Speciation Flashcards
How do we define a species?
Groups of interbreeding natural populations that are reproductively isolated from other such groups.
If they met they wouldn’t be able to reproduce.
What are 3 other species concepts.
- recognition species concept
- ecological species concept
- phenetic species concept
Describe allopatric speciation.
- a group within the population is geographically isolated
- selection pressures and variation in the separate population cause it to gain adaptations
- when the two populations are reintroduced they can no longer reproduce
What is a ring species.
Extremes can be very different morphologically, we don’t normally know if they can interbreed.
In ‘ring species’ the two ends meet so we can see that geographic variation does lead to new speices.
Name 6 examples of geographic barriers in allopactric speciation.
- continental drift
- the sea
- ocean currents
- a desert
- mountain ranges
- distance
What is reinforcement?
Assortative mating. Individuals that avoid hybridisation should have greater fitness, so individuals that mate with their own linage will be selected for.
What is a peripheral isolate.
Peripatric speciation. A small population is on the periphery of a large population, rather than geographically isolated.
What is the founder effect.
A loss of genetic variation because the new population is smaller causing there to be less alleles within the population.
What is parapatric speciation.
A new species from within a contiguous population by:
- new niche or range
- reinforcement
What is a stepped cline?
A stepped cline shows a zone in which hybridisation occurs, usually indicating a parapatric or allopatric speciation event.
What is sympatric speciation?
A new species froms in the geographical range of the ancestor.
