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Survival wisdom hidden in islands: Why do some animals lose the ability to fly?
As many species become residents of island ecosystems, they gradually adapt to these unique environments, exhibiting a phenomenon known as "island syndrome." This phenomenon describes the changes in the morphology, ecology, and lifestyle of island species relative to mainland species. These changes are caused by different ecological pressures in the living environment. This article takes an in-depth look at the reasons behind the loss of the ability to fly in island animals, and the impact this process has on their survival strategies.
Ecological driving factors
Island ecosystems are unable to accommodate sufficient prey biomass, thus reducing the presence of large predators, and thus the predation pressure faced by island animals is significantly reduced. This eliminates the need for many species to possess abilities to escape predators, such as the ability to fly. In comparison, organisms in continental areas face higher competition and predation risks, resulting in greater morphological diversity and differentiation of survival strategies.
Minimization of wings
The reduction or complete loss of wings is a striking phenomenon in many island organisms. Many flightless species exhibit characteristics that contrast with their ancestors. For example,
Among the species that have adapted to island life, such as the solitary bird of Poha Village and the ancient dodo, their wings have almost disappeared, showing an extreme trend of survival adaptation. This shift allowed the birds to reduce the demand on their wing muscles, resulting in stronger bones to cope with the island's stable environment."The spotted-headed monk pigeon in Mauria and some smaller birds in Australia have lost the ability to fly because they no longer need to escape predators."
Adaptive color change
With the reduction of sexual selection, color changes have occurred in some island species, mainly in the fading or uniformity of colors to reduce energy consumption. This phenomenon is particularly evident in many island birds, whose feathers tend to be more uniform and dull in color. This is not only because there is less biodiversity within the islands, it also means there is less identification pressure between species and less sexual selection driving color and traits.
Adjustment of breeding strategy
Island organisms also display some uniqueness in their reproductive strategies. To adapt to island environments, these animals tend to select fewer offspring and provide greater parental investment to increase the survival chances of individual offspring. This phenomenon contrasts with the highly competitive breeding situation on the continent. In some island reptiles, such as lizards, the pattern is even more pronounced.
Intelligence and physiological changes
As predation risk decreases, brain size of island animals tends to decrease significantly. This is mainly because in low-predation environments, the presence of a brain no longer brings an absolute advantage for survival. Some extinct species, such as the dwarf hippopotamus of Madagascar, had significantly smaller brains than their mainland ancestors. This phenomenon is common among island organisms, further supporting the idea of the "cheap tissue hypothesis", in which organisms gradually reduce their metabolic demands on organs that do not require much intelligence.
Threats and protection
Island organisms lack the ability to escape predation, making them particularly vulnerable to invasion by alien species. For example, when humans first introduced species such as dogs, pigs, and rats to the island of Mauritius in the seventeenth century, it ultimately led to the extinction of the dodo. The incident highlights the importance of ecosystem management and provides lessons for protecting island life.
Taken as a whole, island ecosystems exhibit a fascinating array of ecological adaptation and evolution processes that reflect species' dynamic responses to environmental stresses. Such adaptations are not only expressions of survival strategies but also the epitome of natural selection. In the future, when faced with the challenges of human activities and climate change, how will these animals readjust their survival strategies? Can they find a new way out?
