Deep-Sea Asteroids: High Genetic Variability in a Stable Environment

Ayala, Francisco J.; Valentine, James W.; Hedgecock, Dennis; Barr, Lorraine G.

doi:10.1111/j.1558-5646.1975.tb00201.x

Cited by 53 publications

(8 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Conversely, our values fit well with previous genetic studies conducted on shallow-water polychaetes (Grassle & Grassle, 1976;Nicklas & Hoffman, 1979;Bristow & Vadas, 1991) which reported percentages of polymorphic loci varying from 50 to 70 per cent and heterozygosities which often exceed 0.15. These results are also close to those reported for deep-sea nonhydrothermal organisms (Ayala et a!., 1975;Siebenaller, 1978) and contradict the hypothesis that both the stability of the environmental conditions (Gooch & Schopf, 1972) and the high genetic exchanges within nonlimited populations (Soulé, 1976) are responsible for the apparent high genetic variability of these nonhydrothermal deep-sea organisms. Surprisingly, levels of genetic diversity vary according to the alvinellid genera.…”

Section: Discussionsupporting

confidence: 83%

Genetic differentiation of deep-sea hydrothermal vent alvinellid populations (Annelida: Polychaeta) along the East Pacific Rise

et al. 1995

View full text Add to dashboard Cite

The alvinellid polychaetes, which live in the hottest part of the deep-sea hydrothermal environment, have a nested island-like distribution and locally are subjected to extinctions. They are sedentary and exhibit a peculiar reproductive behaviour and a development which may result in little or no planktonic stage (i.e. larval dispersal). The genetic variation within and among populations of the three main species (A/vine/la pompejana, A/vine/la caudata and Para/vinella grasslei) inhabiting vents along the East Pacific Rise was examined at a hierarchy of spatial scales using allozyme electrophoresis. The genetic diversity of P. grasslei is high (H0 = 0.24), about twice that of both the Alvinella species (H0 = 0.10). The three species show a strong tendency towards a heterozygote deficiency which systematically occurs at the same loci in nearly all the populations. These structures are particularly obvious in the genus Alvinella and might be explained by differential allozyme fitness. Populations display considerable genetic differentiation at the microgeographical scale, which could be explained by repeated founder effects in populations, but it varies from species to species according to their possible ability to be transported by crabs from vent to vent. However, the genetic variation among populations separated by at least 1000 km is of the same magnitude as that found within the 13°N/EPR segment. These results demonstrate that each species maintains its genetic identity along the oceanic rifts despite the evidence for founder effects.To explain this phenomenon, we hypothesize that in such a harsh environment, genetic drift in alvinellid populations could be balanced by a uniform selective pressure stemming from the vent chemistry.Keywords: allozymes, Alvinellidae, FST, genetic variation, hydrothermal vents. IntroductionGenetic variation in subdivided populations at equilibrium results from a balance between gene flow, natural selection and genetic drift. In sessile marine invertebrates, numerous studies have reported a correspondence between the ability of larvae to disperse and the amount of genetic differentiation between populations. It is generally admitted that a long larval planktonic phase favours extensive gene flow resulting in little differentiation among populations over large geographical distances, whereas a short *Correspondence dispersal period or direct development are the main grounds for significant differences between marine populations (Avise, 1994). Nevertheless, whatever the dispersal strategy adopted by organisms, local genetic differentiation in populations may also be a result of selection and/or some form of drift derived from bottleneck effects.Fauna inhabiting deep-sea hydrothermal vents represent ideal biological material with which to study the relative contributions of these influences. These endemic organisms experience natural radioactivity (Cherry et a!., 1992) (Tunnicliffe, 1991). As a consequence, this island-like arrangement of vents along the ridge axes results in a pecul...

show abstract

Section: Discussionsupporting

confidence: 83%

Genetic differentiation of deep-sea hydrothermal vent alvinellid populations (Annelida: Polychaeta) along the East Pacific Rise

et al. 1995

View full text Add to dashboard Cite

show abstract

“…Whether species and populations in more variable or unpredictable environments have more or less genetic variability than those in more constant or predictable environments has been of theoretical in- terest to many biologists (see discussions by Levins, 1968;Beardmore, 1970;Grassle, 1972;Selander and Kaufman, 1973;Ayala et al, 1975;Bryant, 1976;Hedrick et al, 1976;Soule, 1976;Valentine, 1976;Grassle and Grassle, 1977). While some electrophoretic studies have tended to support one view or the other, in general, there has been no clear trend in favor of any particular hypothesis (Lewontin, 1974a;Soule, 1976).…”

Section: Environmental Correlatesmentioning

confidence: 99%

Genetic Variability in Reproduction Rates in Marine Phytoplankton Populations

Brand¹

1981

Evolution

View full text Add to dashboard Cite

“…For deterministic factors, in temporally stable environments some forms of balancing selection could account for the differences in the level of heterozygosity of the examined populations. A relation between temporal stability and genetic variability has been suggested by many authors to explain their results on populations adapted to environments characterized by extreme temporal stability (Ayala et al, 1975;Sbordoni, 1980;Valentine and Ayala, 1978).…”

Section: Introductionmentioning

confidence: 99%