Representatives of the genus Sars (Crustacea: Cladocera: Chydorinae) belong to the smallest known water fleas. Although species of are widely distributed and often abundant in acidic and mountain water bodies, their diversity is poorly studied. Morphological and genetic approaches have been complicated by the minute size of these microcrustaceans. As a result, taxonomists have avoided revising these species. Here, we present genetic data on species diversity across the Northern Hemisphere with particular attention to the species complex. We analyzed 82 16S rRNA sequences (all newly obtained), and 78 COI sequences (39 were newly obtained). The results revealed at least twelve divergent phylogenetic lineages, possible cryptic species, of , with different distribution patterns. As expected, the potential species diversity of this genus is significantly higher than traditionally accepted. The complex is represented by nine divergent clades in the Northern Hemisphere, some of them have relatively broad distribution ranges and others are more locally distributed. Our results provide a genetic background for subsequent morphological analyses, formal descriptions of species and detailed phylogeographical studies.
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http://dx.doi.org/10.7717/peerj.10804 | DOI Listing |
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Space and Earth Observation Centre, Finnish Meteorological Institute, Helsinki, Finland.
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School of Atmospheric Sciences, Sun Yat-Sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China.
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College of Horticulture, Sichuan Agricultural University, Chengdu 611130, China.
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The diphyllobothriid tapeworm Dibothriocephalus dendriticus, one of the causative agents of the fish-borne zoonosis dibothriocephalosis, is mainly distributed in the Arctic/subarctic and temperate zones of the Northern Hemisphere (Europe, North America, and Asia), but also in the southern cone region of South America (Patagonia). The genetic structure and gene flow among 589 individuals of D. dendriticus, representing 20 populations, were studied using the mitochondrial cox1 gene as the first choice marker and 10 polymorphic nuclear microsatellite loci as a dominant molecular tool.
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