2.2.1 evolution: drift and selection Flashcards
what is evolution
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 processes of genetic drift
what does natural selection act on
the genetic variation in populations
how does variation in traits arise
mutation
what is mutation
the original source of new sequences of DNA. they can be novel alleles. most mutations are harmful or neutral
can mutations be beneficial to the fitness of an individual
yes
how much offspring do populations produce
more than the environment can support
which individuals tend to survive longer and produce more offspring, breeding to pass on alleles that confer an advantage to the next generation
individuals with variations that are better suited to their environment
what does selection result 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
the non random process involving the selection of alleles that increase the individual’s chances of mating and producing offspring
what may sexual selection lead to
sexual dimorphism, which is when the different sexes of a species have distinct differences in size or appearance
what can cause sexual selection
male-male rivalry and female choice
what is male male rivalry
large size or weaponry which increases access to females through conflict
what does female choice involve
females assessing the fitness of males
when does genetic drift occur
when chance events cause unpredictable fluctuations in allele frequencies from one generation to the next