1. One last time: haplodiploidy reproduction 0.5 of genome from dad X 1.0 = 0.5 0.5 of genome from mom X 0.5 = 0.25 + r = 0.75 Leafcutter ant queen + workers Male leafcutter ant

2. SEXUAL SELECTION A type of natural selection that acts differently on males and females of the same species Traits that increase mating success are selected for Pheasants

3. SEXUAL SELECTION Damselflies

4. SEXUAL SELECTION Elephant seals Sexual dimorphism: male and female have different forms

5. SEXUAL SELECTION Why aren’t all species dimorphic?

7. SEXUAL SELECTION Dimorphism arises from competition for mates Males produce sperm: cheap Females produce eggs: expensive # mates # kids BATEMAN PRINCIPLE

8. The sex that invests most in reproduction is a limiting resource that opposite sex competes for Female is usually limiting sex (expecially in mammals), but not always

9. SEXUAL SELECTION Role reversal Greater Painted Snipe

10. SEXUAL SELECTION Which is the limiting sex? Pipefish Seahorse Sea dragon

11. SEXUAL SELECTION Parental care Male may be needed to care for young

12. SEXUAL SELECTION Sage grousePeacock

13. SEXUAL SELECTION 1. Runaway selection: trait initially useful for survival is exaggerated by sexual selection Long-tailed Widowbird

14. SEXUAL SELECTION 1. Runaway selection: trait initially useful for survival is exaggerated by sexual selection

15. SEXUAL SELECTION 2. Handicap principle: ornaments show that males are high-quality Ornaments expensive to produce, only males in good condition can have them Ornamental males less likely to have disease

16. SEXUAL SELECTION Satin bowerbird

17. OPTIMIZING FITNESS Natural selection should favor strategies that lead to higher fitness Every trait has costs and benefits

18. OPTIMIZING FITNESS Gulls “mob” predators that approach nest sites

19. OPTIMIZING FITNESS How daring should the gull be? Distance from predator (m) 1231.52.53.50.5 Units of Fitness Cost of action Benefits of action Daring mobber Cautious mobber

20. OPTIMIZING FITNESS Optimal strategy: Benefits - Costs = Maximum Natural selection should favor optimal strategy

21. GENE FLOW the movement of genes from one population to another “Hide” allele “Run” allele

22. TYPES OF SELECTION 1. Directional Trait Frequency Evolutionary change 2. Stabilizing Most common: maintains status quo 3. Disruptive Speciation

23. DIRECTIONAL SELECTION Darwin’s finches Severe drought 1976-1977 Killed plants with small seeds: birds with larger beaks survived better Geospiza fortis 10.5 mm11 mm Boag and Grant 1981

24. STABILIZING SELECTION Human birth weight Extreme light weight and extreme heavy weight both selected against 8 lbs

25. DISRUPTIVE SELECTION Three-spined sticklebacks Dolph Schluter benthic limnetic Descended from common ancestor Selection favored large fish near shore and small fish in open water Assortative mating led to speciation Assortative mating: Like mates with like; non- random mating