1. Evolution and Natural Selection

2. Testable Hypotheses Use if…then… logic Collect data
Reject the null hypothesis
Support the hypothesis
Devise another test, and another, and another!
Proximate: overexpress avpr1a gene in polygynous males
Ultimate: Allow females to select mates, find they would choose more than 1

3. Charles Darwin, 1859, The Origin of the Species

4. Darwinian Theory Evolutionary change is inevitable if:
Variation exists, such that members of a species differ in some of their characteristics
Heredity exists, such that parents are able to pass on some of their distinctive characteristics to their offspring
There are differences in reproductive success, such that some individuals have more surviving offspring than others in their population, thanks to their distinctive characteristics.

5. Natural Selection
Relies on transmission of genes, small segments of DNA that encode proteins: heredity
Genes exist in more than one form, or allele, giving rise to variation
If a given allele allows for greater reproductive success, it will be passed on to more offspring, and eventually become more common in the population

8. Prairie Vole AVPR1a gene polymorphisms

9. Discussion Question
If you wanted to invent the term “genetic success” for use in evolutionary studies based on natural selection theory, what would your definition be?

10. Natural selection in the lab: Carol Lynch
Natural selection in the lab: Carol Lynch. how much cotton mice collect to make their nests is a natural variation in the population. In each generation, big nesters were bred with big nesters, and so on.

11. Rapid Evolution of beak size

12. Infanticide
Understanding the evolution of puzzling, seemingly maladaptive behaviors.
Form groups of a male, several females, and their offspring. Males exchange groups with disastrous consequences.

13. Infanticide
1. Leave the mothers no option but to mate with the killer male-Darwinian theory
With no infant, the mother resumes cycling sooner, become impregnated sooner, more babies with killer male
2. Social pathology due to overcrowding
Maladaptive, aggressive behavior by males
3. Population regulation
Adaptive killing preserves food supplies, other resources
Three hypotheses

14. Group Selection
Groups that lacked the ability to keep the population in harmony with the available resources went extinct, while those with infanticidal males were able to balance and thus persist.
Beneficiary of group selection is not the male himself, but the entire group.
Selection acting on individual differences usually has a stronger effect than group selection
Proposed by V.C. Wynne-Edwards in Generally acknowledged, but natural selection is preferred theory. George C. Williams’ Adaptation and Natural Selection in 1966 challenged Wynne-Edwards’ theory.

15. Discussion Question
Lemmings: Many leave their homes and travel during conditions of population crowding, often dying in streams and lakes. One hypothesis states that the lemmings are committing suicide, so that those remaining can use the limited resources and survive to prevent extinction of the species.
What theory was used to propose this hyothesis? How could you test it? (See next)