Data from: Gene flow of a forest-dependent bird across a fragmented landscape

Habitat loss and fragmentation can affect the persistence of populations
by reducing connectivity and restricting the ability of individuals to
disperse across landscapes. Dispersal corridors promote population
connectivity and therefore play important roles in maintaining gene flow
in natural populations inhabiting fragmented landscapes. In the prairies,
forests are restricted to riparian areas along river systems which act as
important dispersal corridors for forest dependent species across large
expanses of unsuitable grassland habitat. However, natural and
anthropogenic barriers within riparian systems have fragmented these
forested habitats. In this study, we used microsatellite markers to assess
the fine-scale genetic structure of a forest-dependent species, the
black-capped chickadee (Poecile atricapillus), along 10 different river
systems in Southern Alberta. Using a landscape genetic approach, landscape
features (e.g., land cover) were found to have a significant effect on
patterns of genetic differentiation. Populations are genetically
structured as a result of natural breaks in continuous habitat at small
spatial scales, but the artificial barriers we tested do not appear to
restrict gene flow. Dispersal between rivers is impeded by grasslands,
evident from isolation of nearby populations (~ 50 km apart), but also
within river systems by large treeless canyons (>100 km).
Significant population genetic differentiation within some rivers
corresponded with zones of different cottonwood (riparian poplar) tree
species and their hybrids. This study illustrates the importance of
considering the impacts of habitat fragmentation at small spatial scales
as well as other ecological processes to gain a better understanding of
how organisms respond to their environmental connectivity. Here, even in a
common and widespread songbird with high dispersal potential, small breaks
in continuous habitats strongly influenced the spatial patterns of genetic
variation.