Chapter 23 - Evolution Flashcards
Natural Selection
Result of differential survival and reproduction. It is the only mechanism of evolution that consistently causes a population to become better adapted to its environment.
Genetic Drift
evolution due to chance events and causes unpredictable fluctuations in allele frequencies. Genetic drift can have a particularly significant effect in a small population, such as during a bottleneck or founder event.
Gene Flow
When alleles are transferred into or out of a population due to the migration of fertile individuals or their gametes. Gene flow can bring new alleles (beneficial, harmful, or neutral) into a population.
Microevolution
Generation-to-generation change in the allele frequencies in a population
How to sexual selection and inbreeding differ?
Unlike inbreeding, sexual selection changes allele frequencies and affects only genes involved in attracting mates.
Gene Pool
All of the alleles in all the gametes produced in each generation can be considered as a single group
Inbreeding Depression
decline in average fitness that takes place when homozygosity increases and heterozygosity drops
Directional Selection
a pattern that increases the frequency of one allele. Eventually, other alleles may be lost.
Stabilizing Selection
individuals with intermediate traits reproduce more than others with extreme traits.
Disruptive Selection
Favours extreme phenotypes
Heterozygote Advantage
heterozygous individuals have higher fitness than homozygous individuals do, thus maintaining genetic variation in the population.
Founder Effect
Immigrants establish new population that is likely to have different allele frequencies than the source population by chance
Genetic Bottleneck
High mortality strikes individuals at random and the new population that is likely to have different allele frequencies than the source population by chance
Sexual Dimorphism
any trait that differs between males and females of the same species.
