S3-2.2 Wednesday, Jan. 4 The consequences of a poecilogonous life history for dispersal ability, genetic structure and gene flow in coastal populations of the polychaete Streblospio benedicti ZAKAS, Christina*; WARES, John P; University of Georgia; University of Georgia email@example.com
In many species, alternative developmental pathways lead to the production of two distinct phenotypes, promoting the evolution of morphological novelty and diversification. One such species, the poecilogonous marine annelid Streblospio benedicti, is an ideal system to study the evolutionary consequences of larval life history mode because adults either produce many small planktotrophic larvae that spend weeks feeding in the water column, or fewer, larger lecithotrophic larvae that complete development more rapidly. Larval type influences transport time by ocean currents, which dictates dispersal potential and gene flow, and thus has sweeping evolutionary effects on the potential for local adaptation and on rates of speciation, extinction, and molecular evolution. Here we further develop S. benedicti as a model system for studies of life history evolution by using next-generation sequencing to characterize the transcriptome for a pooled set of embryos, larvae, and juveniles. We developed and validated 84 novel single nucleotide polymorphism (SNPs) markers for this species that we use to distinguish populations on the U.S. East and West Coast. Using these markers we found that in their native East Coast, populations of S. benedicti have high population genetic structure, but that this structure is dictated predominately by geography rather then developmental type. Interestingly, very little genetic differentiation is recovered between individuals of different development types when they occur in the same or nearby populations, further supporting that this is a true case of poecilogony. In addition, we were able to demonstrate that the recently introduced West Coast populations (~100ya) likely originated from a lecithotrophic population in Delaware.