International Journal of Molecular Zoology 2024, Vol.14, No.2, 111-127 http://animalscipublisher.com/index.php/ijmz 118 The navigation and orientation mechanisms employed by migratory animals are diverse and highly adapted to their specific migratory challenges. The magnetic compass and geomagnetic field detection provide a fundamental navigational tool, especially in featureless environments. Celestial navigation using the sun and stars offers reliable directional cues that complement the magnetic compass. Olfactory and visual cues enhance navigation through familiar and complex landscapes, ensuring precise orientation and successful migration. These sophisticated mechanisms highlight the remarkable navigational capabilities of migratory species and underscore the importance of integrating multiple sensory inputs for successful long-distance travel. 7 Case Study: In-Depth Analysis 7.1 Case study 1: Migratory drop-offs in fork-tailed flycatcher The fork-tailed flycatcher (Tyrannus savana) provides a compelling example of migration cessation, where individuals stop migrating and establish sedentary populations. Gómez-Bahamón et al. (2020) found that species differentiation in the fork-tailed flycatcher is closely related to changes in migratory behavior. Through detailed analysis of the genomic data and morphological characteristics of this bird, the research team revealed how the loss of migratory behavior contributed to species differentiation. The cessation of migration led the fork-tailed flycatcher to form distinct sedentary populations, which differ from migratory populations in terms of breeding time and geographic location, resulting in reproductive isolation. By analyzing numerous genetic markers, the study discovered significant genomic differentiation between migratory and sedentary fork-tailed flycatchers. Neighbor-joining tree and maximum likelihood analysis showed that the sedentary populations formed a monophyletic group, distinctly separated from the migratory populations. Changes in migratory behavior have significant impacts on species diversity and evolution. This phenomenon not only affects the ecological habits of birds but can also promote new species formation through reproductive isolation and genomic differentiation (Figure 2) (Gómez-Bahamón et al., 2020). This finding underscores the crucial role of migratory behavior in avian diversity and species differentiation, providing new insights into the evolution of other migratory animals (Jahn et al., 2019; Gómez-Bahamón et al., 2020). 7.2 Case Study 2: Migration strategies of moose (Alces alces) Borowik et al. (2021) explored the stability of moose (Alces alces) within their seasonal ranges and linked annual migration patterns to seasonal space use. The study found that some moose migrate between summer and winter ranges (partial migration), while others remain in the same area year-round. Migratory individuals showed significantly higher stability within their seasonal ranges compared to non-migratory moose, especially during summer. The home range size of migratory moose in summer was notably smaller than in winter, whereas non-migratory moose showed little difference in home range size between the two seasons. In all seasons, the home range size of male moose was significantly larger than that of females. This is likely due to the greater energy and nutritional demands of males. Additionally, male moose are more active during the mating season, further expanding their range. During summer, moose have smaller, more stable home ranges because food resources are more abundant and evenly distributed, allowing moose to frequently revisit the same feeding sites. In contrast, winter food resources are scarce and dispersed, requiring moose to move more frequently to obtain sufficient food, resulting in larger, less stable home ranges (Borowik et al., 2021). Environmental changes (such as climate warming) could affect moose's annual migration strategies, thereby altering their seasonal space use and individual fitness. The study results indicate significant differences in the home range size and behavior patterns of moose across seasons. Migration behavior significantly impacts the stability and size of seasonal home ranges. Future research should further explore the impact of food resource distribution and regeneration capacity on moose space use. Additionally, combining this with studies on animal adaptability can provide a comprehensive understanding of the effects of environmental changes on moose behavior and ecosystems.
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