The key difference between intrasexual and intersexual selection is that intrasexual selection refers to sexual selection within the members of the same sex to access mates while intersexual selection refers to sexual selection which occurs between two sexes when members of one sex choose the members of the opposite sex.
Sexual selection is a mode of natural selection which determines mating pairs and the genes passing to offspring. Intersexual selection and intrasexual selection are two different types of sexual selection. Intersexual selection is an interaction between two sexes where the members of one sex choose the members of the opposite sex. In contrast, the intrasexual selection is the competition between members of the same sex to access mates.
CONTENTS
1. Overview and Key Difference
2. What is Intrasexual Selection
3. What is Intersexual Selection
4. Similarities Between Intrasexual and Intersexual Selection
5. Side by Side Comparison – Intrasexual vs Intersexual Selection in Tabular Form
6. Summary
What is Intrasexual Selection?
Intrasexual selection is the sexual selection that occurs between the members of the same sex to access mates. It usually involves competition between males to mate with females.
Figure 01: Intrasexual Selection
The competition seen in male primates is a form of intrasexual selection. A strong large, aggressive male primate tries to keep other male primates away from the females so that he can be their primary mate. This male primate can mate and pass its genetic material to the offspring. Moreover, male deers and horned beetles fight with the members of their same sex for mating with females nearby. This mode of sexual selection ensures the getting of good genetic material to offspring. Therefore, it is a mode of natural selection.
What is Intersexual Selection?
Intersexual selection is the sexual selection that occurs between two sexes. In other words, the intersexual selection is the sexual selection that occurs when the members of one sex (usually females) choose members of the opposite sex. Therefore, the intersexual selection is a result of interactions between males and females. One sex, especially males, shows traits or behavioural patterns to attract the opposite sex (females).
Figure 02: Intersexual Selection
For example, peahens choose peacocks with brightly coloured tails in order to reproduce or mate. The trait of the brightly coloured tail is thus passed to the next generation as a result of females mating with male peacocks having brightly coloured tails. However, there is no physical competition between peacocks with brightly coloured tails and other male peacocks. Several other examples of intersexual selection include plumage on birds, mating calls of frogs, and courtship displays in fish.
What are the Similarities Between Intrasexual and Intersexual Selection?
- Intrasexual and intersexual selection are two types of sexual selection.
- Both types of sexual selection pass good genes to the next generation.
- Both intersexual and intrasexual selection influence the development of sexually selected traits in numerous species.
What is the Difference Between Intrasexual and Intersexual Selection?
Intrasexual selection is a major type of sexual selection in which the completion between the members of the same sex occurs when selecting mates. In contrast, the intersexual selection is a type of sexual selection which occurs between sexes as a result of interactions between males and females. So, this is the key difference between intrasexual and intersexual selection. Furthermore, in the intrasexual selection, males fight with other males and chase them away from the site while in the intersexual selection, males show traits and behavioural patterns to attract females.
Below tabulation summarizes the differences between intrasexual and intersexual selection.
Summary – Intrasexual vs Intersexual Selection
Sexual selection is the selection pressure on males and females to choose mates. There are two types of selection as intrasexual selection and intersexual selection. Intrasexual selection is the sexual selection within the same sex. In contrast, the intersexual selection is the sexual selection between sexes. Thus, this is the key difference between intrasexual and intersexual selection. Intersexual selection is a result of interactions between males and females. Intrasexual selection is a result of competition between the members of the same sex.
Reference:
1. Scheyd, Glenn. “Intrasexual Selection.” SpringerLink, Springer, Cham, 1 Jan. 1970, Available here.
Image Courtesy:
1. “Sheep, rams, headbutt, animals, nature, competition, males, countryside, battle, outdoors, wildlife” (CC0) via Pikist
2. “Peacock Bird Feather Free Photo” (CC0) via Needpix