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Carroll C.,Klamath Center for Conservation Research | Fredrickson R.J.,1310 Lower Lincoln Hills Drive | Lacy R.C.,Chicago Zoological Society
Conservation Biology | Year: 2014

Restoring connectivity between fragmented populations is an important tool for alleviating genetic threats to endangered species. Yet recovery plans typically lack quantitative criteria for ensuring such population connectivity. We demonstrate how models that integrate habitat, genetic, and demographic data can be used to develop connectivity criteria for the endangered Mexican wolf (Canis lupus baileyi), which is currently being restored to the wild from a captive population descended from 7 founders. We used population viability analysis that incorporated pedigree data to evaluate the relation between connectivity and persistence for a restored Mexican wolf metapopulation of 3 populations of equal size. Decreasing dispersal rates greatly increased extinction risk for small populations (<150-200), especially as dispersal rates dropped below 0.5 genetically effective migrants per generation. We compared observed migration rates in the Northern Rocky Mountains (NRM) wolf metapopulation to 2 habitat-based effective distance metrics, least-cost and resistance distance. We then used effective distance between potential primary core populations in a restored Mexican wolf metapopulation to evaluate potential dispersal rates. Although potential connectivity was lower in the Mexican wolf versus the NRM wolf metapopulation, a connectivity rate of >0.5 genetically effective migrants per generation may be achievable via natural dispersal under current landscape conditions. When sufficient data are available, these methods allow planners to move beyond general aspirational connectivity goals or rules of thumb to develop objective and measurable connectivity criteria that more effectively support species recovery. The shift from simple connectivity rules of thumb to species-specific analyses parallels the previous shift from general minimum-viable-population thresholds to detailed viability modeling in endangered species recovery planning. © 2013 Society for Conservation Biology.

Carroll C.,Klamath Center for Conservation Research | Lawler J.J.,University of Washington | Roberts D.R.,University of Alberta | Roberts D.R.,Albert Ludwigs University of Freiburg | Hamann A.,University of Alberta
PLoS ONE | Year: 2015

Metrics that synthesize the complex effects of climate change are essential tools for mappingfuture threats to biodiversity and predicting which species are likely to adapt in place to new climatic conditions, disperse and establish in areas with newly suitable climate, or facethe prospect of extirpation. The most commonly used of such metrics is the velocity of climate change, which estimates the speed at which species must migrate over the earth'ssurface to maintain constant climatic conditions. However, "analog-based" velocities, which represent the actual distance to where analogous climates will be found in the future, mayprovide contrasting results to the more common form of velocity based on local climate gradients. Additionally, whereas climatic velocity reflects the exposure of organisms to climatechange, resultant biotic effects are dependent on the sensitivity of individual species as reflected in part by their climatic niche width. This has motivated development of bioticvelocity, a metric which uses data on projected species range shifts to estimate the velocity at which species must move to track their climatic niche.We calculated climatic and bioticvelocity for the Western Hemisphere for 1961-2100, and applied the results to example ecological and conservation planning questions, to demonstrate the potential of such analog-based metrics to provide information on broad-scale patterns of exposure and sensitivity. Geographic patterns of biotic velocity for 2954 species of birds, mammals, andamphibians differed from climatic velocity in north temperate and boreal regions. However, both biotic and climatic velocities were greatest at low latitudes, implying that threats toequatorial species arise from both the future magnitude of climatic velocities and the narrow climatic tolerances of species in these regions, which currently experience low seasonaland interannual climatic variability. Biotic and climatic velocity, by approximating lower and upper bounds on migration rates, can inform conservation of species and locally-adaptedpopulations, respectively, and in combination with backward velocity, a function of distance to a source of colonizers adapted to a site's future climate, can facilitate conservation ofdiversity at multiple scales in the face of climate change. © 2015 Carroll et al.This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Rohlf D.J.,Lewis and Clark Law School | Carroll C.,Klamath Center for Conservation Research | Hartl B.,Center for Biological Diversity
BioScience | Year: 2014

The concept of conservation-reliant species has become increasingly prominent, particularly with species listed or under consideration for listing under the US Endangered Species Act (ESA). We have concerns about the trend toward what we see as an overly broad definition of conservation reliance. In addition to being of limited practical utility, overuse of the conservation reliant label can mask important legal and policy issues associated with species recovery and delisting. We propose a biology-based definition of conservation-reliant species - specifically, one based on the degree to which a species needs direct and ongoing human manipulation of its life cycle or environment in order to persist in the wild. This definition could assist managers in developing recovery priorities and allocating scarce recovery funds. In addition, a biological definition of conservation reliance could assist society and policymakers in considering whether the ESA's focus on self-sufficiency in the wild remains relevant as a definition of conservation success. © 2014 The Author(s) 2014.

Carroll C.,Klamath Center for Conservation Research | Rohlf D.J.,Pacific Environmental Advocacy Center | Li Y.-W.,Defenders of Wildlife | Hartl B.,Center for Biological Diversity | And 2 more authors.
Conservation Letters | Year: 2015

Many species listed under the US Endangered Species Act (ESA) face continuing threats and will require intervention to address those threats for decades. These species, which have been termed conservation-reliant, pose a challenge to the ESA's mandate for recovery of self-sustaining populations. Most references to conservation-reliant species by federal agencies involve the restoration of population connectivity. However, the diverse threats to connectivity faced by different species have contrasting implications in the context of the ESA's mandate. For species facing long-term threats from invasive species or climate change, restoration of natural dispersal may not be technically feasible in the foreseeable future. For other species, restoration of natural dispersal is feasible, but carries economic and political cost. Federal agencies have used a broad definition of conservation reliance to justify delisting of species in the latter group even if they remain dependent on artificial translocation. Distinguishing the two groups better informs policy by distinguishing the technical challenges posed by novel ecological stressors from normative questions such as the price society is willing to pay to protect biodiversity, and the degree to which we should grow accustomed to direct human intervention in species' life cycles as a component of conservation in the Anthropocene Epoch. © 2014 The Authors. Conservation Letters published by Wiley Periodicals, Inc.

Carroll C.,Klamath Center for Conservation Research | Dunk J.R.,Humboldt State University | Dunk J.R.,U.S. Department of Agriculture | Moilanen A.,University of Helsinki
Global Change Biology | Year: 2010

The effectiveness of a system of reserves may be compromised under climate change as species' habitat shifts to nonreserved areas, a problem that may be compounded when well-studied vertebrate species are used as conservation umbrellas for other taxa. The Northwest Forest Plan was among the first efforts to integrate conservation of wide-ranging focal species and localized endemics into regional conservation planning. We evaluated how effectively the plan's focal species, the Northern Spotted Owl, acts as an umbrella for localized species under current and projected future climates and how the regional system of reserves can be made more resilient to climate change. We used the program maxent to develop distribution models integrating climate data with vegetation variables for the owl and 130 localized species. We used the program zonation to identify a system of areas that efficiently captures habitat for both the owl and localized species and prioritizes refugial areas of climatic and topographic heterogeneity where current and future habitat for dispersal-limited species is in proximity. We projected future species' distributions based on an ensemble of contrasting climate models, and incorporating uncertainty between alternate climate projections into the prioritization process. Reserve solutions based on the owl overlap areas of high localized-species richness but poorly capture core areas of localized species' distribution. Congruence between priority areas across taxa increases when refugial areas are prioritized. Although core-area selection strategies can potentially increase the conservation value and resilience of regional reserve systems, they accentuate contrasts in priority areas between species and over time and should be combined with a broadened taxonomic scope and increased attention to potential effects of climate change. Our results suggest that systems of fixed reserves designed for resilience can increase the likelihood of retaining the biological diversity of forest ecosystems under climate change. © 2009 Blackwell Publishing Ltd.

Carroll C.,Klamath Center for Conservation Research | Johnson D.S.,National Oceanic and Atmospheric Administration | Dunk J.R.,Humboldt State University | Dunk J.R.,U.S. Department of Agriculture | Zielinski W.J.,U.S. Department of Agriculture
Conservation Biology | Year: 2010

Biologists who develop and apply habitat models are often familiar with the statistical challenges posed by their data's spatial structure but are unsure of whether the use of complex spatial models will increase the utility of model results in planning. We compared the relative performance of nonspatial and hierarchical Bayesian spatial models for three vertebrate and invertebrate taxa of conservation concern (Church's sideband snails [Monadenia churchi], red tree voles [Arborimus longicaudus], and Pacific fishers [Martes pennanti pacifica]) that provide examples of a range of distributional extents and dispersal abilities. We used presence-absence data derived from regional monitoring programs to develop models with both landscape and site-level environmental covariates. We used Markov chain Monte Carlo algorithms and a conditional autoregressive or intrinsic conditional autoregressive model framework to fit spatial models. The fit of Bayesian spatial models was between 35 and 55% better than the fit of nonspatial analogue models. Bayesian spatial models outperformed analogous models developed with maximum entropy (Maxent) methods. Although the best spatial and nonspatial models included similar environmental variables, spatial models provided estimates of residual spatial effects that suggested how ecological processes might structure distribution patterns. Spatial models built from presence-absence data improved fit most for localized endemic species with ranges constrained by poorly known biogeographic factors and for widely distributed species suspected to be strongly affected by unmeasured environmental variables or population processes. By treating spatial effects as a variable of interest rather than a nuisance, hierarchical Bayesian spatial models, especially when they are based on a common broad-scale spatial lattice (here the national Forest Inventory and Analysis grid of 24 km 2 hexagons), can increase the relevance of habitat models to multispecies conservation planning. © 2010 Society for Conservation Biology. No claim to original US government works.

Carroll C.,Klamath Center for Conservation Research | Mcrae B.H.,The Nature Conservancy | Brookes A.,University of Washington
Conservation Biology | Year: 2012

Centrality metrics evaluate paths between all possible pairwise combinations of sites on a landscape to rank the contribution of each site to facilitating ecological flows across the network of sites. Computational advances now allow application of centrality metrics to landscapes represented as continuous gradients of habitat quality. This avoids the binary classification of landscapes into patch and matrix required by patch-based graph analyses of connectivity. It also avoids the focus on delineating paths between individual pairs of core areas characteristic of most corridor- or linkage-mapping methods of connectivity analysis. Conservation of regional habitat connectivity has the potential to facilitate recovery of the gray wolf(Canis lupus),a species currently recolonizing portions of its historic range in the western United States. We applied 3 contrasting linkage-mapping methods (shortest path, current flow, and minimum-cost-maximum-flow) to spatial data representing wolf habitat to analyze connectivity between wolf populations in central Idaho and Yellowstone National Park (Wyoming). We then applied 3 analogous betweenness centrality metrics to analyze connectivity of wolf habitat throughout the northwestern United States and southwestern Canada to determine where it might be possible to facilitate range expansion and interpopulation dispersal. We developed software to facilitate application of centrality metrics. Shortest-path betweenness centrality identified a minimal network of linkages analogous to those identified by least-cost-path corridor mapping. Current flow and minimum-cost-maximum-flow betweenness centrality identified diffuse networks that included alternative linkages, which will allow greater flexibility in planning. Minimum-cost-maximum-flow betweenness centrality, by integrating both land cost and habitat capacity, allows connectivity to be considered within planning processes that seek to maximize species protection at minimum cost. Centrality analysis is relevant to conservation and landscape genetics at a range of spatial extents, but it may be most broadly applicable within single- and multispecies planning efforts to conserve regional habitat connectivity. © 2011 Society for Conservation Biology.

Carroll C.,Klamath Center for Conservation Research | Vucetich J.A.,Michigan Technological University | Nelson M.P.,Michigan State University | Rohlf D.J.,Pacific Environmental Advocacy Center | Phillips M.K.,123 Research Drive
Conservation Biology | Year: 2010

The U.S. Endangered Species Act (ESA) defines an endangered species as one "at risk of extinction throughout all or a significant portion of its range." The prevailing interpretation of this phrase, which focuses exclusively on the overall viability of listed species without regard to their geographic distribution, has led to development of listing and recovery criteria with fundamental conceptual, legal, and practical shortcomings. The ESA's concept of endangerment is broader than the biological concept of extinction risk in that the "esthetic, ecological, educational, historical, recreational, and scientific" values provided by species are not necessarily furthered by a species mere existence, but rather by a species presence across much of its former range. The concept of "significant portion of range" thus implies an additional geographic component to recovery that may enhance viability, but also offers independent benefits that Congress intended the act to achieve. Although the ESA differs from other major endangered-species protection laws because it acknowledges the distinct contribution of geography to recovery, it resembles the "representation, resiliency, and redundancy" conservation-planning framework commonly referenced in recovery plans. To address representation, listing and recovery standards should consider not only what proportion of its former range a species inhabits, but the types of habitats a species occupies and the ecological role it plays there. Recovery planning for formerly widely distributed species (e.g., the gray wolf [Canis lupus]) exemplifies how the geographic component implicit in the ESA's definition of endangerment should be considered in determining recovery goals through identification of ecologically significant types or niche variation within the extent of listed species, subspecies, or "distinct population segments." By linking listing and recovery standards to niche and ecosystem concepts, the concept of ecologically significant type offers a scientific framework that promotes more coherent dialogue concerning the societal decisions surrounding recovery of endangered species. © 2010 Society for Conservation Biology.

Hamann A.,University of Alberta | Roberts D.R.,University of Alberta | Barber Q.E.,University of Alberta | Carroll C.,Klamath Center for Conservation Research | Nielsen S.E.,University of Alberta
Global Change Biology | Year: 2015

The velocity of climate change is an elegant analytical concept that can be used to evaluate the exposure of organisms to climate change. In essence, one divides the rate of climate change by the rate of spatial climate variability to obtain a speed at which species must migrate over the surface of the earth to maintain constant climate conditions. However, to apply the algorithm for conservation and management purposes, additional information is needed to improve realism at local scales. For example, destination information is needed to ensure that vectors describing speed and direction of required migration do not point toward a climatic cul-de-sac by pointing beyond mountain tops. Here, we present an analytical approach that conforms to standard velocity algorithms if climate equivalents are nearby. Otherwise, the algorithm extends the search for climate refugia, which can be expanded to search for multivariate climate matches. With source and destination information available, forward and backward velocities can be calculated allowing useful inferences about conservation of species (present-to-future velocities) and management of species populations (future-to-present velocities). © 2014 The Authors. Global Change Biology Published by John Wiley & Sons Ltd.

Although well-studied vertebrates such as the Northern Spotted Owl (NSO) are often used as focal species in regional conservation plans, range shifts associated with climate change may compromise this role. I used the Maxent (maximum entropy) method to develop NSO distribution models from data on NSO locations, forest age, and an ensemble of climate projections. NSO presence was positively associated with the proportion of old and mature forest at two spatial scales. Winter precipitation was the most important climate variable, consistent with previous studies suggesting negative effects on survival and recruitment. Model results suggest that initial niche expansion may be followed by a contraction as climate change intensifies, but this prediction is uncertain due to variability in predicted changes in precipitation between climate projections. Although new reserves created by the US Northwest Forest Plan prioritized areas with greater biological importance for the NSO than did pre-existing reserves, the latter areas, which lie predominantly at higher elevations, increase in importance under climate change. In contrast with previous analyses of the region's localized old-forest-associated species, vegetation rather than climate dominated NSO distribution models. Rigorous assessment of the implications of climate change for focal species requires development of dynamic vegetation models that incorporate effects of competitor species and altered disturbance regimes. The results suggest that, lacking such data, models that combine climate data with current data on habitat factors such as vegetation can inform conservation planning by providing less-biased estimates of potential range shifts than do niche models based on climate variables alone. © 2010 Elsevier Ltd.

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