Divergence in life-history traits among three populations of the sea snake Emydocephalus anulatus

Life-history traits such as rates of growth, survival and reproduction can
vary though time within a single population, or through space among
populations, due to abiotically-driven changes in resource availability.
In terrestrial reptiles, parameters such as temperature and rainfall
generate variation in life-histories – but other parameters likely are
more important in marine systems. We studied three populations of sea
snakes (Emydocephalus annulatus) in adjacent bays in the IndoPacific
archipelago of New Caledonia. The extreme philopatry of individual snakes
allows us to unambiguously allocate each animal to one of the three
populations. Although water temperatures and rainfall do not differ over
this small scale, one site experiences more intense winds, restricting
opportunities for foraging. Our 18-year mark-recapture dataset
(>1,200 snakes, >2,400 captures) reveals significant
divergence among populations in life-history traits. Survival rates and
population densities were similar among sites, but snakes at the most
wind-exposed site (Anse Vata) exhibited lower body condition, slower
growth, less frequent production of litters, and smaller litters.
Weather-driven variation in feeding rates thus may affect life-history
traits of marine snakes as well as their terrestrial counterparts, but
driven by different parameters (e.g., wind exposure rather than variation
in temperatures or rainfall).