Summary
Competition between sperm from different males to fertilise eggs, shaping anatomy and behaviour.
In depth
Strategies: mate guarding, copulatory plugs, large testes and sperm displacement. Chimpanzees have relatively large testes compared with gorillas.
When females mate with several males, selection acts on sperm number, speed, plugging and seminal fluid effects. Species with high promiscuity tend to have larger testes relative to body size.
Example: certain insect males transfer protective nuptial gifts alongside sperm.
Sperm competition occurs when sperm of two or more males compete to fertilise a female's eggs, a result of females mating with multiple males. It selects for large testes, high sperm numbers, sperm removal structures and mate guarding.
Damselfly males scoop out rival sperm; some insects add mating plugs; sperm form varies, with cooperative sperm groups in some mice. Females can bias paternity through cryptic choice.
Example: in chimpanzees, a promiscuous species, males have much larger testes for body size than gorillas, which have harems.
Remember: competition continues after mating, selecting traits that act inside the female tract.
Frequently asked questions
What is Sperm Competition?
Competition between sperm from different males to fertilise eggs, shaping anatomy and behaviour.
Which area of biology covers Sperm Competition, and how advanced is it?
Sperm Competition is one of the 53 topics in Animal Behaviour. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Sexual Conflict, Courtship, Parental Investment.
Can you give an example of Sperm Competition?
Some damselflies remove rival sperm with their penis.
What should I learn before Sperm Competition?
Work through the Beginner topics in Animal Behaviour first, such as Animal Behaviour, Innate Behaviour, Learned Behaviour, then return to Sperm Competition. Advanced topics assume the Intermediate vocabulary.
What topics are related to Sperm Competition?
The closest topics to Sperm Competition are Sexual Conflict, Courtship, Parental Investment, Animal Personality. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Sperm Competition?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Sperm Competition. To practise the whole of Animal Behaviour, use the Animal Behaviour quiz.
How is Sperm Competition different from Sexual Conflict?
Sperm Competition: Competition between sperm from different males to fertilise eggs, shaping anatomy and behaviour. Sexual Conflict: Differences in the evolutionary interests of males and females drive arms races in mating traits. Read both side by side and note what each one explains.
How should I study Sperm Competition step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Sexual Conflict and explain the difference aloud. Finally, take the Animal Behaviour quiz and come back to this page for any question you miss.