The scaling of genetic diversity in a changing and fragmented world (original) (raw)
Most species do not live in a constant environment over space or time. Their environment is often heterogeneous with a huge variability in resource availability and exposure to pathogens or predators, which may affect the local densities of the species. Moreover, the habitat might be fragmented, preventing free and isotropic migrations between local sub-populations (demes) of a species, making some demes more isolated than others. For example, during the last ice age populations of many species migrated towards refuge areas from which re-colonization originated when conditions improved. However, populations that could not move fast enough or could not adapt to the new environmental conditions may face extinctions. Populations living in these types of dynamic environments are often referred to as metapopulations and modeled as an array of subdivisions (or demes) that exchange migrants with their neighbors. Several studies have focused on the description of their demography, probabili...
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Spatial and temporal patterns of genetic diversity in a fragmented and transient landscape
Evolutionary Ecology, 2020
Anthropogenic disturbance has the potential to influence metapopulation dynamics by altering habitat quality and connectivity. In particular, species with limited vagility and specific habitat preferences, such as the Florida scrub lizard (Sceloporus woodi), are likely to be affected by landscape-altering events. In the Ocala National Forest (ONF) of central Florida, subpopulations of Florida scrub lizards encounter cycles of fire suppression, clear-cutting, and prescribe burning that give rise to a transient landscape and potentially lead to repeated colonization and founder events. As such, Florida scrub lizards in the ONF provide an ideal opportunity in which to explore metapopulation dynamics in a transient landscape. We predict that Florida scrub lizards quickly colonize newly clear-cut patches, disperse from fire-suppressed patches as vegetation density increases, and maintain stable populations in stands consistently managed with prescribe burning. Additionally , we predict that anthropogenically-maintained sand corridors facilitate Florida scrub lizard dispersal between patches. To this end, we used microsatellite markers to quantify genetic variation among Florida scrub lizard subpopulations at two time points separated by approximately six generations because habitat turnover can obscure connectivity-occupancy relationships when analyzed with snapshot data, and spatial analyses to test correlations between landscape metrics (e.g. patch area and proximity) and genetic diversity. Microsatellite markers revealed significant and varied temporal shifts in genetic differentiation among subpopulations, which our analyses indicate are linked to changes in landscape structure. Collectively, our results suggest that the spatial distribution of suitable patches of habitat (i.e. stands of quality habitat) can influence population genetic structure, and that corridors can facilitate gene flow between subpopulations in fragmented and transient landscapes.
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