Assay validation and interspecific comparison of salivary glucocorticoids in three amphibian species

Amphibians are one of the most threatened groups of species, facing stressors ranging from habitat degradation and pollution to disease and overexploitation. Stress hormones (glucocorticoids, GCs) provide one quantitative metric of stress,and developing non-invasive methods for measuring GCs in amphibians would clarify how diverse environmental stressors impact individual health in this taxonomic group. Saliva is an advantageous matrix for quantifying GCs, as it is sampled less invasively than plasma while still detecting both baseline and acute elevation of GCs within a short timeframe. Little work has employed this method in amphibian species, and it has never been pharmacologically and biologically validated. Here, we conduct analytical, pharmacological and biological validation experiments for measuring salivary corticosterone in three amphibian species: the American bullfrog (Rana catesbeiana), the green frog (Rana clamitans) and the northern leopard frog (Rana pipiens). These species are faced with a broad range of environmental challenges, and in part of its range R. pipiens populations are currently in decline. In addition to demonstrating that this method can be reliably used in multiple amphibian species, we present an examination of intrinsic biological factors (sex, body condition) that may contribute to GC secretion, and a demonstration that saliva can be collected from free-living animals in the field to quantify corticosterone. Our findings suggest that saliva may be useful for less invasively quantifying GCs in many amphibian species

Beyond a warming fingerprint: individualistic biogeographic responses to heterogeneous climate change in California.

Understanding recent biogeographic responses to climate change is fundamental for improving our predictions of likely future responses and guiding conservation planning at both local and global scales. Studies of observed biogeographic responses to 20th century climate change have principally examined effects related to ubiquitous increases in temperature - collectively termed a warming fingerprint. Although the importance of changes in other aspects of climate - particularly precipitation and water availability - is widely acknowledged from a theoretical standpoint and supported by paleontological evidence, we lack a practical understanding of how these changes interact with temperature to drive biogeographic responses. Further complicating matters, differences in life history and ecological attributes may lead species to respond differently to the same changes in climate. Here, we examine whether recent biogeographic patterns across California are consistent with a warming fingerprint. We describe how various components of climate have changed regionally in California during the 20th century and review empirical evidence of biogeographic responses to these changes, particularly elevational range shifts. Many responses to climate change do not appear to be consistent with a warming fingerprint, with downslope shifts in elevation being as common as upslope shifts across a number of taxa and many demographic and community responses being inconsistent with upslope shifts. We identify a number of potential direct and indirect mechanisms for these responses, including the influence of aspects of climate change other than temperature (e.g., the shifting seasonal balance of energy and water availability), differences in each taxon's sensitivity to climate change, trophic interactions, and land-use change. Finally, we highlight the need to move beyond a warming fingerprint in studies of biogeographic responses by considering a more multifaceted view of climate, emphasizing local-scale effects, and including a priori knowledge of relevant natural history for the taxa and regions under study

sp_gc_glmm_full_11apr

This is the file that contains information for automatically adding species co-occurrence score to the accelerometer data using the provided R script. This file is for Tamias speciosus

Tamias alpinus and Tamias speciosus accelerometer raw data compiled & cropped

All data both species compiled - USE THIS DATA FOR THE R COD

al_gc_glmm_full_11apr

This is the file that contains information for automatically adding species co-occurrence score to the accelerometer data using the provided R script. This file is for Tamias alpinus

Data from: Ecological specialization, variability in activity patterns, and response to environmental change

Differences in temporal patterns of activity can modulate the ambient conditions to which organisms are exposed, providing an important mechanism for responding to environmental change. Such differences may be particularly relevant to ecological generalists, which are expected to encounter a wider range of environmental conditions. Here, we compare temporal patterns of activity for partially sympatric populations of a generalist (the lodgepole chipmunk, Tamias speciosus) and a more specialized congener (the alpine chipmunk, T. alpinus) that have displayed divergent responses to the past century of environmental change. Although mean activity budgets were similar between species, analyses of individual-level variation in locomotion revealed that T. alpinus exhibited a narrower range of activity patterns than T. speciosus. Further analyses revealed that T. alpinus was more active earlier in the day, when temperatures were cooler, and that activity patterns for both species changed with increased interspecific co-occurrence. These results are consistent with the greater responsiveness of T. alpinus to changes in environmental conditions. In addition to highlighting the utility of accelerometers for collecting behavioral data, our findings add to a growing body of evidence suggesting that the greater phenotypic variability displayed by ecological generalists may be critical to in situ responses to environmental change

R code for analyzing "raw_data_dryad.csv"

R code for analyzing and visualizing accelerometer dat

Supplementary Methods, Tables, and Figures from Ecological specialization, variability in activity patterns and response to environmental change

Study site locations and sample sizes, PCA results, and GLMM variables; Graphical representation of extracted locomotion curve features; Boxplots showing glucocorticoids before/after accelerometers; Sum of squared error scree plot for cluster analysis

Supplementary Methods, Tables, and Figures from Ecological specialization, variability in activity patterns and response to environmental change

Study site locations and sample sizes, PCA results, and GLMM variables; Graphical representation of extracted locomotion curve features; Boxplots showing glucocorticoids before/after accelerometers; Sum of squared error scree plot for cluster analysis