Recommended
More Related Content
What's hot
What's hot (20)
Similar to Sexual behavior (sexual asymmetry & sexual dimorphism)
Similar to Sexual behavior (sexual asymmetry & sexual dimorphism) (20)
More from Surjya Kumar Saikia
More from Surjya Kumar Saikia (20)
Recently uploaded
Recently uploaded (20)
Sexual behavior (sexual asymmetry & sexual dimorphism)
- 1. (Asymmetry of sex/Sexual dimorphism) Dr. Surjya Kumar Saikia Department of Zoology Visva-Bharati SEXUAL BEHAVIOR
- 2. Learning objectives ■ Understand basic biological reasons of delivering sexual behavior in animals. ■ Describe variations in animals mating.
- 3. Animal Behavior and Evolution • If behaviors increase fitness, they are likely to become more common over time • If they decrease fitness, they are likely to become less common
- 4. Reproductive Strategy Reproductive strategies are structural, functional and behavioral adaptations that improve the chances of fertilization and/or increase the survival rate Simply, it refers to the way an animal mates and/or raises offspring
- 5. Reproductive strategies lead to reproductive success, a key way for survival of the population Mate selection Reproductive Strategy Animal Behavior
- 6. Fundamental asymmetry 2 consequences Because eggs are expensive, females produce relatively few young over lifetime. Fitness limited by access to resources Sperm is inexpensive, so males can go for limitless offspring. Fitness limited by the number of females it can mate with
- 7. Many strategies for mate selection Sexual selection necessary : Better Mate choice Monogamy Polygyny Polyandry Promiscuity
- 8. Whom to select? How to select?
- 9. BIRDS: A TOOL OF STUDY FOR SEXUAL SELECTION Plumage
- 10. Pxfuel.com crushpixel.com pixabay.com Pxfuel.com Blue bird Famingo Pxhere.com Famingo Violet Necked Lory Wikimedia commons
- 18. BIRDS: A TOOL OF STUDY FOR SEXUAL SELECTION Song Pixy.org
- 19. Fisher’s runaway model Fitness Tail length Total male fitness (survival + mating) Fitness due to survival Survival Selection Sexual Selection Female choice adaptive for survival Ronald Fisher Mate choice originally evolved to facilitate adaptive choice for traits conferring a survival advantage
- 20. On what factors do female birds base their choice of mates? • Males with bright plumage or beaks. This feature appears due to ingestion of carotenoids beak color = honest signal of health Some Clues
- 21. (1)Mating system: Polygynous species are more sexually dimorphic than monogamous species. However, few species are highly polygynous and male-male competition is difficult to investigate in nocturnal primates. (2) Larger species are more sexually dimorphic than smaller species. (3) Terrestrial species tend to be more sexually dimorphic than arboreal species. Factors related to sexual dimorphism
- 22. What we have learnt… Mate selection is the best and essential reproductive strategy for survival. The first asymmetry is the sexual dimorphism between male and female. Such dimorphism helps in selecting mate for successful reproduction. There are a large numbers of dimorphism takes place among animals. Fisher’s runaway model explains why some animals maintain attractive but morphologically challengeable features increasing sexual differences.