Fine-scale effects of habitat loss and fragmentation despite large-scale gene flow for some regionally declining woodland bird species

Harrisson, Katherine A.; Pavlova, Alexandra; Amos, Nevil; Takeuchi, Naoko; Lill, Alan; Radford, James Q.; Sunnucks, Paul

doi:10.1007/s10980-012-9743-2

Cited by 70 publications

(65 citation statements)

References 59 publications

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“…1C; . We also expected more pronounced genetic responses to fragmentation for the more philopatric sex: males in all species (Mulder 1995, Doerr et al 2011, Debus and Ford 2012, Harrisson et al 2013, 2014 except the Grey Shrike-thrush (which has been inferred to have male-biased dispersal; Pavlova et al 2012) and the Spotted and Striated Pardalotes (for which there was no evidence of sex-biased dispersal; Harrisson et al 2012). Sex-biased effects of fragmentation were expected to be particularly marked in the obligate cooperative breeders among the target species (Superb Fairy-wren and Brown Treecreeper), in which male offspring often stay as helpers at the nest, and to some degree in the facultative cooperative breeder (Eastern Yellow Robin).…”

Section: Introductionmentioning

confidence: 93%

Species‐ and sex‐specific connectivity effects of habitat fragmentation in a suite of woodland birds

Amos

Harrisson

Radford

et al. 2014

Ecology

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Loss of functional connectivity following habitat loss and fragmentation could drive species declines. A comprehensive understanding of fragmentation effects on functional connectivity of an ecological assemblage requires investigation of multiple species with different mobilities, at different spatial scales, for each sex, and in different landscapes. Based on published data on mobility and ecological responses to fragmentation of 10 woodland-dependent birds, and using simulation studies, we predicted that (1) fragmentation would impede dispersal and gene flow of eight "decliners" (species that disappear from suitable patches when landscape-level tree cover falls below species-specific thresholds), but not of two "tolerant" species (whose occurrence in suitable habitat patches is independent of landscape tree cover); and that fragmentation effects would be stronger (2) in the least mobile species, (3) in the more philopatric sex, and (4) in the more fragmented region. We tested these predictions by evaluating spatially explicit isolation-by-landscape-resistance models of gene flow in fragmented landscapes across a 50 x 170 km study area in central Victoria, Australia, using individual and population genetic distances. To account for sex-biased dispersal and potential scale- and configuration-specific effects, we fitted models specific to sex and geographic zones. As predicted, four of the least mobile decliners showed evidence of reduced genetic connectivity. The responses were strongly sex specific, but in opposite directions in the two most sedentary species. Both tolerant species and (unexpectedly) four of the more mobile decliners showed no reduction in gene flow. This is unlikely to be due to time lags because more mobile species develop genetic signatures of fragmentation faster than do less mobile ones. Weaker genetic effects were observed in the geographic zone with more aggregated vegetation, consistent with gene flow being unimpeded by landscape structure. Our results indicate that for all but the most sedentary species in our system, the movement of the more dispersive sex (females in most cases) maintains overall genetic connectivity across fragmented landscapes in the study area, despite some small-scale effects on the more philopatric sex for some species. Nevertheless, to improve population viability for the less mobile bird species, structural landscape connectivity must be increased.

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Section: Introductionmentioning

confidence: 93%

Species‐ and sex‐specific connectivity effects of habitat fragmentation in a suite of woodland birds

Amos

Harrisson

Radford

et al. 2014

Ecology

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“…From a population genetics perspective, numerous studies have demonstrated that breaks in connectivity resulting from habitat fragmentation can modify the genetic structure and diversity of a variety of organisms, including mammals (Epps et al 2005), birds (Harrisson et al 2012), invertebrates (Keller et al 2004), and fishes (Morita et al 2009). However, empirical studies have shown that genetic sensitivity to habitat fragmentation is variable among species and is mainly conditioned by their dispersal abilities (Debinski and Holt 2000;Blanchet et al 2010).…”

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confidence: 99%

Influence of Forest Road Culverts and Waterfalls on the Fine‐Scale Distribution of Brook Trout Genetic Diversity in a Boreal Watershed

Torterotot¹,

Perrier²,

Bergeron³

et al. 2014

Trans Am Fish Soc

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Habitat fragmentation has become an increasing concern in conservation biology and is of prime importance with the expansion of forest road networks toward boreal and arctic regions. The aim of this study was to evaluate the effects of artificial and natural barriers to fish movement on the fine‐scale distribution of genetic diversity in Brook Trout Salvelinus fontinalis. We genotyped 995 individuals sampled from 25 locations in a boreal watershed fragmented by culverts and natural waterfalls. Using a landscape genetics approach, we tested whether the presence of both types of barrier resulted in decreased genetic diversity and increased divergence within isolated locations. Results showed that genetic divergence was enhanced between sites separated by barriers and that genetic diversity was reduced within sites located upstream of barriers. Moreover, the observed changes in levels of divergence and diversity were correlated with the number of barriers. Overall, our results suggested that the effects of culverts and natural waterfalls were similar. To our knowledge, this is the first study illustrating the effects of forest road culverts and natural waterfalls on the distribution of genetic diversity in Brook Trout within a boreal watershed. We discuss our results in the context of boreal forest road network expansion and in light of the need to better understand the potential impacts of road infrastructure on the long‐term persistence of fish populations. Received January 24, 2014; accepted July 11, 2014

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“…Approaches include assessing how organisms respond to habitat area within a set radius of sampling sites (Polyakov et al 2013;Carrara et al 2015), comparing the effect of patch size (Nufio et al 2011;Hadley et al 2014), and analysing the influence of habitat amount in predefined landscape-units (Harrisson et al 2012;Lima and Mariano-Neto 2014). In such studies, area of habitat is often defined as the total extent of native vegetation cover, or cover of a particular vegetation type, within or relating to the sampling units.…”

Section: Introductionmentioning

confidence: 99%

Non-random patterns of vegetation clearing and potential biases in studies of habitat area effects

2017

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Context Native vegetation extent is often a proxy for habitat area in studies of human-modified landscapes. However, the loss and retention of native vegetation is rarely random among landscapes. Instead, the extent of native vegetation in landscapes may be correlated with abiotic factors, thereby obscuring or distorting relationships between ecological phenomena and area. Objectives We asked: (1) how has the potential for non-random vegetation loss to confound area effects been addressed in the landscape ecology literature? (2) Are consistent patterns of non-random vegetation loss and retention evident from modified regions of two countries? Methods We reviewed 118 papers that related area to an ecological response, to determine whether potential biases associated with non-random vegetation loss and retention were considered. We then analysed *18,000 100 km 2 landscape units in Australia and South Africa to identify how different abiotic factors correlate with the extent of native vegetation retained in those landscapes. Results Only 21% of the studies we reviewed explicitly or implicitly considered spatial biases in vegetation clearing. Yet, across modified regions of Australia and South Africa, landscape-scale native vegetation extent was consistently and often strongly related to abiotic factors, particularly soil properties and topographic variability. Conclusion Patterns of vegetation clearing and retention commonly reflect underlying abiotic heterogeneity. These biases, which are infrequently highlighted in studies focussing on area effects, have implications for how we assess the importance of vegetation extent for species and assemblages. Failure to account for correlates of vegetation extent risks erroneous area-based conservation prescriptions in human-modified environments.

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Fine-scale effects of habitat loss and fragmentation despite large-scale gene flow for some regionally declining woodland bird species

Cited by 70 publications

References 59 publications

Species‐ and sex‐specific connectivity effects of habitat fragmentation in a suite of woodland birds

Species‐ and sex‐specific connectivity effects of habitat fragmentation in a suite of woodland birds

Influence of Forest Road Culverts and Waterfalls on the Fine‐Scale Distribution of Brook Trout Genetic Diversity in a Boreal Watershed

Non-random patterns of vegetation clearing and potential biases in studies of habitat area effects

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