Speciation Pathways

Question 1

Anagenesis/phyletic evolution

Answer 1

A population accumulates enough changes that it would be reproductively isolated from its ancestral population (no branching)
Doesn’t lead to diversity in life, rare

Question 2

Cladogenesis

Answer 2

Branching speciation. Splitting of a population leads to 2 separate species. Responsible for the millions of species in the history of life on earth.

Question 3

Allopatric speciation

Answer 3

Splitting of a gene pool by a physical geologic barrier or physical space geographic
Geographic isolation results from the physical distance separating the groups
Most speciation is allopatric

Question 4

Allopatric examples

Answer 4

Isthmus breaks island forms
Mountain ranges form
Lakes dry up or reced
Canyons form
Separate squirrel species on north and south sides of the Grand Canyon

Question 5

Sympatric speciation

Answer 5

Speciation occurs without physical separation from parental population. Occurs in the midst of.
Offspring with a differing number of chromosomes are reproductively isolated from parent population. Self fertilization may occur.
Happens in plants

Question 6

Polyploidy

Answer 6

Extra set of chromosomes due to mistake in meiosis

Question 7

Polyploidy example

Answer 7

Bread wheat is a polyploidy of wild wheat

Question 8

Autopolyploid

Answer 8

Polyploid can self fertilize but can’t interbreed with parent species