How do populations adapt genetically?
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Populations adapt genetically through various mechanisms rooted in evolutionary biology. Genetic adaptation hinges primarily on changes in allele frequencies, driven by natural selection, genetic drift, mutations, and gene flow over generations.
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Natural Selection: This is the primary force driving adaptation. Traits that enhance survival and reproduction become more common in the population. For instance, noted that individuals with traits that enable them to raise more children to maturity pass on their DNA more effectively, leading these traits to become more prevalent over time 1.
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Mutations: Mutations introduce new genetic variations, which can be beneficial, neutral, or harmful. Beneficial mutations can lead to adaptations that enhance survival. An example is the Bajau people, who have evolved larger spleens, allowing them to stay underwater longer—a beneficial trait for freediving 2.
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Genetic Drift: This is a random process that can cause allele frequencies to change over time, particularly in small populations. This change can lead to the fixation or loss of alleles, contributing to genetic differentiation among populations.
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Gene Flow: The movement of genes between populations contributes to genetic diversity. For example, discussed how human populations exhibit low variation in their reproductive systems, allowing continued fertility even after long separations, thus promoting genetic adaptation through gene flow 3.
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Gene's Eye View: This perspective focuses on genes as the primary unit of selection. Genes that are more effective at replicating themselves will become more common in the population. explained that genes are passed on intact, and their selfish behavior (maximizing their representation in the next generation) drives genetic adaptation 4.
Through these processes, populations develop adaptations that enhance their survival and reproductive success in changing environments, illustrating the dynamic nature of genetic evolution.
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