Pleistocene‐driven diversification in freshwater zooplankton: Genetic patterns of refugial isolation and postglacial recolonization in Leptodora kindtii (Crustacea, Cladocera)

Abstract

In this study we investigate the extent to which successive range fragmentations, postglacial expansions, and recolonizations influenced intraspecific genetic diversity and patterns of diversification in freshwater zooplankton. Specifically, we explore the global phylogeography of the Holarctic predatory cladoceran Leptodora kindtii Focke, 1844. Phylogenetic analyses based on the mitochondrial cytochrome c oxidase subunit I recover seven deeply divergent lineages (11.8-20.0%) comprising two sister clades within the Nearctic and east Palearctic and three related clades within the west Palearctic. Strong continental endemism was also supported by the nuclear 18S ribosomal gene. Intra-continental divergence levels (, 6%) suggest that many speciation events in Leptodora were initiated by glacial isolation. Demographic and network analyses indicate that in the Nearctic and west Palearctic, regions heavily affected by the Pleistocene glaciations, Leptodora persisted in both classic (e.g., Cascadia, Mississippi, southern Europe) and cryptic refugia (e.g., northeastern Europe, Carpathian basin). Strong signatures of late Pleistocene range expansions and secondary contact were observed in most clades. Deeper intraspecific phylogeographic structure occurs across much finer geographic scales in unglaciated regions of the east Palearctic than across glaciated Nearctic and west Palearctic regions. Leptodora's ecological and biological characteristics, such as a reliance on temperate, permanent lakes, weak dispersal ability, and specific geological settings likely shaped the complex pattern of diversification in this important planktonic predator. Our data suggest the Pleistocene glaciations were important in the diversification of Holarctic freshwater zooplankton.

Phylogeography of the Chydorus sphaericus Group (Cladocera: Chydoridae) in the Northern Palearctic

“…The existence of unique clades in the Eastern Palearctic has been detected in several other cladoceran groups [9, 78–80]. So the apparent increased diversity of this region seems relevant in both littoral and planktonic cladocerans.…”

“…At the same time, some specific taxa were detected by morphological methods in the Eastern Siberia and preliminarily identified as "American" ones [50, 86]. The Eastern Siberian-Nearctic connection has been detected in previous genetic studies in other cladocerans [7, 78–80], but Eastern Siberia is still poorly represented. Thus far, only Daphnia of this region is just beginning to be studied with the use of molecular markers [87–88].…”

Evolutionary refugia and ecological refuges: key concepts for conserving Australian arid zone freshwater biodiversity under climate change

“…Refugia have also been important in the evolution and ecology of aquatic organisms in extreme polar climates. Arctic lakes have acted as refugia for freshwater invertebrates, the cladoceran crustaceans Daphnia and Leptodora (Weider & Hobaek, ; Millette et al ., ), and freshwater fishes, the lake trout, Salvelinus spp (Wilson & Hebert, ), during multiple Pleistocene glaciation events.…”

Annotated Checklist of Chinese Cladocera (Crustacea: Branchiopoda). Part I. Haplopoda, Ctenopoda, Onychopoda and Anomopoda (families Daphniidae, Moinidae, Bosminidae, Ilyocryptidae)

“…Records: cited from various localities in China under the name L. kindtii; Uéno, 1937: 208 (Non-ho (viz Nen Jiang) near Qiqihar); : 552 (Ulungur Hu; Xingkai Hu=Lake Khanka); Mashiko, 1951b: 141 (Hankou, Dongting Hu);: 109/IV: 31 (Wuli Hu); : 29/ X: 22 (Tai Hu); Du & Lai, 1959: 305 (Tai Hu); Chiang & Du, 1979: 80-82 Figure 2, however, most of these records beg morphological as well as genetical confirmation. Millette et al (2011) confirmed the existence of two species in the Eastern Palaearctic, but did not mention any hybrids. Genetical studies of Leptodora need to be continued.…”