Evaluating the Effectiveness of Corridors: a Genetic Approach

Abstract

The effectiveness of corridors in maintaining dispersal in fragmented landscapes is a question of considerable conservation and ecological importance. We tested the efficacy of corridors as residual landscape structures in maintaining population structure in the red-backed vole ( Clethrionomys gapperi ), a closed-canopy specialist, and the deer mouse ( Peromyscus maniculatus ), a habitat generalist. In coniferous forests managed for timber production in northeastern Washington, we sampled pairs of populations in three landscape classes: (1) contiguous landscapes, in which sites were located completely within a matrix of closed-canopy forest; (2) corridor landscapes, in which sites were connected by a corridor of closed-canopy forest; and (3) isolated landscapes, in which sites were separated from one another by clearcut or young regeneration stands. For each species, we used four microsatellite loci to quantify genetic distance between population pairs. Nei's genetic distance ( D s ) increased from smallest to largest in the order of contiguous, corridor, and isolated landscapes for C. gapperi. For P. maniculatus, genetic distances across landscape configurations were not significantly different. The differences between the two species indicate that they respond differently to the presence of forest corridors. In managed forests, corridors between unlogged habitats appear to maintain higher population connectivity for C. gapperi than landscapes without corridors. Evaluación de la Efectividad de Corredores: Una Estrategia GenéticaResumen: La efectividad de los corredores para mantener la dispersión en paisajes fragmentados es una situación de considerable importancia ecológica y de conservación. Evaluamos la efectividad de los corredores como estructuras residuales del paisaje en el mantenimiento de la estructura poblacional del ratón de campo de dorso café ( Clethrionomys gapperi ), un especialista de dosel cerrado, y del ratón ciervo ( Peromyscus maniculatus ) un generalista de hábitats. Hicimos un muestreo en pares de poblaciones en bosques de coníferas manejados para la producción maderera en tres clases de paisaje de Washington nororiental: (1) contiguo, sitios localizados completamente dentro de una matriz de bosque con dosel cerrado; (2) corredor, sitios conectados por un corredor de bosque con dosel cerrado; y (3) aislado, sitios separados uno del otro por talas o por rodales de regeneración joven. Para cada especie, usamos cuatro loci microsatélite para cuantificar la distancia génica entre pares de poblaciones. Para C. gapperi , las distancias genéticas de Nei ( D s ) se incrementaron en los paisajes en el siguiente orden: contiguo, corredor, y aislado. Para P. maniculatus , las distancias genéticas a lo largo de configuraciones del paisaje no fueron significativamente diferentes. Las diferencias entre estas dos especies indican que responden de diferente manera a la presencia de corredores forestales. En bosques manejados, los corredores entre hábitats sin talar aparentemente mantienen una conectividad ...

Does connectivity exist for remnant boreal caribou (Rangifer tarandus caribou) along the Lake Superior Coastal Range? Options for landscape restoration

“…Persistence of wide-ranging species of conservation concern in patchy habitat strongly depends on habitat quality and the ability of animals to move between habitat patches (Fahrig, 2003) as well as corridors for migration to allow for movement (Hale et al, 2001;Mech & Hallett, 2001). Therefore, the identification of dispersal events between source and isolated populations may aid conservation and habitat restoration efforts in gaining a better understanding of population connectivity and in determining favourable migration routes.…”

“…Now referred to as the "discontinuous distribution", this area is being managed as a linkage to support temporary occupancy or movement between the continuous ranges to the north and the LSCR (Ministry of Natural Resources, 2009) (Figure 1). Between 1974 and2009, the population in PNP, representing roughly one quarter of the most intact habitat in the LSCR, declined at approximately 4% per year and became increasingly isolated from neighbouring ranges (Patterson et al, 2014). Although PNP's population has recently been described as extirpated (Bergerud et al, 2015), an animal was observed in the north end of the Park in the spring of 2015 and an aerial survey completed in 2016 estimated that 55 (95% CI: 13-227) animals still inhabit the mainland and nearshore islands in the LSCR (Shuter et al, 2016).…”

The ongoing extinction event: a deep time, eco-evolutionary perspective for mitigation and reconciliation management

“…When effective, corridors can reverse the trend towards diminished genetic and demographic conditions and thereby reduce the peril of extinction while protecting, perhaps enhancing, the biodiversity of the region [95,96]. Although the efficacy of wildlife corridors to promote dispersion of plants and animals is a contentious issue [97,98], there are many recent empirical studies that indicate they can be effective dispersal paths for species between isolated habitats [99][100][101][102][103]. Alternatively, the modeling results of Falcy and Estades [104] "indicate that, for a given amount of habitat, patch enlargement can increase population size more than the establishment of biological corridors."…”

Mammals of Cabo Blanco: History, diversity, and conservation after 45 years of regrowth of a Costa Rican dry forest

“…Animals and plants should have more opportunities to move among patches, thus maintaining genetic diversity in their populations and lessening the likelihood of the random extinction of small isolated populations (Beier and Noss, 1998;Mech and Hallett, 2001;Lemckert et al, 2005). Corridors may promote not only the biodiversity of plants and animals, but also their biological interactions such as pollination and seed dispersal (Tewksbury et al, 2002;Kirchner et al, 2003).…”