Divergent clades or cryptic species? Mito-nuclear discordance in a Daphnia species complex

BMC Evolutionary Biology

Research Article

Ali Mohammadyari¹  Adam Petrusek²  Klaus Schwenk³  Anne Thielsch³  Alexis Knell³ 

[1] Faculty of Science, Department of Biology, Ferdowsi University of Mashhad, Mashhad, Iran;Faculty of Science, Department of Ecology, Charles University, Prague, Czechia;Institute for Environmental Sciences, Molecular Ecology, University of Koblenz-Landau, Landau in der Pfalz, Germany;

关键词: Interspecific hybridization;    Adaptive introgression;    Ancestral polymorphism;    Incomplete lineage sorting;    Cladocera;    Daphnia longispina;   

DOI  :  10.1186/s12862-017-1070-4

 received in 2017-06-08, accepted in 2017-11-08,  发布年份 2017

来源: Springer

【 摘 要 】

BackgroundGenetically divergent cryptic species are frequently detected by molecular methods. These discoveries are often a byproduct of molecular barcoding studies in which fragments of a selected marker are used for species identification. Highly divergent mitochondrial lineages and putative cryptic species are even detected in intensively studied animal taxa, such as the crustacean genus Daphnia. Recently, eleven such lineages, exhibiting genetic distances comparable to levels observed among well-defined species, were recorded in the D. longispina species complex, a group that contains several key taxa of freshwater ecosystems. We tested if three of those lineages represent indeed distinct species, by analyzing patterns of variation of ten nuclear microsatellite markers in six populations.ResultsWe observed a discordant pattern between mitochondrial and nuclear DNA, as all individuals carrying one of the divergent mitochondrial lineages grouped at the nuclear level with widespread, well-recognized species coexisting at the same localities (Daphnia galeata, D. longispina, and D. cucullata).ConclusionsA likely explanation for this pattern is the introgression of the mitochondrial genome of undescribed taxa into the common species, either in the distant past or after long-distance dispersal. The occurrence of highly divergent but rare mtDNA lineages in the gene pool of widespread species would suggest that hybridization and introgression in the D. longispina species complex is frequent even across large phylogenetic distances, and that discoveries of such distinct clades must be interpreted with caution. However, maintenance of ancient polymorphisms through selection is another plausible alternative that may cause the observed discordance and cannot be entirely excluded.

【 授权许可】

CC BY   
© The Author(s). 2017