Unit 2, Topic 2

Absolute fitness

the ratio between the number of individuals of a particular genotype after selection to those before selection

Bottleneck effect

a sharp reduction in the size of a population due to environmental events or human activities

Co-evolution

the process by which two or more species evolve in response to selection pressures imposed by each other

Commensalism

symbiosis in which only one of the species benefits (+/0)

Evolution

the change over time in the proportion of individuals in a population differing in one or more inherited traits

Female choice

a mechanism of sexual selection in which females assess males' fitness and choose the males with which they will mate

Fitness

a measure of the tendency of some organisms to produce more surviving offspring than competing members of the same species

Founder effects

when the gene pool of a new population is not representative of that in the original gene pool! occurs through the isolation of a few members of a population from a larger population

Gene pool

the total number of genes and their alleles in a population of one species

Genetic drift

the random increase or decrease in frequency of DNA sequences from one generation to the next, particularly in small populations

Hardy-Weinberg (HW) principle

in the absence of evolutionary influences, allele and genotype frequencies in a population will remain constant over the generations

Male-male rivalry

a mechanism of sexual selection in which males fight for females, often using weaponry such as antlers and tusks

Mutualism

both species in the interaction are interdependent on each other for resources or other services! as both organisms gain from the relationship, the interaction is (+/+)

Natural selection

the non-random increase in the frequency of advantageous alleles and the non-random decrease in the frequency of deleterious alleles

Parasitism

symbiosis in which the parasite benefits in terms of energy or nutrients and the host is harmed as the result of the loss of these resources (+/-)

Red Queen hypothesis

states that, in a co-evolutionary relationship, change in the traits of one species can act as a selection pressure on the other species

Relative fitness

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

Selection pressures

the environmental factors that influence which individuals in a population pass on their alleles

Sexual dimorphism

females are generally inconspicuous! males usually have more conspicuous markings, structures and behaviours

Sexual selection

the non-random process involving the selection of alleles that increase the individual's chances of mating and producing offspring

Symbiosis

co-evolved intimate relationships between members of two different species