Meeting Abstract

53.1  Saturday, Jan. 5  Developmental mode, poecilogony, and population structure of the pyramidellid snail Boonea impressa TEICHHOLTZ, P.J. ; University of Michigan pteich@umich.edu

Poecilogony, the expression of more than one developmental mode in a single species, is usually not viewed as an evolutionarily stable strategy. Poecilogonous species are typically considered transitional states between discrete developmental modes. However, poecilogony may also represent a successful bet-hedging strategy that maximizes fitness under unpredictable conditions. Although species with this condition offer promising systems for illuminating the evolution of life histories, aspects of larval ecology and implications of different developmental modes on population dynamics, poecilogony is difficult to confirm in many cases, and only a few poecilogonous species are known. Many suspected poecilogonous species turn out to be cryptic species complexes. Proper recognition of cryptic speciation is thus necessary for determining the actual prevalence of this condition and identifying appropriate systems for further study. Here I investigated a potential case of poecilogony among Gulf coast populations of the marine snail Boonea impressa. Populations of B. impressa from Galveston Bay and Aransas Bay have been reported as exhibiting direct development and lecithotrophy, respectively. To determine whether cryptic speciation was present in, I utilized molecular phylogenetic and population genetic approaches based on analyses of mitochondrial (COI) and nuclear (ITS2) gene sequences to assess reproductive isolation and genetic structure of three Gulf coast populations of B. impressa. While no clear evidence of cryptic species was found, significant population structure was evident both within and between populations. This pattern is similar to the substantial population structure observed among other confirmed poecilogonous species. Together these results show that intraspecific variation in developmental mode contributes to the diversification of marine invertebrates.