Speciation Flashcards
What is allopolyploidy?
2 closely related species hybridize and form polyploid offspring
What is autopolyploidy?
diploid individual may produce tetraploid offspring each of which has 4 complete sets of chromosomes
What is clinical variation?
environment changes from different elevations (Ex. mountains)
What is a ring species?
“could mate” Ex. Big and small dogs mating, very artificial
What are unreduced gametes?
gametes spontaneously get the same number of chromosomes as a somatic cell
What are the 3 specific types of speciation?
- Allopatric speciation
- Parapatric speciation
- Sympatric speciation
What is allopatric speciation?
when 2 populations are geographically separated
What are the 3 types of allopatric speciation?
- Species Cluster
- Hybrid Zones
- Reinforcement
What is a species cluster?
a group of close related species recently descended from a common ancestor
What are hybrid zones?
where members of each population may mate with individuals from the other before pre zygotic reproductive isolation is complete
What is reinforcement?
natural selection promotes the evolution of pre zygotic isolating mechanisms which favours individuals who mate only with members of their own population when post zygotic isolating mechanisms cause hybrid offspring to have lower fitness
What is genetic divergence in allopatric populations?
many traits that function as pre zygotic isolating mechanisms may have originally evolved in response to sexual selection
What is parametric speciation?
speciation arising between adjacent populations, populations also adapt to different environmental conditions
What is sympatric speciation?
reproductive isolation evolves between distinct subgroups that arise within a population
What is a host race?
isolation from populations in the same species as a consequence of their adaptation to feed on a specific host plant species
What are the 3 post zygotic isolating mechanisms?
- hybrid inviability
- hybrid sterility
- hybrid breakdown
What is hybrid inviability?
when the result of hybrid organisms die as embryos or at an early age because the 2 sets of developmental instructions do not interact properly
What is hybrid sterility?
hybrids between closely related species produce adult offspring but they are not fertile and cannot reproduce
What is hybrid breakdown?
when first generation hybrids are healthy and fertile but second generations exhibit reduced survival or fertility
What are the 5 methods of pre zygotic speciation?
- Ecological isolation
- Temporal isolation
- Behavioural isolation
- Mechanical isolation
- Gametic isolation
What is ecological isolation?
species living in the same geographical region but do not interbreed
What is temporal isolation?
species that live in the same habitat but mate at different times of the day or year
What is behavioural isolation?
when the signals used for one species are not recognized by another species
What is mechanical isolation?
differences in the structure of reproductive organs or other body parts that prevent individuals from breeding
