Topic 8: Speciation Flashcards

• what is mircoevolution


  evolution at the population level
• how fast can microevolution occur

  very quickly - over generations
• what changes in microevolution

  changes in allele frequency in a population over time
• how does microevolution occur

  Occurs mainly through natural selection (results in adaptation) or genetic drift
• what is macroevolution


  broad patters of evolutionary change above species level
• in macroevolution, changes occur on what time scale


  changes occurring on geological time scales
• what are two examples of macroevolution


  -origin of novel traits like wings-origin of new groups like mammals
• why is the distinction between micro- and macroevolution arbitrary

  because theyre fundamentally identical processes on different time scales
• macroevolution is the result of what


  result of gradual compounding of small changes (cumulative microevolution + cumulative mutations)
• What is the biological species concept (BSC)?

  a species consists of a group of actually or potentially interbreeding individuals
• What holds a species together genetically?

  gene flow between populations of a species
• BSC is based on what

  the potential to interbreed rather than on physical similarity
• how are species isolated from other species

  reproductively isolated from other species
• what are the limitations of BSC?

  -cannot be applied to fossils or asexual organisms (including all prokaryotes)-emphasizes the absence of gene flow
• BSC suggests that two different species would never what


  never mate and produce offspring
• what is successful hydridization

  gene flow that occurs between distinct species
• what are other species concepts emphasize unity within a species rather than the separateness of different species

  -morphological species concept-ecological species concept
• What is the morphological species concept?

  defines a species by structural features
• what does the morphological species concept apply to

  applies to sexual and asexual species but relies on subjective criteria
• what is the ecological species concept

  a species is a set of organisms adapted to a particular set of resouces, called a niche, in the enviornment
• how does the ecological species concept view a species


  views a species in terms of its ecological niche
• what does the ecological species concept apply to

  sexual and asexual species
• What is the phylogenetic species concept?

  defines a species as the smallest group of individuals on a phylogenetic tree
• what does the phylogenetic species concept apply to

  sexual and asexual species
• based on evolutionary history a species is a what on a phylogeny

  is a 'tip
• prokaryote species defined as what

  as a monophyletic and genomically coherent cluster of individual organisms
• it can be difficult to determine the degree of phylogenetic difference required to what

  separate species
• it can be difficult to determine the degree of what required to separate species

  phylogenetic difference
• what is reproductive isolation


  the existence of biological factors that impede two species from producing viable, fertile offspring
• what are hydribs

  are offspring of crosses between different species
• reproductive isolation can be classified by what


  by whether reproductive barriers act before (prezygotic) or after (postzygotic) fertilization
• What is a prezygotic barrier?


  prevents the zygote from ever forming through various isolation patterns
• What is a postzygotic barrier?

  a reproductive barrier that prevents hybrid zygotes produced by two different species from developing into viable, fertile adults
• what are the 3 ways prezygotic barriers prevent fertilization

  -impeding different species from attempting to mate-preventing the successful completion of mating-preventing fertilization if mating is successful
• What are the 5 prezygotic barriers?

  -habitat isolation-temporal isolation-behavioural isolation-mechanical isolation-gametic isolation
• What is habitat isolation?

  Two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers
• What is temporal isolation?

  species breed at different times of the say, different seasons, or different years cannot miz their gametes
• What is behavioral isolation?

  Courtship rituals and other behaviours unique to a species are effective barriers
• what is behavioural isolation restricted to


  restricted to animals
• what is mechanical isolation?

  Morphological differences can prevent successful mating (anatomically incompatible)