Meeting Abstract
Understanding the genetic basis of life-history traits is a long-standing goal of evolutionary biology. Many closely related species have contrasting life-history strategies, suggesting that the switches in early development that lead to divergent life-histories evolve quickly and frequently. Life-history changes that originate in early development have profound downstream effects on a species’ morphology, ecology, genetic diversity, and even speciation rate. How do such switches in development mode evolve, and what is the underlying genetic architecture? To address this, we use an emerging model in developmental evolution, the polychaete Streblospio benedicti, which has two contrasting, but highly-heritable offspring types. We compare transcriptome sequences of adult individuals of the two development modes to determine the extent of genomic differentiation that contributes to life-history mode. We find that there is extensive allele sharing across the two types, and minimal fixed differences, most of which are likely not associated with developmental mode. This suggests that the evolution of a genetic developmental dimorphism is not associated with longstanding genetic isolation or by genomically extensive divergence. Rather, differences at a few developmentally important loci, or modest allele-frequency differences at many loci, may be responsible for the drastic life-history differences.
