Data from: Inferring the degree of incipient speciation in secondary contact zones of closely related lineages of Palearctic green toads (Bufo viridis subgroup)
Dufresnes, Christophe, University of Lausanne
Bonato, Lucio, University of Padua
Novarini, Nicola, Museo di Storia Naturale di Venezia, Sezione Erpetologia e Ittiologia delle Acque Interne, Venezia, Italy
Betto-Colliard, Caroline, University of Lausanne
Perrin, Nicolas, University of Lausanne
Published Feb 25, 2014 on Dryad.
Cite this dataset
Dufresnes, Christophe et al. (2014). Data from: Inferring the degree of incipient speciation in secondary contact zones of closely related lineages of Palearctic green toads (Bufo viridis subgroup) [Dataset]. Dryad. https://doi.org/10.5061/dryad.85pr1
Reproductive isolation between lineages is expected to accumulate with divergence time, but the time taken to speciate may strongly vary between different groups of organisms. In anuran amphibians, laboratory crosses can still produce viable hybrid offspring >20 My after separation, but the speed of speciation in closely related anuran lineages under natural conditions is poorly studied. Palearctic green toads (Bufo viridis subgroup) offer an excellent system to address this question, comprising several lineages that arose at different times and form secondary contact zones. Using mitochondrial and nuclear markers, we previously demonstrated that in Sicily, B. siculus and B. balearicus developed advanced reproductive isolation after Plio-Pleistocene divergence (2.6 My, 3.3–1.9), with limited historic mtDNA introgression, scarce nuclear admixture, but low, if any, current gene flow. Here, we study genetic interactions between younger lineages of early Pleistocene divergence (1.9 My, 2.5–1.3) in northeastern Italy (B. balearicus, B. viridis). We find significantly more, asymmetric nuclear and wider, differential mtDNA introgression. The population structure seems to be molded by geographic distance and barriers (rivers), much more than by intrinsic genomic incompatibilities. These differences of hybridization between zones may be partly explained by differences in the duration of previous isolation. Scattered research on other anurans suggests that wide hybrid zones with strong introgression may develop when secondary contacts occur <2 My after divergence, whereas narrower zones with restricted gene flow form when divergence exceeds 3 My. Our study strengthens support for this rule of thumb by comparing lineages with different divergence times within the same radiation.
Microsatellite genotypes and mitochondrial D-loop haplogroups dataset
The file includes microsatellite genotypes (12 markers) and mitochondrial D-loop haplogroups of Bufo viridis/balearicus green toads sampled in the Po valley. "NA" indicates missing data. Microsatellites null alleles (estimated with MICROCHECKER) are indicated as "0". For details on the mitochondrial D-loop haplogroups, please refer to the paper.