2 - evolution Flashcards
Describe the process of evolution
Evolution is the change over time in the proportion of individuals in a population differing in one or more inherited traits.
Describe the process of natural selection
The process of natural selection hinges upon the fact that there is variation within a population.
Describe the process of 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.
What might sexual selection lead to?
sexual dimorphism.
Sexual selection can be due to male-male rivalry and female choice. Describe these processes
Male-male rivalry = large size or weaponry increases access to females through conflict.
Female choice involves females assessing the fitness of males.
Describe the process of genetic drift
Genetic drift occurs when chance events cause unpredictable fluctuations in allele frequencies from one generation to the next.
Why is genetic drift more important in small populations?
Genetic drift is more important in small populations because alleles are more likely to be lost from the gene pool.
What is the importance of the bottleneck effect and founder effect on genetic drift?
Population bottlenecks occur when a population size is reduced for at least one generation.
Define the term selection pressures and give examples
Selection pressures are the environmental factors that influence which individuals in a population pass on their alleles.
What happens where selection pressures are strong?
Where selection pressures are strong, the rate of evolution can be rapid.
Describe the Hardy-Weinberg (HW) principle
The hardy-weinberg principle states that in the absence of evolutionary influences, allele and genotype frequencies in a population will remain constant over the generations.
What can the HW principle be used to determine?
The HW principle can be used to determine whether a change in allele frequency is occurring in a population over time.
What is fitness an indication of?
Fitness is an indication of an individual’s ability to be successful at surviving and reproducing.
Define the term absolute fitness
Absolute fitness is the ratio between the number of individuals of a particular genotype after selection, to those before selection.
Define the term relative fitness
Relative fitness is the ratio of the number of surviving offspring per individual of a particular genotype to the number of surviving offspring per individual of the most successful genotype.
