1. Sexual Selection and Dimorphism
Characteristics evolve because they have been passed from one generation to the next via the genes
This requires the organism:
To live to reproductive age
To mate successfully
To ensure the offspring’s survival

2. Natural & Sexual Selection
Natural selection
Ability to survive in a particular environment (fitness)
Sexual selection
Ability to attract/find a mate and reproduce successfully
These are separate processes – the characteristics that facilitate reproduction do not necessarily increase survival chances

3. Sexual Dimorphism
Male
Female

4. Sexual Dimorphism
Male
Female

5. Sexual Dimorphism
Male
Female

6. Sexual Dimorphism

7. Sexual Dimorphism
In many species, males have characteristics (e.g. brighter colouration, exaggerated tails) that serve to attract females
Suggests that males are competing for the attention of females
Suggests that, in many species, females do the choosing