International Journal of Molecular Evolution and Biodiversity 2024, Vol.14, No.4, 197-207 http://ecoevopublisher.com/index.php/ijmeb 200 3.4 Introduction of invasive species and competition The introduction of invasive species can lead to increased competition for resources, which can drive local adaptation in native avian species. The house sparrow (Passer domesticus), introduced to Australia from Europe, has been used as a model to study local adaptation in invasive species. Genomic analyses have identified loci subject to selection across varied climates, with some outlier genes linked to traits important for local adaptation, such as heat-shock proteins and immune response genes (Andrew et al., 2018). This highlights the role of genetic adaptation in enabling invasive species to thrive in new environments. 3.5 Anthropogenic factors: urbanization, agriculture, and industry Urbanization, agriculture, and industrial activities are major anthropogenic factors that impact avian species. These activities can lead to habitat modification, pollution, and increased human-wildlife interactions, all of which can exert selective pressures on avian populations. For instance, urbanization can alter selection pressures on growth traits, necessitating adaptive plastic or evolutionary changes in response to changing environments (Sauve et al., 2021). Additionally, the evolutionary potential of avian populations is closely linked to their preexisting genetic diversity, which can influence their ability to adapt to anthropogenic changes. 4 Case Study: Genetic Adaptation in Arctic Terns 4.1 Overview of the environmental challenges faced by arctic terns Arctic terns (Sterna paradisaea) are renowned for their extraordinary migratory behavior, undertaking the longest known annual migration of any organism, traveling between breeding sites in the Arctic and temperate regions to survival and molting areas in the Antarctic pack-ice zone (Figure 2) (Alerstam et al., 2019). This extensive migration exposes them to a wide range of environmental conditions, including varying temperatures, food availability, and predation pressures. During the breeding season, Arctic terns are central place foragers, restricted to the first 50 cm of the water column, and must adjust their foraging behaviors to compensate for extrinsic factors such as local weather and fisheries (Morten et al., 2022). Additionally, contamination of Arctic marine environments with persistent organic pollutants (POPs) poses a significant challenge, although studies have shown that male Arctic terns can rapidly eliminate these contaminants during the breeding season (Mallory et al., 2019). 4.2 Detailed analysis of genetic changes observed in this species Recent genomic studies have provided insights into the genetic adaptations of Arctic terns to their challenging environments. For instance, the use of light-level geolocators has revealed significant segregation in time and space between tern populations in the same flyway, suggesting adaptive genetic differentiation based on migration patterns and environmental conditions encountered during their extensive journeys (Alerstam et al., 2019). Furthermore, the genetic basis of phenotypic plasticity in Arctic terns has been explored through the study of ecomorphs in related species, which show substantial changes in genotype-phenotype relationships in response to different environmental conditions (Küttner et al., 2014). These findings suggest that Arctic terns may also possess hidden genetic variation that evolves with ecological specialization, allowing them to adapt to diverse and changing environments. 4.3 Discussion on the adaptive significance of these genetic changes The genetic adaptations observed in Arctic terns are crucial for their survival and reproductive success in the face of rapid environmental changes. The ability to rapidly eliminate contaminants, as seen in male Arctic terns, likely provides a significant advantage in maintaining health and reproductive fitness during the breeding season (Mallory et al., 2019). The observed genetic differentiation based on migration patterns and environmental conditions highlights the importance of local adaptation in ensuring that Arctic terns can exploit optimal foraging areas and avoid competition and predation (Alerstam et al., 2019). Additionally, the potential for hidden genetic variation to be exposed under different environmental conditions suggests that Arctic terns have a robust capacity for phenotypic plasticity, enabling them to respond to and thrive in a wide range of ecological niches.
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