International Journal of Molecular Evolution and Biodiversity 2024, Vol.14, No.5, 252-262 http://ecoevopublisher.com/index.php/ijmeb 253 2 Overview of Reptilian Physiology and Ecology 2.1 Diversity of Reptiles and Their Ecological Roles Reptiles represent one of the most diverse and ecologically significant groups of vertebrates, having successfully colonized a wide range of habitats across the globe. This group includes lizards, snakes, turtles, crocodilians, and the tuatara, each playing unique roles in their respective ecosystems. Lizards and snakes, which belong to the order Squamata, are particularly diverse, with lizards alone comprising over 6 650 species (Meiri, 2018). These species have adapted to various ecological niches, from deserts to rainforests, showcasing a remarkable array of morphological and physiological traits that enable them to thrive in different environments (Pincheira-Donoso et al., 2013). Turtles (order Testudines) and crocodilians (order Crocodylia) are less diverse but equally important. Turtles are found in both aquatic and terrestrial habitats, contributing to nutrient cycling and seed dispersal, while crocodilians are apex predators in many freshwater ecosystems, playing a crucial role in maintaining the balance of these environments. The tuatara, a unique reptile from New Zealand, represents the order Rhynchocephalia and provides valuable insights into the evolutionary history of reptiles. Despite their ecological importance, many reptile species are under threat due to habitat loss, climate change, and other anthropogenic factors, highlighting the need for comprehensive conservation efforts (Nordstrom et al., 2022). 2.2 Climate Sensitivity in Reptiles Reptiles, being ectothermic animals, are particularly sensitive to changes in their thermal environment. Temperature, humidity, and precipitation significantly influence their behavior, physiology, and overall fitness. For instance, the thermal physiology of reptiles, including traits like critical thermal maximum (CTmax) and thermal preference (Tpref), is crucial for their survival and reproductive success. However, studies have shown that developmental environments do not significantly affect these thermal physiological traits, suggesting that reptiles may rely more on behavioral or evolutionary adaptations to cope with changing temperatures (Zhang et al., 2023). The ability of reptiles to adapt to climate change through phenotypic plasticity and genetic adaptation is a subject of ongoing research. While phenotypic plasticity allows for immediate responses to environmental changes, genetic adaptation may provide long-term solutions. However, the rate of thermal trait evolution in reptiles is often slow, particularly at the warm end of the thermal performance curve, which may limit their ability to keep pace with rapid climate changes (Bodensteiner et al., 2020). Understanding the interactions between plasticity, behavior, and genetic adaptation is essential for predicting how reptiles will respond to future climate scenarios (Urban et al., 2013; Valero et al., 2021). Additionally, the use of advanced techniques like environmental DNA (eDNA) can enhance our ability to monitor and conserve reptile populations in the face of climate change. 3 Phenotypic Plasticity in Response to Climate Change 3.1 Definition and Mechanisms of Phenotypic Plasticity Phenotypic plasticity refers to the ability of an organism to alter its morphology, physiology, or behavior in response to environmental changes. This adaptability is crucial for survival in rapidly changing climates, as it allows organisms to maintain functionality and fitness without requiring genetic changes. Phenotypic plasticity can manifest as temporary or reversible changes, such as alterations in body size, coloration, or metabolic rates, which can be adjusted back when environmental conditions revert to their original state. For instance, reptiles often exhibit changes in their morphology and physiology in response to varying thermal environments, which can significantly impact their survival and reproductive success (Noble et al., 2018). The mechanisms underlying phenotypic plasticity are diverse and complex. They include changes in gene expression, hormonal regulation, and cellular processes that enable organisms to respond to environmental cues. For example, reptiles may adjust their metabolic rates or alter their developmental pathways in response to temperature fluctuations, which can affect their growth rates, survival, and reproductive output (Fox et al., 2019). These plastic responses are often mediated by specific genes that are sensitive to environmental conditions, allowing for rapid and reversible changes in phenotype. Understanding these mechanisms is essential for predicting how reptiles and other organisms will cope with ongoing climate change.
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