S3-2.3 Wednesday, Jan. 4 Developmental mode polymorphism and population connectivity in the polychaete Pygospio elegans KESäNIEMI, J.E.*; KNOTT, K.E.; University of Jyväskylä, Finland; University of Jyväskylä, Finland email@example.com
The tube building polychaete Pygospio elegans is poecilogonous, producing both dispersive planktotrophic larvae and brooded lecithotrophic larvae released as benthic juveniles. Because these larvae have differing dispersal potential, variation in developmental mode both within and among populations can have a significant impact on population connectivity and distribution of genetic variation. An assessment of population connectivity is therefore interesting, since gene flow between populations will diminish potential divergence between populations. If developmental plasticity is an adaptation for coping with variable environmental conditions, dispersing offspring should fare well in many environments and resulting gene flow is expected to be high. If divergence is occurring between different populations (either via selection or drift) gene flow among populations will be reduced. I use data from microsatellite markers to estimate divergence and connectivity among 19 European P. elegans populations. A transition zone affecting marine species distribution is commonly seen between the Baltic and North Sea. In P. elegans, low but significant structure is seen between these regions, and preliminary analyses show asymmetrical gene flow among populations. Results also indicate high gene flow among the mainly planktonic North Sea and English Channel populations, and higher levels of differentiation among the Baltic Sea populations that have longer brooding. Highest allelic richness, an indication of larger effective population size, is observed in the North Sea, the English Channel and Germany. Correlations of genetic divergence and geographic distances are explored with a variety of methods.