Meeting Abstract

24.5  Wednesday, Jan. 5  Divergence of Baltic Sea populations of the poecilogonous polychaete Pygospio elegans reflects barriers to dispersal and predominant developmental mode KESANIEMI, J.E.; KNOTT, K.E.*; University of Jyvaskyla; University of Jyvaskyla emily.knott@jyu.fi

Pygospio elegans is a poecilogonous species capable of producing either planktonic or brooded larvae following sexual reproduction. The different larvae are expected to also differ in dispersal potential, which in turn is expected to have ramifications for the genetic connectivity of populations. We surveyed the genetic structure of populations ranging from the Baltic Sea to the North Sea using species specific microsatellite markers. Populations from Finland were significantly differentiated from other populations. Here, P. elegans is known to reproduce asexually as well as with brooded larvae. Populations that produce planktonic larvae (from the UK and France) showed very low differentiation. A general trend of increasing differentiation with distance was observed. Differentiation in microsatellite loci was related to DNA sequence diversity in the mitochondrial gene cytochrome oxidase subunit I with highly differentiated populations being also less diverse. Barriers to dispersal related to distance and a change in salinity can explain to observed results. We propose that brooding in this species may provide a selective advantage after recruitment to extreme environments, providing a potential evolutionary explanation for how poecilogony could be a transitional stage in speciation.