Modes of evolution mainly among

marine invertebrates

An observational approach

by

H.J. Mac Gillavry

Geological Institute of the University of Amsterdam

Rapid advances, mainly in macro-molecular biology, eluding ecological genetics) and from mathematical

make it models based such information. necessary to return periodically to the sum on It is common-

total of observational information and to rebuild place, but only partially correct, to say that genetic

is limited of intra- theory on evolution from the ground up. The possi- information largely to a study

bility of incorporation of genetic informationby viral specific variation and to the intra-specific evolution

the non-deleterious nature of of local insular term local here includes infection, many point- or races (the mutations (which follows from phylogenetic estimates the laboratory environments). Views on evolution

based distances the limit is on minimum mutation in specific beyond species (whatever meant by this), derived obtained detour proteins), and the relevance of the genetic environ- as from genetics, are by a

ment to mutation (obvious from physico-chemical through theoretical and mathematical models >). An-

but few of the data which other less that considerations), are a new point, frequently made, is most genetic from of may be mentioned. Less obvious, but equally neces- information is obtained the study non-marine

and and of sary is a reappraisal of paleontologie information. An plants, nowadays equally non-

this field the marine bacteria and virus. Macro-molecular important gain in is greater accessibility biology, the wealth thanks the form of of immense of facts mainly to the new genetics, is rapidly beginning to

efforts of Invertebrate Pale- contribute the of evolution far R. C. Moore (Treatise on to problem over

The contributions of ontology), J. Piveteau (Traité de Paléontologie), and greater taxonomie distances. of for this level of inferen- L. Hyman the recent fauna (The Invertebrates). paleontology at are necessity

This will deal with information tial. paper paleontologie obtained first from personal observation and secondly The observation of evolutionary phenomena and

from literature. successions, on the other hand, is by its nature the

Discussions evolution should make clear dis- field of of there is on a study paleontologists. Again some

between: the mechanism of vertebrates. This for tinction a) evolution, b) emphasis on is understandable, observed evolutionary phenomena and successions, the vertebrates are possibly the only phylum which and the over-all of c) panorama of faunal and floral presents an intelligible succession classes, com- evolution. plete even with a number of intermediate links. In

of the over-all is the second skulls and skeletons, their Appraisal panorama represented place by very for far of instance by the visionary works of Teilhard de complexity, are more expressive evolutionary

Chardin for critical than in other words (see SIMPSON, 1960a, a review). change e.g., Foraminifera; they

take The emphasis is on evolution towards man, and not provide a wealth of features that one can hold

towards orchids mammals and other of. the other hand or octopi; verte- On they are more rigidly inte- brates profit by reflection. Speculation in this field, grated functionally, in particular under the strict

whether obtained revelation terrestrial and thus have less by or otherwise, is requirements of life, bound to be rather and should be tolerance for evolution 2 airy, in any case non-adaptive variation or ). based integrated with a thorough understanding of the two Most paleontologie information is on a com- other still far removed from such of material derived from scattered aspects. We are parison museum

understanding. localities, and the arrangement of this material in Ideas the mechanism of on evolution stem largely supposed phylogenetic lineages. A more rigid study

from information classical based supplied by genetics (in- on sampling continuous sections, continuously

Downloaded from Brill.com09/29/2021 04:28:25PM via free access 70 H. J. MAC GILLAVRY

fossiliferous and with non-varying lithologie facies the field of genetics of Foraminifera is still complete-

is required. Such rigid temporal control is not easy ly virgin. A useful compendium of many observed limited Foraminifera to obtain. Common situations are: a) a num- cases of evolutionary change among is ber of fossiliferous beds is separated by barren inter- provided by the Van der Vlerk jubilee volume (Vox

drawback vals; b) a section, though continuously fossiliferous, Koenigswald e.a. ed., 1963). A of the

shows of facies that is lack of will be in the many changes or assemblage, so group expression: it difficult,

single species or lineages are not found in uninter- case of fossil forms, to find forty characters, the

of minimum for methods. rupted sequence; finally the possibility immigra- required some multivariate

tion and related forms should be The from studies of well- replacement by kept impressions acquired my

in mind. Such studies have so far been few; well sections are:

Brinkmann's studies known examples are of Kosmo- a. The great majority of species do not show any

ceratidae and Trueman's studies of Gryphaea. The appreciable evolutionary change at all. These species

fact that Trueman's results have recently been ques- appear in the section (first occurrence) without ob-

demonstrates then should in stable tioned that even one pro- vious ancestor underlying beds, are once

ceed with 3 material that the and without caution ). It is on such established, disappear higher up leaving

of numerical will be of obvious descendants. Such 6 use taxonomy great phylo- any "relay expansion" ) for the market genetic importance. What, to my knowledge, is com- is typical open of neritic (sublittoral)

of the benthos. pletely lacking, is a quantitative study entire

fauna of such successions. A study of this kind should b. One or two species vary rather wildly without

attention the of forms which do have little of this pay to percentage any time-sense. I experience type;

not show it to be rather any evolutionary change. appears common among Liassic Lage- forms During my work as an oil paleontologist I had the nidae, although this family also contains some

opportunity to study sections meeting these rigid exhibiting sustained change (BARNARD, 1963). Notable

marl formation of East the requirements (the Tertiary recent examples among Gastropoda are species

Java, for instance). As an ardent student of evolu- of Neritina where one can hardly find two specimens

the watch for with the The of these tion, moreover, I was continually on same pattern. genetics species evidence of evolutionary change. The first conclusion should be exceedingly interesting; I do not know

work has done this 7 to emerge was that such .instances are hard to find, whether any been on problem ). and that do not show after many species any evolutionary c. One species, a diligent search, was thought

all. It be contended that more de- show a sustained This a small Tritaxia change at may a to change. is

tailed and quantitative examination, for which there in the Miocene of South Sumatra, which changes

commercial would have disclosed from triserial biserial uniserial the is no time in work, through to in

more but such an should not be adult. However, was found that in the end it many cases, opinion it belief triserial form. based on a mere founded only on theoretical reverts to its original

considerations. limited d. few forms show My studies were to Foramini- Only a really sustained change.

benthonic and to lesser extent This be either fera, mainly forms, a may change along divergent lines, as of to Ostracoda. Foraminifera are of particular interest in the case of Bolivinoides (HILTERMANN, 1963) because forms have with which have the many a life-cycle alternating I no personal experience, or change

a adult which is be directional, often with generations: diplont generation, may parallel development often adult branches. This is the rare, gives rise by embryogenesis to an along independent in particular

which is the more fre- Foraminifera GILLAVRY, haplont generation normally case among larger (MAC

quent by far, and which by gametogenesis gives rise 1963). The evolution of these forms is composed of

4 at first to zygotes from which again grow diplont adults ). the successive introduction of new features,

The have the have in saltative diplonts many nuclei; haplonts part of a population (non-directional,

only one nucleus up to the moment of gametogenesis. change) and the elaboration of the morphologic con-

The therefore reduc- group provides a unique genetical sequences of these new features by nepionic

situation animals: selection be relaxed in tion The is therefore among may (directional). parallelism com-

the in the far and of non-directional introduction non-numerous diplont generation; more posite consists a the other of features direc- frequent haplont generation, on hand, any of the same succession new plus

selective unless small bal- tional elaboration reduction advantage, extremely or by nepionic (acceleration, be anced by other factors, could lead to complete ex- tachygenesis); divergent changes may superposed

clusion unfavourable situa- this. directional in- of variants, leading to a upon The component occurs

tion without further selection 5 As far I of the the entire ). as know, dependently in lineages same genus;

Downloaded from Brill.com09/29/2021 04:28:25PM via free access MODES OF EVOLUTION MAINLY AMONG MARINE INVERTEBRATES 71

faunae complex may take place in the same, though not Foraminifera among the Tertiary well-sample

dif- of Indonesia. also that such forms necessarily anatomically homologous manner, in It is likely consti- ferent families. tute the bulk of the material studied by geneticists.

observations with other What the Integrating these aspects is studied, however, is established form,

of three main hence the These have not lost evolution, one may roughly distinguish term wild-type. species but have modes of evolution. The distinction is of course over- their potential for variation they incorporated schematised. mechanisms for stability and for the maintenance of

1. radiation and tend Not investi- Evolutionary (explosive or eruptive wild-type, to penalise change.

evolution; the term adaptive radiation is not used gated by geneticists is the obscure ancestor: thus it

because of its theoretical implications). This is the is not the evolution of such forms which is being

evolution of dashes 8 the bottom of examined but the stabilised result. It should be inter- ) at a phylogenetic

which illustrates lack of about the the of tree, our knowledge esting to study genetics some rare struggling

involved. which not remnant of a processes Nor, as was pointed out by many species is obviously a onc£ the decline. authors, is it likely that geneticists are working with more powerful lineage now on

all discussion Sustained — the word any material of this kind. Almost on 3. change. Lineages species

the and based belief be used here — which show sustained subject is speculative on a in evo- can not aptly

lution all of constitute marine inverte- at levels, justified by similarity organisa- change a minority among and and chemical of brates. the of the few tion by cytologic similarity re- Hence continuous use same

cent forms. Presumably this evolution is extremely examples in the literature on evolution. In contrast

the simultaneous with the modes described there rapid. A good example is appear- two previously, is

the of the and abundance of material evidence. Some- ance in Lower Agnostida usually an

the other orders of the Trilobita. The argument here is times, as in the case of the Miogypsininae, entire

of and be followed from the first of similarity anatomic morphologic organisation. history can appearance

2. Opportunistic adaptation. This is the normal the subfamily feature in a few aberrant individ-

market ancestral has al- mode of the open (àyopa)» where the ever uals of an Rotalia-population. As

influences favour form, been stated there be an element of direc- changing synecologic now one ready may

then another, but where faunal equilibrium is main- tion (orthogenesis in a descriptive sense). Moreover

tained for stretch of time between disturbance the of and be a one same succession changes stages may and the next. This mode provides the possibility of followed independently in different related lineages

related using index fossils (species level) and permits the (program evolution), or even in not closely

of biozone boundaries. The word homoeo- drawing adaptation groups (homoeomorphic parallelism, i.e.,

is introduced for want of a descriptive term, and be- moi-phic stages attained not by different pathways the of related cause its use seems justified in this case. Again mate- but by the same path). In case lineages rial evidence This of there off of side is practically non-existent. type is some branching lineages, which,

tend evolve in the direction. evolution may likewise be extremely rapid. Or per- however, to same

form combination Whether there and diver- haps a certain or genetic originates is branching, even some

of such with other is therefore among a struggling population negligible gence regard to features, not

numbers that no record remains. Once a successful relevant. Nor is it relevant whether directional evo-

has been obtained the form will lution rectilinear for of need type resulting spread is or not, rate change also explosively and become established and stable, until not remain constant. Linearity depends on the

the of the replaced, ousted, exterminated, or forced to a new kind of scale used, or on position origin

sudden burst of opportunistic adaptation by some before transformation to logarithms. the used The word direction often used newcomer (relay expansion in general sense is incautiously, as before). A good example is the index-fossil Homo in the tenet that natural selection is the only factor sapiens: the search for ancestors of this species has which gives direction to evolution. There is no direc- been far than in other tion involved in the introduction of more intensive any case, yet phylogenetic a the evidence is still and controversial. Whole of in Foraminifera, nor in the meagre new type aperture adop-

seem to tion Daonella. groups be largely characterised by this mode: of a pelagic mode of living by Most

and the evolution of the Trilobita, Brachiopoda, even , marine invertebrates, opportunistic which were and which then does not show directional element, but a probably largely pelagic mode, any did not belong to the sublittoral benthos, although dimensionless diversification. The word direction

have lived close to the bottom. should be used when has true dimen- some may Species only a change be made behaving in this manner constitute the majority of sion. Furthermore a distinction can between

Downloaded from Brill.com09/29/2021 04:28:25PM via free access 72 H. J. MAC GILLAVRY

trend and dimensional of and directional a a change along an axis Sustained, in particular change, reference in diversification. The latter is most clearly among marine invertebrates appears to be associated

looks side of of with of low faunal with expressed when one at one a sheaf environments diversity, i.e.,

diverging lineages. For instance if size increase few species which occur in a great number of speci-

is (Cope's rule) were a general trend, where do all the mens. Some caution needed, because many pale-

smaller animals the from? Some of the faunae of rather in world come ontologie marine megafossils show a

smallest mammals and beetles that have ever existed low diversity, much more so than would be expected

Size decrease is less from a of faunae. Nevertheless I are living right now. conspicuous knowledge recent

be believe the be of than size increase unless body length plotted loga- association to true. Settlement a

rithmically. More often, however, diversification does new or relatively unoccupied ecologie niche thus may

in lead not involve direction except a vague way. A trend to sustained change, and not to evolutionary

which involves the of related This is a direction majority radiation, nor to opportunistic adaptation. con-

of Such trend be with the settlement of lineages a group. a can vague or trasts relatively unoccupied with diverse where settlement of a more definite character; this admittedly in- areas environments,

The distinction best does lead radiation. volves a subjective judgment. is to evolutionary

illustrated the of The understandable: by example size increase as com- association is exceptional en-

reduc- pared with the more definitetrend of nepionic vironments are specific and synecologic conditions

tion Foraminifera. Trends should be determined other members of the among larger are chiefly by same

established under rigid temporal control, i.e., from group.

continuous sections. The following examples illustrate the association:

Sustained change is not only well documented be- pelagic environment: Graptoloidea, pelagic

of numbers of available but cause large specimens Foraminifera;

it benthos: also, by its very nature, because proceeds through deep-water Pygopidae (Brachio-

considerable of other a length time. Usually, in poda);

words, the change is slow. The percentual rate of limestone-belt with low diversity:

the nepionic reduction per million years in Cycloclypeus larger Foraminifera of Tertiary; Fusulinidae; Ru-

is 7.5% (calculated from Mac Gillavry, 1956 with dists;

Haldane's formula in Simpson, calcula- brackish water: ?Cerithium. 1955, p. 15;

tion by compound interest gives 7.3%). This is within In all cases the evidence for exceptional environ-

the of horse dentition is based low and not range of evolutionary rates ment direct, i.e., on diversity,

1955, on the side of on the ascribed facies. The limestone- (Simpson, p. 16), though high inferentially evolution which leads belt low different the range. The to Orbulina of diversity is an entirely environ-

(pelagic Foraminifera) is exceptionally rapid, but still ment from coral reefs.

well documented 9 The evolution of be ). program Graptoloidea may

Directional change within a lineage is important less firmly established than formerly thought, but

for stratigraphie dating, but the change is gradational sustained change is obvious, and directional change

and does the of The of Foramini- not, as a rule, permit drawing sharp likely. taxonomie situation pelagic

biozone unless threshold fera is chaotic that it is difficult boundaries, a precise can so at present to judge

be defined as in the case of Orbulina. what is to be believed, but sustained change is clear-

that values obtained for and the of Orbulina clear- It is noteworthy high are ly established, origin is a

the coefficient of variation in the case of evolving cut example of directional change. Larger Foramini-

features Foraminifera of the fera also found in faunae of among larger (values are greater diversity, order of 12 20%; and but then have been Fusulinidae to MAC GILLAVRY, 1965, un- may transported.

published data). Similar high values are also obtained occur in richer faunae in the Pennsylvanian cyclo-

here there evidence of in the case of Kosmoceratidae (average: 12.4%; SIMP- thems of Kansas, but again is

The SON, 1955, p. 68). average value for evolving transport.

features of horse dentition is 6.4% (recalculated from The converse of the "rule" of association is not

least in SIMPSON, 1955, p. 13, 74). In Microtus dentition, on true. The deep (hadal) sea is a refuge area at

the obtained for those those where also has left other hand, high values are cases a species a pale-

features which evolve most 10 All record. The environment is (GUTHRIE, 1965) . ontologie hypersaline

of the values, except those Kosmoceratidae, refer to probably too impermanent to produce long range effects. have features which are invariant with regard to individual But Lingula (brackish) and Dipnoi sur- nevertheless growth. vived in spite of such impermanence;

Downloaded from Brill.com09/29/2021 04:28:25PM via free access MODES OF EVOLUTION MAINLY AMONG MARINE INVERTEBRATES 73

their evolutionary performance has been negligible extremely shallow water deposits of the Upper Juras- Pinnidae for the past 150 million years or so. Here also the sic, Boulonnais), ( of New Mex-

well be directional exceptional environment may have acted as a refuge. ico). However there may cases of

Triassic Pteriidae became pelagic but did not per- change in normal environments: the "rule" is not a

for sist long. It is noteworthy that free-swimming hundred percent law.

Pelecypoda (various species of the families Pteriidae,

Pectinidae, and Limidae) derive from a group (Ani- Summary

which the evolution been Three modes of evolution evolu- somyaria) in main has to- are distinguished: 1.

wards attached mode of The is 2. 3. an living. group tionary radiation, opportunistic adaptation, sus- characterized by a directional reduction of the ante- tained change. Material evidence of evolution is al-

rior adductor muscle; families most the first in the again many (though non-existent in mode, very slight

not all nor always) occur in autochthonous faunae second. Opportunistic adaptation is characteristic of

which Ostreidae the sublittoral is are poor in species: (brackish), Myti- benthos; sustained change asso-

lidae (mudflats), Bakewelliidae (e.g., Isognomon in ciated with low faunal diversity.

NOTES

5 ') A few dangers of the theoretical detour may be pointed ) The haplont generation must be indifferent to most

out: of selection else would a) estimates pressure depend greatly allele differences studied in genetics: how one

upon the mathematical model used (VAN VALEN, 1965); ever obtain normal Mendelian ratios or internally con-

the Volterra-Gause sistent b) principle, based on observation, linkage maps? Much selection among bacteria and

but the generalised on theoretical grounds, is contradicted by virus, on other hand, may be regarded as haplont

the diversity studies of WILLIAMS, (1964, chapter 9). Note selection. Certation as observed in the case of mammal

mathemat- and of tube that diversity parameter estimates depend on sperm pollen penetration in plants, is a

ical model, but diversity graphs not. The rule does not rather special case. It is not covered by SIMPSON'S (1955,

hold for Craptoloidea or pelagic Foraminifera; insect col- p. 138) definition of selection, which excludes selection

lectors will be familiar with many instances of coexist- towards a stable or fluctuating equilibrium, and which

ence: species of Aspidomorpha (Coleoptera, Cassidini) live includes mutation pressure. Note, moreover, that PANDEY

together on Hypomoea plants in South Sumatra; Sorgen- (1967) considers it possible that: "natural selection for S

frei's studies AGER mutation does the onNassa, quotedby (1963, p. 257) show specification not operate at gameto-

coexistence with but but at one instance of level .. the level." I am competition, only phytic ., only sporophytic

complete exclusion of three species out of four. Species indebted to professor J. Heimans and professor F. Bian-

will not only differ morphologically but also ecologically, chi for information on certation. etc., but it has to be shown that these differences prevent

mutual exclusion. if there differences of 6 used Moreover, are no ) The term "relay expansion" is here in a general

this the react and not restricted to nature, group will as one population, so sense (SIMPSON, 1960b, p. 162) re- that there would be for elimination of form another the not any reason the of placement one by in same ecologie

it is here meant one of the constituent species except by accident. niche (GLAESSNER, 1965, p. 120). Thus

to include the extermination of snakes and ground-

2 Skeletons ) of birds, however, are much more stable. breeding birds on Jamaica by the introduction of the

Perhaps the functional requirements in this case are so mongoose.

to strict as preclude further evolution once a functional

7 since the arrangement has been acquired. ) This variability is the more interesting beau-

of so valued tiful colour patterns many Gastropods, by 3 of ) For relevant literature see BURNABY (1965) and PHILIP collectors, are not visible during the life the . number of (1967). A reversed succession was independently observed This, for instance, is the case in a Conus by B. J. ROMEIN on Gryphaea material from northern species. H. K. Mienis and H. E. Coomans inform me that

France (1953, unpublished master's thesis). the periostracum of Neritina (Vitta) virginea, the varia-

bility of which I have observed on Jamaica, is thin and

4 of the ) There seems now to be agreement that meiosis occurs transparent. However, species genus Neritina s.s.

For just before embryogenesis in the few cases adequately have a thicker periostracum and are equally variable. studied, but it is dangerous to generalize, as Foraminifera the lack of genetical information on Neritina see ANDREWS

differ in life greatly cycle. (1941, p. 105).

Downloaded from Brill.com09/29/2021 04:28:25PM via free access 74 H. J. MAC GILLAVRY

8 One is In his ) almost irresistibly tempted to pun. tween slowly and rapidly evolving features. paper

Guthrie cites instances of increase relative varia- many of

9 ) During a discussion in Utrecht professor C. W. DROO- bility of evolving or selected features. Note, however,

that I should that Guthrie obtains the values GER and his group convinced me place greatest relative variability

for Orbulina in this category in spite of its more rapid measurements which are small in absolute value: they evolution. would thus be more susceptible to lowering by class

other interval correction if classed in the same units as

10 ) Guthrie's study distinguishes stable and rapidly features. In the second place it is not quite clear how

not evolving features. His study does differentiate be- some of these measurements were taken in the more

primitive form.

BIBLIOGRAPHY

AGER, D. V., 1963: Principles of Paleoecology. McGraw — 1963: Phylomorphogenesis and evolutionary trends of

Hill. Cretaceous orbitoidal Foraminifera. Evolutionary trends

E. 1941: Neritina in in Elsevier Publ. ANDREWS, A., virginea, L., Jamaica, Foraminifera, pp. 139-197. Cy.

— Part I: B.W.I. The Nautilus 54, 3, pp. 98-106. 1965: Variability of larger Foraminifera. natu-

BARNARD, T., 1963: Evolution in certain biocharacters of ral position of zero values. Proc. Kon. Ned. Ak. Wet.

trends 335-355. selected Lagenidae. Evolutionary in Amsterdam, ser. B 68, 5, pp.

79-92. K. Com- Foraminifera, pp. Elsevier Publ. Cy. PANDEY, K., 1967: Origin of genetic variability:

BURNABY, T. P., 1965: Reversed coiling trend in Gryphaea binations of Peroxydase isozymes determine multiple

S arcuata. Geological Journal 4, 2, pp. 257-278, Liver- allelism of the gene. Nature 213, no. 5077, pp. 669- pool. 672. fossiler Additionalobservations the evolu- GLAESSNER, M. F., 1965: Vorkommen Dekapoden PHILIP, G. M., 1967: on

(Crustacea) in Fisch-Schiefern. Senckenbergiana Le- tion of Gryphaea. Geological Journal 5, 2, pp. 329-338,

thaea 46a, pp. 111-122. Liverpool.

GUTHRIE, R. D., 1965: Variability in characters under- SIMPSON, G. G., 1955: The major features of evolution.

Microtus 2d. Colum- going rapid evolution, an analysis of molars. Columbia Biological Series, XVII, printing.

Evolution 19, 2, pp. 214-233. bia Univ. Press.

HILTERMANN, H., 1963: Zur Entwicklung der Benthos- — 1960a: On the remarkable testament of the Jesuit pale-

Foraminifere Bolivinoides. Evolutionary trends in Fora- ontologist PIERRE TEILHARD DE CHARDIN. Scientific

198-223. Elsevier Publ. 201-207. minifera, pp. Cy. American, 202, 4, pp. its KOENIGSWALD, G. H. R. VON, EMEIS, J. D., BUNING, W. L. — 1960b: The history of life. In: The evolution of life,

& WAGNER, C. W., editors, 1963: Evolutionary trends origin, history, and future. Univ. of Chicago Press.

in to Foraminifera, a collection of papers dedicated VAN VALEN, L., 1965: Selection in natural populations.

I. M. III. Measurement and estimation. Evolution VAN DER VLERK. Elsevier Publ. Cy. 19, 4, pp.

MAC GILLAVRY, H. J., 1956: Mutation pressure, a possible 514-528.

cause of directional evolution in Cycloclypeus Car- WILLIAMS, C. B., 1964: Patterns in the balance of nature.

penter (Foraminifera). Verh. Kon. Ned. Geol.-Mijn- Theoretical and Experimental Biology 3. Academic

bouwk. Gen., Geol. Ser. 16. H. A. BROUWER jubilee Press, London and New York.

volume, pp. 296-308.

Downloaded from Brill.com09/29/2021 04:28:25PM via free access