Long-term effects of vent dynamics on the genetic structure of populations in hydrothermal vent alvinellid polychaetes
Jollivet, D.; Chevaldonné, P.; Planque, B. (1997). Long-term effects of vent dynamics on the genetic structure of populations in hydrothermal vent alvinellid polychaetes, in: Biologie des sources hydrothermales profondes = Biology of deep-sea hydrothermal vents: Journées d'échanges du Programme DORSALES = DORSALES Workshop Roscoff 6-8 octobre 1997. Cahiers de Biologie Marine, 38(2): pp. 127 In: (1997). Biologie des sources hydrothermales profondes = Biology of deep-sea hydrothermal vents: Journées d'échanges du Programme DORSALES = DORSALES Workshop Roscoff 6-8 octobre 1997. Cahiers de Biologie Marine, 38(2)[s.n.][s.l.]. 111-149 pp., more In: Cahiers de Biologie Marine. Station Biologique de Roscoff: Paris. ISSN 0007-9723; e-ISSN 2262-3094, more |  |
| Authors | | Top | - Jollivet, D.
- Chevaldonné, P., more
- Planque, B.
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| Abstract | Dispersal strategies so far inferred from deep-sea hydrothermal vents seem to be constrained by phylogenetic features rather than habitat. Deep-sea vent mussels or archaegastropods exhibit long-range dispersal planktonotrophic larvae whereas several vent polychaetes or galatheid crabs appear to undergo benthic developmental stages. However, most of the vent species apparently succeed in maintaining a genetic homogeneity among disjunct populations over connected ridge systems. Such a paradox could be explained by the vent instability. In situ observations have shown that hydrothermal activity is shifting along fast-spreading centers, and generates numerous ephemeral vents which life-time does not exceed a few 10s of years. Vent instability is likely to generate continuous extinction/recolonization patterns in populations but could also imply the coalescence and splitting of venting areas in a chaotic fashion. It may therefore produce transient contact-zones between populations. In order to test this hypothesis, temporal evolution of the genetic structure of alvinellid populations was assessed at a fictitious diallelic locus using a neutral (no selection) model in which migration, genetic drift and vent-site spatial-temporal dynamics are considered. The principle of such a model is to alternate periods of generations in which populations settle, grow and exchange migrants according to a specific mode of dispersal, and chaotic events in which a varying proportion of randomly-chosen vent-sites is relocated as new venting areas, these areas being devoid of organisms and therefore recolonized by migrants originated from nearby populations. The effect of vent displacement, dispersal mode, larval travelling time and vent extinction rate were tested on alvinellid populations by following the whole metapopulation size, the total number of migrants and the allelic frequency at each population over 100 000 generations. As little is actually known about the entire larval life of alvinellid polychactes, alternative dispersal situations (dispersal modes 1-4) in which varying proportions of offsprings settle in their own mother population, from high self-recruitment to no self-recruitment at all, were tested. |
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