Genotypic similarities among the parthenogenetic Darevskia rock lizards with different hybrid origins

BMC Evolutionary Biology

Çetin Ilgaz¹  Kamil Candan¹  Ferhat Matur¹  Yusuf Kumlutaş¹  Mehmet Kürşat Şahin²  Mariam Gabelaia³  Marine Murtskhvaladze³  David Tarkhnishvili³  Natia Barateli³  Cort L. Anderson³  Giorgi Iankoshvili³  Sofiko Kurdadze³  Meriç Erdolu⁴  Eduard Galoyan⁵  Marine Arakelyan⁶  Alexey Yanchukov⁷  Faruk Çolak⁷ 

[1] Faculty of Science, Department of Biology, Dokuz Eylül University, İzmir, Turkey;Faculty of Science, Department of Biology, Hacettepe University, Ankara, Turkey;Institute of Ecology, Ilia State University, Tbilisi, Georgia;Middle East Technical University, Faculty of Science, Department of Biology, Ankara, Turkey;Moscow State University, Moscow, Russia;Yerevan State University, Yerevan, Armenia;Zonguldak Bülent Ecevit University, Zonguldak, Turkey;

关键词: Darevskia;    Parthenogenesis;    Microsatellites;    Mitochondrial DNA;    Backcrosses;    Allele conversion;    Caucasian rock lizards;   

DOI  :  10.1186/s12862-020-01690-9

来源: Springer

【 摘 要 】

BackgroundThe majority of parthenogenetic vertebrates derive from hybridization between sexually reproducing species, but the exact number of hybridization events ancestral to currently extant clonal lineages is difficult to determine. Usually, we do not know whether the parental species are able to contribute their genes to the parthenogenetic vertebrate lineages after the initial hybridization. In this paper, we address the hypothesis, whether some genotypes of seven phenotypically distinct parthenogenetic rock lizards (genus Darevskia) could have resulted from back-crosses of parthenogens with their presumed parental species. We also tried to identify, as precise as possible, the ancestral populations of all seven parthenogens.ResultsWe analysed partial mtDNA sequences and microsatellite genotypes of all seven parthenogens and their presumed ansectral species, sampled across the entire geographic range of parthenogenesis in this group. Our results confirm the previous designation of the parental species, but further specify the maternal populations that are likely ancestral to different parthenogenetic lineages. Contrary to the expectation of independent hybrid origins of the unisexual taxa, we found that genotypes at multiple loci were shared frequently between different parthenogenetic species. The highest proportions of shared genotypes were detected between (i) D. sapphirina and D. bendimahiensis and (ii) D. dahli and D. armeniaca, and less often between other parthenogens. In case (ii), genotypes at the remaining loci were notably distinct.ConclusionsWe suggest that both observations (i-ii) can be explained by two parthenogenetic forms tracing their origin to a single initial hybridization event. In case (ii), however, occasional gene exchange between the unisexual and the parental bisexual species could have taken place after the onset of parthenogenetic reproduction. Indeed, backcrossed polyploid hybrids are relatively frequent in Darevskia, although no direct evidence of recent gene flow has been previously documented. Our results further suggest that parthenogens are losing heterozygosity as a result of allelic conversion, hence their fitness is expected to decline over time as genetic diversity declines. Backcrosses with the parental species could be a rescue mechanism which might prevent this decline, and therefore increase the persistance of unisexual forms.

【 授权许可】

CC BY