Multi‐scale processes in metapopulations: contributions of stage structure, rescue effect, and correlated extinctions

Sutherland, Chris; Elston, David A.; Lambin, Xavier

doi:10.1890/12-0172.1

Cited by 41 publications

(57 citation statements)

References 51 publications

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“…In addition to zero trapping effort at these sites, and also due to weather constraints, not all sites with positive detections were trapped. Without a formal mechanism to account for such missing data, Sutherland et al (2012) used a restricted data set from 1999 to 2007 to investigate metapopulation dynamics. We will describe a method to overcome the problem of missing data.…”

Section: Water Vole Metapopulation and Data Collectionmentioning

confidence: 99%

“…We follow the SPOM formulation described in Sutherland et al (2012), which models transition probabilities as a function of abundance directly, relaxing the assumption that population size scales with patch size. The SPOM allows estimation of w i,t , the probability that patch i is occupied in time t. No information is available regarding the occupancy states prior to the initial sampling period, so occupancy states in the initial year, z i,1 , are modeled as Bernoulli random variables governed by parameter w 1 :…”

Section: Demographic Spatially Explicit Metapopulation Process Modelmentioning

confidence: 99%

“…Following Sutherland et al (2012), connectivity is calculated based on the number of juveniles occupying a neighboring site, e.g., N juv j;tÀ1 . When a patch is unoccupied, N Ã j;tÀ1 ¼ 0 and therefore does not contribute to connectivity.…”

Section: Demographic Spatially Explicit Metapopulation Process Modelmentioning

confidence: 99%

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A demographic, spatially explicit patch occupancy model of metapopulation dynamics and persistence

Sutherland

Elston

Lambin

2014

Ecology

121

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Abstract. Patch occupancy models are extremely important and popular tools for understanding the dynamics, and predicting the persistence, of spatially structured populations. Typically this endeavor is facilitated either by models from classic metapopulation theory focused on spatially explicit, dispersal-driven colonization-extinction dynamics and generally assuming perfect detection, or by more recent hierarchical site occupancy models that account for imperfect detection but rarely include spatial effects, such as dispersal, explicitly. Neither approach explicitly considers local demographics in a way that can be used for future projections. However, despite being arguably of equal importance, dispersal and connectivity, local demography, and imperfect detection are rarely modeled explicitly and simultaneously. Understanding the spatiotemporal occurrence patterns of spatially structured populations and making biologically realistic long-term predictions of persistence would benefit from the simultaneous treatment of space, demography, and detectability. We integrated these key ideas in a tractable and intuitive way to develop a demographic and spatially realistic patch occupancy model that incorporates components of dispersal, local demographic stage-structure, and detectability. By explicitly relating stage-specific abundances to measurable patch properties, biologically realistic projections of long-term metapopulation dynamics could be made. We applied our model to data from a naturally fragmented population of water voles Arvicola amphibius to describe observed patch occupancy dynamics and to investigate long-term persistence under scenarios of elevated stage-specific local extinction. Accounting for biases induced by imperfect detection, we were able to estimate: stable, and higher than observed metapopulation occupancy; high rates of patch turnover and stage-specific colonization and extinction rates ( juvenile and adult, respectively); and juvenile dispersal distances (average 2.10 km). We found that metapopulation persistence in the presence of elevated extinction risk differed depending on which life stage was exposed, and was more sensitive to elevated juvenile rather than adult extinction risk. Predictions of persistence when dynamics are stage-specific suggest that metapopulations may be more resilient to changes in the environment than predicted when relationships are based on patch size approximations rather than population sizes. Our approach allows explicit consideration of local dynamics and dispersal in spatially structured and stage-structured populations, provides a more detailed mechanistic understanding of metapopulation functioning, and can be used to investigate future extinction risk under biologically meaningful scenarios.

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Section: Water Vole Metapopulation and Data Collectionmentioning

confidence: 99%

Section: Demographic Spatially Explicit Metapopulation Process Modelmentioning

confidence: 99%

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A demographic, spatially explicit patch occupancy model of metapopulation dynamics and persistence

Sutherland

Elston

Lambin

2014

Ecology

121

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“…The presence or absence of water voles is therefore determined by the detection or non-detection, during each of multiple site visits, of highly distinctive latrines that are composed of pellets deposited repeatedly and prominently on emergent rocks or 'beaches'. Latrines are used to mark territories at sites occupied by established colonies, although, given that they are a highly dispersive species Sutherland et al 2012), are sometimes observed at very low frequencies at unoccupied sites (Woodroffe and Lawton 1990). In Appendix S1 (available in the Supplementary Material for this paper), we provide evidence that fewer latrines are found at sites that are more likely to be false positives.…”

Section: Case Study: the Assynt Water Vole Metapopulationmentioning

confidence: 99%

“…Repeated visits were separated by no more than 2 weeks (see Sutherland et al (2012) for a full description of the water vole metapopulation and data collection). Like for many site-occupancy studies, our data are binary detection or non-detection data, with no auxiliary information, and so, retrospective classification of observations into multiple states is not possible as is required by the multi-state modelling approach that could otherwise be used to characterise two (or more) types of occupancy, i.e.…”

Section: Case Study: the Assynt Water Vole Metapopulationmentioning

confidence: 99%

Accounting for false positive detection error induced by transient individuals

2013

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Context. In metapopulations, colonisation is the result of dispersal from neighbouring occupied patches, typically juveniles dispersing from natal to breeding sites. When occupancy dynamics are dispersal driven, occupancy should refer to the presence of established, breeding populations. The detection of transient individuals at sites that are, by definition, unoccupied (i.e. false positive detections), may result in misleading conclusions about metapopulation dynamics. Until recently, the issue of false positives has been considered negligible and current efforts to account for such error have been restricted to the context of species misidentification. However, the detection of transient individuals visiting multiple sites while dispersing is a distinct source of false positives that can bias estimates of occupancy because visited sites do not contribute to metapopulation dynamics in the same way as do sites occupied by established, reproducing populations. Although transient-induced false positive error presents a challenge to occupancy studies aiming to account for all sources of detection error and estimate occupancy without bias, accounting for it has received little attention.Aims. Using a novel application of an existing occupancy model, we sought to account for false positives that result from transient individuals being observed at truly unoccupied sites (i.e. where no establishment has occurred).Methods. We applied a Bayesian multi-season occupancy model correcting for false negative and false positive errors, to 3 years of detection or non-detection data from a metapopulation of water voles, Arvicola amphibious, in which both types of patch-state misclassification are suspected.Key results. We provide evidence that transient individuals can cause false positive detection errors. We then demonstrate the flexibility of the occupancy model to account for both false negative and false positive detection errors beyond the typical application to species misidentification. Accounting for both types of observation error reduces the bias in estimates of occupancy and avoids misleading conclusions about the status of (meta) populations by allowing for the distinction to be made between resident and transient occupancy.Conclusion. In many species, transience may result in patch-state misclassification which needs to be accounted for so as to draw correct inference about metapopulation status. Making the distinction between occupancy by established populations and visitation by transients will influence how we interpret patch occupancy dynamics, with important implications for the management of wildlife.Implications. The ability to estimate occupancy free of bias induced by false positive detections can help ensure that downward trends in occupancy are detected despite such declines being accompanied by increasing frequency of transients associated with, for example, reductions in mate availability or failure to establish. Our approach can be applied to any occupancy study in which false positive detecti...

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Indirect connectivity estimates of amphibian breeding wetlands from spatially explicit occupancy models

Brooks

Smith

Frimpong

et al. 2019

Aquatic Conservation

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In conservation science, metapopulation models are frequently used to explore the spatial dynamics of organisms, and ultimately guide management decisions for threatened and endangered species. Pond‐breeding amphibians are often touted as a classic example of metapopulation structure. However, empirical assessment of this assumption is lacking for many species owing to the prohibitively high costs of movement studies. Our aim was to use spatially explicit occupancy models to evaluate metapopulation dynamics in an endangered amphibian. First, dynamic, spatially explicit occupancy‐based metapopulation models were fitted to 8 years of presence–absence data for the endangered reticulated flatwoods salamander, Ambystoma bishopi. Models were constructed to evaluate the spatial distribution of salamanders across the landscape, rate of patch turnover, and connectivity between patches. Second, the same data were analysed adopting an eigenvector mapping approach and spatial correlograms to investigate habitat characteristics associated with occupancy state. The second approach also yields an independent measure of patch connectivity to corroborate findings from the dynamic model. Both models predicted a steep drop‐off in connectivity with increasing isolation, and no evidence was found of interactions between wetlands separated by distances greater than 1.5 km. The best predictor of salamander occupancy status was the amount of understorey vegetation in wetland basins. Taken together, the two modelling approaches provide complementary information regarding the key determinants of occupancy in the focal species. Furthermore, several results directly translate to management recommendations. Connectivity between distant sites is low, and thus management units should be demarcated accordingly. Understorey vegetation represents egg‐laying habitat and refugia for larvae, and hence should be targeted in future restoration efforts. The methodologies employed in this paper have broad applicability to studies of pond‐breeding amphibians, particularly in situations where direct measures of dispersal are unobtainable.

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Multi‐scale processes in metapopulations: contributions of stage structure, rescue effect, and correlated extinctions

Cited by 41 publications

References 51 publications

A demographic, spatially explicit patch occupancy model of metapopulation dynamics and persistence

A demographic, spatially explicit patch occupancy model of metapopulation dynamics and persistence

Accounting for false positive detection error induced by transient individuals

Indirect connectivity estimates of amphibian breeding wetlands from spatially explicit occupancy models

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