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Klingler KB, Nichols LB, Hekkala ER, Stewart JAE, Peacock MM. Life on the edge-a changing genetic landscape within an iconic American pika metapopulation over the last half century. PeerJ 2023; 11:e15962. [PMID: 37790628 PMCID: PMC10542391 DOI: 10.7717/peerj.15962] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 08/03/2023] [Indexed: 10/05/2023] Open
Abstract
Declines and extirpations of American pika (Ochotona princeps) populations at historically occupied sites started being documented in the literature during the early 2000s. Commensurate with global climate change, many of these losses at peripheral and lower elevation sites have been associated with changes in ambient air temperature and precipitation regimes. Here, we report on a decline in available genetic resources for an iconic American pika metapopulation, located at the southwestern edge of the species distribution in the Bodie Hills of eastern California, USA. Composed of highly fragmented habitat created by hard rock mining, the ore dumps at this site were likely colonized by pikas around the end of the 19th century from nearby natural talus outcrops. Genetic data extracted from both contemporary samples and archived natural history collections allowed us to track population and patch-level genetic diversity for Bodie pikas across three distinct sampling points during the last half- century (1948-1949, 1988-1991, 2013-2015). Reductions in within-population allelic diversity and expected heterozygosity were observed across the full time period. More extensive sampling of extant patches during the 1988-1991 and 2013-2015 periods revealed an increase in population structure and a reduction in effective population size. Furthermore, census records from the last 51 years as well as archived museum samples collected in 1947 from a nearby pika population in the Wassuk range (Nevada, USA) provide further support of the increasing isolation and genetic coalescence occurring in this region. This study highlights the importance of museum samples and long-term monitoring in contextualizing our understanding of population viability.
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Affiliation(s)
- Kelly B. Klingler
- Department of Environmental Conservation, University of Massachusetts Amherst, Amherst, Massachusetts, United States
| | - Lyle B. Nichols
- Department of Life Sciences, Santa Monica College, Santa Monica, California, United States
| | - Evon R. Hekkala
- Department of Biological Sciences, Fordham University, Bronx, New York, United States
| | - Joseph A. E. Stewart
- Department of Plant Sciences, University of California, Davis, Davis, California, United States
| | - Mary M. Peacock
- Department of Biology, University of Nevada, Reno, Reno, Nevada, United States
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2
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Millar CI, Smith AT. Return of the pika: American pikas re-occupy long-extirpated, warm locations. Ecol Evol 2022; 12:e9295. [PMID: 36177131 PMCID: PMC9475130 DOI: 10.1002/ece3.9295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 08/08/2022] [Accepted: 08/14/2022] [Indexed: 11/30/2022] Open
Abstract
American pikas (Ochotona princeps), small mammals related to rabbits, occur in mountainous regions of western North America, where they live in shattered-rock habitats (talus). Aspects of their physiology and life history create situations that appear to put pikas at risk from warming climates. Some low-elevation, warm sites that historically harbored pikas have become extirpated, and the assumption is that these will not be re-colonized under current climate trends. Unexpectedly, in 2021, we found that pikas had re-colonized two very warm, low-elevation, dry sites in eastern California, USA, in the Bodie Mountains and Mono Craters. Resident pikas appear to have been absent at both sites for ≥10 years. These findings suggest that pikas, which are normally diurnally active, are able to overcome thermal dispersal barriers and re-colonize long-extirpated sites, perhaps by moving during cool nights. Our data also highlight the often unrecognized suitability of pika habitat in warm regions where the interiors of taluses can remain stably cool even when external air temperatures are hot.
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Affiliation(s)
| | - Andrew T. Smith
- School of Life SciencesArizona State UniversityTempeArizonaUSA
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Whipple AL, Ray C, Wasser M, Kitchens JN, Hove AA, Varner J, Wilkening JL. Temporal vs. spatial variation in stress-associated metabolites within a population of climate-sensitive small mammals. CONSERVATION PHYSIOLOGY 2021; 9:coab024. [PMID: 34026212 PMCID: PMC8127223 DOI: 10.1093/conphys/coab024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 02/04/2021] [Accepted: 03/30/2021] [Indexed: 06/12/2023]
Abstract
Temporal variation in stress might signify changes in an animal's internal or external environment, while spatial variation in stress might signify variation in the quality of the habitats that individual animals experience. Habitat-induced variations in stress might be easiest to detect in highly territorial animals, and especially in species that do not take advantage of common strategies for modulating habitat-induced stress, such as migration (escape in space) or hibernation (escape in time). Spatial and temporal variation in response to potential stressors has received little study in wild animals, especially at scales appropriate for relating stress to specific habitat characteristics. Here, we use the American pika (Ochotona princeps), a territorial small mammal, to investigate stress response within and among territories. For individually territorial animals such as pikas, differences in habitat quality should lead to differences in stress exhibited by territory owners. We indexed stress using stress-associated hormone metabolites in feces collected non-invasively from pika territories every 2 weeks from June to September 2018. We hypothesized that differences in territory quality would lead to spatial differences in mean stress and that seasonal variation in physiology or the physical environment would lead to synchronous variation across territories through time. We used linear mixed-effects models to explore spatiotemporal variation in stress using fixed effects of day-of-year and broad habitat characteristics (elevation, aspect, site), as well as local variation in habitat characteristics hypothesized to affect territory quality for this saxicolous species (talus depth, clast size, available forage types). We found that temporal variation within territories was greater than spatial variation among territories, suggesting that shared seasonal stressors are more influential than differences in individual habitat quality. This approach could be used in other wildlife studies to refine our understanding of habitat quality and its effect on individual stress levels as a driver of population decline.
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Affiliation(s)
- Ashley L Whipple
- Department of Ecology and Evolutionary Biology, University of
Colorado, Boulder, CO 80309, USA
- Institute of Arctic and Alpine Research, University of
Colorado, Boulder, CO 80303, USA
| | - Chris Ray
- Department of Ecology and Evolutionary Biology, University of
Colorado, Boulder, CO 80309, USA
- Institute of Arctic and Alpine Research, University of
Colorado, Boulder, CO 80303, USA
| | - Max Wasser
- Department of Ecology and Evolutionary Biology, University of
Colorado, Boulder, CO 80309, USA
| | - James N Kitchens
- Department of Biology, Warren Wilson College,
Asheville, NC 28778, USA
| | - Alisa A Hove
- Department of Biology, Warren Wilson College,
Asheville, NC 28778, USA
| | - Johanna Varner
- Department of Biological Sciences, Colorado Mesa
University, Grand Junction, CO 81501, USA
| | - Jennifer L Wilkening
- US Fish and Wildlife Service, Southern Nevada Fish and Wildlife
Office, Las Vegas, NV 89130, USA
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4
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Klingler KB, Jahner JP, Parchman TL, Ray C, Peacock MM. Genomic variation in the American pika: signatures of geographic isolation and implications for conservation. BMC Ecol Evol 2021; 21:2. [PMID: 33514306 PMCID: PMC7853312 DOI: 10.1186/s12862-020-01739-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 12/17/2020] [Indexed: 01/12/2023] Open
Abstract
Background Distributional responses by alpine taxa to repeated, glacial-interglacial cycles throughout the last two million years have significantly influenced the spatial genetic structure of populations. These effects have been exacerbated for the American pika (Ochotona princeps), a small alpine lagomorph constrained by thermal sensitivity and a limited dispersal capacity. As a species of conservation concern, long-term lack of gene flow has important consequences for landscape genetic structure and levels of diversity within populations. Here, we use reduced representation sequencing (ddRADseq) to provide a genome-wide perspective on patterns of genetic variation across pika populations representing distinct subspecies. To investigate how landscape and environmental features shape genetic variation, we collected genetic samples from distinct geographic regions as well as across finer spatial scales in two geographically proximate mountain ranges of eastern Nevada. Results Our genome-wide analyses corroborate range-wide, mitochondrial subspecific designations and reveal pronounced fine-scale population structure between the Ruby Mountains and East Humboldt Range of eastern Nevada. Populations in Nevada were characterized by low genetic diversity (π = 0.0006–0.0009; θW = 0.0005–0.0007) relative to populations in California (π = 0.0014–0.0019; θW = 0.0011–0.0017) and the Rocky Mountains (π = 0.0025–0.0027; θW = 0.0021–0.0024), indicating substantial genetic drift in these isolated populations. Tajima’s D was positive for all sites (D = 0.240–0.811), consistent with recent contraction in population sizes range-wide. Conclusions Substantial influences of geography, elevation and climate variables on genetic differentiation were also detected and may interact with the regional effects of anthropogenic climate change to force the loss of unique genetic lineages through continued population extirpations in the Great Basin and Sierra Nevada.
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Affiliation(s)
| | - Joshua P Jahner
- Department of Biology, University of Nevada, Reno, 89557, USA
| | - Thomas L Parchman
- Department of Biology, University of Nevada, Reno, 89557, USA.,Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, NV, 89557, USA
| | - Chris Ray
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, 80309-0334, USA
| | - Mary M Peacock
- Department of Biology, University of Nevada, Reno, 89557, USA. .,Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, NV, 89557, USA.
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5
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Abstract
Abstract
The American pika (Ochotona princeps) is commonly perceived as a species that is at high risk of extinction due to climate change. The purpose of this review is two-fold: to evaluate the claim that climate change is threatening pikas with extinction, and to summarize the conservation status of the American pika. Most American pikas inhabit major cordilleras, such as the Rocky Mountain, Sierra Nevada, and Cascade ranges. Occupancy of potential pika habitat in these ranges is uniformly high and no discernible climate signal has been found that discriminates between the many occupied and relatively few unoccupied sites that have been recently surveyed. Pikas therefore are thriving across most of their range. The story differs in more marginal parts of the species range, primarily across the Great Basin, where a higher percentage of available habitat is unoccupied. A comprehensive review of Great Basin pikas revealed that occupied sites, sites of recent extirpation, and old sites, were regularly found within the same geographic and climatic space as extant sites, and suggested that pikas in the Great Basin tolerated a broader set of habitat and climatic conditions than previously understood. Studies of a small subset of extirpated sites in the Great Basin and in California found that climate variables (most notably measures of hot temperature) were associated more often with extirpated sites than occupied sites. Importantly, upward contraction of the lower elevation boundary also was found at some sites. However, models that incorporated variables other than climate (such as availability of upslope talus habitat) often were better predictors of site persistence. Many extirpations occurred on small habitat patches, which were subject to stochastic extinction, as informed by a long-term pika metapopulation study in Bodie, California. In addition, several sites may have been compromised by cattle grazing or other anthropogenic factors. In contrast, several low, hot sites (Bodie, Mono Craters, Craters of the Moon National Monument and Preserve, Lava Beds National Monument, Columbia River Gorge) retain active pika populations, demonstrating the adaptive capacity and resilience of pikas in response to adverse environmental conditions. Pikas cope with warm temperatures by retreating into cool interstices of their talus habitat and augment their restricted daytime foraging with nocturnal activity. Pikas exhibit significant flexibility in their foraging tactics and are highly selective in their choice of available vegetation. The trait that places pikas at greatest risk from climate change is their poor dispersal capability. Dispersal is more restricted in hotter environments, and isolated low-elevation sites that become extirpated are unlikely to be recolonized in a warming climate. The narrative that American pikas are going extinct appears to be an overreach. Pikas are doing well across most of their range, but there are limited, low-elevation losses that are likely to be permanent in what is currently marginal pika habitat. The resilience of pikas in the face of climate change, and their ability or inability to persist in marginal, hot environments, will continue to contribute to our understanding of the impact of climate change on individual species.
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Affiliation(s)
- Andrew T Smith
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
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Westover M, Lizewski K, Klingler K, Smith F. Isotopic niche of the American pika (Ochotona princeps) through space and time. CAN J ZOOL 2020. [DOI: 10.1139/cjz-2019-0212] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Anthropogenic climate change is influencing the ecology and distribution of animals. The American pika (Ochotona princeps (Richardson, 1828)) is considered a model species for studying the effects of climate on small alpine mammals and has experienced local extirpation across its range. Using stable isotope analysis of two seasonal molts and bone collagen, we characterize the isotopic carbon and nitrogen niche of pika populations across their range and through time. We find pika isotopic diet to be stable across both time and space compared with other animals and considering the geographic and environmental extent of their range. We find that climatic, not geographic, factors explain part of the isotopic variation across their range. Both δ13C and δ15N from the fall-onset molt decrease with relative humidity of the environment and δ15N values from bone collagen increase with temperature and precipitation. We find a small but significant seasonal difference in δ13C, which could be explained by microbial enrichment of cached haypiles. We establish a baseline of pika isotopic diet and patterns related to climate across their range. We conclude that differences in isotopic signature between pika populations likely reflect the physiology of their forage plants in different environmental conditions.
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Affiliation(s)
- M.L. Westover
- University of New Mexico, Department of Biology, MSC03-2020, 219 Yale Boulevard Northeast, Albuquerque, NM 87131, USA
| | - K.A. Lizewski
- University of New Mexico, Department of Biology, MSC03-2020, 219 Yale Boulevard Northeast, Albuquerque, NM 87131, USA
| | - K.B. Klingler
- University of Nevada, Reno, Department of Biology, 1664 N. Virginia Street, Reno, NV 89557, USA
| | - F.A. Smith
- University of New Mexico, Department of Biology, MSC03-2020, 219 Yale Boulevard Northeast, Albuquerque, NM 87131, USA
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White ER, Smith AT. The role of spatial structure in the collapse of regional metapopulations. Ecology 2018; 99:2815-2822. [PMID: 30347111 DOI: 10.1002/ecy.2546] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 10/02/2018] [Indexed: 11/10/2022]
Abstract
Many wildlife populations are either naturally, or as a result of human land use, patchily distributed in space. The degree of fragmentation-specifically the remaining patch sizes and habitat configuration-is an important part of population dynamics. Demographic stochasticity is also likely to play an important role in patchy habitats that host small local populations. We develop a simulation model to evaluate the significance of demographic stochasticity and the role fragmentation plays in the determination of population dynamics and the risk of extinction of populations on habitat patches. Our model is formulated as a Markov-chain stochastic process on a finite, spatially explicit array of patches in which probability of successful dispersal is a function of interpatch distance. Unlike past work, we explicitly model local population dynamics and examine how these scale up to the entire population. As a test case, we apply the model to the American pika (Ochotona princeps) population living on the ore dumps in the ghost mining town of Bodie, California. This population has been studied nearly continuously for over four decades and has been of conservation concern as the southern half of the population declined precipitously beginning in 1989. Our model suggests that both the specific configuration of habitat and landscape heterogeneity are necessary and sufficient predictors of the eventual extinction of the southern constellation of patches. This example has important implications, as it suggests that fragmentation alone can lead to regional extinctions within metapopulations.
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Affiliation(s)
- Easton R White
- Center for Population Biology, University of California-Davis, Davis, California, 95616, USA
| | - Andrew T Smith
- School of Life Sciences, Arizona State University, Tempe, Arizona, 85287-4501, USA
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