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1.
Fine-scale landscape change can alter dispersal patterns of animals, thus influencing connectivity or gene flow within a population.
Furthermore, dispersal patterns of different species may be influenced by the landscape in varying ways. Our research first
aimed to examine whether the spatial genetic structure within populations of closely related bird species differs in response
to the same landscape. Second, we examined whether individual-level movement characteristics are a mechanistic driver of these
differences. We generated a priori predictions of how landscape features will influence dispersal (particularly the response
of individuals to habitat boundaries both natural and human-induced) based on a movement model developed by Fahrig (Funct
Ecol 21:1003–1015, 2007). This model allowed us to predict genetic relatedness patterns in populations of two passerine bird species with different
life-history traits from Queensland, Australia (yellow-throated scrubwren Sericornis citreogularis, a habitat specialist; white-browed scrubwren Sericornis frontalis, a habitat generalist). We quantified our predictions using cost-distance modelling and compared these to observed pairwise
genetic distances (a
r
) between individuals as calculated from microsatellite markers. Mantel tests showed that our a priori models correlated with
genetic distance. Euclidean distance was most closely correlated to genetic distance for the generalist species (r = 0.093, P = 0.002), and landscape models that included the avoidance of unsuitable habitat were best for the specialist species (r = 0.107, P = 0.001). Our study showed that predictable movement characteristics may be the mechanism driving differences in genetic
relatedness patterns within populations of different bird species. 相似文献
2.
Metapopulation models are frequently used for analysing species–landscape interactions and their effect on structure and dynamic
of populations in fragmented landscapes. They especially support a better understanding of the viability of metapopulations.
In such models, the processes determining metapopulation viability are often modelled in a simple way. Animals’ dispersal
between habitat fragments is mostly taken into account by using a simple dispersal function that assumes the underlying process
of dispersal to be random movement. Species-specific dispersal behaviour such as a systematic search for habitat patches is
likely to influence the viability of a metapopulation. Using a model for metapopulation viability analysis, we investigate
whether such specific dispersal behaviour affects the predictions of ranking orders among alternative landscape configurations
rated regarding their ability to carry viable metapopulations. To incorporate dispersal behaviour in the model, we use a submodel
for the colonisation rates which allows different movement patterns to be considered (uncorrelated random walk, correlated
random walk with various degrees of correlation, and loops). For each movement pattern, the landscape order is determined
by comparing the resulting mean metapopulation lifetime Tm of different landscape configurations. Results show that landscape orders can change considerably between different movement
patterns. We analyse whether and under what circumstances dispersal behaviour influences the ranking orders of landscapes.
We find that the ‘competition between patches for migrants’ – i.e. the fact that dispersers immigrating into one patch are
not longer available as colonisers for other patches – is an important factor driving the change in landscape ranks. The implications
of our results for metapopulation modelling, planning and conservation are discussed. 相似文献
3.
Beyond the least-cost path: evaluating corridor redundancy using a graph-theoretic approach 总被引:1,自引:1,他引:0
The impact of the landscape matrix on patterns of animal movement and population dynamics has been widely recognized by ecologists.
However, few tools are available to model the matrix’s influence on the length, relative quality, and redundancy of dispersal
routes connecting habitat patches. Many GIS software packages can use land use/land cover maps to identify the route of least
resistance between two points—the least-cost path. The limitation of this type of analysis is that only a single path is identified,
even though alternative paths with comparable costs might exist. In this paper, we implemented two graph theory methods that
extend the least-cost path approach: the Conditional Minimum Transit Cost (CMTC) tool and the Multiple Shortest Paths (MSPs)
tool. Both methods enable the visualization of multiple dispersal routes that, together, are assumed to form a corridor. We
show that corridors containing alternative dispersal routes emerge when favorable habitat is randomly distributed in space.
As clusters of favorable habitat start forming, corridors become less redundant and dispersal bottlenecks become visible.
Our approach is illustrated using data from a real landscape in the Brazilian Atlantic forest. We explored the effect of small,
localized disturbance on dispersal routes linking conservation units. Simulated habitat destruction caused the appearance
of alternative dispersal routes, or caused existing corridors to become narrower. These changes were observed even in the
absence of significant differences in the length or cost of least-cost paths. Last, we discuss applications to animal movement
studies and conservation initiatives. 相似文献
4.
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
5.
6.
Matthew J. Smith Matthew G. Betts Graham J. Forbes Daniel G. Kehler Maryse C. Bourgeois Stephen P. Flemming 《Landscape Ecology》2011,26(5):709-721
Landscape composition and configuration, often termed as habitat loss and fragmentation, are predicted to reduce species population
viability, partly due to the restriction of movement in the landscape. Unfortunately, measuring the effects of habitat loss
and fragmentation on functional connectivity is challenging because these variables are confounded, and often the motivation
for movement by target species is unknown. Our objective was to determine the independent effects of landscape connectivity
from the perspective of a mature forest specialist—the northern flying squirrel (Glaucomys sabrinus). To standardize movement motivation, we translocated 119 squirrels, at varying distances (0.18–3.8 km) from their home range
across landscapes representing gradients in both habitat loss and fragmentation. We measured the physical connectedness of
mature forest using an index of connectivity (landscape coincidence probability). Patches were considered connected if they
were within the mean gliding distance of a flying squirrel. Homing success increased in landscapes with a higher connectivity
index. However, homing time was not strongly predicted by habitat amount, connectivity index, or mean nearest neighbour and
was best explained as a simple function of sex and distance translocated. Our study shows support for the independent effects
of landscape configuration on animal movement at a spatial scale that encompasses several home ranges. We conclude that connectivity
of mature forest should be considered for the conservation of some mature forest specialists, even in forest mosaics where
the distinction between habitat and movement corridors are less distinct. 相似文献
7.
Visual interpretation of remotely sensed imagery has long been used for landscape pattern analysis. Few studies, however,
have investigated human variation in estimates of within-patch composition for classification of those patches, particularly
in urban settings. This paper compares the agreement of two approaches—visual interpretation and object-based—to estimate
the proportion cover of landscape features within delineated patches, and investigates the spatial patterns of patches with
large disagreement between the two approaches. The two approaches were compared for the Gwynns Falls watershed, Maryland,
USA. Three methods were used to assess agreement: a traditional error matrix based procedure and two fuzzy methods, a plus-one
modification of the traditional procedure, and a fuzzy set theory method. We found that while visual interpretation does not
work effectively when patches contain a mix of different types of features, accuracy increases with patches that are either
dominated by a specific feature, or do not contain a specific feature. The overall accuracies of estimates by visual interpretation
also vary by features, ranging from 63.3% for pavement to 93.8% for bare soil. Patches with large disagreement between the
two approaches cluster spatially at locations where the urban landscape is more structurally complex, suggesting the accuracy
of visual interpretation may be affected by patch shape complexity, and the spatial configuration of the landscape features
within the patches. These results provide important insights into the accuracy of thematic maps based on visual interpretation,
not only for ecologists and managers who are using the maps, but also for those who produce the maps. 相似文献
8.
Individual-based landscape genetic analyses provide empirically based models of gene flow. It would be valuable to verify
the predictions of these models using independent data of a different type. Analyses using different data sources that produce
consistent results provide strong support for the generality of the findings. Mating and dispersal movements are the mechanisms
through which gene flow operates in animal populations. The best means to verify landscape genetic predictions would be to
use movement data to independently predict landscape resistance. We used path-level, conditional logistic regression to predict
landscape resistance for American black bear (Ursus americanus) in a landscape in which previous work predicted population connectivity using individual-based landscape genetics. We found
consistent landscape factors influence genetic differentiation and movement path selection, with strong similarities between
the predicted landscape resistance surfaces. Genetic differentiation in American black bear is driven by spring movement (mating
and dispersal) in relation to residential development, roads, elevation and forest cover. Given the limited periods of the
year when gene flow events primarily occur, models of landscape connectivity should carefully consider temporal changes in
functional landscape resistance. 相似文献
9.
Movement of animals is a key process affecting population dynamics. Information on factors that affect pathway use is essential for identifying and protecting pathways, and important for maintaining connectivity among populations. We present an innovative, non-invasive, approach for predicting pathways of reintroduced Asiatic wild ass (Equus hemionus) in Israel, which is based on understanding the effects of landscape factors on pathways use. The approach includes: Predicting pathways, by employing a least cost pathway (LCP) GIS models based on several landscape factors, so as to efficiently direct a field survey and explore the wild ass’s general preferences of pathway types; Collecting empirical data by surveying the dung density of wild ass along each of the predicted pathways and using the data as an index of pathway use; Evaluating the predicted pathways against the empirical data collected, to estimate the general pathway preferences of the wild ass; and Developing and evaluating alternative generalized linear models, according to a priori hypotheses based on empirical data so as to quantify the effect of different landscape factors on pathway use. The analyses were conducted for the entire landscape, and then for two distinct landscape types, open landscape and landscape-barriers (mountain ridges), as subsets of the entire landscape. There were clear differences in the mean number of faeces counts between the LCPs, indicating that the wild ass prefers certain pathway types as a function of landscape features. We further found that the factors affecting E. hemionus pathway usage—vegetation; slopes; canyons; and 4-wheel drive routes—varied largely between the two major landscape types studied, demonstrating the importance of studying space use patterns at different landscape terrains. This information can be applicable to landscape planning measures that aim to enhance protection of the species. This approach provides a framework for studying animal space-use patterns of a variety of species, including elusive species, in a heterogeneous landscape. 相似文献
10.
Marion Valeix Andrew J. Loveridge Zeke Davidson Hillary Madzikanda Hervé Fritz David W. Macdonald 《Landscape Ecology》2010,25(3):337-351
Within a landscape where prey has an aggregated distribution, predators can take advantage of the spatial autocorrelation
of prey density and intensify their search effort in areas of high prey density by using area-restricted search behaviour.
In African arid and semi-arid savannas, large herbivores tend to aggregate around scarce water sources. We tested the hypothesis
that water sources are a key determinant of habitat selection and movement patterns of large free-ranging predators in such
savannas, using the example of the African lion. We used data from 19 GPS radio-collared lions in Hwange National Park, Zimbabwe.
Maps of lions’ trajectories showed that waterholes are key loci on the lions’ route-maps. Compositional analyses revealed
that lions significantly selected for areas located within 2 km of a waterhole. In addition, analysis of lions’ night paths
showed that when lions are close to a waterhole (<2 km), they move at lower speed, cover shorter distances per night (both
path length and net displacement) and follow a more tortuous path (higher turning angle, lower straightness index and higher
fractal dimension) than when they are further from a waterhole. Hence, our results strongly suggest that lions adopt area-restricted
searching in the vicinity of waterholes, and reduce their search effort to minimize the time spent far from a waterhole. They
provide an illustration of how key habitat features that determine the dispersion of prey (e.g. waterholes in this study)
have an influence on the spatial ecology and movement patterns of terrestrial predators. 相似文献
11.
Habitat fragmentation often has negative consequences for genetic diversity, and thereby for the viability of populations.
However, these negative consequences might be counteracted by gene flow as the latter provides functional connectivity between
apparently isolated habitat fragments. Gene flow is itself influenced by landscape structure and composition, and it is therefore
important to understand the relationship between gene flow and landscape structure and composition. We used linear LAD regression
models to investigate the relationship between contemporary gene flow by pollen in the rare, insect-pollinated forest tree
Sorbus domestica and several landscape features. None of the landscape components—which included closed forest, deep valleys, open land and
settlements—proved to be an impermeable barrier to gene flow by pollen. We found evidence that settlements, large open areas,
and a pronounced topography increased long-distance gene flow in the landscape as compared to a random model including all
possible gene flow trajectories. These results are encouraging from a conservation view, as gene flow in species pollinated
by generalist insects seems to provide functional connectivity and may help to maintain genetic diversity in rare plant species
in fragmented landscapes. 相似文献
12.
Identification of functional corridors with movement characteristics of brown bears on the Kenai Peninsula,Alaska 总被引:2,自引:1,他引:2
Tabitha A. Graves Sean Farley Michael I. Goldstein Christopher Servheen 《Landscape Ecology》2007,22(5):765-772
We identified primary habitat and functional corridors across a landscape using Global Positioning System (GPS) collar locations
of brown bears (Ursus arctos). After deriving density, speed, and angular deviation of movement, we classified landscape function for a group of animals
with a cluster analysis. We described areas with high amounts of sinuous movement as primary habitat patches and areas with
high amounts of very directional, fast movement as highly functional bear corridors. The time between bear locations and scale
of analysis influenced the number and size of corridors identified. Bear locations should be collected at intervals ≤6 h to
correctly identify travel corridors. Our corridor identification technique will help managers move beyond the theoretical
discussion of corridors and linkage zones to active management of landscape features that will preserve connectivity. 相似文献
13.
Thomas Broquet Nicolas Ray Eric Petit John M. Fryxell Françoise Burel 《Landscape Ecology》2006,21(6):877-889
Empirical studies of landscape connectivity are limited by the difficulty of directly measuring animal movement. ‘Indirect’
approaches involving genetic analyses provide a complementary tool to ‘direct’ methods such as capture–recapture or radio-tracking.
Here the effect of landscape on dispersal was investigated in a forest-dwelling species, the American marten (Martes americana) using the genetic model of isolation by distance (IBD). This model assumes isotropic dispersal in a homogeneous environment
and is characterized by increasing genetic differentiation among individuals separated by increasing geographic distances.
The effect of landscape features on this genetic pattern was used to test for a departure from spatially homogeneous dispersal.
This study was conducted on two populations in homogeneous vs. heterogeneous habitat in a harvested boreal forest in Ontario
(Canada). A pattern of IBD was evidenced in the homogeneous landscape whereas no such pattern was found in the near-by harvested
forest. To test whether landscape structure may be accountable for this difference, we used effective distances that take
into account the effect of landscape features on marten movement instead of Euclidean distances in the model of isolation
by distance. Effective distances computed using least-cost modeling were better correlated to genetic distances in both landscapes,
thereby showing that the interaction between landscape features and dispersal in Martes americana may be detected through individual-based analyses of spatial genetic structure. However, the simplifying assumptions of genetic
models and the low proportions in genetic differentiation explained by these models may limit their utility in quantifying
the effect of landscape structure. 相似文献
14.
Understanding how organisms respond to landscape heterogeneity is foundational to landscape ecology. We characterized seasonal
scales of movement of white-tailed deer (Odocoileus viginianus) in an agricultural–forest matrix using first-passage time analysis (FPT) for 62 GPS-collared individuals. We investigated
whether those scales were driven by demographic or landscape features. We found FPT for each individual across all seasons
was typically dominated by a peak in variance of FPT/area at scales (radii) from 425 to 1,675 m. These peaks occurred at scales
consistent with seasonal space use. We observed additional lower magnitude peaks at larger scales (3,000–6,000 m) and small
scales (25–150 m). Peaks at larger scales were associated with seasonal migrations and dispersal events. Small scale peaks
may represent resting or foraging behavior. Female movements were organized at smaller scales than males in the spring/summer
season. Models relating landscape features to movement scales suggest that deer perceive and move within the landscape differently
as the roles of dominant land-cover types shift seasonally. During winter, configuration (interspersion/juxtaposition) of
land-cover types is more important to deer than during spring/summer and fall. During spring/summer and fall, movement behavior
may be dictated by reproductive and harvest activities. 相似文献
15.
John A. Wiens 《Landscape Ecology》2008,23(2):125-128
In 1983, a group of incipient landscape ecologists met to discuss the nature and future directions for landscape ecology.
The themes emerging from this conference—movement of materials, organisms, and energy through a landscape; the genesis of
landscape patterns; the effects of landscape structure on the spread of disturbances; and the potential contributions of landscape
ecology to resource management—established a foundation for the development of landscape ecology in North America over the
following decades. I discuss these contributions in the light of where landscape ecology is today.
相似文献
John A. WiensEmail: |
16.
Robert A. Long Therese M. Donovan Paula MacKay William J. Zielinski Jeffrey S. Buzas 《Landscape Ecology》2011,26(3):327-340
Terrestrial carnivores typically have large home ranges and exist at low population densities, thus presenting challenges
to wildlife researchers. We employed multiple, noninvasive survey methods—scat detection dogs, remote cameras, and hair snares—to
collect detection–nondetection data for elusive American black bears (Ursus americanus), fishers (Martes pennanti), and bobcats (Lynx rufus) throughout the rugged Vermont landscape. We analyzed these data using occupancy modeling that explicitly incorporated detectability
as well as habitat and landscape variables. For black bears, percentage of forested land within 5 km of survey sites was an
important positive predictor of occupancy, and percentage of human developed land within 5 km was a negative predictor. Although
the relationship was less clear for bobcats, occupancy appeared positively related to the percentage of both mixed forest
and forested wetland habitat within 1 km of survey sites. The relationship between specific covariates and fisher occupancy
was unclear, with no specific habitat or landscape variables directly related to occupancy. For all species, we used model
averaging to predict occurrence across the study area. Receiver operating characteristic (ROC) analyses of our black bear
and fisher models suggested that occupancy modeling efforts with data from noninvasive surveys could be useful for carnivore
conservation and management, as they provide insights into habitat use at the regional and landscape scale without requiring
capture or direct observation of study species. 相似文献
17.
Virginie M. Stevens Emmanuelle Polus Renate A. Wesselingh Nicolas Schtickzelle Michel Baguette 《Landscape Ecology》2005,19(8):829-842
Despite the importance assigned to inter-patch movements in fragmented systems, the structure of landscape between suitable habitat patches, the matrix, is often considered as to be of minor interest, or totally ignored. Consequently, models predicting metapopulation dynamics typically assume that dispersal and movement abilities are independent of the composition of the matrix. The predictions of such models should be invalided if that crucial assumption is unverified. In order to test the hypothesis of a patch-specific resistance, we led an experimental study to assess the matrix effects on the movement ability of juvenile Natterjack toads (Bufo calamita). The movement behaviour of first year toadlets, the dispersal stage in this species, was investigated in an arena experiment. Toadlet mobility was assessed in five landscape components that were mimicked in the lab: sandy soil, road, forest, agricultural field, and pasture. We analysed several movement components including move length, speed, efficiency and turning angle distribution. Our results showed that movement ability was strongly affected by the land cover, even if body size modulated the behavioural responses of toadlets. Performances were the best in the arenas mimicking sand and roads, and the worst in the forest arena, toadlet moves being three to five times less effective in the latter. The mobility was intermediate in the two other arenas. We propose here a new method to quantify functional connectivity, based on quantitative estimates of relative values for resistance of landscape components. This method offers a reliable alternative for resistance value estimates to subjective expert advice or inference from genetic population structure. 相似文献
18.
Stevens Virginie M. Polus Emmanuelle Wesselingh Renate A. Schtickzelle Nicolas Baguette Michel 《Landscape Ecology》2004,19(8):829-842
Despite the importance assigned to inter-patch movements in fragmented systems, the structure of landscape between suitable habitat patches, the matrix, is often considered as to be of minor interest, or totally ignored. Consequently, models predicting metapopulation dynamics typically assume that dispersal and movement abilities are independent of the composition of the matrix. The predictions of such models should be invalided if that crucial assumption is unverified. In order to test the hypothesis of a patch-specific resistance, we led an experimental study to assess the matrix effects on the movement ability of juvenile Natterjack toads (Bufo calamita). The movement behaviour of first year toadlets, the dispersal stage in this species, was investigated in an arena experiment. Toadlet mobility was assessed in five landscape components that were mimicked in the lab: sandy soil, road, forest, agricultural field, and pasture. We analysed several movement components including move length, speed, efficiency and turning angle distribution. Our results showed that movement ability was strongly affected by the land cover, even if body size modulated the behavioural responses of toadlets. Performances were the best in the arenas mimicking sand and roads, and the worst in the forest arena, toadlet moves being three to five times less effective in the latter. The mobility was intermediate in the two other arenas. We propose here a new method to quantify functional connectivity, based on quantitative estimates of relative values for resistance of landscape components. This method offers a reliable alternative for resistance value estimates to subjective expert advice or inference from genetic population structure. 相似文献
19.
Matrix habitats are known to influence the movement patterns of a variety of species but it is less well known whether these
effects have strong implications for spatial population dynamics, including the spread of biological introductions. Using
a spatially explicit simulation model parameterized with empirical data, we examine how grass and shrub matrix habitats, each
offering different resistance to dispersal, influence the spread and impact of a biocontrol agent, Aphthona lacertosa, on the invasive weed, leafy spurge. Model predictions indicate that differential responses to matrix habitat have little
effect on the agent’s spread over the study landscape and this is supported by statistical models fit to observed A. lacertosa incidence on the same landscape. Subsequent experimentation with the simulation model suggested that A. lacertosa colonization rates were largely unaffected by increases in amount of the more restrictive shrub matrix. However, simulations
of an hypothetical species with greater overall dispersal ability but reduced dispersal rate through shrub matrix showed that
colonization rates were noticeably reduced when the percentage of shrub matrix on the landscape approached 50%. Combined these
results suggest that some tailoring of release strategies may be required to accommodate the unique dispersal capabilities
of different biocontrol agents on particular release landscapes, but for A. lacertosa there appears to be little effect of matrix habitat structure on rates of spread. 相似文献
20.
Bryan C. Pijanowski Almo Farina Stuart H. Gage Sarah L. Dumyahn Bernie L. Krause 《Landscape Ecology》2011,26(9):1213-1232
We summarize the foundational elements of a new area of research we call soundscape ecology. The study of sound in landscapes
is based on an understanding of how sound, from various sources—biological, geophysical and anthropogenic—can be used to understand
coupled natural-human dynamics across different spatial and temporal scales. Useful terms, such as soundscapes, biophony,
geophony and anthrophony, are introduced and defined. The intellectual foundations of soundscape ecology are described—those
of spatial ecology, bioacoustics, urban environmental acoustics and acoustic ecology. We argue that soundscape ecology differs
from the humanities driven focus of acoustic ecology although soundscape ecology will likely need its rich vocabulary and
conservation ethic. An integrative framework is presented that describes how climate, land transformations, biodiversity patterns,
timing of life history events and human activities create the dynamic soundscape. We also summarize what is currently known
about factors that control temporal soundscape dynamics and variability across spatial gradients. Several different phonic
interactions (e.g., how anthrophony affects biophony) are also described. Soundscape ecology tools that will be needed are
also discussed along with the several ways in which soundscapes need to be managed. This summary article helps frame the other
more application-oriented papers that appear in this special issue. 相似文献