Meeting Abstract

128.7  Tuesday, Jan. 7 15:00  Dimorphic Development in Streblospio benedicti: Characterizing key morphological shifts between larval types using hybrid crosses ZAKAS, C*; ROCKMAN, MV.; New York University; New York University christinazakas@gmail.com

Mechanisms of early development can constrain body plan evolution, but the extent to which these developmental constraints shape larval morphology, and thus suites of life-history traits, remains unresolved. Poecilogonous species, such as the marine polychaete Streblospio benedicti, produce two distinct larval types and are ideal systems to study differentiation between contrasting developmental plans. S. benedicti has a population-level egg size dimorphism- a ~5 fold difference in egg size occurs between morphs- with cascading effects on larval development. Distinct morphological differences between the larval types are well described in some populations, including the presence of larval bristles, the ability (or need) for larval feeding, and the timing of emergence of adult features such as palps and branchiae. Here, we characterize these traits in a number of populations of both larval types to determine the amount of variation at the population and family level. We also cross adults of both morphological types to establish the extent that key larval features are maternally or zygotically controlled in the F1s, and thus begin to uncover the potential mechanisms that drive the evolution of larval mode.