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Chitwood MC, Lashley MA, Kilgo JC, Moorman CE, Deperno CS. White-tailed deer population dynamics and adult female survival in the presence of a novel predator. J Wildl Manage 2015. [DOI: 10.1002/jwmg.835] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Michael C. Chitwood
- Fisheries, Wildlife, and Conservation Biology Program; Department of Forestry and Environmental Resources; North Carolina State University; Raleigh NC 27695 USA
| | - Marcus A. Lashley
- Fisheries, Wildlife, and Conservation Biology Program; Department of Forestry and Environmental Resources; North Carolina State University; Raleigh NC 27695 USA
| | - John C. Kilgo
- USDA Forest Service; Southern Research Station; P.O. Box 700; New Ellenton SC 29809 USA
| | - Christopher E. Moorman
- Fisheries, Wildlife, and Conservation Biology Program; Department of Forestry and Environmental Resources; North Carolina State University; Raleigh NC 27695 USA
| | - Christopher S. Deperno
- Fisheries, Wildlife, and Conservation Biology Program; Department of Forestry and Environmental Resources; North Carolina State University; Raleigh NC 27695 USA
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52
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Prugh LR, Arthur SM. Optimal predator management for mountain sheep conservation depends on the strength of mesopredator release. OIKOS 2015. [DOI: 10.1111/oik.02017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Laura R. Prugh
- Inst. of Arctic Biology, Univ. of Alaska Fairbanks; Fairbanks AK 99775 USA
| | - Stephen M. Arthur
- Dept of Wildlife Conservation; Alaska Dept of Fish and Game; 1300 College Rd Fairbanks AK 99701 USA
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Hervieux D, Hebblewhite M, DeCesare N, Russell M, Smith K, Robertson S, Boutin S. Reply to the comment by Harron on “Widespread declines in woodland caribou ( Rangifer tarandus caribou) continue in Alberta”. CAN J ZOOL 2015. [DOI: 10.1139/cjz-2014-0321] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Estimation of demographic trends from vital rates provides a powerful means to estimate population trends in cryptic or difficult to study species such as woodland caribou (Rangifer tarandus caribou (Gmelin, 1788)). Using such methods, Hervieux et al. (2013; Can. J. Zool. 91(12): 872–882) recently showed 11 of 14 woodland caribou populations in Alberta were declining at ∼8%/year following up to 18 years of monitoring. Harron (2015; Can. J. Zool. 93(2): 149–150) critiques our original study, claiming that negative biases in our demographic monitoring exaggerate our conclusions of widespread caribou declines. Here, we systematically review each of Harron’s claims of bias, rejecting each of his claims upon careful review of the mechanisms by which his purported claims would manifest in our population trend estimation. Therefore, we conclude that Harron’s scientific critique was superficial and misleading. Delays in conservation actions raised by Harron’s critique risk diminishing opportunities to conserve and recover this federally and provincially protected species.
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Affiliation(s)
- D. Hervieux
- Operations Division (Fisheries and Wildlife), Alberta Environment and Sustainable Resource Development, Grande Prairie, AB T8V 6J4, Canada
| | - M. Hebblewhite
- Wildlife Biology Program, Department of Ecosystem and Conservation Sciences, College of Forestry and Conservation, University of Montana, Missoula, MT 59812, USA
| | - N.J. DeCesare
- Wildlife Biology Program, Department of Ecosystem and Conservation Sciences, College of Forestry and Conservation, University of Montana, Missoula, MT 59812, USA
| | - M. Russell
- Operations Division (Fisheries and Wildlife), Alberta Environment and Sustainable Resource Development, Grande Prairie, AB T8V 6J4, Canada
| | - K. Smith
- Operations Division (Fisheries and Wildlife), Alberta Environment and Sustainable Resource Development, Grande Prairie, AB T8V 6J4, Canada
| | - S. Robertson
- Operations Division (Fisheries and Wildlife), Alberta Environment and Sustainable Resource Development, Grande Prairie, AB T8V 6J4, Canada
| | - S. Boutin
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
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54
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Wolf S, Hartl B, Carroll C, Neel MC, Greenwald DN. Beyond PVA: Why Recovery under the Endangered Species Act Is More than Population Viability. Bioscience 2015. [DOI: 10.1093/biosci/biu218] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Hervieux D, Hebblewhite M, Stepnisky D, Bacon M, Boutin S. Managing wolves (Canis lupus) to recover threatened woodland caribou (Rangifer tarandus caribou) in Alberta. CAN J ZOOL 2014. [DOI: 10.1139/cjz-2014-0142] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Across Canada, woodland caribou (Rangifer tarandus caribou (Gmelin, 1788)) populations are declining because of human-induced changes to food webs that are resulting in apparent competition-induced increases in predator-caused caribou mortality. We tested the hypothesis that wolf (Canis lupus L., 1758) population reduction could reverse declines in a woodland caribou population following a BACI (before-after-control-impact) design conducted over a 12-year period in west-central Alberta, Canada. We monitored annual survival for 172 adult female caribou and calf recruitment from 2000 through 2012 and conducted a provincial government delivered wolf population reduction program annually during the winters of 2005–2006 to 2012 (inclusive) in an area centered on the Little Smoky range. Wolf removal translated to a 4.6% increase in mean population growth rate of the Little Smoky population mostly through improvements in calf recruitment. In contrast, the Red Rock Prairie Creek control population exhibited a 4.7% decline. Although the wolf population reduction program appeared to stabilize the Little Smoky population, it did not lead to population increase, however, with λ remaining approximately equal to 1. Therefore, we recommend, if required, predation management be combined with effective habitat conservation and long-term planning to effect the recovery of species, such as woodland caribou, which are declining as a result of habitat-mediated apparent competition.
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Affiliation(s)
- Dave Hervieux
- Resource Management - Operations Division, Alberta Environment and Sustainable Resource Development, Grande Prairie, AB T8V 6J4, Canada
| | - Mark Hebblewhite
- Wildlife Biology Program, Department of Ecosystem and Conservation Sciences, College of Forestry and Conservation, University of Montana, Missoula, MT 59812, USA
| | - Dave Stepnisky
- Resource Management - Operations Division, Alberta Environment and Sustainable Resource Development, Grande Prairie, AB T8V 6J4, Canada
| | - Michelle Bacon
- Resource Management - Operations Division, Alberta Environment and Sustainable Resource Development, Grande Prairie, AB T8V 6J4, Canada
| | - Stan Boutin
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
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56
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Marescot L, Forrester TD, Casady DS, Wittmer HU. Using multistate capture–mark–recapture models to quantify effects of predation on age-specific survival and population growth in black-tailed deer. POPUL ECOL 2014. [DOI: 10.1007/s10144-014-0456-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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57
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Richard E, Simpson SE, Medill SA, McLoughlin PD. Interacting effects of age, density, and weather on survival and current reproduction for a large mammal. Ecol Evol 2014; 4:3851-60. [PMID: 25614799 PMCID: PMC4301048 DOI: 10.1002/ece3.1250] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2014] [Revised: 07/31/2014] [Accepted: 08/05/2014] [Indexed: 11/15/2022] Open
Abstract
Individual-based study of natural populations allows for accurate and precise estimation of fitness components and the extent to which they might vary with ecological conditions. By tracking the fates of all 701 horses known to have lived on Sable Island, Canada, from 2009 to 2013 (where there is no predation, human interference, or interspecific competition for food), we present a detailed analysis of structured population dynamics with focus on interacting effects of intraspecific competition and weather on reproduction and survival. Annual survival of adult females (0.866 ± 0.107 [[Formula: see text] ± SE]) was lower than that of 3-year-olds (0.955 ± 0.051), although annual fecundity (producing a foal in a year that was observed during our census) was higher in adults (0.616 ± 0.023) compared to 3-year-olds (0.402 ± 0.054). Milder winters and lower densities during gestation increased fecundity. Density negatively impacted survival for all age and sex categories; however, highest adult female survival was observed during high-density years coupled with a harsh winter, the result expected if pregnancy loss during winter or loss of foals in spring improved survival. Three-year-old females, which reproduced at lower rates, experienced higher survival than adults. Our results contrast with a previous study of feral horses that suggested recently feral ungulates might be artificially selected to reproduce even when costs to survival are high. In part, this may be because of the comparably long history of feralization (250 years; at least 25 generations) for Sable Island horses.
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Affiliation(s)
- Emmanuelle Richard
- Department of Biology, University of Saskatchewan112 Science Place, Saskatoon, SK, S7N 5E2, Canada
| | - Steven E Simpson
- Department of Biology, University of Saskatchewan112 Science Place, Saskatoon, SK, S7N 5E2, Canada
| | - Sarah A Medill
- Department of Biology, University of Saskatchewan112 Science Place, Saskatoon, SK, S7N 5E2, Canada
| | - Philip D McLoughlin
- Department of Biology, University of Saskatchewan112 Science Place, Saskatoon, SK, S7N 5E2, Canada
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58
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Wolf AJ, Hellgren EC, Schauber EM, Bogosian V, Kazmaier RT, Ruthven DC, Moody RW. Variation in vital‐rate sensitivity between populations of Texas horned lizards. POPUL ECOL 2014. [DOI: 10.1007/s10144-014-0450-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Alexander J. Wolf
- Cooperative Wildlife Research LabSouthern Illinois University62901‐6504CarbondaleILUSA
- Missouri Department of Conservation2929 County Rd. 62663638EllingtonMOUSA
| | - Eric C. Hellgren
- Cooperative Wildlife Research LabSouthern Illinois University62901‐6504CarbondaleILUSA
- Department of Wildlife Ecology and ConservationUniversity of FloridaP.O. Box 11043032611‐0430GainesvilleFLUSA
| | - Eric M. Schauber
- Cooperative Wildlife Research LabSouthern Illinois University62901‐6504CarbondaleILUSA
| | - Victor Bogosian
- Cooperative Wildlife Research LabSouthern Illinois University62901‐6504CarbondaleILUSA
- Eagle Bluffs Conservation Area6700 W. Route K65203ColumbiaMOUSA
| | - Richard T. Kazmaier
- Department of Life, Earth, and Environmental SciencesWest Texas A & M University79016CanyonTXUSA
| | - Donald C. Ruthven
- Texas Parks and Wildlife Department, Matador Wildlife Management Area, 3036 FM 325679248PaducahTXUSA
| | - Raymond W. Moody
- Natural Resources72nd ABW/CE, 7535 5th St.73145Tinker Air Force BaseOKUSA
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59
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Hawkes LA, McGowan A, Broderick AC, Gore S, Wheatley D, White J, Witt MJ, Godley BJ. High rates of growth recorded for hawksbill sea turtles in Anegada, British Virgin Islands. Ecol Evol 2014; 4:1255-66. [PMID: 24834324 PMCID: PMC4020687 DOI: 10.1002/ece3.1018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 02/04/2014] [Accepted: 02/08/2014] [Indexed: 12/01/2022] Open
Abstract
Management of species of conservation concern requires knowledge of demographic parameters, such as rates of recruitment, survival, and growth. In the Caribbean, hawksbill turtles (Eretmochelys imbricata) have been historically exploited in huge numbers to satisfy trade in their shells and meat. In the present study, we estimated growth rate of juvenile hawksbill turtles around Anegada, British Virgin Islands, using capture–mark–recapture of 59 turtles over periods of up to 649 days. Turtles were recaptured up to six times, having moved up to 5.9 km from the release location. Across all sizes, turtles grew at an average rate of 9.3 cm year−1 (range 2.3–20.3 cm year−1), and gained mass at an average of 3.9 kg year−1 (range 850 g–16.1 kg year−1). Carapace length was a significant predictor of growth rate and mass gain, but there was no relationship between either variable and sea surface temperature. These are among the fastest rates of growth reported for this species, with seven turtles growing at a rate that would increase their body size by more than half per year (51–69% increase in body length). This study also demonstrates the importance of shallow water reef systems for the developmental habitat for juvenile hawksbill turtles. Although growth rates for posthatching turtles in the pelagic, and turtles larger than 61 cm, are not known for this population, the implications of this study are that Caribbean hawksbill turtles in some areas may reach body sizes suggesting sexual maturity in less time than previously considered.
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Affiliation(s)
- Lucy A Hawkes
- Centre for Ecology & Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus Penryn, TR10 9EZ, U.K
| | - Andrew McGowan
- Centre for Ecology & Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus Penryn, TR10 9EZ, U.K
| | - Annette C Broderick
- Centre for Ecology & Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus Penryn, TR10 9EZ, U.K
| | - Shannon Gore
- Conservation and Fisheries Department, Ministry of Natural Resources and Labour PO Box 3323, Road Town, Tortola, British Virgin Islands
| | | | - Jim White
- The Settlement Anegada, British Virgin Islands
| | - Matthew J Witt
- Environment and Sustainability Institute, University of Exeter, Penryn Campus Penryn, Cornwall, TR10 9EZ, U.K
| | - Brendan J Godley
- Centre for Ecology & Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus Penryn, TR10 9EZ, U.K
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60
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DeCesare NJ, Hebblewhite M, Bradley M, Hervieux D, Neufeld L, Musiani M. Linking habitat selection and predation risk to spatial variation in survival. J Anim Ecol 2013; 83:343-52. [PMID: 24099266 PMCID: PMC4285818 DOI: 10.1111/1365-2656.12144] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 09/02/2013] [Indexed: 11/30/2022]
Abstract
1. A central assumption underlying the study of habitat selection is that selected habitats confer enhanced fitness. Unfortunately, this assumption is rarely tested, and in some systems, gradients of predation risk may more accurately characterize spatial variation in vital rates than gradients described by habitat selection studies. 2. Here, we separately measured spatial patterns of both resource selection and predation risk and tested their relationships with a key demographic trait, adult female survival, for a threatened ungulate, woodland caribou (Rangifer tarandus caribou Gmelin). We also evaluated whether exposure to gradients in both predation risk and resource selection value was manifested temporally through instantaneous or seasonal effects on survival outcomes. 3. We used Cox proportional hazards spatial survival modelling to assess the relative support for 5 selection- and risk-based definitions of habitat quality, as quantified by woodland caribou adult female survival. These hypotheses included scenarios in which selection ideally mirrored survival, risk entirely drove survival, non-ideal selection correlated with survival but with additive risk effects, an ecological trap with maladaptive selection and a non-spatial effect of annual variation in weather. 4. Indeed, we found positive relationships between the predicted values of a resource selection function (RSF) and survival, yet subsequently incorporating an additional negative effect of predation risk greatly improved models further. This revealed a positive, but non-ideal relationship between selection and survival. Gradients in these covariates were also shown to affect individual survival probability at multiple temporal scales. Exposure to increased predation risk had a relatively instantaneous effect on survival outcomes, whereas variation in habitat suitability predicted by an RSF had both instantaneous and longer-term seasonal effects on survival. 5. Predation risk was an additive source of hazard beyond that detected through selection alone, and woodland caribou selection thus was shown to be non-ideal. Furthermore, by combining spatial adult female survival models with herd-specific estimates of recruitment in matrix population models, we estimated a spatially explicit landscape of population growth predictions for this endangered species.
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Affiliation(s)
- Nicholas J DeCesare
- Wildlife Biology Program, Department of Ecosystem and Conservation Science, College of Forestry and Conservation, University of Montana, Missoula, MT, USA
| | - Mark Hebblewhite
- Wildlife Biology Program, Department of Ecosystem and Conservation Science, College of Forestry and Conservation, University of Montana, Missoula, MT, USA
| | - Mark Bradley
- Parks Canada, Jasper National Park, Box 10, Jasper, Alberta, Canada
| | - David Hervieux
- Sustainable Resource Development, Government of Alberta, Grande Prairie, Alberta, Canada
| | - Lalenia Neufeld
- Parks Canada, Jasper National Park, Box 10, Jasper, Alberta, Canada
| | - Marco Musiani
- Faculty of Environmental Design, University of Calgary, 2500 University Dr NW, Calgary, Alberta, Canada
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Ellis MM, Crone EE. The role of transient dynamics in stochastic population growth for nine perennial plants. Ecology 2013; 94:1681-6. [PMID: 24015512 DOI: 10.1890/13-0028.1] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Martha M Ellis
- Wildlife Biology Program, University of Montana, Missoula, Montana 59812, USA.
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Good intentions gone wrong: did conservation management threaten Endangered huemul deer Hippocamelus bisulcus in the future Patagonia National Park? ORYX 2013. [DOI: 10.1017/s0030605312000531] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
AbstractConservation interventions increasingly involve active management of relative species abundances, especially when taxa of conservation concern are threatened by complex food web interactions. Unfortunately, the complexity of such interspecific interactions means that well-meaning management interventions can have unexpected, sometimes detrimental, effects on the species they are intended to protect. Here we report that the abrupt removal of an abundant non-native prey species (domestic sheep) and the cessation of predator control, actions intended to protect huemul deer Hippocamelus bisulcus in the future Patagonia National Park, appear to have had negative effects on this Endangered ungulate. During and following the changes in predator–prey management, predation of huemul fawns and females older than 1 year by native culpeo foxes Lycalopex culpaeus and pumas Puma concolor increased 3- and 5-fold, respectively. Predictions from demographic models suggest that elevated mortality rates of female huemul older than 1 year will, on average, cause this population of huemul to decline. These results highlight risks of unintended consequences when aggressive management actions are taken to protect taxa embedded in complex food webs. They also suggest that careful consideration of both inter- and intra-trophic level effects among all species in a system is warranted before conservation interventions are undertaken.
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63
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Forrester TD, Wittmer HU. A review of the population dynamics of mule deer and black-tailed deer Odocoileus hemionus
in North America. Mamm Rev 2013. [DOI: 10.1111/mam.12002] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Tavis D. Forrester
- Department of Wildlife, Fish, and Conservation Biology; University of California; One Shields Avenue Davis California 95616 USA
| | - Heiko U. Wittmer
- Department of Wildlife, Fish, and Conservation Biology; University of California; One Shields Avenue Davis California 95616 USA
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64
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Devenish-Nelson ES, Harris S, Soulsbury CD, Richards SA, Stephens PA. Demography of a carnivore, the red fox, Vulpes vulpes: what have we learnt from 70 years of published studies? OIKOS 2012. [DOI: 10.1111/j.1600-0706.2012.20706.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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65
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Johnson HE, Hebblewhite M, Stephenson TR, German DW, Pierce BM, Bleich VC. Evaluating apparent competition in limiting the recovery of an endangered ungulate. Oecologia 2012; 171:295-307. [DOI: 10.1007/s00442-012-2397-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Accepted: 06/08/2012] [Indexed: 11/29/2022]
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66
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Andrello M, Nicolè F, Till-Bottraud I, Gaggiotti OE. Effect of stage-specific vital rates on population growth rates and effective population sizes in an endangered iteroparous plant. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2012; 26:208-217. [PMID: 22268810 DOI: 10.1111/j.1523-1739.2011.01815.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Effective population size (N(e)) determines the strength of genetic drift and can influence the level of genetic diversity a population can maintain. Assessing how changes in demographic rates associated with environmental variables and management actions affect N(e) thus can be crucial to the conservation of endangered species. Calculation of N(e) through demographic models makes it possible to use elasticity analyses to study this issue. The elasticity of N(e) to a given vital rate is the proportional change in N(e) associated with a proportional increase in that vital rate. In addition, demographic models can be used to study N(e) and population growth rate (λ) simultaneously. Simultaneous examination is important because some vital rates differ diametrically in their associations with λ and N(e). For example, in some cases increasing these vital rates increases λ and decreases N(e). We used elasticity analysis to study the effect of stage-specific survival and flowering rates on N(e), annual effective population size (N(a)), and λ in seven populations of the endangered plant Austrian dragonhead (Dracocephalum austriacum). In populations with λ ≥ 1, the elasticities of N(e) and N(a) were similar to those of λ. Survival rates of adults were associated with greater elasticities than survival rates of juveniles, flowering rates, or fecundity. In populations with λ < 1, N(e) and N(a) exhibited greater elasticities to juvenile than to adult vital rates. These patterns are similar to those observed in other species with similar life histories. We did not observe contrasting effects of any vital rate on λ and N(e); thus, management actions that increase the λ of populations of Austrian dragonhead will not increase genetic drift. Our results show that elasticity analyses of N(e) and N(a) can complement elasticity analysis of λ. Moreover, such analyses do not require more data than standard matrix models of population dynamics.
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Affiliation(s)
- Marco Andrello
- Université de Grenoble 1, CNRS UMR 5553, LECA, BP53, F-38041 Grenoble Cedex 09, France.
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67
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Johnson HE, Mills LS, Wehausen JD, Stephenson TR, Luikart G. Translating effects of inbreeding depression on component vital rates to overall population growth in endangered bighorn sheep. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2011; 25:1240-1249. [PMID: 22070275 DOI: 10.1111/j.1523-1739.2011.01739.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Evidence of inbreeding depression is commonly detected from the fitness traits of animals, yet its effects on population growth rates of endangered species are rarely assessed. We examined whether inbreeding depression was affecting Sierra Nevada bighorn sheep (Ovis canadensis sierrae), a subspecies listed as endangered under the U.S. Endangered Species Act. Our objectives were to characterize genetic variation in this subspecies; test whether inbreeding depression affects bighorn sheep vital rates (adult survival and female fecundity); evaluate whether inbreeding depression may limit subspecies recovery; and examine the potential for genetic management to increase population growth rates. Genetic variation in 4 populations of Sierra Nevada bighorn sheep was among the lowest reported for any wild bighorn sheep population, and our results suggest that inbreeding depression has reduced adult female fecundity. Despite this population sizes and growth rates predicted from matrix-based projection models demonstrated that inbreeding depression would not substantially inhibit the recovery of Sierra Nevada bighorn sheep populations in the next approximately 8 bighorn sheep generations (48 years). Furthermore, simulations of genetic rescue within the subspecies did not suggest that such activities would appreciably increase population sizes or growth rates during the period we modeled (10 bighorn sheep generations, 60 years). Only simulations that augmented the Mono Basin population with genetic variation from other subspecies, which is not currently a management option, predicted significant increases in population size. Although we recommend that recovery activities should minimize future losses of genetic variation, genetic effects within these endangered populations-either negative (inbreeding depression) or positive (within subspecies genetic rescue)-appear unlikely to dramatically compromise or stimulate short-term conservation efforts. The distinction between detecting the effects of inbreeding depression on a component vital rate (e.g., fecundity) and the effects of inbreeding depression on population growth underscores the importance of quantifying inbreeding costs relative to population dynamics to effectively manage endangered populations.
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Affiliation(s)
- Heather E Johnson
- University of Montana, Wildlife Biology Program, College of Forestry and Conservation, Missoula, MT 59812, U.S.A., email
| | - L Scott Mills
- University of Montana, Wildlife Biology Program, College of Forestry and Conservation, Missoula, MT 59812, U.S.A
| | - John D Wehausen
- White Mountain Research Station, University of California, 3000 East Line Street, Bishop, CA 93514, U.S.A
| | - Thomas R Stephenson
- Sierra Nevada Bighorn Sheep Recovery Program, California Department of Fish and Game, 407 West Line Street, Bishop, CA 93514, U.S.A
| | - Gordon Luikart
- University of Montana, Flathead Biological Station and Division of Biological Sciences, Polson, MT 59860, U.S.A. and the Centro de Investigação em Biodiversidade e Recursos Genéticos and Universidade do Porto (CIBIO-UP), Vairão, Portugal
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68
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Taylor RL, Walker BL, Naugle DE, Mills LS. Managing multiple vital rates to maximize greater sage-grouse population growth. J Wildl Manage 2011. [DOI: 10.1002/jwmg.267] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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69
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DeCesare NJ, Hebblewhite M, Bradley M, Smith KG, Hervieux D, Neufeld L. Estimating ungulate recruitment and growth rates using age ratios. J Wildl Manage 2011. [DOI: 10.1002/jwmg.244] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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70
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Cahn ML, Conner MM, Schmitz OJ, Stephenson TR, Wehausen JD, Johnson HE. Disease, population viability, and recovery of endangered Sierra Nevada bighorn sheep. J Wildl Manage 2011. [DOI: 10.1002/jwmg.232] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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71
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Johnson HE, Scott Mills L, Wehausen JD, Stephenson TR. Combining ground count, telemetry, and mark-resight data to infer population dynamics in an endangered species. J Appl Ecol 2010. [DOI: 10.1111/j.1365-2664.2010.01846.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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