Natural selection is a key mechanism of evolution, acting on the heritable traits of individuals within a population. Here's how it drives the evolution of species:
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Variation: Within any population, individuals have variations in their traits (e.g., size, color, speed), which can arise from random mutations, genetic recombination, and other factors.
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Inheritance: Traits that confer advantages or disadvantages can be passed from parents to offspring through genetic inheritance. Only those traits that are heritable can be affected by natural selection.
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Competition and Survival: Individuals in a population compete for limited resources (such as food, mates, and habitat). Due to environmental pressures and resource constraints, not all individuals will survive to reproduce.
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Differential Reproduction: Individuals with traits that provide better chances of survival and reproduction are more likely to pass those advantageous traits onto the next generation. This is often summarized as "survival of the fittest," where "fittest" refers to those best adapted to their environment, not necessarily the strongest.
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Adaptation: Over time, the advantageous traits become more common in the population, leading to gradual changes and adaptations. As generations pass, the population may evolve significantly, potentially leading to the development of new species, especially if populations become isolated and adapt to different environments.
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Speciation: When populations of the same species become isolated (geographically or reproductively), they can undergo different evolutionary pressures, leading to distinct adaptations and eventually speciation – the formation of new species.
Natural selection acts on existing variations within a population, driving the evolution of species by promoting traits that enhance an organism's fitness in its environment, leading to long-term changes in the characteristics of the population over generations.
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