Abstract
Habitat fragmentation due to both natural and anthropogenic forces continues to threaten the evolution and maintenance of biological diversity. This is of particular concern in tropical regions that are experiencing elevated rates of habitat loss. Although less well-studied than tropical rain forests, tropical dry forests (TDF) contain an enormous diversity of species and continue to be threatened by anthropogenic activities including grazing and agriculture. However, little is known about the processes that shape genetic connectivity in species inhabiting TDF ecosystems. We adopt a landscape genetic approach to understanding functional connectivity for leaf-toed geckos (Phyllodactylus tuberculosus) at multiple sites near the northernmost limit of this ecosystem at Alamos, Sonora, Mexico. Traditional analyses of population genetics are combined with multivariate GIS-based landscape analyses to test hypotheses on the potential drivers of spatial genetic variation. Moderate levels of within-population diversity and substantial levels of population differentiation are revealed by F ST and D est. Analyses using structure suggest the occurrence of from 2 to 9 genetic clusters depending on the model used. Landscape genetic analysis suggests that forest cover, stream connectivity, undisturbed habitat, slope, and minimum temperature of the coldest period explain more genetic variation than do simple Euclidean distances. Additional landscape genetic studies throughout TDF habitat are required to understand species-specific responses to landscape and climate change and to identify common drivers. We urge researchers interested in using multivariate distance methods to test for, and report, significant correlations among predictor matrices that can impact results, particularly when adopting least-cost path approaches. Further investigation into the use of information theoretic approaches for model selection is also warranted.
Highlights
Dispersal is a fundamental process that can greatly influence ecological and demographic trajectories within and between subpopulations [1]
By combining rapidly evolving molecular markers such as microsatellites with novel approaches to statistical analysis, landscape genetics identifies a suite of environmental variables likely to influence population genetic structure [19,20,21]
Genetic diversity All microsatellite data were deposited in Dryad
Summary
Dispersal is a fundamental process that can greatly influence ecological and demographic trajectories within and between subpopulations [1]. Dispersal often leads to gene flow, the transfer of genetic information from one population to another [2,3]. Landscape heterogeneity often plays a substantial role in the ability and/or choice of an organism to disperse or not [9,10,11] Both natural and anthropogenic habitat fragmentation can detrimentally affect the connectivity and persistence of populations [12,13,14,15]. Landscape genetics seeks to explicitly quantify the influence of landscape and environmental variables on microevolutionary processes such as gene flow and natural selection [16,17]. The approach extends traditional population genetic studies by explaining the spatial distribution of genetic variation using components of the landscape. Relatively little is known about the processes influencing functional connectivity in species inhabiting this megadiverse region
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