The Process of Speciation Chapter 16-3 The Process of Speciation

Introduction Speciation is the formation of new species Different species can not interbreed to produce FERTILE offspring. Individuals in different species have a different gene pool.

Reproductive isolation: the inability of a species to breed successfully with related species due to geographical, behavioral, or time of reproduction differences. Populations must be reproductively isolated from each other for a new species to evolve.

Three ways that reproductive isolation occurs. 1. Behavioral isolation 2. Temporal isolation 3. Geographic isolation

Behavioral isolation occurs when populations are capable of interbreeding BUT have differences in courtship rituals or other types of behavior.

Example: Eastern and Western meadowlarks -Their regions overlap -They can interbreed but do not -Different courtship rituals (attracted by different songs)

Geographic isolation - can occur when populations are separated by geographic barriers such as rivers, mountains, or bodies of water. Example: -The Kaibab squirrel evolved from the Abert squirrel when it was isolated from the main population by the Colorado River. Abert Kaibab

Temporal Isolation Occurs when two or more species reproduce at different times of the year. Example: three similar species of orchid in the same rain forest releases pollen on different times of the year.

Testing Natural Selection in Nature How could differences in beak size lead to reproductive isolation? Birds with the same beak size prefer to mate with each other. Since, big-beaked and smaller-beaked birds would not choose to mate with each other, their gene pools would remain isolated.

Studying Evolution Since Darwin Why is the study of evolution important in the scientific world? By understanding evolutionary theory, we have been able to respond to changes in the living world in ways that have improved human life. Ex. Bacteria resistance to antibiotics