Abstract
Genetic variation is often lower at high latitudes, which may compromise the adaptability and hence survival of organisms. Here we show that genetic variability is negatively correlated with northern latitude in European green toads (Bufotes viridis). The result holds true for both putatively neutral microsatellite variation and supposedly adaptive MHC Class IIB variation. In particular, our findings have bearing on the conservation status of this species in Sweden, on the northern limit of its distribution where local populations are small and fragmented. These genetically impoverished populations are closely related to other populations found around the Baltic Sea basin. The low neutral and adaptive variation in these fringe populations compared to population at central ranges confirms a pattern shared across all other amphibians so far studied. In Sweden, the situation of green toads is of concern as the remaining populations may not have the evolutionary potential to cope with present and future environmental challenges.
Highlights
A general trend in latitudinal studies of genetic variation is the loss of genetic variability towards the poles (e.g. Adams and Hadly 2012; Miraldo et al 2016; Smith et al 2017)
◂Fig. 4 a neighbor-joining tree and b unrooted phylogenetic network of major histocompatibility complex (MHC) Class II B sequences; sequences found in Swedish samples are indicated in bold, with asterisks; c geographic occurrence of these sequences
The main purpose of this study was to investigate the genetic diversity of Bufotes viridis green toad populations throughout its vast range, with a particular focus on the isolated and red-listed Swedish populations
Summary
A general trend in latitudinal studies of genetic variation is the loss of genetic variability towards the poles (e.g. Adams and Hadly 2012; Miraldo et al 2016; Smith et al 2017). Populations of many species become smaller and more fragmented with increasing latitude Wan et al 2018) This observation is explained by harsher environmental conditions and increasing seasonality with longer and harder winters towards the north (Vellend 2005; Vellend and Geber 2005). During the Quaternary, large parts of the northern hemisphere were completely covered by glaciers and uninhabitable for any form of life (Hewitt 1996, 1999). Since the retreat of the glaciers after the last glacial maximum (LGM) approximately 20.000 years ago, northern species have expanded across the formerly uninhabitable areas. While doing so populations have lost variation during the recolonization process (Hewitt 2000, 2004)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
