Hybridization between land snails as a result of climatic shifts
Molecular genetic studies have shown that hybridization occurs much more frequently also in animals than was previously assumed. Genes are often exchanged between closely related species. Often the species remain separated despite the gene exchange. However, hybridization can also result in the fusion of species or the origin of new species. The factors affecting the evolutionary results and the frequency of the different outcomes have only been inadequately explored so far.
Man-made climate change results in shifts of the ranges of many species. Such range shifts increase the likelihood that closely related species encounter and, thus, the likelihood of hybridization. Natural climate changes such as those during and after the ice ages also led to range shifts and hybridization.
In a research group on hybrids funded by state research funding program of Hamburg, we investigate the effects of climate fluctuations during and after the ice ages on speciation processes. As a model system, door snails of the genus Charpentieria are used. A group of populations of this genus has survived the glacials in mountain regions in the Southern Alps, which were not covered by the alpine glaciers. Other Charpentieria populations have survived the ice ages in valleys south of the alpine glaciers. As a result of postglacial climate warming and the melting of the glaciers, these have spread into the Alps again, where they encountered populations that survived the glacials in the montane refugia in several places. In some cases, the populations that were separated during the glacials were already differentiated to such an extent that only little hybridization occurred that did not result in a fusion of the taxa. By contrast, in one region hybridization has resulted in a nearly continuous transition between the previously isolated populations. We investigate the genetic basis of the differentiation of different populations with the help of next generation seqencing methods such as ddRAD-Seq and we try to understand the genetic and environmental factors that led to the different evolutionary outcomes. This project may contribute to a prediction of the evolutionary impact of man-made climate change.
Doctoral thesis Jie Xu (funded by Hamburg state research funding program).
- Xu, J. & Hausdorf, B. 2021. Repeated hybridization increased diversity in the door snail complex Charpentieria itala in the Southern Alps. Mol. Phylogenet. Evol., 155: 106982.