - 5.7235 D.ochrophaeus 25 0.598 0.010 Y = 2.1773X - 5.1407 D.fuscus (v) 26 0.837 0.001 Y = 2.2845X - 5.2727 D. [uscus (0) 18 0.687 0.010 Y = 1.7484X - 3.3944 D. monticola 35 -0.163 < 0.100 D. quadramac. 26 0.390 0.050 Y = 1.0700X - 0.8825 able habitats in the Appalachians. In the sion lines relatively homogeneous, but not Balsam Mountains D. fuscus has a similar in removing all of the curvilinearity. D. distribution, but does not extend as high wrighti appears to have somewhat higher as does D.
Load more

Recommended publications
  • Helminth Infection, Fecundity, and Age of First Pregnancy in Women
    RESEARCH | REPORTS PARASITOLOGY 70% of the population, the most common being hookworm (56%) and A. lumbricoides (15 to 20%) (11, 17). In both animal and human studies, parasites Helminth infection, fecundity, and have been shown to influence host reproduction via sexual behavior, brood or litter size, offspring age of first pregnancy in women size, incubation periods, conception rates, and pregnancy loss (18–22). In most cases, parasitism Aaron D. Blackwell,1,2,3* Marilyne A. Tamayo,4 Bret Beheim,2,5 reduces host reproduction by compromising Benjamin C. Trumble,1,2,3,6,7 Jonathan Stieglitz,2,5,8 Paul L. Hooper,2,9 reproductive organs or reducing energy budgets Melanie Martin,1,2,3 Hillard Kaplan,2,5 Michael Gurven1,2,3 (14, 23). However, among Tsimane adults, mor- bidity from intestinal helminth infections is low, Infection with intestinal helminths results in immunological changes that influence particularly for A. lumbricoides. Controlling for co-infections, and might influence fecundity by inducing immunological states affecting age and co-infection in our sample, hookworm conception and pregnancy. We investigated associations between intestinal helminths and infection is associated with slightly lower body fertility in women, using 9 years of longitudinal data from 986 Bolivian forager-horticulturalists, mass index (BMI) (generalized linear model, 2 experiencing natural fertility and 70% helminth prevalence. We found that different species b = –0.77 kg/m , P < 0.001) and hemoglobin (b = of helminth are associated with contrasting effects on fecundity. Infection with roundworm –0.19 g/dl, P =0.005),whereasA. lumbricoides is 2 (Ascaris lumbricoides) is associated with earlier first births and shortened interbirth intervals, not (b = –0.34 kg/m , P = 0.180; b = –0.07 g/dl, whereas infection with hookworm is associated with delayed first pregnancy and extended P = 0.413).
    [Show full text]
  • Fecundity Selection Theory: Concepts and Evidence
    bioRxiv preprint doi: https://doi.org/10.1101/015586; this version posted February 23, 2015. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. Fecundity selection theory: concepts and evidence Daniel Pincheira-Donoso1,3 & John Hunt2 1Laboratory of Evolutionary Ecology of Adaptations, School of Life Sciences, University of Lincoln, Brayford Campus, Lincoln, LN6 7DL, Lincolnshire, United Kingdom 2Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Cornwall Campus, Penryn, Cornwall, TR10 9EZ, UK 3Corresponding author: [email protected] ABSTRACT Fitness results from the optimal balance between survival, mating success and fecundity. The interactions between these three components of fitness vary importantly depending on the selective context, from positive covariation between them, to antagonistic pleiotropic relationships when fitness increases in one reduce fitness of others. Therefore, elucidating the routes through which selection shapes life history and phenotypic adaptations via these fitness components is of primary significance to understand ecological and evolutionary dynamics. However, while the fitness components mediated by natural (survival) and sexual (mating success) selection have extensively been debated from most possible perspectives, fecundity selection remains considerably
    [Show full text]
  • Life Table of Orius Insidiosus (Hemiptera: Anthocoridae) Feeding on Sitotroga Cerealella (Lepidoptera: Gelechiidae) Eggs
    Research article http://www.revistas.unal.edu.co/index.php/refame Life table of Orius insidiosus (Hemiptera: Anthocoridae) feeding on Sitotroga cerealella (Lepidoptera: Gelechiidae) eggs Tabla de vida de Orius insidiosus (Hemiptera: Anthocoridae) alimentado con huevos de Sitotroga cerealella (Leideoptera: Gelechiidae) doi: 10.15446/rfna.v69n1.54745 Jhon Alexander Avellaneda Nieto1, Fernando Cantor Rincon1, Daniel Rodríguez Caicedo1* ABSTRACT Key words: To use a natural enemy to control an insect pest, it is important to determine the biological parameters Biological control of the native populations of the predator. The goal of this study was determinate the biological Pirate bugs parameters of O. insidiosus fed on Sitotroga cerealella eggs. A batch of 225 O. insidiosus eggs were Stock colony laid into bean pods. The bean pods were kept in glass jars, and the eggs and first instar nymphs were Sabana de Bogotá counted daily. All nymphs were extracted and individualized in Petri dishes. The presence/absence of exuvie was observed daily as a way to assess the emergence of adults from the nymphal stage. Seventeen adult couples were placed into Petri dishes with a segment of bean pod. The bean pod segments were extracted and replaced daily, counting the number of eggs present on the pods. The life cycle, survival percentage, sex ratio, male/female longevity, pre ovoposition, ovoposition and post ovoposition periods were determined. Finally, fertility life table parameters were estimated. The nymphal development time was 12.0 ± 0.22 days, with 80.47% ± 3.23 survival, while the total development time was 15.0 ± 0.23 days, with 66.67% ± 1.90 survival.
    [Show full text]
  • Fecundity Selection Theory: Concepts and Evidence
    bioRxiv preprint doi: https://doi.org/10.1101/015586; this version posted February 23, 2015. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. Fecundity selection theory: concepts and evidence Daniel Pincheira-Donoso1,3 & John Hunt2 1Laboratory of Evolutionary Ecology of Adaptations, School of Life Sciences, University of Lincoln, Brayford Campus, Lincoln, LN6 7DL, Lincolnshire, United Kingdom 2Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Cornwall Campus, Penryn, Cornwall, TR10 9EZ, UK 3Corresponding author: [email protected] ABSTRACT Fitness results from the optimal balance between survival, mating success and fecundity. The interactions between these three components of fitness vary importantly depending on the selective context, from positive covariation between them, to antagonistic pleiotropic relationships when fitness increases in one reduce fitness of others. Therefore, elucidating the routes through which selection shapes life history and phenotypic adaptations via these fitness components is of primary significance to understand ecological and evolutionary dynamics. However, while the fitness components mediated by natural (survival) and sexual (mating success) selection have extensively been debated from most possible perspectives, fecundity selection remains considerably
    [Show full text]
  • Fecundity and Survival in Relation to Resistance to Oxidative Stress in a Free-Living Bird
    Ecology, 89(8), 2008, pp. 2584–2593 Ó 2008 by the Ecological Society of America FECUNDITY AND SURVIVAL IN RELATION TO RESISTANCE TO OXIDATIVE STRESS IN A FREE-LIVING BIRD 1,4 2 1 3 2 PIERRE BIZE, GODEFROY DEVEVEY, PATRICIA MONAGHAN, BLANDINE DOLIGEZ, AND PHILIPPE CHRISTE 1Division of Environmental and Evolutionary Biology, Glasgow University, Graham Kerr Building, Glasgow G20 8QQ United Kingdom 2Department of Ecology and Evolution, University of Lausanne, Biophore, 1015 Lausanne, Switzerland 3Department of Biometry and Evolutionary Biology, CNRS UMR 5558, University Lyon I, Baˆtiment Gregor Mendel, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex, France Abstract. Major life history traits, such as fecundity and survival, have been consistently demonstrated to covary positively in nature, some individuals having more resources than others to allocate to all aspects of their life history. Yet, little is known about which resources (or state variables) may account for such covariation. Reactive oxygen species (ROS) are natural by-products of metabolism and, when ROS production exceeds antioxidant defenses, organisms are exposed to oxidative stress that can have deleterious effects on their fecundity and survival. Using a wild, long-lived bird, the Alpine Swift (Apus melba), we examined whether individual red cell resistance to oxidative stress covaried with fecundity and survival. We found that males that survived to the next breeding season tended to be more resistant to oxidative stress, and females with higher resistance to oxidative stress laid larger clutches. Furthermore, the eggs of females with low resistance to oxidative stress were less likely to hatch than those of females with high resistance to oxidative stress.
    [Show full text]
  • Natural Family Planning ………..……………………………………………
    Summer/Fall 2014 ● Vol. 25, Nos. 3 & 4 Richard J. Fehring, PhD, RN, FAAN – Marquette University College of Nursing In this issue Natural Family Planning ………..……………………………………………. 2 Fertility/Infertility …………...………………………………………………... 7 Pregnancy ….……………………………………………………….…………. 9 Menstrual Cycle ………………………………………………………………. 10 Under the Microscope ………………………………………………………... 12 A Brief History of Natural Family Planning Current Medical Research is a publication of the Natural Family Planning Program of the United States Conference of Catholic Bishops. © 2014 USCCB. The managing editor is Theresa Notare, PhD, Assistant Director. Permission is granted to reproduce in whole or in part, in print and/or electronically, with the following statement: Current Medical Research, © 2014 USCCB, volume # (year): page #. Used with permission. 1 Natural Family Planning Natural Family Planning Differentiates Women’s Perception of the Availability of Reproductive Health Services in Catholic Hospitals Catholic hospitals and health care systems provide approximately 10% of the health care in the United States. Furthermore, in some smaller communities Catholic hospitals and Catholic health care services are the only health services available. Previous research has shown that Catholic hospitals that follow Catholic Church teachings prevent the use of “standard” (i.e. immoral) reproductive services and that obstetricians and gynecologists view Catholic health systems as preventing the availability of “full” (but often immoral) reproductive services. Researchers theorized that women patients of reproductive age would be surprised and disturbed if they understood that Catholic health care systems are limited in the provision of some types of women’s health care services (Guiahi, Sheeder, and Teal 2014). Therefore, these researchers set out to determine if women of reproductive age would expect different reproductive services in a Catholic hospital compared to a secular or non-Catholic hospital.
    [Show full text]
  • The Evolution of Pueriparity Maintains Multiple Paternity in a Polymorphic Viviparous Salamander Lucía Alarcón‑Ríos 1*, Alfredo G
    www.nature.com/scientificreports OPEN The evolution of pueriparity maintains multiple paternity in a polymorphic viviparous salamander Lucía Alarcón‑Ríos 1*, Alfredo G. Nicieza 1,2, André Lourenço 3,4 & Guillermo Velo‑Antón 3* The reduction in fecundity associated with the evolution of viviparity may have far‑reaching implications for the ecology, demography, and evolution of populations. The evolution of a polygamous behaviour (e.g. polyandry) may counteract some of the efects underlying a lower fecundity, such as the reduction in genetic diversity. Comparing patterns of multiple paternity between reproductive modes allows us to understand how viviparity accounts for the trade-of between ofspring quality and quantity. We analysed genetic patterns of paternity and ofspring genetic diversity across 42 families from two modes of viviparity in a reproductive polymorphic species, Salamandra salamandra. This species shows an ancestral (larviparity: large clutches of free aquatic larvae), and a derived reproductive mode (pueriparity: smaller clutches of larger terrestrial juveniles). Our results confrm the existence of multiple paternity in pueriparous salamanders. Furthermore, we show the evolution of pueriparity maintains, and even increases, the occurrence of multiple paternity and the number of sires compared to larviparity, though we did not fnd a clear efect on genetic diversity. High incidence of multiple paternity in pueriparous populations might arise as a mechanism to avoid fertilization failures and to ensure reproductive success, and thus has important implications in highly isolated populations with small broods. Te evolution of viviparity entails pronounced changes in individuals’ reproductive biology and behaviour and, by extension, on population dynamics1–3. For example, viviparous species ofen show an increased parental invest- ment compared to oviparous ones because they produce larger and more developed ofspring that are protected from external pressures for longer periods within the mother 4–7.
    [Show full text]
  • Thamnophis Gigas)
    Herpetological Conservation and Biology 13(1):80–90. Submitted: 2 June 2017; Accepted: 11 December 2017; Published 30 April 2018. REPRODUCTIVE FREQUENCY AND SIZE-DEPENDENCE OF FECUNDITY IN THE GIANT GARTERSNAKE (THAMNOPHIS GIGAS) JONATHAN P. ROSE1, JULIA S.M. ERSAN, GLENN D. WYLIE, MICHAEL L. CASAZZA, AND BRIAN J. HALSTEAD U.S. Geological Survey, Western Ecological Research Center, Dixon Field Station, 800 Business Park Drive, Suite D, Dixon, California 95620, USA 1Corresponding author, email: [email protected] Abstract.—How reproductive output changes with age or size is a key life-history trait that can affect which demographic rates most influence population growth. Although many studies have investigated the reproductive ecology of gartersnakes, we know little about reproduction in the threatened Giant Gartersnake, Thamnophis gigas. We used X-radiography to determine reproductive status and estimated fecundity for 73 female T. gigas collected from several regions within the range of this species in the Sacramento Valley of California, USA, and synthesize these data with data from litters born in captivity to improve our understanding of reproduction in this species. Average total litter size determined from X-rays (15.9) and captive-born litters (15.5) are within the ranges reported from other gartersnakes, but captive-born litters had high rates of stillbirth. Only 154 of 202 neonates from captive snakes were born alive, and seven of 13 litters contained at least one stillborn neonate. We found that fecundity was positively related to maternal snout-vent length, and some evidence that larger litters contained smaller neonates. The proportion of X-rayed females that were gravid was 0.50 in 2014, 0.47 in and 2015, and 0.64 in 2016.
    [Show full text]
  • The Evolution of Demographic Tactics in Lizards: a Test of Some Hypotheses Concerning Life History Evolution
    J. evol. biol. 11 (1998) 329–364 1010–061X/98/030329–36 $ 1.50+0.20/0 The evolution of demographic tactics in lizards: a test of some hypotheses concerning life history evolution J. Clobert,1 T. Garland Jr.2 and R. Barbault1 1Laboratoire d’Ecologie, Uni6ersite´ Pierre et Marie Curie, Baˆtiment A, Case 237, 7 quai Saint Bernard, 75252 Paris cedex 05, France 2Department of Zoology, 430 Lincoln Dri6e, Uni6ersity of Wisconsin, Madison, WI 53706-1381, USA Key words: Comparative methods; demographic tactics; life history; phylogeny; dimension numbers; lizards. Abstract We analyze, with an augmented data base, patterns of covariation of the three primary demographic parameters (age at maturity, fecundity, adult survival, all measured in the same unit of time) in lizards. This also constitutes a first attempt to use all three of these parameters for this group of species. We attempt to place these analyses in the framework of recent theories on life history evolution (Ferrie`re and Clobert, 1992; Charnov, 1993). Life history data were collected from the literature and from our original work, and a composite phylogeny was assembled, based on a variety of published sources. Using a phylogenetically based statistical method (independent contrasts), the allometric (log-log) relationship of fecundity (and of clutch size) in relation to snout-vent length was found to differ significantly between the two major clades of extant lizards, Iguania (43 species in our data set) and Scleroglossa (47 species). We therefore emphasize analyses done separately for the two clades. Without removing correlations with body size, the relationships between fecundity and survival, and between fecundity and age at maturity, were also found to differ between clades, which differs from Charnov’s (1993) predic- tions.
    [Show full text]
  • F(L P)-1 12 DAVID G
    Heredity (1974), 32 (1), 11-34 THEORETICALSEX RATIOS OF DIOECIOUS AND GYNODIOECIOUS ANGIOSPERMS DAVID G. LLOYD Botany Department, University of Canterbury, Christchurch, New Zealand Received3.1.73 SUMMARY The following parameters affecting the frequency of male and female plants in sexually dimorphic Angiosperms are defined: relative fecundity (as seed parent), F, differential survival, S, and gamete success, G, all as male/female quotients, and the probability of fertilisation of ovules on female plants, in terms of the number of pollinator visits to the flowers, x. Four different modes of inheritance of gynodioecy and dioecy are examined: (a) Heterozygous female model—female Mm, male mm. (b) Dual male model—female mm, male MM and Mm. (c) Heterozygous male model—female mm, male Mm only. (d) Cytoplasmic inheritance. The equilibrium frequencies of females and (for three models) the rates of change in female frequency per generation at non-equilibrium frequencies are expressed in terms of the controlling parameters. The conditions necessary for sexual dimorphism and the changes in fre- quencies of the sex genotypes as the number of pollinator visits increase and the relative seed fecundity decreases towards zero (dioecy) are derived for each model. Differential survival of the sexes (and differential gamete success in the heterozygous male model) cause an increase at equilibrium in the sex surviving more frequently or the sex derived from the more successful gamete. In a dioecious population, the ratio of the sexes is equal to their relative survival or their relative gamete success. Populations at non-equilibrium frequencies return more rapidly to equilibrium with the heterozygous male model than with the heterozygous female and cytoplasmic models.
    [Show full text]
  • Sexual Dimorphism in Lizard Body Shape: the Roles of Sexual Selection and Fecundity Selection
    Sexual dimorphism in lizard body shape: The roles of sexual selection and fecundity selection Olsson, M; Shine, R; Wapstra, E; Ujvari, Beata; Madsen, Thomas Published in: Evolution 2002 Link to publication Citation for published version (APA): Olsson, M., Shine, R., Wapstra, E., Ujvari, B., & Madsen, T. (2002). Sexual dimorphism in lizard body shape: The roles of sexual selection and fecundity selection. Evolution, 56(7), 1538-1542. Total number of authors: 5 General rights Unless other specific re-use rights are stated the following general rights apply: Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal Read more about Creative commons licenses: https://creativecommons.org/licenses/ Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. LUND UNIVERSITY PO Box 117 221 00 Lund +46 46-222 00 00 BRIEF COMMUNICATIONS Evolution, 56(7), 2002, pp. 1538±1542 SEXUAL DIMORPHISM IN
    [Show full text]
  • What Does a Fly's Individual Fecundity Pattern Look Like?
    Mechanisms of Ageing and Development 124 (2003) 605Á/617 www.elsevier.com/locate/mechagedev What does a fly’s individual fecundity pattern look like? The dynamics of resource allocation in reproduction and ageing V.N. Novoseltsev a,b,1,2, J.A. Novoseltseva a,3, A.I. Yashin b,c,* a Institute of Control Sciences, 117997 Profsoyuznaya 65, Moscow, Russia b Max-Planck Institute for Demographic Research, 114 Doberaner Str., D 18057 Rostock, Germany c Sanford Institute of Public Policy, Duke University, Durham, NC 27708-466, USA Received 2 December 2002; received in revised form 29 January 2003; accepted 11 February 2003 Abstract Reproduction is usually characterised by an average fecundity pattern having a maximum at earlier ages and a subsequent gradual decline later on. An individual fecundity trajectory does not follow such a pattern and has no maximum. A three-stage pattern, which includes maturation, maturity and reproductive senescence, is a more appropriate description. An analysis of the power balance of an adult female fly during its life course allows us to predict two critical periods in an individual life history. The first crisis occurs at early ages when the increasing power demand becomes greater than the power supply. It often results in premature death. The surviving flies enjoy maturity and lay eggs at a presumably constant rate. The second critical period at advanced ages ends up in a senescence-caused death. Our approach predicts that there will be a bimodal death time distribution for a population of flies. # 2003 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Fecundity pattern; Resource allocation; Premature death; Homeostenosis 1.
    [Show full text]