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Biology subjects

Clark, R. W.

Publications and source records attributed to Clark, R. W..

2 recordsLinked to original sources

Thermal Dynamics of Ectotherm Behavioral Strategies: Insights from Agent-Based Simulations

Terrestrial ectotherms use dynamic behavioral thermoregulation strategies that typically rely on finding thermal refugia to avoid unfavorable conditions. Traditional analytic approaches rely on analysis of thermal indices to describe thermal conditions organisms may or may not choose, though computational simulations could potentially be used to analyze thermoregulatory behavior explicitly. Here, we leverage a novel simulation framework that integrates data from operative thermal models deployed in microhabitats available to ectotherms to showcase the trade-offs between two basic thermoregulatory strategies: maintaining a thermal optimum point or attempting to keep their body temperature within a preferred thermal range. We assess the output from simulations of these behavioral strategies to understand their influence on body temperature regulation and occupancy of thermal refugia, and then compare our findings from an empirical case study. Results from our analysis suggest that these two general strategies do not impact thermoregulation as strongly as previously assumed. We also found that occupancy of thermal refugia appeared to be driven by environmental conditions rather than the thermoregulation strategy. Although our case study showed promise in providing insights into predicting use of thermal refugia, understanding microhabitat occupancy from thermal data alone may require finer scale temporal data, or the integration of other factors such as foraging dynamics or predation avoidance. HighlightsO_LIAgent-Based simulation framework which explicitly models ectotherm behavioral thermoregulation. C_LIO_LIAnalysis shows minimal differences between varying thermoregulation strategies. C_LIO_LISimulations identify cathermal activity patterns regardless of behavioral strategy. C_LIO_LIResults show promise of empirical applications. C_LI

ecology↗

Elucidating dispersal ecology of reclusive species through genetic analyses of parentage and relatedness: the island night lizard (Xantusia riversiana) as a case study.

Characterizing dispersal and movement patterns are vital to understanding the evolutionary ecology of species. For many reclusive species, such as reptiles, the observation of direct dispersal may be difficult or intractable. However, dispersal distances and patterns may be characterized through indirect genetic methods. We used genetic and capture data from the island night lizard (Xantusia riversiana) to estimate natal dispersal distances through indirect genetic methods, characterize movement and space use patterns, and compare these distances to previous estimates made from more traditional ecological approaches. We found that indirect estimates of natal dispersal were greater than previous field-based estimates of individual displacement of 3-5 m. Parent-offspring differences had a mean of approximately 14 m on Santa Barbara Island (SBI) and 41 m on San Clemente Island (SCI) whereas Wrights {sigma} was estimated at 16 m on SBI and 20 m for SCI. Spatial autocorrelation with correlograms of Morans I revealed large differences in the scale of autocorrelation between islands (SBI=375 m, SCI=1,813 m). Interpretation of these distances as average per generation distance of gene flow was incongruent with parentage analyses and {sigma}. We also used variograms to evaluate the range of spatial autocorrelation among two inter-individual genetic differences. The range of spatial autocorrelation again identified different scales on the two islands (102 - 169 m on SBI and 955 - 1,424 m on SCI). No evidence of sex-biased dispersal was found on either island. However, a permutation logistic regression revealed that related individuals >0.8 years old were more likely to be captured together on both islands. Overall, our findings suggest that field-based estimates of individual displacement within this species may underestimate genetic dispersal. We suggest indirect inferences of natal dispersal distances should focus on parentage analyses and Wrights {sigma} for parameter estimation of individual movement, whereas the ranges identified by spatial autocorrelation and variograms are likely to be relevant at the metapopulation or patch scales. Furthermore, characterization of capture patterns and relatedness revealed kin-affiliative behavior in X. riversiana, which may be indicative of delayed dispersal and cryptic sociality. These results highlight the power of parentage- and relatedness-based analyses for characterizing aspects of the movement ecology of reclusive species that may be difficult to observe directly. These data can then be leveraged to support future conservation and population modeling efforts and assess extinction risks and management strategies.

ecology↗