Spermophilus beldingi

Jenkins, Stephen H.; Eshelman, Bruce D.

doi:10.2307/3503911

Cited by 40 publications

(24 citation statements)

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“…6-7 km 2 in both eras), and it agrees with the previously identified importance of meadows and riparian ecosystems for small mammals in the Sierras [13,66]. This could also explain the range contraction of the long-tailed vole, a meadow specialist [67,68], which occurs from low-to high elevations. We found positive effects of Jeffrey pine, a high elevation pine, for this species.…”

Section: Discussionsupporting

confidence: 76%

The relative influence of change in habitat and climate on elevation range limits in small mammals in Yosemite National Park, California, U.S.A.

Santos

Smith

Thorne³

et al. 2017

Clim Chang Responses

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Background: Different processes determine species' geographic ranges, including species' responses to changing climate, habitat, or both simultaneously. Here we ask which combination of factors best predicts shifts in the upper and lower elevation range limits and overall range of small mammal species in Yosemite National Park, California, USA across the last 100 years. Methods: We used species distribution models (SDMs) to predict elevation range dynamics of small mammals between 1910 and 1930 and 2003 and 2010, based on combinations of habitat and climate variables, and compared the predicted SDM distribution with the "observed" range from occupancy modelling (OM). Results: SDM model convergence was successful for eight species. Predictions of elevation range shifts from the SDMs agreed with OM for four of these species; while the other four could be partially predicted. SDMs predicted shifts in lower limits (six correct) better than upper limits (five correct). The five correctly predicted upper limit shifts were best predicted with climate; whereas five out of the six lower elevation shifts included habitat. SDMs were best at predicting range contraction at higher elevations. Conclusions: Climate generally had a stronger effect on range dynamics than habitat, especially at higher elevations. However, at mid-elevations SDMs showed an increasing importance of habitat on range shifts at these elevations, in the cases range shifts were reliably predicted. Predicting elevation range shifts on the basis of climate or habitat alone is insufficient, as habitat and climate play varying roles at different elevations, associated with different processes underlying range shifts. Failure to predict observed range shifts may arise from biotic interactions, behaviour flexibility, or evolutionary adaptation, aspects which are only beginning to be incorporated into distribution modelling frameworks.

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Section: Discussionsupporting

confidence: 76%

The relative influence of change in habitat and climate on elevation range limits in small mammals in Yosemite National Park, California, U.S.A.

Santos

Smith

Thorne³

et al. 2017

Clim Chang Responses

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“…This categorization into dietary guild corresponds to other findings that a wider dietary niche breadth was associated with range changes (Angert et al ). We also found that those herbivores generally not synchronous with vegetation dynamics were species that use mostly herbaceous vegetation types, such as open areas [ M. californicus, M. longicaudus (Smolen and Keller ), and S. trowbridgii (George )], meadows [ U. beldingi (Jenkins and Eshelman ), and M. montanus (Sera and Early )], riparian [ Z. princeps (Hart et al )], and rock slab [ T. alpinus (Clawson et al )]. Such vegetation types tend not to be as spatially dynamic because they are mostly tied to the local topography and geologic structure.…”

Section: Discussionmentioning

confidence: 78%

Synchronicity in elevation range shifts among small mammals and vegetation over the last century is stronger for omnivores

2014

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In mountain ecosystems, species can be said to respond synchronously to environmental change when the elevation ranges of vegetation types and their associated vertebrates expand or contract in the same direction. Conversely, the response is asynchronous when the elevation ranges of vegetation types and associated vertebrates change in different directions. The capacity of vertebrate species to respond synchronously with change in the elevation ranges of the vegetation that comprises their habitat is likely a function of their ecological traits. Here we combine measures of elevation range shifts in 23 vertebrate species with those of their associated vegetation types across 80 yr, on a large elevation transect in California's Sierra Nevada mountains that encompasses Yosemite National Park. Half the species’ shifts were synchronous with vegetation shifts, ¼ of the species were asynchronous, and the others showed no relationship. Most species that responded synchronously to changes in vegetation elevation ranges expanded their elevation range, and are inhabitants of low and intermediate elevations. In contrast, those species whose range shifts were asynchronous to associated vegetation shifts inhabit high elevations. These species experienced contraction in elevation range even while their associated vegetation types expanded. However, these species were responding synchronously to a subset of their associated vegetation types. Considering trait‐based predictors, omnivores were more synchronous than herbivores. Our results on synchronous and asynchronous elevation shifts with vegetation may permit more accurate modeling of future ranges for vertebrates in California's Sierra Nevada. The approach also offers a new method for use in assessment of vertebrate vulnerability in other mountain regions, and can be an important component of assessing their vulnerability to climate change.

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“…Over their range in western USA, Belding's ground squirrels are common in high alpine meadows (Jenkins and Eshelman, 1984), which are invariably covered with a meter or more of snow in early spring when they emerge from hibernation. Starting in early May, my assistants and I searched the study site daily for evidence of recently emerged squirrels.…”

Section: Methodsmentioning

confidence: 99%

Food supplements modulate changes in leucocyte numbers in breeding male ground squirrels

Bachman

2003

Journal of Experimental Biology

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SUMMARY Immunosuppression may be an important cost of reproduction in breeding males. It can result from elevated levels of testosterone or stress hormones and may serve to lower the energetic cost of maintaining immune function at a time of high demand. This suggests that greater access to energy resources could reduce immunosuppression as a cost of reproduction, minimizing the trade-off between energetic investment in current reproductive effort and survival. I examined the impact of food availability on immune function by provisioning male Belding's ground squirrels in the field from the time they emerged from hibernation to the start of breeding. Temporal changes in immune status, measured by leucocyte counts, differed between provisioned males and un-provisioned controls. Provisioning advanced the increase in lymphocytes and neutrophils from after breeding to before. At the start of breeding, the leucocyte count was three times greater in provisioned males than in controls and was still nearly twice as great at the end of breeding. Control males increased all leucocyte numbers after breeding. This experiment demonstrates that variation in food intake can lead to individual variation in the extent of immunosuppression during breeding and therefore that reduced immune function may not be an obligatory cost of reproduction.

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Spermophilus beldingi

Cited by 40 publications

References 0 publications

The relative influence of change in habitat and climate on elevation range limits in small mammals in Yosemite National Park, California, U.S.A.

The relative influence of change in habitat and climate on elevation range limits in small mammals in Yosemite National Park, California, U.S.A.

Synchronicity in elevation range shifts among small mammals and vegetation over the last century is stronger for omnivores

Food supplements modulate changes in leucocyte numbers in breeding male ground squirrels

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