Meeting Abstract

34.2  Friday, Jan. 4  Unexpected patterns of connectivity and phylogeographic breaks in Mediterranean marine cave mysids RASTORGUEFF, P.-A.*; CHEVALDONNé, P.; LEJEUSNE, C.; Aix-Marseille Université – UMR CNRS 7263 IMBE; Aix-Marseille Université – UMR CNRS 7263 IMBE; Estación Biológica de Doñana – CSIC pierre-alexandre.rastorgueff@imbe.fr

Habitat fragmentation is a major threat to biodiversity by reducing habitat availability and interpopulation connectivity. Submarine caves represent a naturally fragmented habitat allowing to understand how habitat fragmentation affects connectivity. We worked on the Mediterranean brooding cave-dwelling mysids Hemimysis margalefi and Harmelinella mariannae which disperse only as adults. At the Mediterranean scale, our phylogeographic study based on several mitochondrial and nuclear molecular markers revealed that H. margalefi is actually composed of five highly divergent lineages, likely representing as many events of ongoing allopatric speciation. Populations of the different lineages are highly structured genetically mostly according to the general current circulation and the geography of the Mediterranean, habitat fragmentation and poor dispersal abilities. However, some well-known barriers to gene flow appear to have a surprisingly reduced influence on this species. Compared to H. margalefi, the little-known H. mariannae shows far less structured populations. This is particularly puzzling since this species, considered rare, has a more fragmented habitat. At small geographical scale, the use of microsatellite markers has evidenced differences in the genetic population structuring of H. margalefi compared to mitochondrial data. Understanding marine population connectivity in fragmented habitats has proved more complex than previously thought and may benefit from unconventional biological models such as marine cave mysids.