Comparison of Genetic Variation among Rocky Intertidal Snails on the Sanriku Coast, with Data of Genetic Structure of Nucella heyseana Before and After the Great East Japan Earthquake and Tsunami in 2011

Abstract

Genetic variation is often determined by species' specific life history traits, but natural disturbances are also expected to affect it. However, studies of the latter are limited due to the contingency of disturbances. Here, we focus on six rocky intertidal snails, including Nucella heyseana which is suitable model species for a comparison of genetic diversity and structure before and after the Great East Japan Earthquake and tsunami in 2011. They are distributed on the Sanriku coast, where the marine ecosystems have been repeatedly affected by tsunamis. Two years after the 2011 tsunami, we evaluated genetic diversity and the levels of genetic connectivity of snails representing different developmental types: five planktonic larval developers and one direct developer (N. heyseana). There was no significant genetic differentiation among populations in the planktonic larval developers, while N. heyseana exhibited significant genetic differentiation. Comparing the genetic diversity before and after the 2011 tsunami, we detected changes in haplotype frequencies and a decline in genetic diversity (Hachinohe population). Given its low dispersal ability, the effects of a massive disturbance can vary among populations. Comparative genetic studies can contribute to understanding the influence of massive natural disturbances on the genetic structure and diversity of marine species.