Evolution 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?
Changes in allele frequency occur through the non-random processes of natural selection and sexual selection, and the random process of genetic drift.
What is natural selection?
Natural selection acts on genetic variation in populations
What is Variation?
Variation in traits arises as a result of mutation. Mutation is the original source of new sequences of DNA. These new sequences can be novel alleles. Most mutations are harmful or neutral, but in rare cases they may be beneficial to the fitness of an individual.
What happens when populations produce more offspring than the offspring can support?
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.
Results of Selection?
Selection results in the non-random increase in the frequency of advantageous alleles and the non-random decrease in the frequency of deleterious alleles.
What is sexual selection?
Sexual selection is the non-random process involving the selection of alleles that increase the individuals chances of mating and producing offspring.
What can sexual selection lead to?
May lead to Sexual dimorphism
What can sexual selection lead to?
Male to male rivalry
Female choice
What is male to male rivalry?
Male to male rivalry: large size or weaponary increases access to females through conflict.
What is Female choice?
Female choice involves females assessing the fitness of males.
How does a genetic drift occur?
It occurs when chance events cause unpredictable fluctuations in allele frequencies from one generation to the next
Effect of genetic drift on small populations?
Alleles are more likely to be lost from the gene pool
Population bottlenecks
Population bottlenecks occur when a population size is reduced to at least one generation.
Founder effect
Occurs through the isolation of a few members of a population from a larger population. The gene pool of the new population is not representative of that in the original gene pool.
