Meeting Abstract

P3-31   -   Fine-scale reproductive and embryological differences between the two larval types of the poecilogonous annelid Streblospio benedicti Cole, SM*; Zakas, C; North Carolina State University, Raleigh, NC; North Carolina State University, Raleigh, NC smcole3@ncsu.edu

Streblospio benedicti is a marine annelid that is poecilogonous, where a single species produces two different larval types: small, feeding planktotrophs and large, yolk-feeding lecithotrophs. This study compares the two developmental morphs during reproduction, embryogenesis, and larval development. We looked at three different populations with different development types: one planktotrophic (Bayonne, NJ), one lecithotrophic (Long Beach, CA), and one potentially mixed population (Baruch Marine Lab, SC). To determine differences in life history traits between the developmental types, we measured adult female size, embryo area, and fecundity for each of the populations. We determined differences in reproductive output between the types and also subtle variation that may exist between populations. We created a timeline of embryogenesis and larval development, from the one-cell stage to free-swimming larvae, to compare differences in size and timing between the developmental modes. In addition, we crossed the two types and measured these same life-history traits in the offspring of F₁ females, which have intermediate reproductive traits. This analysis of reproductive and embryological differences lays the groundwork for understanding how the different larval types of S. benedicti develop, and how these developmental differences affect transitions in life history.