Reproductive isolation

Day 13

Speciation key process under BSC

reduced gene flow → genetic divergence → reproductive barriers → reproductive isolation → seperate species

Allopatric speciation

speciation by geographic isolation

Types of Allopatric speciation

vicariance

dispersal/ founders’ effect

peripatric speciation

Vicariance

a previously continuous population is split by a geographic barrier

dispersal/founders effect

a small group moves to a new isolated location and becomes separate from the original population

peripatric speciation

a small population at the end of the species range becomes geographically isolated

Sympatric speciation

Speciation without geographic isolation

- disruptive selection

-polyploidization

Adaptive radiation

a single lineage rapidly produces many descendants species with a wide range of adaptive forms

Why adaptive radiation?

ecological opportunity

• availability for different kinds of resources or more of them

Vacant niches

trait innovation

• evolution of a key trait that allowed descendants to live in new areas or exploit new resources