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World's Deadliest - Elephant Seal vs. Elephant Seal

Example of Intrasexual Selection Retrieved from:https://www.youtube.com/watch?v=RVJduMnXAns


Natural Selection & Sexual Selection An Illustrated Introduction

Further explanation of sexual selection definitions.

Intrasexual Selection[]

Members of the same sex (of the same species) compete, fight or engage in combat with one another over the opportunity to mate with a female. 

As Darwin explains it "not on a struggle for existence, but on a struggle between the males for possession of the females" 

Intrasexual selection describes a situation in which


Amazing! Bird sounds from the lyre bird - David Attenborough - BBC wildlife-0

Example of Intersexual selection demonstrated by the lyre bird. Retrieved from http://www.youtube.com/watch?v=VjE0Kdfos4Y

reproductive success hinges on the actions of a single sex (Freeman & Herron, 2007).

Intersexual Selection[]

Simply put, females choice. When the females chooses the best mate based on display or ornaments. Intersexual selection describes situations in which reproductive success is dependent on interplay between both sexes (Freemon & Herron, 2007).


Freeman, S. Herron, J. (2007). Evolutionary Analysis (4th  ed.). San Francisco, CA: Pearson Benjamin Cummings.