Ice age cloning – comparison of the Quaternary evolutionary histories of sexual and clonal forms of spiny loaches (Cobitis; Teleostei) using the analysis of mitochondrial DNA variation

Abstract

Recent advances in population history reconstruction offered a powerful tool for comparisons of the abilities of sexual and clonal forms to respond to Quaternary climatic oscillations, ultimately leading to inferences about the advantages and disadvantages of a given mode of reproduction. We reconstructed the Quaternary historical biogeography of the sexual parental species and clonal hybrid lineages within the Europe-wide hybrid complex of Cobitis spiny loaches. Cobitis elongatoides and Cobitis taenia recolonizing Europe from separated refuges met in central Europe and the Pontic region giving rise to hybrid lineages during the Holocene. Cobitis elongatoides due to its long-term reproductive contact with the remaining parental species of the complex--C. tanaitica and C. spec.--gave rise to two clonal hybrid lineages probably during the last interglacial or even earlier, which survived the Würmian glaciation with C. elongatoides. These lineages followed C. elongatoides postglacial expansion and probably decreased its dispersal rate. Our data indicate the frequent origins of asexuality irrespective of the parental populations involved and the comparable dispersal potential of diploid and triploid lineages.

A northern glacial refugium for bank voles ( Clethrionomys glareolus )

“…This finding is supported by evidence from animal fossils, which provide records of woodland species of small mammals in deposits from the last glaciation in the Carpathians (10,11). Furthermore, divergent mtDNA sequences from extant Carpathian populations of several temperate vertebrate species, including amphibians (12,13) and fish (14,15), indicate the maintenance of separate lineages that may have persisted in the Carpathians during the last glaciation. Various lines of evidence thus point to the existence of a glacial refugium for temperate species in the Carpathians.…”

The evolutionary history of the allopolyploid Squalius alburnoides (Cyprinidae) complex in the northern Iberian Peninsula

“…However, the low frequency of hybrid males and the absence of AA males make the northern populations more dependent on the sympatric sexual species, S. carolitertii. Thus, the northern hybrid populations have more competition with the sexual species that probably reduces their dispersal potential and settlement, similar to what has been proposed for the spiny loaches (Janko et al, 2005). The absence of AA males and of symmetrical tetraploids from the Mondego populations (Figure 1) reduces the incorporation of new genetic material in the A genome, resulting in decreased genetic diversity compared with the southern populations and perhaps restricting their long term persistence (Pala and Coelho, 2005).…”

Sperm-dependent parthenogens delay the spatial expansion of their sexual hosts

“…This problem has many more or less plausible explanations, but our previous analysis (Janko et al 2005) suggests that C. taenia expanded as a 'pure' sexual population, which was 'infected'…”

“…Such A c c e p t e d m a n u s c r i p t hybridizations likely take place during interglacial periods, when sexual species intermittently come into reproductive contact and the resulting gynogenetic hybrid all-female lineages subsequently invade the areas of parental species (Janko et al 2005). Two of the parental species, C. taenia and C. elongatoides, are widespread in Europe, but whereas the former species inhabits most of the eastern, western and northern Europe, the latter is restricted to the Danubian watershed and to upper stretches of the Odra and Elbe rives.…”