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Summary1. The ability to identify regions of high functional connectivity for multiple wildlife species is of conservation interest with respect to habitat management and corridor planning. We present a method that does not require independent, field-collected data, is insensitive to the placement of source and destination sites (nodes) for modeling connectivity, and does not require the selection of a focal species. 2. In the first step of our approach, we created a cost surface that represented permeability of the landscape to movement for a suite of species. We randomly selected nodes around the perimeter of the buffered study area and used circuit theory to connect pairs of nodes. When the buffer was removed, the resulting current density map represented, for each grid cell, the probability of use by moving animals. 3. We found that using nodes that were randomly located around the perimeter of the buffered study area was less biased by node placement than randomly selecting nodes within the study area. We also found that a buffer of ≥ 20% of the study area width was sufficient to remove the effects of node placement on current density. We tested our method by creating a map of connectivity in the Algonquin to Adirondack region in eastern North America, and we validated the map with independently collected data. We found that amphibians and reptiles were more likely to cross roads in areas of high current density, and fishers (Pekania [Martes] pennanti) used areas with high current density within their home ranges. 4. Our approach provides an efficient and cost effective method of predicting areas with relatively high landscape connectivity for multiple species..

We investigated the relationships among landscape quality, gene flow, and population genetic structure of fishers (Martes pennanti) in ON, Canada. We used graph theory as an analytical framework considering each landscape as a network node. The 34 nodes were connected by 93 edges. Network structure was characterized by a higher level of clustering than expected by chance, a short mean path length connecting all pairs of nodes, and a resiliency to the loss of highly connected nodes. This suggests that alleles can be efficiently spread through the system and that extirpations and conservative harvest are not likely to affect their spread. Two measures of node centrality were negatively related to both the proportion of immigrants in a node and node snow depth. This suggests that central nodes are producers of emigrants, contain high-quality habitat (i.e., deep snow can make locomotion energetically costly) and that fishers were migrating from high to low quality habitat. A method of community detection on networks delineated five genetic clusters of nodes suggesting cryptic population structure. Our analyses showed that network models can provide system-level insight into the process of gene flow with implications for understanding how landscape alterations might affect population fitness and evolutionary potential.

There is now unequivocal evidence for global climate change; however, its potential impacts on evolutionary processes remain unclear. Many species have responded to contemporary climate change through shifts in their geographic range. This could lead to increased sympatry between recently diverged species; likely increasing the potential for hybridization. Recently, following a series of warm winters, southern flying squirrels (Glaucomys volans) in Ontario, Canada rapidly expanded their northern range limit resulting in increased sympatry with the closely related northern flying squirrel (Glaucomys sabrinus). This provided the opportunity to test the prediction that contemporary climate change can act as a catalyst creating conditions for the formation of hybrid zones. Following extensive sampling and molecular analyses (nuclear and mitochondrial DNA), we identified the occurrence of hybridization between sympatric G. sabrinus and G. volans. There was evidence of backcrossing but not of extensive introgession, consistent with the hypothesis of recent rather than historic hybridization. To our knowledge, this is the first report of hybrid zone formation following a range expansion induced by contemporary climate change. This is also the first report of hybridization between North American flying squirrel species.

Th eoretical models predict strong infl uences of habitat loss and fragmentation on species distributions and demography, but empirical studies have shown relatively inconsistent support across species and systems. We argue that species ' responses to landscape-scale habitat loss and fragmentation are likely to appear less idiosyncratic if it is recognized that species perceive the same landscapes in diff erent ways. We present a new quantitative approach that uses species distribution models (SDMs) to measure landscapes (e.g. patch size, isolation, matrix amount) from the perspective of individual species. First, we briefl y summarize the few eff orts to date demonstrating that once diff erences in habitat distributions are controlled, consistencies in species ' responses to landscape structure emerge. Second, we present a detailed example providing step-by-step methods for application of a species-centered approach using freely available land-cover data and recent statistical modeling approaches. Th ird, we discuss pitfalls in current applications of the approach and recommend avenues for future developments. We conclude that the species-centered approach off ers considerable promise as a means to test whether sensitivity to habitat loss and fragmentation is mediated by phylogenetic, ecological, and life-history traits. Cross-species generalities in responses to habitat loss and fragmentation will be challenging to uncover unless landscape mosaics are defi ned using models that refl ect diff ering species-specifi c distributions, functional connectivity, and domains of scale. Th e emergence of such generalities would not only enhance scientifi c understanding of biotic processes driving fragmentation eff ects, but would allow managers to estimate species sensitivities in new regions.

Urbanization and associated environmental changes are causing global declines in vertebrate populations. In general, population declines of the magnitudes now detected should lead to reduced effective population sizes for animals living in proximity to humans and disturbed lands. This is a cause for concern because effective population sizes set the rate of genetic diversity loss due to genetic drift, the rate of increase in inbreeding and the efficiency with which selection can act on beneficial alleles. We predicted that the effects of urbanization should decrease effective population size and genetic diversity, and increase population-level genetic differentiation. To test for such patterns, we repurposed and reanalysed publicly archived genetic datasets for North American birds and mammals. After filtering, we had usable raw genotype data from 85 studies and 41 023 individuals, sampled from 1008 locations spanning 41 mammal and 25 bird species. We used census-based urban–rural designations, human population density and the Human Footprint Index as measures of urbanization and habitat disturbance. As predicted, mammals sampled in more disturbed environments had lower effective population sizes and genetic diversity, and were more genetically differentiated from those in more natural environments. There were no consistent relationships detectable for birds. This suggests that, in general, mammal populations living near humans may have less capacity to respond adaptively to further environmental changes, and be more likely to suffer from effects of inbreeding.

The release of domesticated organisms into natural populations may adversely affect these populations through predation, resource competition, and the introduction of disease. Additionally, the potential for hybridization between wild and domestic conspecifics is of great concern because it can alter the evolutionary integrity of the affected populations. Wild American mink (Neovison vison) populations may be threatened not only by competition for resources with domestic mink originating from farms, but by breeding with such escapees. Using 10 microsatellite loci, we genotyped mink from Ontario, Canada, sampled from two farms, two putatively mixed populations in regions surrounding the mink farms, and two wild populations with no recent history of mink farming. Using individual-based Bayesian population assignment, we identified four population clusters, including one wild, and three domestic populations. The latter were not clustered by farm but rather by distinct line-bred colour phases. Population clustering also identified domestic and hybrid mink in the free-ranging populations. Nearly two-thirds of the mink sampled in the two putatively mixed populations (78% and 43%) were either farm escapees or descendants of escapees. Principal components analysis of allele frequencies supported our Bayesian assignment results. The power of our assignment test was assessed using simulated hybrid genotypes which suggested that our overall correct classification rate was 96.2%. The overwhelming presence of domestic animals and their hybridization with mink in natural populations is of great concern for the future sustainability of wild mink populations.

We undertook a large-scale survey of the distribution of northern, Glaucomys sabrinus (Shaw, 1801), and southern, Glaucomys volans (L., 1758), flying squirrels in Ontario, Canada. Livetrapping was conducted along a northsouth transect spanning about 500 km, from 42.5°N to 47.2°N. During 2002-2004, we conducted 42 971 trap-nights at 26 sites and captured 232 northern and 538 southern flying squirrels. During 2002 and 2003, southern flying squirrels occurred >200 km farther north than we expected. However, the range of this species appeared to contract to the south by about 240 km after the winter of 2004. Weather and food data suggested that cold temperatures during January and February 2004 combined with a failed mast crop in the autumn of 2003 resulted in an energetic bottleneck and subsequent population crash. We speculate that prior to 2004 southern flying squirrels had expanded their geographic range in response to recent climate warming. In particular, the nine winters between 1994 and 2004 were relatively warm. By measuring the range expansion over this warm interval, we were able to estimate a rate of spread of 22 km per year, and a diffusion coefficient of 6.9 × 10 7 m 2 per generation.