Bio 107 General Ecology

1. Evolution and Behavior of
Species

2. Natural Selection
• Backbone of Darwin’s Theory of Evolution
• Drives evolution
• is the process by which organisms best adapted to their
environment survive and those less adapted are
eliminated.
• The nonrandom differential reproduction of genotypes
with selective forces in the environment.

3. Four components of natural selection :
• Variation
• Inheritance
• High rate of population growth.
• Differential survival and reproduction.

4. 2 processes involved in Evolution
• Adaptation
– traits that confer an advantage to those individuals who leave
more offspring
• Speciation
– The smallest independently evolving unit.

6. SPECIATION
• Occurs when gene flow
within the common gene
pool is interrupted by an
isolating mechanisms.

7. Biological species concept
• defines a species as members of populations that actually
or potentially interbreed in nature, not according to
similarity of appearance.

8. Speciation
http://scienceblogs.com/evolvingthoughts/2007/03/11/basic-concepts-allopatry-and-s/

10. Sympatric Speciation
• Industrial Melanism

11. Main Features of Speciation
1. Reduced selection pressure
2. Isolation of subpopulation of the species so that
interbreeding with the main stock is prevented or at least
reduced.
3. The development of distinctive genotypes in
subpopulation as a result of some combination of
founder effect, drift and natural selections.

12. 4. Reuniting of subspecies group with the parental stock but
without the resumption of interbreeding.
5. Intense competition between the two reunited groups so
that further divergence in the traits is hastened.

13. Domestication

14. Extinction

15. Causes of Extinction: Habitat Alteration

16. Hunting

17. Predator control

19. Mutation

20. Immigration

21. Individual Selection

22. Resource Prediction

23. • gg