2.2

• evolution

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

  occurs when chance events cause unpredictable fluctuations in allele frequencies from one generation to the next
• natural selection

  non-random process which certain alleles occurs more frequently in a population because they confer a select advantage
• sexual selection

  is a non-random process which involved the selection of alleles that increase an individuals chances of mating and producing offspring
• sexual dimorphism

  when the appearance and behaviour of males and females is different, and females are generally inconspicuous, males usually have more conspicuous markings, structures and behaviours
• female choice

  a mechanism of sexual selection in which females assess male's fitness and choose the males with which they will mate
• 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 others
• commensalism

  symbiosis in which two or more species evolve in response to selection pressures imposed by each other
• fitness

  an indication of an individuals ability to be successful at surviving and reproducing compared to other 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 from a larger population
• hardy-weinberg 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