Origin of Species

• what does evolution require?

  changes in allele and genotype frequency = microevolution
• what are the four evolutionary forces that result in change?

  mutation, gene flow, genetic drift and natural selection
• what is gene flow?

  the movement of genes between populations
• what is the gene pool?

  all of the alleles in a population
• how would the gene pool be considered closed?

  if the population is isolated
• what are the three modes of selection pressures?

  stabilising, directional and disruptive
• what is the carrying capacity?

  the average population size of a species in a particular habitat
• what are K selection species?

  density dependent species with traits which enable reproduction with fewer resources
• what are R selection species?

  density independent species with traits that promote rapid reproduction
• what is speciation driven by?

  population divergence
• what are the two types of speciation?

  allopatric and sympatric
• what is allopatric speciation?

  speciation in geographic isolation and physical separation - there is no gene flow, so gene pools are isolated, causing the population to differentiate over time and be unable to reproduce to create viable, healthy offspring when they do regroup in the future
• what is sympatric speciation?

  speciation with no isolation who no longer reproduce for mechanical or behavioural reasons
• what are the two types of reproductive barriers?

  pre zygotic and post zygotic
• what are pre zygotic barriers?

  mechanisms that prevent reproduction occur before the mating event has taken place
• what are post zygotic barriers?

  mechanisms which prevent reproduction occurring after the mating event has taken place
• what are the three types of pre zygotic barriers?

  behavioural isolation, temporal isolation and mechanical isolation
• what is gradualism?

  when evolution occurs slowly at a constant rate, giving rise to a new species
• what is punctuated equilibrium?

  when the appearance of a new characteristic gives rise to a new species relatively rapidly, which then persist unchanged for a long time (equilibrium)
• what is coevolution?

  when the selection pressures on one species are influenced by the evolution of another
• what are the three types of coevolution?

  interspecific competition, exploitation and mutualism
• what is insect aposematism?

  the term used to describe the bright colouration seen used as a warning to an organism that it is dangerous or unpalatable
• what is mutualism?

  coevolution though a mutually positive association
• give an example of mutual coevolution?

  pollination using flowers
• what are the two main reproductive costs?

  mating effort and parental effort
• what is there a trade of between in parental care?

  quality and quantity
• which sex often puts in more parental effort?

  female
• which sex often puts in more mating effort?

  male
• what is sexual selection?

  the force in evolution which causes the evolution of traits which give the owners a mating advantage over others of the same sex
• what do we call the traits which give their owners a mating advantage over others of the same sex?

  secondary sexual traits
• what is it called when males or females are bigger than the other sex?

  size dimorphism
• what is the operational sex ratio?

  the number of fertile viable individuals which are currently in the position to reproduce
• which sex gets has to be competitive?

  the sex with the greater potential rate of reproduction
• what are the two types of sexual selection?

  intra-sexual selection and inter-sexual selection
• what is intra-sexual selection?

  competition for mates between individuals of the same sex
• what is inter-sexual selection?

  mate choice by the female
• name three examples of secondary sex characteristics?

  weapons like antlers, size and rituals and displays
• what are the two main ideas for how elaborate traits evolve?

  runaway theory and the handicap principle