Meeting Abstract
S3.10 Tuesday, Jan. 4 Speciation in marine microeukaryotes RUNDELL, R.J.*; LEANDER, B.S.; University of British Columbia rrundell@interchange.ubc.ca
Marine microeukaryotes include unicellular “protists” and microscopic metazoans from a vast array of environments: from the pelagic zone, to the inner body spaces of invertebrates, to the interstices of marine sand in the nearshore and deep sea. The diversity of habitats alone suggests that diversification patterns among these groups might vary widely. When you consider that the category “marine microeukaryotes” includes some of the most ancient, as well as recently evolved groups of organisms on Earth, spanning the tree of eukaryotic life, it is clear that understanding speciation in these groups presents a challenge. Indeed, we are just beginning to tackle the enormous microeukaryotic diversity present in the marine realm. One of the first steps in this process, for Recent species, is linking morphology with environmental DNA sequences, as well as sampling and isolating individual species in previously unexplored localities for detailed analyses. Interstitial microeukaryotes, particularly meiofaunal metazoans (which often lack planktonic larvae), provide interesting insights into diversification patterns in the marine realm. We have uncovered many undescribed species, and high levels of endemism, particularly among meiofaunal turbellarian flatworms and acoels. There is little reason to doubt that geographical isolation plays an important role in the evolution of reproductive isolation in these species, as it does in terrestrial systems, although barriers to dispersal and range limits are not always clear. Increased efforts to understand the natural history of marine meiofaunal species might also reveal environmental heterogeneity within the interstitial milieu that could be important for the accumulation of species in certain localities, where multiple, often morphologically convergent, species of unicellular eukaryotes and micro-metazoans co-exist.
