Review: Speciation

Speciation

The process by which new species form from existing species.

Allopatric speciation

Speciation that occurs when populations are geographically isolated from each other.

Sympatric speciation

Speciation that occurs without geographical isolation, often through genetic changes.

Adaptive radiation

Rapid evolution of diversely adapted species from a common ancestor.

Reproductive isolation

Barriers that prevent species from interbreeding.

Prezygotic barriers

Barriers that prevent fertilization from occurring.

Postzygotic barriers

Barriers that occur after fertilization, affecting hybrid viability or fertility.

Gene flow

The transfer of genetic material between populations.

Natural selection

The process where organisms better adapted to their environment tend to survive and reproduce.

Hybrid zone

Region where different species meet and mate, producing hybrids.

Molecular clock

A method to estimate the time of species divergence using molecular data.

Speciation example: Darwin's finches

Different species evolved from a common ancestor due to varied environments on the Galápagos Islands.

True or false: Allopatric speciation requires physical barriers.

True, because geographical separation is essential.

Difference between allopatric and sympatric speciation

Allopatric involves physical separation; sympatric occurs in the same location.

Fill in the blank: Speciation can occur through ________ isolation.

reproductive

Question: What is adaptive radiation?

A process where a single ancestral species diversifies rapidly.

True or false: Natural selection always leads to speciation.

False, because natural selection can occur without leading to new species.

Example of prezygotic barrier

Temporal isolation, where species breed at different times.

Example of postzygotic barrier

Hybrid sterility, like mules from horse and donkey parents.

Question: How does gene flow affect speciation?

It can prevent speciation by mixing genetic traits between populations.