Evolution (a) Drift and Selection Flashcards
Evolution is…
The change over time in the proportion of individuals in a population differing in one or more inherited traits.
During evolution,changes in allele frequency occur though…
The non-random process of natural selection and sexual selection. and the random process of genetic drift.
Steps of natural selection
Natural selection acts on genetic variation in a population. Populations produce more offspring than the environment can support. Individuals with variations that are better suited to their environment tend to survive longer and produce more offspring, breeding tp pass on those alleles that conferred an advantage to the next generation.
Selection results in…
The non-random incraese in the frequency of advantageous alleles, and the non-random decrease in the frequency of deleterious alleles.
Sexual selection is…
The non-random process involving the selection of alleles that increase the individuals chances of mating and producing offspring.
Sexual selection increases…
Reproductive success
Sexual selection may lead to…
Sexual dimorphism
Sexual selection…
Can be due to male-male rivalry and female choice.
Male-Male rivalry is when…
Large size or weaponry increases access to females through conflict
Female choice involves…
Females assessing the fitness of males
Selection pressures are…
The environmental factors that influence which individuals in a population pass on their alleles.
Selection pressures can be: biotic…
Competition, predation, disease
Selection pressures can be: abiotic…
Changes in temperature, light, humidity, pH, salinity
When selection pressures are strong, ther rate of evolution will be…
Rapid
Genetic drift occurs when…
Chance events cause unpredictable fluctuations in allele frequencies from one generation to the next.
Genetic drift is more important in…
Small populations, as alleles are more likely to be lost from the gene pool.
Population bottlenecks occur when…
a population size is reduced for at least one generation
Founder effects occur through…
The isolation of a few members of a population from a larger population
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.
The conditions for maintaining the HW equilibrium are…
No natural selection, random mating, no mutation, large population size, ane no gene flow (through migration, in or out)
grump(u is backwards)
The HW principle can be used to determine…
Whether a change in allele frequency is occurring in a population over time. Change suggests that evolution is occurring.
A gene pool is altered by genetic drift because…
Certain alleles may be under-represented or over-represented and allele frequencies change
