Evolution flashcards

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What is natural selection?

The process where organisms with phenotypes better adapted to their environment tend to survive and reproduce more successfully, passing on their advantageous alleles to the next generation.

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Distinguish between allopatric and sympatric speciation.

Allopatric speciation occurs when populations are geographically isolated, leading to reproductive isolation. Sympatric speciation occurs within the same geographical area, often due to mechanisms like polyploidy or disruptive selection.

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What is the Hardy-Weinberg equation for allele frequencies?

$p + q = 1$, where 'p' is the frequency of the dominant allele and 'q' is the frequency of the recessive allele in a population.

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What is the Hardy-Weinberg equation for genotype frequencies?

$p^2 + 2pq + q^2 = 1$, where $p^2$ is the frequency of the homozygous dominant genotype, $2pq$ is the frequency of the heterozygous genotype, and $q^2$ is the frequency of the homozygous recessive genotype.

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What is stabilising selection?

A type of natural selection that favours intermediate phenotypes and selects against extreme variations. It reduces phenotypic variation and maintains the status quo. Example: human birth weight.

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What is directional selection?

A type of natural selection where an extreme phenotype is favoured, causing the allele frequency to shift over time in the direction of that phenotype. Example: antibiotic resistance in bacteria.

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What is disruptive selection?

A type of natural selection that selects against the average individual in a population and favours individuals at both extremes of the phenotypic range. It can lead to the formation of two distinct subpopulations.

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What is the founder effect?

A type of genetic drift that occurs when a new population is established by a small number of individuals whose gene pool may differ, by chance, from the source population.