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Fitness is a measure of reproductive success (how many offspring an organism leaves in the next generation, relative to others in the group). Natural selection can act on traits determined by alternative alleles of a single gene, or on polygenic traits (traits determined by many genes). Natural selection on traits determined by multiple genes ...
Transcript. Natural selection is a mechanism of evolution and explains how species adapt to their environment over time through variations in traits. Examples include the peppered moth adapting to industrial pollution, yearly flu virus changes, and antibiotic-resistant bacteria. Understanding natural selection is essential for studying living ...
- 18 min
- Sal Khan
Nov 10, 2023 · Natural selection is the adaptation strategy of living organisms on Earth. It occurs when they acquire and evolve a trait with time that provides them a distinct advantage for their survival and reproduction over other organisms in the population. Darwin called them ‘survival of the fittest.’. Organisms with better adaptive traits survive ...
Jun 3, 2024 · Evolution - Natural Selection, Adaptation, Genetics: The central argument of Darwin’s theory of evolution starts with the existence of hereditary variation. Experience with animal and plant breeding had demonstrated to Darwin that variations can be developed that are “useful to man.” So, he reasoned, variations must occur in nature that are favourable or useful in some way to the organism itself in the struggle for existence. Favourable variations are ones that increase chances for ...
Evolution is not the same as adaptation or natural selection. Natural selection is a mechanism, or cause, of evolution. Adaptations are physical or behavioral traits that make an organism better suited to its environment. Heritable variation comes from random mutations. Random mutations are the initial cause of new heritable traits.
A diagram showing natural selection in action. 1) Mice in a population have brown or tan fur. The environment is mostly dark rock. 2) Tan mice are more likely to be eaten by predators. Brown mice are more likely to survive and have offspring. 3) After many generations, the brown fur trait is more common in the population.
Natural selection is a process by which a species changes over time in response to changes in the environment, or competition between organisms, in order for the species to survive. The members of ...
