Species and speciation Flashcards
What is a species?
The basic unit used in classification.
What are prezygotic isolating mechanisms?
Mechanisms that prevent the formation of hybrid zygotes.
Give examples of prezygotic isolating mechanisms.
Ecological/habitat isolation, seasonal/temporal variation, sexual or ethological isolation, mechanical isolation, isolation by different pollinators and gametic isolation.
What are post zygotic isolating mechanisms?
Mechanisms that reduce the viability of hybrid zygotes once formed.
What are examples of post zygotic isolating mechanisms?
Hybrid inviability, hybrid sterility and hybrid breakdown.
What is recognition concept?
The idea that a set of organisms recognise eachother as potential mates.
What is the ecological concept?
The idea that populations form discrete phentic clusters because the ecological and evolutionary processes that control how resources are divided up tend to produce those clusters.
What is the cladistic concept?
That species are the sections of lines between the branch points of the tree.
What are the different ways in which speciation can occur?
Allopatric, parapatric, sympatric and peripatric.
What is allopatric speciation?
Speciation due to a geographical barrier.
What is parapatric speciation?
When populations occupy specific niches so they are separated by ecological factors.
What is sympatric speciation?
Speciation when the populations occupy the same environment.
What is peripatric speciation?
Speciation due to an isolated peripheral population.
What is the Neo-Darwinian view for how divergence occurs between population?
The idea that different selection forces are present due to differing environments and as populations are in distinct areas, each will have different mutations and genetic combinations for selection to act upon.
What is the Mayr view for how divergence occurs between populations?
That the chance isolation of small fragments of a population may allow the spread of genes that were previously at a selective disadvantage. Initial events physical and simply luck.
