2. drift and selection Flashcards
what is evolution?
Evolution is the change over time in the proportion of individuals in a population differing in one or more inherited traits
what happens during evolution?
During evolution, changes in allele frequency occur through the non-random processes of natural selection and sexual selection, and the random process of genetic drift
what does natural selection act on?
Natural selection acts on genetic variation in populations
what do populations produce?
Populations produce more offspring than the environment can support
who survives longer?
Individuals with variations that are better suited to their environment tend to survive longer and produce more offspring, breeding to pass on those alleles that conferred an advantage to the next generation
what is sexual selection?
Sexual selection is the non-random process involving the selection of alleles that increase the individual’s chances of mating and producing offspring
when does genetic drift occur?
Genetic drift occurs when chance events cause unpredictable fluctuations in allele frequencies from one generation to the next
what is sexual selection due to?
Sexual selection can be due to male-male rivalry and female choice
what can sexual selection lead to?
Sexual selection may lead to sexual dimorphism
when is genetic drift more important?
Genetic drift is more important in small populations, as alleles are more likely to be lost from the gene pool
bottleneck effect
A population bottleneck or is a sharp reduction in the size of a population due to environmental events such as famines, earthquakes.
founder effect
the reduction in genomic variability that occurs when a small group of individuals becomes separated from a larger population
why is a gene pool altered by genetic drift?
A gene pool is altered by genetic drift because certain alleles may be under-represented or over-represented and allele frequencies change
what happens where selection pressures are strong?
Where selection pressures are strong, the rate of evolution can be rapid
what does the Hardy-Weinberg principle state?
The Hardy-Weinberg (HW) principle states that, in the absence of evolutionary influences, allele and genotype frequencies in a population will remain constant over the generations
