Taxonomy

Question 1

What are the 3 themes of species definitions and their requirements?

Answer 1

Morphological = physically different
Biological = reproductively isolated, intrinsic barriers such as hybrid dysfunction, different niche
Phylogenetic = % nucleotide difference, unique genes, monophyletic, an evolving lineage

Question 2

Definition of species

Answer 2

A metapopulation lineage evolving separately

Question 3

How fast does genetic difference and reproductive isolation happen?

Answer 3

From drosophila studies, in general.
Genetic divergence of 0.9 enough to maintain two taxa as distinct if they become sympatric.
Rapid evolution of pre-zygotic isolation in sympatry takes 200,000 years
In allopatry, takes 2.7m years
Can be very fast (50 years), e.g. in Darwin’s finches in 3 generations

Question 4

Definition of speciation

Answer 4

Lineages separate gradually
Involves reproductive isolation, either pre or post zygotic.
Typically evolves in allopatry; speed greatly increased if sympatric.
Probably involves sexual conflict and resulting arms races between the sexes

Question 5

Describe allopatric speciation

Answer 5

Vicariant - habitat somehow split in half and individuals become separated and speciate
Parapatric - some plants - population speciates at the edge of the larger population