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AbstractThermal physiology helps us understand how ectotherms respond to novel environments and how they persist when introduced to new locations. Researchers generally measure thermal physiology traits immediately after animal collection or after a short acclimation period. Because many of these traits are plastic, the conclusions drawn from such research can vary depending on the duration of the acclimation period. In this study, we measured the rate of change and extent to which cold tolerance (critical thermal minimum [CT min ]) of nonnative Italian wall lizards ( Podarcis siculus ) from Hempstead, New York, changed during a cold acclimation treatment. We also examined how cold acclimation affected heat tolerance (critical thermal maximum [CT max ]), thermal preference ( T pref ), evaporative water loss (EWL), resting metabolic rate (RMR), and respiratory exchange ratio (RER). We predicted that CT min , CT max , and T decreased within 2 wk and that it remained low during the cold acclimation treatment; we suspect that this cold tolerance plasticity reduces risk of exposure to lethal temperatures during winter for lizards that have not yet found suitable refugia. CT pref would decrease with cold acclimation but that EWL and RMR would increase with cold acclimation. We found that CT min also decreased after cold acclimation, while EWL, RMR, and RER increased after cold acclimation, suggesting trade-offs with cold acclimation in the form of decreased heat tolerance and increased energy demands. Taken together, our findings suggest that cold tolerance plasticity aids the persistence of an established population of invasive lizards. More generally, our findings highlight the importance of accounting for the plasticity of physiological traits when investigating how invasive species respond to novel environments.max and T pref also decreased after cold acclimation, while EWL, RMR, and RER increased after cold acclimation, suggesting trade-offs with cold acclimation in the form of decreased heat tolerance and increased energy demands. Taken together, our findings suggest that cold tolerance plasticity aids the persistence of an established population of invasive lizards. More generally, our findings highlight the importance of accounting for the plasticity of physiological traits when investigating how invasive species respond to novel environments.

Identifying how natural (i.e., unaltered by human activity) and anthropogenic landscape variables influence contemporary functional connectivity in terrestrial organisms can elucidate the genetic consequences of environmental change. We examine population genetic structure and functional connectivity among populations of a declining species, the Blainville's horned lizard (Phrynosoma blainvillii), in the urbanized landscape of the Greater Los Angeles Area in Southern California, USA. Using single nucleotide polymorphism data, we assessed genetic structure among populations occurring at the interface of two abutting evolutionary lineages, and at a fine scale among habitat fragments within the heavily urbanized area. Based on the ecology of P. blainvillii, we predicted which environmental variables influence population structure and gene flow and used gravity models to distinguish among hypotheses to best explain population connectivity. Our results show evidence of admixture between two evolutionary lineages and strong population genetic structure across small habitat fragments. We also show that topography, microclimate, and soil and vegetation types are important predictors of functional connectivity, and that anthropogenic disturbance, including recent fire history and urban development, are key factors impacting contemporary population dynamics. Examining how natural and anthropogenic sources of landscape variation affect contemporary population genetics is critical to understanding how to best manage sensitive species in a rapidly changing landscape., (© 2022 The Authors. Molecular Ecology published by John Wiley & Sons Ltd. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.)

Temperature has a substantial effect on both the physiology and behavior of ectothermic animals such as lizards. Physiology and behavior can also be influenced by ontogenetic and sex differences, but these effects are largely understudied in lizards. We examined ontogenetic and sex-based differences in thermal tolerances, preferred temperature, and temperature-dependent evaporative water loss rates in Italian Wall Lizards, Podarcis siculus, collected from an introduced population near Los Angeles, California, USA that were acclimated to laboratory conditions. Podarcis siculus has been introduced to multiple localities in the USA and the Mediterranean region and has demonstrated remarkable ability to adapt to novel climatic conditions. In the California population, adults of both sexes had a higher critical thermal maximum (CT max ) than juveniles, and adult females had a lower critical thermal minimum (CT min ) than juveniles and adult males. Thus, adult females had a significantly wider thermal breadth (CT max - CT min ) compared to adult males and juveniles. Mass-specific evaporative water loss was higher in juveniles compared to adult males at intermediate temperatures. There was no significant difference among groups for preferred temperature. This implies that thermal tolerance, a physiological characteristic, varies with age and sex for this population, whereas thermal preference, a behavioral characteristic, does not. Interestingly, CT min for all age and sex classes was above temperatures likely experienced by some nonnative populations in winter, suggesting individuals need to find urban thermal retreats. These results add to the growing literature demonstrating that thermal tolerances and breadths can vary between sexes and across age classes in squamate species., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Animals often view humans as predators, leading to alterations in their behavior. Even nuanced aspects of human activity like clothing color affect animal behavior, but we lack an understanding of when and where such effects will occur. The species confidence hypothesis posits that birds are attracted to colors found on their bodies and repelled by non-body colors. Here, we extend this hypothesis taxonomically and conceptually to test whether this pattern is applicable in a non-avian reptile and to suggest that species should respond less fearfully to their sexually-selected signaling color. Responses to clothing color could also be impacted by habituation to humans, so we examine whether behavior varied between areas with low and high human activity. We quantified the effects of four T-shirt colors on flight initiation distances (FID) and on the ease of capture in western fence lizards (Sceloporus occidentalis), and we accounted for detectability against the background environment. We found no differences in lizard behavior between sites. However, lizards tolerated the closest approaches and were most likely to be captured when approached with the T-shirt that resembled their sexually-selected signaling color. Because changes in individual behavior affect fitness, choice of clothing color by people, including tourists, hikers, and researchers, could impact wildlife populations and research outcomes.