International Journal of Molecular Zoology 2024, Vol.14, No.3, 182-196 http://animalscipublisher.com/index.php/ijmz 187 5.2 Genomic studies and findings in adaptive traits Advances in genomic methods have facilitated the identification of loci, genes, and mutations underlying adaptive traits. For example, genomic analyses have revealed that gene losses can contribute to morphological, physiological, and metabolic adaptations in mammals, suggesting that gene loss is a widespread mechanism for adaptation (Sharma et al., 2018). Additionally, research on the genetic architecture of adaptation has shown that adaptive loci can be identified by examining genomic regions under selection and connecting these variants to phenotypic traits (Bomblies and Peichel, 2022). These findings provide valuable insights into the molecular mechanisms driving adaptation and highlight the complexity of the genetic basis of adaptive traits. 5.3 Epigenetic factors influencing adaptation Epigenetic mechanisms, such as DNA methylation, histone modifications, and non-coding RNAs, play a significant role in environmental adaptation. Epigenetic variation can contribute to phenotypic plasticity, allowing organisms to rapidly adapt to new environments without genetic changes. For instance, studies on invasive species have shown that epigenetic responses can facilitate rapid adaptation, even in populations with minimal genetic diversity (Carneiro and Lyko, 2020). Moreover, research on clonal animals and plants has demonstrated that epigenetic mechanisms support phenotypic plasticity and stable adaptation to different environments (Vogt, 2017; Vogt, 2022). The interplay between genetic and epigenetic variation is crucial for understanding the adaptive capacity of populations, as both types of variation can jointly promote rapid adaptation to changing environments (Stajic and Jansen, 2021; Chen et al., 2022). In summary, the genetic basis of adaptation involves a complex interplay between genetic diversity, genomic changes, and epigenetic mechanisms. Understanding these factors is essential for predicting the adaptive potential of species and developing effective conservation and management strategies. 6 Case Studies in Place 6.1 Arctic mammals: adaptations to extreme cold Arctic mammals have developed a range of adaptations to survive the extreme cold and seasonal variations in their environment. These adaptations include behavioral, physical, and physiological strategies (Davidson et al., 2020). For instance, many Arctic mammals engage in behaviors such as huddling and shelter building to reduce exposure to the cold. Physiologically, they exhibit seasonal changes in insulation through fur, plumage, and blubber, and circulatory adjustments to preserve core temperature by cooling the periphery and extremities. Additionally, newborn altricial animals show profound tolerance to hypothermia but rely on parental care for warmth, while precocial mammals are well insulated and use non-shivering thermogenesis in brown adipose tissue to generate heat (Blix, 2016). Behavioral plasticity also plays a crucial role, as seen in wild reindeer in high-Arctic Svalbard, which adjust their space use in response to extreme weather events like rain-on-snow and icing, thereby reducing body mass loss and mortality rates, and increasing fecundity (Loe et al., 2016). 6.2 Desert mammals: strategies for surviving in arid environments Desert mammals face the challenges of water and food scarcity, as well as extreme temperatures. Recent genomic research has highlighted the genetic mechanisms underlying these adaptations, revealing a large overlap in functional classes of genes and pathways among different desert mammals. These genetic adaptations are crucial for managing water retention, thermoregulation, and efficient nutrient utilization. However, the complexity of these adaptations and the variety of phenotypes involved necessitate further studies to develop accurate genotype-phenotype-environment maps (Figure 3) (Rocha et al., 2021). The genetic basis of these adaptations underscores the importance of understanding the evolutionary processes that enable mammals to thrive in such harsh environments. The research of Rocha et al. (2021) provides a detailed overview of the genomic strategies used to identify genes associated with desert adaptation in various species. Panel A focuses on population-specific adaptations, highlighting genetic diversity and long haplotypes specific to desert and non-desert populations. Panel B delves into species-specific adaptations, utilizing metrics like dN/dS ratios and gene family evolution to compare desert-adapted species with their non-desert counterparts. Panel C examines differential gene expression in
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