The decrease in the short-tailed squirrel population can be attributed to a process known as natural selection. Here are the key points explaining this phenomenon:
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Survival Advantage: Long-tailed squirrels possess traits that provide them with better abilities for jumping and balancing in trees. This enhances their chances of survival in their arboreal habitat, where agility and balance are crucial for escaping predators and accessing food.
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Reproductive Success: Because long-tailed squirrels are more adept at navigating their environment, they are likely to reproduce more successfully than short-tailed squirrels. This leads to a higher survival rate of their offspring, which also tend to inherit the long-tail trait.
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Selective Pressure: The environment places selective pressure on the population. As long-tailed squirrels thrive and short-tailed squirrels struggle, the dynamics of the population shift. The short-tailed squirrels face increased competition for resources and greater predation risk, leading to higher mortality rates among them.
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Genetic Drift and Allele Frequency: Over time, the frequency of the long-tail trait increases within the population (from 10% to 60%) as the alleles governing this trait are favored. As a result, the genetic diversity of the population shifts towards the long-tail allele, while the genes for short tails become less common.
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Limited Adaptation: If short-tailed squirrels are unable to adapt to the changing environment or to develop traits that improve their survival, their population will continue to decline.
In summary, the decrease in the short-tailed squirrel population results from the advantages that long-tailed squirrels have in their environment, leading to greater survival and reproductive success, while short-tailed squirrels suffer from reduced fitness in comparison.