Ecosphere最新文献

{"title":"Navigating novel resources: A field test of the effects of small mammal personality on dispersal of Quercus seeds","authors":"Ivy Yen,&nbsp;Alessio Mortelliti","doi":"10.1002/ecs2.70268","DOIUrl":"https://doi.org/10.1002/ecs2.70268","url":null,"abstract":"<p>Climate change is shifting the habitable ranges of hundreds of species, and a greater understanding of the mechanisms driving migration velocity may make the difference between extinction and persistence for at-risk species. However, predicting migration velocity is particularly complicated for sessile organisms that rely on animals for the dispersal of their propagules. Extrinsic factors (e.g., seed availability, forest structure) and intrinsic factors of propagules and dispersers (e.g., seed mass, disperser species) interact to influence the seed dispersal process at multiple levels, complicating the conditions under which mutualism can occur. Small mammals are important seed predators and dispersers, and thus, their collective actions may modulate the migration velocity of seed-bearing plants. Recent studies have revealed the importance of disperser intraspecific variation, but the role of behavioral variation—animal personality—is infrequently studied and remains poorly understood. Personality may be critical to consider in the context of novel seeds as inexperienced individuals may default to specific behavioral tendencies and foraging strategies when deciding if and how to utilize resources. In a large-scale field experiment in central Maine (USA), we examined seed selection behavior in two species of small mammals (<i>Peromyscus maniculatus</i> and <i>Myodes gapperi</i>) for eight species of <i>Quercus</i> acorns—two of which are native to Maine and six of which are novel to our populations but expected to migrate northward. We found no discernible effects of seed novelty at any stage of the seed dispersal process, but we found evidence of personality-driven patterns in caching behavior. Docility positively predicted removal probability in voles and distance to burrow caches in mice. Lastly, individual antagonism–mutualism scores for voles were influenced by personality, where shy individuals were more antagonistic to acorns and bold individuals were more mutualistic. Put together, our results indicate that behavioral diversity may be important to consider for the maintenance of ecological function and provide a basis from where conservationists can work toward clarifying plant fitness in their novel ranges, species-specific extinction probabilities, and future trends in forest regeneration.</p>","PeriodicalId":48930,"journal":{"name":"Ecosphere","volume":"16 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ecs2.70268","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144308735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Parasite spatial distribution shapes parasite aggregation on host populations, but not at high parasite density","authors":"Chris Wojan,&nbsp;Allison K. Shaw,&nbsp;Meggan E. Craft","doi":"10.1002/ecs2.70324","DOIUrl":"https://doi.org/10.1002/ecs2.70324","url":null,"abstract":"<p>Spatial aggregation of environmental or trophically transmitted parasites has the potential to influence host–parasite interactions. The distribution of parasites on hosts is one result of those interactions, and the role of spatial aggregation is unclear. We use a spatially explicit agent-based model to determine how spatial aggregation of parasites influences the distribution of parasite burdens across a range of parasite densities and host recovery rates. Our model simulates the random movement of hosts across landscapes with varying spatial configurations of areas occupied by environmental parasites, allowing hosts to acquire parasites they encounter and subsequently lose them. When parasites are more spatially aggregated in the environment, the aggregation of parasite burdens on hosts is higher (i.e., more hosts with few parasites, fewer hosts with many parasites), but the effect is less pronounced at high parasite density and fast host recovery rates. In addition, the correlation between individual hosts' final parasite burdens and their cumulative parasite burdens (including lost parasites) is greater at higher levels of spatial parasite aggregation. Our work suggests that fine-scale spatial patterns of parasites can play a strong role in shaping how hosts are parasitized, particularly when parasite density is low-to-moderate and recovery rates are slow.</p>","PeriodicalId":48930,"journal":{"name":"Ecosphere","volume":"16 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ecs2.70324","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144308967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microbial effects and home-field advantage in holm oak (Quercus ilex) germination","authors":"Francisco I. Pugnaire,&nbsp;Elena Díaz-Santiago,&nbsp;Miguel Hurtado-Martínez,&nbsp;Christian Kindler,&nbsp;Esteban Manrique","doi":"10.1002/ecs2.70251","DOIUrl":"https://doi.org/10.1002/ecs2.70251","url":null,"abstract":"<p>Germination is a critical process influenced by multiple abiotic and biotic factors and depends on the interaction between microorganisms and the environment. As plants select specific sets of microbes that evolve together in response to local conditions, we looked at the role of microorganisms on holm oak (<i>Quercus ilex</i>) germination to test whether soil microbial communities enhanced germination of seeds from its own habitat more than soil communities from other habitats, in accordance with the home-field advantage (HFA) hypothesis reported for litter decomposition. In a growth chamber experiment, we used sterilized seeds from two localities with contrasting environmental conditions sowed on a sterilized substrate, added inocula containing the microbiome extracted from the two soils with a factorial design, and recorded seed germination over two months. Fungi and bacteria extracted from Somiedo, the wet site, enhanced <i>Q. ilex</i> seed germination more than extracts from Ronda, the dry site, pointing to soil microbes as an important controlling factor. There was a significant difference in HFA between the two localities, being positive in Somiedo and negative in Ronda, suggesting that plant–soil coevolution was more difficult in harsher environment than in milder environment. Our results provide evidence of the critical role of soil microbial communities in <i>Q. ilex</i> germination.</p>","PeriodicalId":48930,"journal":{"name":"Ecosphere","volume":"16 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ecs2.70251","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144308737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Functional vertebrate group diversity differentially impacts vector-borne pathogen transmission and genetic diversity","authors":"Marie Lilly,&nbsp;Arielle Crews,&nbsp;Alexandra Lawrence,&nbsp;Jordan Salomon,&nbsp;Samantha Sambado,&nbsp;Liliana Cerna,&nbsp;Kacie Ring,&nbsp;Ceili Peng,&nbsp;Grace Shaw,&nbsp;Shannon Summers,&nbsp;Andrea Swei","doi":"10.1002/ecs2.70292","DOIUrl":"https://doi.org/10.1002/ecs2.70292","url":null,"abstract":"<p>Anthropogenic land use change has led to considerable biodiversity loss, affecting ecosystem functions with unresolved consequences for zoonotic disease transmission. Functional diversity is understudied but potentially important for understanding the role of biodiversity because many zoonotic disease systems are maintained by species with different roles in disease transmission. Here, we explore how functional groups and pathogen genetic diversity influence transmission and human disease risk within the Lyme disease system. Our field and molecular ecology study examined ticks and vertebrates across a fragmented landscape and evaluated several metrics of disease risk. For predicting vector and infected vector density, rodent host richness had a positive effect and was most important, but vector infection prevalence was best predicted by rodent and predator richness together, reflecting how indirect effects may alter tick–host interactions and disease risk. These results indicate that examining species richness generally may obscure important interactions driven by richness within functional groups. Pathogen genotype richness was best predicted by overall vertebrate richness, providing support for the multiple niche polymorphism hypothesis. Our study offers an important perspective on the relationship between biodiversity and disease risk, suggesting that richness within functional groups may offer more nuanced insight into pathogen transmission dynamics than overall biodiversity.</p>","PeriodicalId":48930,"journal":{"name":"Ecosphere","volume":"16 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ecs2.70292","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144308880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Advance, steadfast, retreat? Growth and establishment of white spruce seedlings at treelines in Alaska","authors":"Andreas Burger,&nbsp;Mario Trouillier,&nbsp;Martin Wilmking","doi":"10.1002/ecs2.70317","DOIUrl":"https://doi.org/10.1002/ecs2.70317","url":null,"abstract":"<p>Range dynamics of tree species are largely driven by seedling establishment and survival, mainly at and beyond current treelines. Although numerous studies document the growth of mature white spruce (<i>Picea glauca</i>) trees in Alaska, research on seedling establishment and growth, particularly dendroecological studies addressing climate sensitivity, remains limited. This study examines seedling densities and age distributions, growth performance, and climate–growth correlations of white spruce seedlings at five Alaskan sites: a “dry treeline” with potential drought limitations and the adjacent “dry forest,” a reference forest in Interior Alaska, and a “cold treeline” with expected cold temperature limitations and the adjacent “cold forest” in the Brooks Range. Seedling densities were highest at the cold treeline and especially the cold forest, moderate at the reference forest and dry forest, and very low at the dry treeline. Growth rates and height:diameter ratio were greatest at the dry treeline, with slightly lower growth at the cold treeline and cold forest. We found some evidence for drought sensitivity in spring at the dry treeline and in summer at the dry forest, while warm temperatures in fall positively influenced seedling growth at both sites. Notably, growth was more often significantly correlated with climate during the transitional seasons compared to only once in summer and not at all in winter. This pattern likely reflects that seedling growth, especially at the cold sites, is shaped less by direct macroclimatic influences and more by indirect effects on growing season dynamics, such as snow accumulation and melt. Despite growth peaking at the dry treeline, low seedling densities suggest a potential retreat of <i>Pi. glauca</i> at dry, low-elevation treelines in Alaska. In contrast, high seedling densities and growth rates at the cold treeline and cold forest indicate favorable conditions for seedling establishment and densification. The complexity of seedling growth and climate–growth correlations demands careful consideration, as growth is only partially influenced by macroclimate and is likely more strongly shaped by factors like competition, snowpack, soil moisture and temperature, and nutrient availability. Overall, our local data lend credibility to the hypothesized biome shift of white spruce, albeit unfolding at a slow pace.</p>","PeriodicalId":48930,"journal":{"name":"Ecosphere","volume":"16 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ecs2.70317","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144308947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluating mark–resight survey design performance using simulation: A case study of endangered Steller sea lions","authors":"Amanda J. Warlick,&nbsp;Brian S. Fadely,&nbsp;Peter Mahoney,&nbsp;Sharon R. Melin,&nbsp;Tom Gelatt,&nbsp;Kim Raum-Suryan,&nbsp;Sarah J. Converse","doi":"10.1002/ecs2.70269","DOIUrl":"https://doi.org/10.1002/ecs2.70269","url":null,"abstract":"<p>Effective monitoring is fundamental to estimating wildlife population parameters with a level of accuracy and precision that is adequate to inform management decisions. However, managers must balance trade-offs between the costs of monitoring and the resulting data quality to identify cost-effective monitoring survey designs. As such, evaluating the expected performance of monitoring surveys relative to monitoring objectives prior to survey implementation is critical. In this study, we present a simulation framework for examining the accuracy and precision of age-specific survival estimates and the probability of detecting a change in survival within the context of mark–resight monitoring programs. We consider 90 survey designs that vary across marked cohort size, marking frequency, study duration, and resight probability (i.e., detection of marked individuals). We apply this approach to the design of a monitoring program for Steller sea lions (<i>Eumetopias jubatus</i>), which is complicated by heterogeneity in rookery accessibility, population sizes, and abundance trends across the species' range. To identify cost-effective survey designs in the absence of actual survey costs, we evaluated performance with respect to a relative-costs schema. Our results highlight survey designs that reliably meet pre-defined precision targets, with precision and accuracy strongly affected by marked cohort size, marking frequency, and study duration. We found that historical mark–resight survey effort for Steller sea lions has been sufficient to reliably achieve precision targets for younger age class survival probabilities only for rookeries where abundance has been stable or increasing. In contrast, the probability of achieving survival estimates with target levels of precision at rookeries where abundance has been declining is low (&lt;25%) due to smaller marked cohort sizes, less frequent marking at remote sites, and fewer years of available data. Our results indicate that the precision of survival estimates for subpopulations of conservation concern can be improved by longer-term monitoring, although the constraints of monitoring small populations may limit the ability of biologists to detect changes in population dynamics on management-relevant time horizons. Our survey design evaluation framework can be applied in a variety of contexts to assist natural resource managers in developing cost-effective monitoring programs.</p>","PeriodicalId":48930,"journal":{"name":"Ecosphere","volume":"16 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ecs2.70269","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144308736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing the combined influence of biotic and anthropogenic stressors on polar bears to inform conservation planning","authors":"Todd C. Atwood,&nbsp;Bruce G. Marcot,&nbsp;David C. Douglas,&nbsp;Jeffrey F. Bromaghin,&nbsp;Anthony M. Pagano","doi":"10.1002/ecs2.70316","DOIUrl":"https://doi.org/10.1002/ecs2.70316","url":null,"abstract":"<p>Developing conservation strategies for species vulnerable to the effects of climate change, like polar bears (<i>Ursus maritimus</i>), can be challenging given the uncertainty of future environmental conditions. Effective conservation planning requires identifying and ranking threats to the persistence of polar bears throughout their circumpolar range and then assessing the ability of mitigative actions to aid in meeting plan objectives. We used a Bayesian network model to (1) characterize the relative importance of multiple biotic and anthropogenic stressors on four ecoregional polar bear populations, at two future decadal time periods, and based on two Intergovernmental Panel on Climate Change (IPCC) greenhouse gas emissions scenarios (Shared Socioeconomic Pathways [SSPs] 2.6 [low] and 8.5 [high]); and (2) identify achievable management actions that may enhance the prospects of long-term persistence. Normative model runs indicated that populations in all four ecoregions incurred increasing probabilities of being decreased or greatly decreased over time. The probabilities of polar bear populations being decreased or greatly decreased from mid- to end of the century ranged from ~55% to 87% for the SSP 2.6 emissions scenario, and 82% to 94% for the SSP 8.5 emissions scenario among ecoregions. Arctic sea ice conditions and marine prey availability had the greatest influences on future polar bear population outcomes and overrode any relative influence from all other stressors. Hunting mortality was the most influential individual anthropogenic stressor in the Archipelago and Seasonal Ice Ecoregions, whereas terrestrial refugia quality grouped with various anthropogenic activities or factors (e.g., resource extraction, oil spill) was most influential for the Polar Basin Divergent Ice and Polar Basin Convergent Ice ecoregions. Our findings indicate that near-term proactive management of multiple anthropogenic stressors could cumulatively reduce the decline in populations such that if future sea ice habitat loss is eventually curtailed, population abundance would be greater than it would have been otherwise. Additionally, our findings suggest that there is value in tailoring management actions to address ecoregion-specific threats, which may prove useful in informing the development of future circumpolar conservation plans.</p>","PeriodicalId":48930,"journal":{"name":"Ecosphere","volume":"16 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ecs2.70316","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144255934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Recreational trail traffic counts and trail proximity as a driver of ungulate landscape utilization","authors":"Chloe Beaupre,&nbsp;Alissa Bevan,&nbsp;Jessica R. Young,&nbsp;Kevin A. Blecha","doi":"10.1002/ecs2.70305","DOIUrl":"https://doi.org/10.1002/ecs2.70305","url":null,"abstract":"<p>With continual growth in recreational trail use, it is becoming increasingly complicated to balance demands for outdoor recreation opportunities with wildlife conservation. To better understand how mule deer (<i>Odocoileus hemionus</i>) and Rocky Mountain elk (<i>Cervus canadensis</i>) respond to trail-based recreation, we deployed remote cameras in a paired study design to assess ungulate encounter rates relative to recreation traffic counts and distance from trails. Our methodology allowed us to estimate the magnitude of human activity on public land trails, which can be challenging, but is a key step in understanding recreational effects on animal utilization, especially if any interaction in trail proximity and human traffic rates exists. Paired cameras provided a comparison of animal encounter rates on- and off-trail at varying trail proximities, and the on-trail camera also yielded daily recreation traffic counts to assess how animals respond to varying traffic for each camera pair. Elk avoided busier trails and showed a strong positive response to distance from trails, while mule deer exhibited a positive response to higher traffic counts and no measurable effect of trail proximity. We identified a distance to trail threshold of 600–655 m, where elk utilization shifted from lower-than-expected utilization to higher-than-expected utilization, indicating that this elk population was redistributed to some degree within 57.5% of the study area's extent. Quantifying recreation traffic counts was key to understanding species' responses to recreation, highlighting the need for managers to consider both trail placement and human traffic regulation to mitigate recreation impacts.</p>","PeriodicalId":48930,"journal":{"name":"Ecosphere","volume":"16 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ecs2.70305","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144256326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"You can't go home again: Changes in trophic niche following extinction and recolonization of the New Zealand sea lion","authors":"L. C. Wing,&nbsp;S. R. Wing,&nbsp;R. Kinaston,&nbsp;A. J. M. Sabadel,&nbsp;I. Smith","doi":"10.1002/ecs2.70287","DOIUrl":"https://doi.org/10.1002/ecs2.70287","url":null,"abstract":"<p>Recolonization or range expansion of large marine predators can be facilitated by reestablishing formally important trophic linkages within intact coastal marine food webs. We analyzed long-term changes in the structure of coastal marine food webs supporting remnant and recolonizing populations of New Zealand sea lions (<i>Phocarctos hookeri</i>), an apex marine predator, using trophic position and mixture of alternate sources of organic matter as metrics for their resource niche. We measured δ¹³C, δ¹⁵N, and δ¹⁵N_AA of amino acids in collagen of archived prehistoric bone samples and modern bone, muscle, and fur samples. Using the resulting isotopic values, we calculated individual-based estimates of trophic position and basal organic matter source use from pelagic and benthic habitats, phytoplankton versus macroalgae, in the underlying food webs supporting sea lions from the Auckland Islands, Stewart Island, Southland, and Otago among discrete time periods dating to the first human settlements in New Zealand. The data resolved significant changes in trophic position of New Zealand sea lions since the first arrivals of Māori in New Zealand (ca. 1250–1450 CE), the advent of European whaling and sealing (ca. 1650–1850 CE), when sea lions were extirpated from the South Island, and expansion of industrialized fishing (ca. 1950 to present CE) indicating a vastly altered resource landscape for recolonizing populations on the South Island. New Zealand is the last major land mass to be settled by people; therefore, the patterns we observe comprise the complete time course of human influences on the marine ecosystem. These patterns provide a unique understanding of how long-term changes in coastal marine food webs influence the trophic position and population recovery of apex predators.</p>","PeriodicalId":48930,"journal":{"name":"Ecosphere","volume":"16 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ecs2.70287","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144256268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Expanding barriers: Impassable gaps interior to distribution of an isolated mountain-dwelling species","authors":"Erik A. Beever,&nbsp;Adam B. Smith,&nbsp;David Wright,&nbsp;Tom Rickman,&nbsp;Francis D. Gerraty,&nbsp;Joseph A. E. Stewart,&nbsp;Alisha Gill,&nbsp;Kelly Klingler,&nbsp;Megan Robinson","doi":"10.1002/ecs2.70223","DOIUrl":"https://doi.org/10.1002/ecs2.70223","url":null,"abstract":"<p>Global change is expected to expand and shrink species' distributions in complex ways beyond just retraction at warm edges and expansion at cool ones. Detecting these changes is complicated by the need for robust baseline data for comparison. For instance, gaps in species' distributions may reflect long-standing patterns, recent shifts, or merely insufficient sampling effort. We investigated an apparent gap in the distribution of the American pika, <i>Ochotona princeps</i>, along the North American Sierra Nevada. Historical records from this region are sparse, with ~100 km separating previously documented pika-occupied sites. Surveys during 2014–2023 confirmed that the gap is currently unoccupied by pikas, and evidence of past occurrence indicates that the gap has expanded over time, likely due to contemporary global change. Sites lacking evidence of past pika occurrence were climatically and geographically more distant from sites with signs of recent (former) occurrence and currently occupied sites. Formerly and currently occupied sites were partially climatically distinct, suggesting either metapopulation-like dynamics or an extinction debt that may eventually result in further population losses at the edge of suitable climate space. The Feather River gap aligns with one of several “low points” in the otherwise continuous boreal-like conditions spanning the Cascade Range and Sierra Nevada and is coincident with discontinuities in ranges of other mammals. These results highlight the potential for climate-driven fragmentation and range retraction in regions considered climatically and geographically interior to a species' overall distribution.</p>","PeriodicalId":48930,"journal":{"name":"Ecosphere","volume":"16 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ecs2.70223","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144256078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}