1 research outputs found
Concordant morphological and molecular clines in a contact zone of the Common and Spined toad (Bufo bufo and B. spinosus) in the northwest of France
Background: Hybrid zones are regions where individuals of two species meet and produce hybrid progeny, and
are often regarded as natural laboratories to understand the process of species formation. Two microevolutionary
processes can take place in hybrid zones, with opposing effects on population differentiation. Hybridization tends
to produce genetic homogenization, reducing species differences, whereas the presence of mechanisms of
reproductive isolation result in barriers to gene flow, maintaining or increasing differences between taxa.
Results: Here we study a contact zone between two hybridizing toad species, Bufo bufo and B. spinosus, through a
combination of molecular (12 polymorphic microsatellites, four nuclear and two mitochondrial SNP markers) and
morphological data in a transect in the northwest of France. The results show largely concordant clines across
markers, defining a narrow hybrid zone of ca. 30 km wide. Most hybrids in the centre of the contact zone are
classified as F2 or backcrossed individuals, with no individuals assigned to the F1 hybrid class.
Conclusions: We discuss the implications of these results for our understanding of the evolutionary history of these
species. We anticipate that the toad contact zone here described will become an important asset in the study of
hybrid zone dynamics and evolutionary biology because of its easy access and the abundance of the species involvedPeer reviewe