Darwin's sexual selection theory argues that males compete for females through mechanisms like intra-sexual competition between males or inter-sexual choice by females, resulting in the development of secondary sexual characteristics in males like antlers, songs, or colorful feathers. Examples include the vocal cords in frogs, antlers in deer, songs of male birds, and the colorful feathers of peacocks. However, the theory was criticized for not fully explaining sexual dimorphism and for assuming behaviors like promiscuity that could prevent sexual selection from occurring.

2. DARWIN SEXUAL SELECTION THEORY
Sexual selection “depends not
on the struggle for existence,
but on the struggle between
males for possession of females

3. SALIENT FEATURE OF SEXUAL
SELECTION THEORY
Mechanisms of
sexual selection
Intra-
selection
Inter-selection
Competition
& fight
B/w males
For Female
Secondary sexual
characters
Mostly Develop
in males
Female lack
Male
Competition
Direct
Indirect

4. EXAMPLE OF SEXUAL SELECTION
VOCAL
CORDS IN
FROG
ANTLERS IN
DEERS
SONG
PRODUCED BY
MALE BIRD
COLOURED
FEATHERS
OF PEACOCK

5. DRAWBACKS IN DARWIN SEXUAL
SELECTION THEORY
Does not explain sexual dimorphism.
Natural selection would actually select against sexual
selection.
Promiscuous intercourse will prevent or check the action
of sexual selection
Female choice driving evolution was almost universally
mocked and dismissed