O2 L3: Origin of species

Macroevolution

Long timescale (speciation, mass extinctions, etc)

Microevolution

Short timescale (evolutionary changes in frequencies of variant forms of genes w in population)

Modern synthesis

Micro +macro evolution

What is Allopatric speciation?

(In another land)

Ancestral pop geographically divided

Isolated sub populations evolve reproductive barriers

In what ways can allopatric speciation occur?

Vicariance: climate or geology causes fragmentation of population, ancestral fragments left as is, can occur in several species simultaneously

Dispersal: small number of individuals disperse to a distant place (island effect) and form new pop.

Dispersal

What is Sympatric speciation?

Diverging lineages occupy the same geographic area

(Less common than allopatric speciation)

What type of barriers for sympatric speciation?

Reproductive barriers are present, while geographic barriers are absent.

Biological species concept

Focused on sexual reproduction: Species characterized by ability to produce fertile offspring

Morphological species concept

Species characterized by body shape and other morphological features

Ecological species concept:

Species characterized in terms of its ecological niche

What is a species? (Generally)

Individuals descended from a common ancestral population

Reproductively compatible

Genotyping and phenotypic cohesion