Using network theory to prioritize management in a desert bighorn sheep metapopulation

Creech, Tyler G.; Epps, Clinton W.; Monello, Ryan J.; Wehausen, John D.

doi:10.1007/s10980-014-0016-0

Cited by 31 publications

(67 citation statements)

References 47 publications

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“…However, few have combined these two approaches (e.g., Creech et al. ), despite the many advantages of doing so (Urban et al. , Moilanen , Manel and Holderegger ).…”

Section: Discussionmentioning

confidence: 99%

“…One advantage of network‐based methods is the ability to quantify the contribution of particular areas to overall connectivity through centrality metrics, as was done with desert bighorn sheep ( Ovis canadensis ) in southern California (Creech et al. ) and gray wolves ( Canis lupus ) in western North America (Carroll et al. ).…”

Section: Discussionmentioning

confidence: 99%

“…We constructed network models to compare fragmentation across study sites as well as identify which portions of the networks are important for maintaining connectivity (Creech et al. , Galpern et al. ).…”

Section: Methodsmentioning

confidence: 99%

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Replicated landscape genetic and network analyses reveal wide variation in functional connectivity for American pikas

Castillo

Epps

Jeffress

et al. 2016

Ecological Applications

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Landscape connectivity is essential for maintaining viable populations, particularly for species restricted to fragmented habitats or naturally arrayed in metapopulations and facing rapid climate change. The importance of assessing both structural connectivity (physical distribution of favorable habitat patches) and functional connectivity (how species move among habitat patches) for managing such species is well understood. However, the degree to which functional connectivity for a species varies among landscapes, and the resulting implications for conservation, have rarely been assessed. We used a landscape genetics approach to evaluate resistance to gene flow and, thus, to determine how landscape and climate-related variables influence gene flow for American pikas (Ochotona princeps) in eight federally managed sites in the western United States. We used empirically derived, individual-based landscape resistance models in conjunction with predictive occupancy models to generate patch-based network models describing functional landscape connectivity. Metareplication across landscapes enabled identification of limiting factors for dispersal that would not otherwise have been apparent. Despite the cool microclimates characteristic of pika habitat, south-facing aspects consistently represented higher resistance to movement, supporting the previous hypothesis that exposure to relatively high temperatures may limit dispersal in American pikas. We found that other barriers to dispersal included areas with a high degree of topographic relief, such as cliffs and ravines, as well as streams and distances greater than 1-4 km depending on the site. Using the empirically derived network models of habitat patch connectivity, we identified habitat patches that were likely disproportionately important for maintaining functional connectivity, areas in which habitat appeared fragmented, and locations that could be targeted for management actions to improve functional connectivity. We concluded that climate change, besides influencing patch occupancy as predicted by other studies, may alter landscape resistance for pikas, thereby influencing functional connectivity through multiple pathways simultaneously. Spatial autocorrelation among genotypes varied across study sites and was largest where habitat was most dispersed, suggesting that dispersal distances increased with habitat fragmentation, up to a point. This study demonstrates how landscape features linked to climate can affect functional connectivity for species with naturally fragmented distributions, and reinforces the importance of replicating studies across landscapes.

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“…However, few have combined these two approaches (e.g., Creech et al. ), despite the many advantages of doing so (Urban et al. , Moilanen , Manel and Holderegger ).…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Replicated landscape genetic and network analyses reveal wide variation in functional connectivity for American pikas

Castillo

Epps

Jeffress

et al. 2016

Ecological Applications

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“…A better understanding of variation in link importance would help elucidate how network structure influences metacommunity stability, a key goal of spatial ecology Gaggiotti 2004, Holyoak et al 2005). An ability to predict link importance would also pay dividends for biodiversity conservation (Economo 2011, Creech et al 2014. For example, conservation efforts have focused on establishing protected areas such as national parks and wildlife reserves.…”

Section: Introductionmentioning

confidence: 99%

“…As a metric of stability, we calculate cumulative changes in metapopulation persistence, using metapopulation capacity as an asymptotic proxy (Hanski and Ovaskainen 2000, Gilbert and Levine 2013, Grilli et al 2015, among all species in the regional pool. Moreover, graph-theoretical metrics generally rank linkages in terms of proximate factors, such as total network connectivity, rather than the ultimate measure in which we are interested: network stability (Laita et al 2011, Moilanen 2011, Creech et al 2014, Ziolkowska et al 2014). Moreover, graph-theoretical metrics generally rank linkages in terms of proximate factors, such as total network connectivity, rather than the ultimate measure in which we are interested: network stability (Laita et al 2011, Moilanen 2011, Creech et al 2014, Ziolkowska et al 2014).…”

Section: Introductionmentioning

confidence: 99%

How individual links affect network stability in a large‐scale, heterogeneous metacommunity

Brodie

Schnell

2016

Ecology

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Elucidating how dispersal and landscape connectivity influence metacommunity stability will shed light on natural processes structuring ecosystems and help prioritize conservation actions in an increasingly fragmented world. Much of the theoretical and mathematical development of the metacommunity concept has been based on simplified experimental systems or simulated data. We still have limited understanding of how variation in the habitat matrix and species-specific differences in dispersal ability contribute to metacommunity dynamics in heterogeneous landscapes. We model a metacommunity of rainforest mammals in Borneo, a tropical biodiversity hotspot, where protected areas are increasingly isolated by ongoing habitat disturbance and loss. We employ a combination of hierarchical models of local abundance, circuit-theory-based dispersal analysis, and metapopulation models. Our goal was to understand which landscape links were the most important to metapopulation persistence and metacommunity stability. Links were particularly important if they were short and connected two large patches. This was partly because only the very shortest links could be traversed by poorly dispersing species, including small herbivores such as chevrotains (Tragulus spp.) and porcupines. Links that join large patches into a "super-patch" may also promote island-mainland rather than Levins-type metapopulation dynamics for good dispersers, particularly large carnivores such as clouded leopards (Neofelis diardi) and sun bears (Helarctos malayanus), reducing metapopulation extinction risk and thereby enhancing metacommunity stability. Link importance to metacommunity stability was highly correlated between heterogeneous and homogeneous landscapes. But link importance to metapopulation capacity varied strongly across species, and the correlation between heterogeneous and homogeneous landscape matrix scenarios was low for poorly dispersing taxa. This suggests that the environmental conditions in the area between habitat patches, the landscape matrix, is important for assessing certain individual species but less so for understanding the stability of the entire metacommunity.

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Functional connectivity and home range inferred at a microgeographic landscape genetics scale in a desert‐dwelling rodent

Flores‐Manzanero

Luna‐Bárcenas

Dyer

et al. 2018

Ecology and Evolution

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Gene flow in animals is limited or facilitated by different features within the landscape matrix they inhabit. The landscape representation in landscape genetics (LG) is traditionally modeled as resistance surfaces (RS), where novel optimization approaches are needed for assigning resistance values that adequately avoid subjectivity. Also, desert ecosystems and mammals are scarcely represented in LG studies. We addressed these issues by evaluating, at a microgeographic scale, the effect of landscape features on functional connectivity of the desert-dwelling Dipodomys merriami.We characterized genetic diversity and structure with microsatellites loci, estimated home ranges and movement of individuals using telemetry-one of the first with rodents, generated a set of individual and composite environmental surfaces based on hypotheses of variables influencing movement, and assessed how these variables relate to individual-based gene flow. Genetic diversity and structure results evidenced a family-induced pattern driven by first-order-related individuals, notably determining landscape genetic inferences. The vegetation cover and soil resistance optimized surface (NDVI) were the best-supported model and a significant predictor of individual genetic distance, followed by humidity and NDVI+humidity. Based on an accurate definition of thematic resolution, we also showed that vegetation is better represented as continuously (vs. categorically) distributed. Hence, with a nonsubjective optimization framework for RS and telemetry, we were able to describe that vegetation cover, soil texture, and climatic variables influence D. merriami's functional connectivity at a microgeographic scale, patterns we could further explain based on the home range, habitat use, and activity observed between sexes. We describe the relationship between environmental features and some aspects of D. merriami's behavior and physiology. K E Y W O R D Sdesert ecosystems, Dipodomys merriami, functional connectivity, landscape genetics, Merriam's kangaroo rat, resistance surfaces

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Using network theory to prioritize management in a desert bighorn sheep metapopulation

Cited by 31 publications

References 47 publications

Replicated landscape genetic and network analyses reveal wide variation in functional connectivity for American pikas

Replicated landscape genetic and network analyses reveal wide variation in functional connectivity for American pikas

How individual links affect network stability in a large‐scale, heterogeneous metacommunity

Functional connectivity and home range inferred at a microgeographic landscape genetics scale in a desert‐dwelling rodent

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