Over a decade of field physiology reveals life-history specific strategies to drought in garter snakes (Thamnophis legans)

Climate warming and temporal variation in reproductive strategies in the endangered meadow viper

Anthropogenic climate change poses a significant threat to species on the brink of extinction. Many non-avian reptiles are endangered, but uncovering their vulnerability to climate warming is challenging, because this requires analyzing the climate sensitivity of different life stages and modeling population growth rates. Such efforts are currently hampered by a lack of long-term life-history data. In this study, we used over 3 decades of mark-recapture data from a natural population of the endangered meadow viper (Vipera ursinii ursinii) to unravel the patterns of temporal variation in reproductive traits, the local climatic determinants of inter-annual variation in reproduction, and the potential buffering effects of life cycle on population growth rate. We found significant inter-annual variation in body growth, gestation length, post-parturition body condition, clutch success, and offspring traits at birth, while reproductive effort showed little temporal variation. Temperature during gestation was the most critical factor, reducing gestation length and increasing both clutch success and post-parturition body condition. In contrast, neither air humidity nor global radiation affected reproductive outcomes. This population had a negative growth rate with minimal temporal variation, indicating a rapid decline largely independent of climatic conditions. Overall, the viper's life-history traits appeared to be buffered against temporal variation in climatic conditions, with this declining population potentially benefiting on the short term from rising local temperatures.

The Life-History Traits of Soil-Dwelling Nematode (Acrobeloides sp.) Exhibit More Resilience to Water Restriction Than Caenorhabditis elegans

In the context of climate warming, the intensity and frequency of drought occurrences are progressively increasing. However, current research on the impacts of drought on the life-history traits and physiological activities of animals rarely encompasses soil animals that play crucial roles within soil ecosystems. Therefore, this study focused on a soil nematode species (Acrobeloides sp.) and a model nematode (Caenorhabditis elegans) to investigate whether nematodes adjust the trade-off of their life-history traits to confront arid environments, utilizing a Petri dish experiment. Subsequently, we assessed the resilience of the two nematode species to moisture variations by comparing the extent of changes in various indicators (i.e., life-history traits, physiological traits, and oxidative stress) of nematodes before and after drought and rehydration. The results revealed that both nematode species are capable of adapting to arid environments by altering the trade-off between life-history traits. Specifically, they reduce reproductive investment and body mass while maintaining life span, thus responding to drought conditions. Follow-up rehydration experiments post-drought stress highlighted that the soil-dwelling nematode exhibits a superior recovery capacity in response to moisture fluctuations in comparison to the model nematode. To the best of our knowledge, this is the first investigation into life history of drought adaptation within soil-dwelling nematodes. Moreover, the findings hold significant implications for the exploration of drought adaptation and its mechanisms in soil-dwelling animals.

Physiological phenotypes differ among color morphs in introduced common wall lizards (Podarcis muralis)

Many species exhibit color polymorphisms which have distinct physiological and behavioral characteristics. However, the consistency of morph trait covariation patterns across species, time, and ecological contexts remains unclear. This trait covariation is especially relevant in the context of invasion biology and urban adaptation. Specifically, physiological traits pertaining to energy maintenance are crucial to fitness, given their immediate ties to individual reproduction, growth, and population establishment. We investigated the physiological traits of Podarcis muralis, a versatile color polymorphic species that thrives in urban environments (including invasive populations in Ohio, USA). We measured five physiological traits (plasma corticosterone and triglycerides, hematocrit, body condition, and field body temperature), which compose an integrated multivariate phenotype. We then tested variation among co-occurring color morphs in the context of establishment in an urban environment. We found that the traits describing physiological status and strategy shifted across the active season in a morph-dependent manner-the white and yellow morphs exhibited clearly different multivariate physiological phenotypes, characterized primarily by differences in plasma corticosterone. This suggests that morphs have different strategies in physiological regulation, the flexibility of which is crucial to urban adaptation. The white-yellow morph exhibited an intermediate phenotype, suggesting an intermediary energy maintenance strategy. Orange morphs also exhibited distinct phenotypes, but the low prevalence of this morph in our study populations precludes clear interpretation. Our work provides insight into how differences among stable polymorphisms exist across axes of the phenotype and how this variation may aid in establishment within novel environments.

Reptilian Innate Immunology and Ecoimmunology: What Do We Know and Where Are We Going?

Reptiles, the only ectothermic amniotes, employ a wide variety of physiological adaptations to adjust to their environments but remain vastly understudied in the field of immunology and ecoimmunology in comparison to other vertebrate taxa. To address this knowledge gap, we assessed the current state of research on reptilian innate immunology by conducting an extensive literature search of peer-reviewed articles published across the four orders of Reptilia (Crocodilia, Testudines, Squamata, and Rhynchocephalia). Using our compiled dataset, we investigated common techniques, characterization of immune components, differences in findings and type of research among the four orders, and immune responses to ecological and life-history variables. We found that there are differences in the types of questions asked and approaches used for each of these reptilian orders. The different conceptual frameworks applied to each group has led to a lack of unified understanding of reptilian immunological strategies, which, in turn, have resulted in large conceptual gaps in the field of ecoimmunology as a whole. To apply ecoimmunological concepts and techniques most effectively to reptiles, we must combine traditional immunological studies with ecoimmunological studies to continue to identify, characterize, and describe the reptilian immune components and responses. This review highlights the advances and gaps that remain to help identify targeted and cohesive approaches for future research in reptilian ecoimmunological studies.