Chapter 16 Evolution of Populations Section 16-3 The Process of Speciation 16-3 The Process of Speciation Speciation The Formation of New Species Species A Group of Organisms That Breed With One Another And Produce Fertile Offspring Individuals In The Same Species Share A Common Gene Pool
Section 16-3The Process of Speciation
As New Species Evolve, Populations Become More Reproductively Isolated From Each Other
Can Occur Through:
Two or More Populations Are Capable of Interbreeding But Don’t Due To:
Populations May Share Overlapping Territories
Each Species Has Separate Mating Song
Populations Are Separated By Geographic Barriers e.g.
Bodies of Water
Two Or More Species Reproduce At Separate Times
Grants Realized Darwin’s Hypothesis Relied On Two Testable Assumptions:
On A Single Island Grant’s Mapped:
Wing, Leg, Beak Length
Beak Depth & Color
They Verified Genetic Variation
The Grant's studied finches on Daphne Major, a small island (800 sq. yd)
In 1977 island had only 2mm of rain instead of normal 130mm...
The drought resulted in a loss of 84% of medium ground finch population.
Most died of starvation!
They Were Able To Document Several Incidences of Rapid Evolution On Daphne Major Over Several Decades
Speciation In The Galapagos Finches Occurred By Founding Of A New Population, Geographic Isolation, Changes In The New Populations Gene Pool, Reproductive Isolation, And Ecological Competition
A & B Don’t Mate