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1.
Maria Vergara Samuel A. Cushman Fermín Urra Aritz Ruiz-González 《Landscape Ecology》2016,31(6):1241-1260
Context
Multispecies and multiscale habitat suitability models (HSM) are important to identify the environmental variables and scales influencing habitat selection and facilitate the comparison of closely related species with different ecological requirements.Objectives
This study explores the multiscale relationships of habitat suitability for the pine (Martes martes) and stone marten (M. foina) in northern Spain to evaluate differences in habitat selection and scaling, and to determine if there is habitat niche displacement when both species coexist.Methods
We combined bivariate scaling and maximum entropy modeling to compare the multiscale habitat selection of the two martens. To optimize the HSM, the performance of three sampling bias correction methods at four spatial scales was explored. HSMs were compared to explore niche differentiation between species through a niche identity test.Results
The comparison among HSMs resulted in the detection of a significant niche divergence between species. The pine marten was positively associated with cooler mountainous areas, low levels of human disturbance, high proportion of natural forests and well-connected forestry plantations, and medium-extent agroforestry mosaics. The stone marten was positively related to the density of urban areas, the proportion and extensiveness of croplands, the existence of some scrub cover and semi-continuous grasslands.Conclusions
This study outlines the influence of the spatial scale and the importance of the sampling bias corrections in HSM, and to our knowledge, it is the first comparing multiscale habitat selection and niche divergence of two related marten species. This study provides a useful methodological framework for multispecies and multiscale comparatives.2.
Paige E. Howell Erin L. Koen Bronwyn W. Williams Gary J. Roloff Kim T. Scribner 《Landscape Ecology》2016,31(5):1051-1062
Context
Barriers to dispersal influence the ability of individuals to expand into new areas and can ultimately define success of reintroduction programs. American marten (Martes americana) were reintroduced to the Upper Peninsula of Michigan, USA, from multiple, genetically differentiated source populations from 1955 to 1992. Previous research found multiple genetic clusters near release sites with little admixing, suggesting barriers to dispersal exist.Objectives
We sought to identify whether the contact zones between genetic clusters coincided with landscape features hypothesized to influence M. americana dispersal. We also investigated whether the degree of landscape contiguity within each genetic cluster differed among clusters.Methods
We mapped cluster boundaries in M. americana genetic assignment probabilities and used correlation length as a measure of landscape contiguity between genetic clusters. We then evaluated the effects of land cover and roads on spatial genetic structure using a spatial autoregressive model.Results
We found that gene flow was facilitated by contiguous coniferous forest and low incidence of roads. However, the strength of those relationships varied by genetic cluster. Contact zones among some genetic clusters spatially coincided with areas of high road and low conifer contiguity, compared to within-clusters.Conclusions
In contrast to landscape genetic analyses focused on identifying barriers to gene flow, we incorporated methods that are relatively novel in landscape genetics to quantify how landscape contiguity influences spatial genetic structure. Using this method we were able to identify landscape barriers to dispersal at the genetic cluster boundaries for a reintroduced species distributed continuously across the landscape.3.
The understanding and prediction of the responses of animal populations to habitat fragmentation is a central issue in applied
ecology. The identification of habitat variables associated to patch occupancy is particularly important when habitat quality
is affected by human activities. Here, we analyze the influence of patch and landscape characteristics on patch occupancy
by the subterranean herbivorous rodent Ctenomys porteousi. Patch occupancy was monitored in a network of 63 habitat patches identified by satellite imagery analysis which extends
along almost the whole distributional range for C. porteousi. Suitable habitat for the occurrence of C. porteousi is highly fragmented and represents <10% of the total area in its distributional range. The distribution of C. porteousi in the patch network is affected not only by characteristics of the habitat patches, but also by those of the surrounding
landscape matrix. Significant differences between occupied and empty patches were found in several environmental variables.
Overall, occupied patches were larger, less vegetated, more connected, and had larger neighbor patches than empty patches.
A stepwise procedure on a generalized linear model selected four habitat variables that explain patch occupancy in C. porteousi; it included the effects of habitat quality in the matrix surrounding the patch, average vegetation cover in the patch, minimum
vegetation cover in the matrix surrounding the patch, and the area of the nearest neighbor patch. These results indicate that
patch occupancy in C. porteousi is strongly influenced by the availability and quality of habitat both in the patch and in the surrounding landscape matrix. 相似文献
4.
Tzeidle N. Wasserman Samuel A. Cushman Michael K. Schwartz David O. Wallin 《Landscape Ecology》2010,25(10):1601-1612
Individual-based analyses relating landscape structure to genetic distances across complex landscapes enable rigorous evaluation
of multiple alternative hypotheses linking landscape structure to gene flow. We utilize two extensions to increase the rigor
of the individual-based causal modeling approach to inferring relationships between landscape patterns and gene flow processes.
First, we add a univariate scaling analysis to ensure that each landscape variable is represented in the functional form that
represents the optimal scale of its association with gene flow. Second, we use a two-step form of the causal modeling approach
to integrate model selection with null hypothesis testing in individual-based landscape genetic analysis. This series of causal
modeling indicated that gene flow in American marten in northern Idaho was primarily related to elevation, and that alternative
hypotheses involving isolation by distance, geographical barriers, effects of canopy closure, roads, tree size class and an
empirical habitat model were not supported. Gene flow in the Northern Idaho American marten population is therefore driven
by a gradient of landscape resistance that is a function of elevation, with minimum resistance to gene flow at 1500 m. 相似文献
5.
Field dispersal studies are seldom conducted at regional scales even though reliable information on mid-range dispersal distance is essential for models of colonization. The purpose of this study was to examine the potential distance of dispersal of Rhizophora mangle propagules by comparing deposition density with landscape characteristics of mangrove forests. Propagule density was estimated at various distances to mangrove sources (R. mangle) on beaches in southwestern Florida in both high-and low-energy environments, either facing open gulf waters vs. sheltered, respectively. Remote sensing and Geographic Information Systems were used to identify source forests and to determine their landscape characteristics (forest size and distance to deposition area) for the regression analyses. Our results indicated that increasing density of propagules stranded on beaches was related negatively to the distance of the deposition sites from the nearest stands of R. mangle and that deposition was greatly diminished 2 km or more from the source. Measures of fragmentation such as the area of the R. mangle forests were related to propagule deposition but only in low-energy environments. Our results suggest that geographic models involving the colonization of coastal mangrove systems should include dispersal dynamics at mid-range scales, i.e., for our purposes here, beyond the local scale of the forest and up to 5 km distant. Studies of mangrove propagule deposition at various spatial scales are key to understanding regeneration limitations in natural gaps and restoration areas. Therefore, our study of mid-range propagule dispersal has broad application to plant ecology, restoration, and modeling. 相似文献
6.
Jeremy Larroque Sandrine Ruette Jean-Michel Vandel Sébastien Devillard 《Landscape Ecology》2016,31(3):517-531
Context
Quantifying gene flow in natural populations is a key topic in both evolutionary and conservation biology. Understanding the extent to which the landscape matrix facilitates or impedes gene flow is becoming a high priority in a context of worldwide habitat loss and fragmentation.Objectives
Unexpectedly, a lower genetic diversity and a higher genetic structure have been previously observed in the less fragmented and the most forested habitat across four pine marten (Martes martes) populations in France. Our aim was to quantify the effect of landscape on the spatial distribution of genetic diversity in two populations in contrasting habitats.Methods
We conducted an individual-based landscape genetics analysis in a highly fragmented rural plain (Bresse, n = 126) and in a highly forested (50 %) mountainous area (Ariège, n = 88) in France. We tested for isolation-by-resistance using least-cost distances and used a causal modeling approach on 16,384 landscape and 104 elevation resistance scenarios.Results
Landscape structure influenced the genetic differentiation in Bresse, with vegetation providing more genetic connectivity over the study area than open areas, while roads and human buildings showed unexpected low resistance to gene flow. In Ariège, genetic differentiation was mainly associated with changes in elevation, with an optimal elevation for gene flow of around 1700 m, likely associated with changes in vegetation structure.Conclusions
The pine marten seems to be able to cope with human-dominated landscapes and with fragmented forest landscapes, whereas elevation is the major driver of genetic differentiation in our mountainous landscape. Additionally, we highlight the importance of spatial replication in landscape genetics for deriving reliable conservation and management measures over the species distribution.7.
Céline Morilhat Nadine Bernard Jean-Christophe Foltête Patrick Giraudoux 《Landscape Ecology》2008,23(5):569-579
This paper addresses the issue of whether landscape structure affects A. terrestris population kinetics on a neighbourhood spatial scale, and if so, at what spatial scale is that effect at its maximum. We
investigated how the growth of A. terrestris populations is influenced by the landscape context of parcels used for hay production in the French Jura Mountains. Five
landscape metrics (relative area of grassland, mean patch area of grassland, patch density of grassland, woodland patch density
in grassland, grassland–woodland edge density) were computed over an increasing radius around each parcel (max. 3 km). Redundancy
analysis showed that the extent, rate and early onset of A. terrestris population growth were favoured in open grassland areas. Landscape effects on A. terrestris populations as determined by the five metrics are scale-dependent: mean patch area of grassland, patch density of grassland
and woodland patch density in grassland had an impact on a grassland parcel within a neighbourhood radius of about 800 m,
while relative area of grassland and grassland–woodland edge density had an impact within a neighbourhood radius of about
400 m. Those findings corroborate earlier hypotheses about a multifactorial regulation of A. terrestris populations and a spatial hierarchy of regulating factors. They have potential implications in terms of landscape management
and small mammal pest control. 相似文献
8.
To aid effective conservation and management there is a need to understand the effect of landscape on species ecology. The
aim of this research was to assess the effect of landscape parameters on breeding success of barn owls throughout the Rother
and Arun River catchments, Sussex, UK. We used a Geographic Information System to describe the habitat mosaic and landscape
structure within an estimated home range area of 3 km2 around 85 artificial nest box sites. Results showed that land cover was less heterogeneous at successful sites, with home
ranges dominated by a few habitat types of regular patch shapes. Unsuccessful nesting sites had significantly more improved
grassland, suburban land and wetlands than successful sites. Cluster analysis and Principle Components Analysis was used to
assess the similarity of the habitat mosaic within these areas and pellet analysis was undertaken to assess barn owl diet
and prey availability. Ten prey species were recovered from pellets, field vole (Microtus agrestis), common shrews (Sorex araneus) and house mice (Mus musculus) making up nearly 90% of recoveries. However box sites varied in relative proportions of small mammal, and hence prey availability.
Results indicated that land use and landscape structure can affect breeding success in barn owls. Higher levels of poor quality
small mammal habitat were associated with unsuccessful sites. However, at a landscape scale, the habitat mosaic across the
study area lacked variation, limiting analysis and clear correlations between habitat type and positive breeding success,
suggesting that a finer scale was needed in future studies utilising this approach. 相似文献
9.
Holly E. Mutascio Shannon E. Pittman Patrick A. Zollner Laura E. D’Acunto 《Landscape Ecology》2018,33(2):257-274
Context
Invasive Burmese pythons are altering the ecology of southern Florida and their distribution is expanding northward. Understanding their habitat use is an important step in understanding the pathways of the invasion.Objectives
This study identifies key landscape variables in predicting relative habitat suitability for pythons at the present stage of invasion through presence-only ecological niche modeling using geographical sampling bias correction.Methods
We used 2014 presence-only observations from the EDDMapS database and three landscape variables to model habitat suitability: fine-scale land cover, home range-level land cover, and distance to open freshwater or wetland. Ten geographical sampling bias correction scenarios based on road presence and sampling effort were evaluated to improve the efficacy of modeling.Results
The best performing models treated road presence as a binary factor rather than a continuous decrease in sampling effort with distance from roads. Home range-level cover contributed the most to the final prediction, followed by proximity to water and fine-scale land cover. Estuarine habitat and freshwater wetlands were the most important variables to contribute to python habitat suitability at both the home range-level and fine-scale. Suitability was highest within 30 m of open freshwater and wetlands.Conclusions
This study provides quantifiable, predictive relationships between habitat types and python presence at the current stage of invasion. This knowledge can elucidate future targeted studies of python habitat use and behavior and help inform management efforts. Furthermore, it illustrates how estimates of relative habitat suitability derived from MaxEnt can be improved by both multi-scale perspectives on habitat and consideration of a variety of bias correction scenarios for selecting background points.10.
Throughout most of the north-west Iberian Peninsula, chestnut (Castanea sativa) woods are the principal deciduous woodland, reflecting historical and ongoing exploitation of indigenous forests. These
are traditionally managed woodlands with a patchy distribution. Eurasian nuthatches (Sitta europaea) inhabit mature deciduous woods, show high site fidelity, and are almost exclusively found in chestnut woods in the study
area. We studied the presence and abundance of nuthatch breeding pairs over two consecutive years, in relation to the size,
degree of isolation and intensity of management of 25 chestnut woods in NW Spain. Degree of isolation was assessed in view
of the presence of other woodland within a 1-km band surrounding the study wood. Wood size was the only variable that significantly
predicted the presence of breeding pairs (in at least one year, R
2 = 0.69; in both years, R
2 = 0.50). The number of pairs was strongly predicted by wood size, isolation and management (R
2 = 0.70 in 2004; R
2 = 0.84 in 2005); interestingly, more isolated woods had more breeding pairs. Breeding density was likewise significantly
or near-significantly (P ≤ 0.1) higher in small isolated woods, which is possibly attributable to lower juvenile dispersal in lightly forested areas
and/or to lower predator density in smaller and more isolated patches. Breeding density was higher (though not significantly
so) in more heavily managed woods, possibly due to the presence of larger chestnut crops and larger trees (with higher nuthatch
prey abundance). Our findings highlight the complexity of the relationships between the patch properties and the three studied
levels (presence, number and density of pairs), and also the importance of traditionally managed woodlands for the conservation
of forest birds. 相似文献
11.
We sampled 35 lakes in northern Wisconsin to determine the presence of Orconectes rusticus, the rusty crayfish, and related this pattern to several parameters pertaining to potential invasion routes that could influence
the distribution of these crayfish in the lakes. The presence of rusty crayfish in lakes was positively related to an index
of human use and negatively related to the length of stream connections to other lakes containing the crayfish. Humans appear
to act as vectors allowing crayfish to travel along discontinuous routes that otherwise would be inaccessible to them, and
thus, provide crayfish with spatially discontinuous corridors that increase the probability of movement by channelizing the
space between lakes. In contrast, streams correspond closely to the traditional definition of terrestrial corridors, in that
they are spatially continuous. This distribution pattern suggests colonization operating via two corridors with two spatial
scales, making management of the invasion of rusty crayfish complex. 相似文献
12.
We experimentally examined edge effects and movement patterns of the butterfly Parnassius smintheus in two habitat types, its preferred meadow habitat, and intervening forest matrix habitat. We followed the movement of 46 butterflies released at either 5 or 20m from a forest edge in either forest or meadow habitat. In contrast to theoretical predictions, we found that butterflies flew less frequently, shorter distances, and at lower rates in matrix habitat than they did in meadow habitat. Distance from the edge had little effect on these aspects of movement. Flight was strongly influenced by light levels with butterflies flying more readily at higher light levels. Light levels were higher in meadows than in forest explaining much of the difference in movement patterns. Turning angles showed that butterflies flying in meadow habitat avoided forest edges and that this effect extended nearly 25 m into meadows. Analysis of net displacement from the forest edge reinforced this result and showed that there may be attraction to the meadow for butterflies flying within forest. 相似文献
13.
Martin Mikoláš Martin Tejkal Tobias Kuemmerle Patrick Griffiths Miroslav Svoboda Tomáš Hlásny Pedro J. Leitão Robert C. Morrissey 《Landscape Ecology》2017,32(1):163-179
Context
Distribution and connectivity of suitable habitat for species of conservation concern is critical for effective conservation planning. Capercaillie (Tetrao urogallus), an umbrella species for biodiversity conservation, is increasingly threatened because of habitat loss and fragmentation.Objective
We assessed the impact of drastic changes in forest management in the Carpathian Mountains, a major stronghold of capercaillie in Europe, on habitat distribution and connectivity.Methods
We used field data surveys with a forest disturbance dataset for 1985–2010 to map habitat suitability, and we used graph theory to analyse habitat connectivity.Results
Climate, topography, forest proportion and fragmentation, and the distance to roads and settlements best identified capercaillie presence. Suitable habitat area was 7510 km2 in 1985; by 2010, clear-cutting had reduced that area by 1110 km2. More suitable habitat was lost inside protected areas (571 km2) than outside (413 km2). Habitat loss of 15 % reduced functional connectivity by 33 % since 1985.Conclusions
Forest management, particularly large-scale clear-cutting and salvage logging, have substantially diminished and fragmented suitable capercaillie habitat, regardless of the status of forest protection. Consequently, larger areas with suitable habitat are now isolated and many patches are too small to sustain viable populations. Given that protection of capercaillie habitat would benefit many other species, including old-growth specialists and large carnivores, conservation actions to halt the loss of capercaillie habitat is urgently needed. We recommend adopting policies to protect natural forests, limiting large-scale clear-cutting and salvage logging, implementing ecological forestry, and restricting road building to reduce forest fragmentation.14.
Invasive alien species can pose a severe threat to biodiversity and stability of the ecosystems they invade. Predicting distribution
patterns of invasive species in regions outside their native range is a fundamental component of early warning systems. Crofton
weed (Eupatorium adenophorum Spreng.) was first discovered in the Yunnan Province of China around the 1940s. The well-documented invasion history of this
plant species provided the opportunity for us to examine the spatiotemporal patterns of biological invasion by crofton weed.
Using the datasets documenting 441 known localities invaded by crofton weed in China over the past 50 years and 23 environmental
variables generated by the genetic algorithm for rule-set production (GARP) model, we tested the predictability of crofton
weed distribution with a high degree of accuracy. Both the Kappa statistics and the receiver–operator characteristic (ROC)
analysis indicated that it is possible to predict the geographical spread of crofton weed in China. Precipitation in the coldest
quarter of the year, extremely low air temperature, and maximum annual air temperature strongly influenced the predictions.
Our results indicate that crofton weed may break out in Yungui Plateau, Sichuan Basin, southeastern Coastlands, Hainan Island,
and Taiwan although currently it is either absent or has only recently been recorded in these regions. Redundancy analysis
(RDA) ordination results demonstrated that temperature and precipitation play an important role in confining the spread of
crofton weed. Over the past 20 years, crofton weed has spread from subtropical areas with higher annual mean temperature and
lower climatic fluctuations to much cooler and dryer areas at higher altitudes. The distribution of crofton weed was restricted
mainly to regions with mean annual air temperature ranging from 10 to 22°C and annual precipitation from 800 to 2000 mm. Our
results could help in developing and implementing early detection measures to minimize the ecological impacts of crofton weed
invasion in China. 相似文献
15.
Due to complex population dynamics and source–sink metapopulation processes, animal fitness sometimes varies across landscapes
in ways that cannot be deduced from simple density patterns. In this study, we examine spatial patterns in fitness using a
combination of intensive field-based analyses of demography and migration and spatial matrix models of white-footed mouse
(Peromyscus leucopus) population dynamics. We interpret asymptotic population growth rates from these spatial models as fitness-based measures
of habitat-quality and use elasticity analysis to further explore model behavior and the roles of migration. In addition,
we compare population growth rates at the spatial scale of single habitats and the landscape-level scale at which these habitats
are assembled. To this end, we employ emerging techniques in multi-scale estimation of demography and movement and recently
described vec-permutation methods for spatial matrix notation and analysis. Our findings indicate that the loss of low quality
habitats or reductions in movement from these habitats into higher quality areas could negatively affect landscape-level population
fitness. 相似文献
16.
Mélina Houle Daniel Fortin Christian Dussault Réhaume Courtois Jean-Pierre Ouellet 《Landscape Ecology》2010,25(3):419-433
Forest harvesting involves the creation of roads and cutblocks, both of which can influence animal habitat use. We evaluated
the cumulative effects of forestry on habitat selection by six packs of gray wolf (Canis lupus) widely distributed in Quebec’s boreal forest. Resource selection functions were used to evaluate cumulative effects at two
levels. First, we studied how the response of wolves to roads and cutblocks varied within their home range (HR level) as a
function of the local abundance of these habitat features. Second, we assessed whether differences in the response to roads
and cutblocks observed among packs (inter-HR level) could be explained by variations in their average abundance among individual
home ranges. At the HR level, we found that cumulative effects shaped habitat selection of wolves, and the nature of the effects
varied during the year. For example, we detected a decrease in the selection of roads following an increase in local road
density during the rendez-vous and the nomadic periods, but not during the denning period. At the inter-HR level, we found
a functional response to logging activity only during the denning period. Packs with home ranges characterized by a larger
proportion of recent cutblocks selected these cutblocks more strongly. We conclude that cumulative effects of logging activities
occur at multiple levels, and these effects can have profound effects on habitat use by wolves, thereby influencing spatial
predator–prey dynamics. Wildlife conservation and management in boreal ecosystems should thus account for cumulative impacts
of anthropogenic features on animal distribution. 相似文献
17.
Conservation strategies should be based on a solid understanding of processes underlying species response to landscape change.
In forests fragmented by agriculture, elevated nest predation rates have been reported in many forest bird species, especially
near edges. In intensively-managed forest landscapes, timber harvesting might also be associated with negative edge effects
or broader “context” effects on some species when the matrix provides additional resources to their major nest predators.
In this study, we hypothesized that proximity to a forest edge and proportion of cone-producing plantations will increase
nest predation risk in fragments of relatively undisturbed forest. We focused on the Brown Creeper (Certhia americana), an indicator species of late-seral forests. We compared habitat configuration and composition at four spatial scales (0.14,
0.5, 1 and 2 km) around 54 nests and related daily nest survival rate to the distance to the nearest forest edge, mean patch
size of late-seral forest (r = 141 m), proportion of non-forested lands (r = 141 m), density of maintained roads (r = 1 km), proportion of cone-producing spruce plantations (r = 2 km), and year. The best model included distance to the nearest edge and proportion of cone-producing plantations. Distance
of nests to the nearest edge was the best individual predictor of daily nest survival. A larger sample of nests showed a significant
threshold in distance to the nearest forest edge; nests located at least 100 m away were more likely to fledge young. These
results suggest that even in managed forest landscapes, matrix effects can be important and some bird species may exhibit
negative edge effects. 相似文献
18.
Home range size is a result of individual movements and the spatial distribution of a population. While body size, sex, and age are known to influence the area over which an animal ranges, it remains uncertain how landscape heterogeneity influences home range size. We examined elk (Cervus elaphus) seasonal home range sizes in relation to the quantity and spatial heterogeneity of forage biomass, forest cover, topography, snow–water equivalents, and landscape structure in three study landscapes: Yellowstone National Park, Wyoming, USA; eastern slopes of the Canadian Rockies, Alberta; and northern Wisconsin, USA. We used a 95% fixed kernel estimator to measure the home range size and location of all elk. To identify the scales at which important factors influenced home range sizes, we quantified environmental variables within the estimated home range polygon and within concentric circles with radii of 1000, 2000, 3000, 4000, and 5000 m from the home range center. Results indicate that there was an inverse relationship between forage biomass and summer and winter home range sizes in Alberta and Wisconsin, however the relationship was positive in Yellowstone. The size of summer and winter home ranges was positively related to percent forest cover; however this relationship was significant only when forest cover was quantified within the home range polygon or radii that were greater than or equal to 3000 m. Winter home ranges also had a positive relationship with snow–water equivalents. The predictive strength of summer home range models was greatest when landscape variables were quantified within the concentric circles with a radius of 3000 m or more, whereas the predictive strength of the winter models was greatest within the estimated home range polygon. Results suggest that elk ranging patterns reflected complex trade-offs that affect foraging, group dynamics, movement energetics, predation avoidance and thermal regulation. The multi-scale analysis indicates that elk based home ranging decisions on an area equal to their home range, but areas outside of the estimated home range were also important. 相似文献
19.
Anne Villemey William E. Peterman Murielle Richard Annie Ouin Inge van Halder Virginie M. Stevens Michel Baguette Philip Roche Frédéric Archaux 《Landscape Ecology》2016,31(7):1629-1641
Context
Anthropogenic activities readily result in the fragmentation of habitats such that species persistence increasingly depends on their ability to disperse. However, landscape features that enhance or limit individual dispersal are often poorly understood. Landscape genetics has recently provided innovative solutions to evaluate landscape resistance to dispersal.Objectives
We studied the dispersal of the common meadow brown butterfly, Maniola jurtina, in agricultural landscapes, using a replicated study design and rigorous statistical analyses. Based on existing behavioral and life history research, we hypothesized that the meadow brown would preferentially disperse through its preferred grassy habitats (meadows and road verges) and avoid dispersing through woodlands and the agricultural matrix.Methods
Samples were collected in 18 study landscapes of 5 × 5 km in three contrasting agricultural French regions. Using circuit theory, least cost path and transect-based methods, we analyzed the effect of the landscape on gene flow separately for each sex.Results
Analysis of 1681 samples with 6 microsatellites loci revealed that landscape features weakly influence meadow brown butterfly gene flow. Gene flow in both sexes appeared to be weakly limited by forests and arable lands, whereas grasslands and grassy linear elements (road verges) were more likely to enhance gene flow.Conclusion
Our results are consistent with the hypothesis of greater dispersal through landscape elements that are most similar to suitable habitat. Our spatially replicated landscape genetics study allowed us to detect subtle landscape effects on butterfly gene flow, and these findings were reinforced by consistent results across analytical methods.20.
Populations at the periphery of a species’ range often show reduced genetic variability within populations and increased genetic
divergence among populations compared to those at the core, but the mechanisms that give rise to this core-periphery pattern
in genetic structure can be multifaceted. Peripheral population characteristics may be a product of historical processes,
such as founder effects or population expansion, or due to the contemporary influence of landscape context on gene flow. We
sampled collared lizards (Crotaphytus collaris) at four locations within the northern Flint Hills of Kansas, which is at the northern periphery of their range, to determine
the genetic variability and extent of genetic divergence among populations for ten microsatellite loci (n = 229). We found low genetic variability (average allelic richness = 3.37 ± 0.23 SE; average heterozygosity = 0.54 ± 0.05
SE) and moderate population divergence (average FST = 0.08 ± 0.01 SE) among our sample sites relative to estimates reported in the literature at the core of the species’ range
in Texas. We also identified differences in dispersal rates among sampling locations. Gene flow within the Flint Hills was
thus greater than for other peripheral populations of collared lizards, such as the Missouri glade system where most of the
mesic grasslands have been converted to forest since the last glacial retreat, which appears to have greatly impeded gene
flow among populations. Our findings signify the importance of considering landscape context when evaluating core-peripheral
trends in genetic diversity and population structure. 相似文献