International Journal of Molecular Evolution and Biodiversity 2024, Vol.14, No.4, 197-207 http://ecoevopublisher.com/index.php/ijmeb 203 6.3 Predictions for future adaptive responses based on current genetic trends Based on current genetic trends, future adaptive responses in avian species are likely to be complex and multifaceted. Predictions suggest that while some species may continue to exhibit phenotypic plasticity, others may face significant evolutionary constraints. For instance, the potential for evolutionary rescue through the spread of climate-adaptive genetic variation depends on a population's adaptive capacity and landscape connectivity. Enhancing landscape connectivity could facilitate the spread of adaptive traits and reduce the risk of extinction (Razgour et al., 2019). Furthermore, the role of cognitive abilities in buffering against climate change is becoming increasingly evident. Species with larger relative brain sizes have shown weaker phenotypic responses to climate warming, suggesting that behavioral flexibility may mitigate some of the adverse effects of climate change. 7 Role of Migration in Genetic Adaptation 7.1 The influence of migratory patterns on genetic diversity Migratory patterns play a crucial role in shaping the genetic diversity of avian species. Migration can lead to gene flow between geographically separated populations, thereby increasing genetic diversity. For instance, the willow warbler (Phylloscopus trochilus) exhibits significant genetic differences between its northern and southern subspecies, which are attributed to their distinct migratory routes and wintering areas. These differences are maintained by chromosomal inversions that are associated with migratory phenotypes and environmental gradients (Lundberg et al., 2021). Additionally, the genetic basis of migratory behavior has been demonstrated in various bird species, indicating that migratory activity and directional preferences are inherited traits. This genetic control over migration can lead to rapid evolutionary changes, as seen in obligate partial migrants where novel migratory habits can evolve in less than 25 years. 7.2 How migration affects the genetic adaptation of avian species Migration affects genetic adaptation by enabling birds to exploit different environments, which can lead to the selection of advantageous traits. For example, the genetic determination of migration strategies in large soaring birds, such as the greater spotted eagle (Clanga clanga) and the lesser spotted eagle (Clanga pomarina), shows that genetic factors significantly influence migration timing and wintering distributions. This genetic influence allows these species to adapt their migration strategies to changing environmental conditions (Väli et al., 2018). Furthermore, the genetic correlation between migratory activity and the frequency of migrants in a population suggests that selection can act on both the incidence and the extent of migratory behavior, facilitating rapid evolutionary changes. 7.3 Case studies of migratory birds exhibiting genetic adaptation Several case studies highlight the genetic adaptation of migratory birds: The willow warbler’s northern and southern subspecies exhibit different migratory routes and wintering areas, maintained by chromosomal inversions. These genetic differences are associated with adaptations to distinct environmental gradients, demonstrating how migration can drive genetic divergence (Lundberg et al., 2021). In a hybrid zone between two groups of Swainson’s thrushes, genetic mapping revealed that migratory orientation is strongly associated with specific genomic regions. This genetic basis for migration orientation suggests that these birds can rapidly adapt to new migratory routes and environmental conditions (Delmore et al., 2016). Older, more experienced whooping cranes have been observed to innovate new migration behaviors in response to global changes. These new behaviors, such as establishing overwintering sites closer to breeding grounds, are facilitated by the age structure of the population, highlighting the role of experience and genetic adaptation in response to environmental changes (Teitelbaum et al., 2016). These case studies illustrate the complex interplay between migration, genetic diversity, and adaptation in avian species, emphasizing the importance of genetic factors in shaping migratory behaviors and enabling rapid responses to environmental changes.
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