Biology Essay on Sperm Competition

Topics: Reproduction, Sex, Natural selection Pages: 2 (718 words) Published: April 19, 2013
Sperm competition is the physical process of trying to be the first to fertilise a Female’s eggs with you’re sperm. Sperm competition is very common in many evolutionary processes. Many species, like the waterfowl duck species have adapted certain behaviours and morphologies that help to promote their sperm competition and result in their sperm being the most favourable and their genes passed into the gene pool.

Some of the waterfowl species have elaborate morphology that promotes sperm competition. The female has a lot of say in who fathers her young, she can control the length of her vagina and is more likely to pick the male with the best shaped penis, the longest penis or the stiffest. This way she can have the best genes for her offspring. Through co-evolution the female has been able to mirror the shape of the male’s penis with her vagina. The female can control the males sperm content inside of her because of her blind ending pouches and therefore reduces forced copulation. The female ducks have certain behavioural characteristics that indicate they are ready for copulation. Certain muscles in the vagina show signs that they are preparing to mate including relaxing (Patricia L. R. Brennan 2009).

The male gentalia found in waterfowl is very uncommon among birds. (Patricia L. R. Brennan 2009). Fertilisation partners can be influenced by certain bodily functions and structures. The penis is generally located, inverted, in the Phallic sack. When the penis is erect it is still adaptable and is not limited to stiff movements, this is because of the arrangement of the axial orthogonal arrays. Mechanical barriers were tested to see if ejaculation would still continue if the female’s vagina did not mirror penis shape, ejaculation is still possible if the penis is not fully inverted. The penis has a rough texture that contributes to the spiral shaped (Patricia L. R. Brennan 2009). The penis shape, size and inversion are all adaptions resulting from...
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