Consequences of impediments to animal movements at different scales: A conceptual framework and review

Abstract

Aim: The persistence of animal populations depends on individuals moving successfully around a landscape, but habitat fragmentation can hinder this by reducing functional connectivity. The proximate cause of population declines in fragmented habitat is dependent on the spatial and temporal scales of movement restrictions. Location: Global.Methods: We present a conceptual framework highlighting the relationship between spatial and temporal scales, and three mechanisms through which detrimental impacts can occur when movement is disrupted in fragmented landscapes: limited resource access, restricted demographic exchange and impeded gene flow. We then review the literature to identify the proportion of studies conducted on each mechanism and whether biases existed in how often each was studied among different geographic zones or taxa. A random selection of 250 articles was classified by the mechanism, geographic region and taxon studied in each article.Results: Our conceptual framework highlighted that each of the three mechanisms tends to be characterized by movement restriction at progressively larger spatial and temporal scales. In our literature review, we found that the overwhelming majority (77%) of articles investigated impeded gene flow, and only 17% and 10% explored restricted demographic exchange and limited resource access, respectively. Work on limited resource access was disproportionately low for particular taxonomic groups, such as reptiles and amphibians.Main conclusions: Distinguishing which mechanisms are disrupted in a particular system is crucial because addressing each is likely to require a distinct conservation management response. We encourage greater focus on the less-studied mechanisms of restricted demographic exchange and limited resource access. K E Y W O R D Sdemographic rescue, food availability, genetic diversity, habitat fragmentation, habitat loss, literature review, matrix, spatial scale, structural connectivity

Comparative landscape genetics reveals the evolution of viviparity reduces genetic connectivity in fire salamanders

“…Restricted gene flow and low fecundity are two factors that often reduce population genetic diversity (Cosgrove et al, 2018;Ellegren & Galtier, 2016 Table S5). This result could question whether the pueriparous plot exclusively contains pueriparous fire salamanders or a mixture of pueriparous and larviparous individuals.…”

Genetic tagging in the Anthropocene: scaling ecology from alleles to ecosystems

“…Dispersers can only be identified from populations with divergent genetic signatures, thus well connected populations with many dispersers will be poor candidates for direct genetic methods to estimate connectivity (Proctor et al 2005). The use of family triads (or limited pedigrees) is an emerging direct genetic method that overcomes the inability to detect dispersers in well-mixed populations and allows the identification of both apparent and realized connectivity (Cosgrove et al 2017, Cayuela et al 2018see Proctor et al 2018a for an example). The use of family triads in connectivity studies will ultimately provide insight into the assumed link between apparent and realized connectivity (Cayuela et al 2018), and perhaps more importantly, the efficacy of mitigation efforts (Sawaya et al 2014), like sex-specific wildlife crossing structures across highways (Ford et al 2017).…”

“…In a few cases, direct methods have been applied to uncover continental-scale connectivity issues (Segelbacher et al 2003, Proctor et al 2012. In light of the burgeoning pulse of large landscape connectivity initiatives across the world (Pulsford et al 2015, Travis Belote et al 2016, direct genetic methods that link habitat loss with realized connectivity are an important opportunity for improved connectivity research (Cosgrove et al 2017).…”

“…The use of family triads (or limited pedigrees) is an emerging direct genetic method that overcomes the inability to detect dispersers in well‐mixed populations and allows the identification of both apparent and realized connectivity (Cosgrove et al. , Cayuela et al. ; see Proctor et al.…”

“…), direct genetic methods that link habitat loss with realized connectivity are an important opportunity for improved connectivity research (Cosgrove et al. ).…”