Friday, February 22, 2013

Bad news guys... size does matter. Well, if you're a Hottentot golden mole, that is.

The Hottentot golden mole (Amblysomus hottentotus) makes its home in sub-Saharan Africa, where it lives in a network of tunnels feeding on earthworms and insect larvae. They are polygamous and the female is able to mate all year round, allowing males and females to reproduce whenever they meet. But given that Hot
tentot moles are blind, how do females determine the quality of a mate?

The evidence suggests they judge him according to his penis length. All Hottentot golden moles have small penises relative to their size (while a male measures between 74-97mm long, its penis will be in the range of 1.2-2.5mm in length). But there is great variation in length between males - much more variation than in other body dimensions - which is a strong sign of sexual selection.

"The basic role of a penis is to put sperm as close to the site of fertilisation as possible, and perhaps to get it as far ahead of sperm of other males as possible," said Bill Bateman (University of Pretoria, South Africa). "Therefore it makes sense for males to invest, in the evolutionary sense, in big or long penises." For example, if a mole is a poor hunter he would not have the energy to invest in growing a long penis, and then female could tell he was not a great candidate for high-quality offspring.

Photo credit: Justin Nicolau.

http://www.bbc.co.uk/nature/21321171

http://www.wired.co.uk/news/archive/2013-02/21/golden-mole-penis-size-matters

http://www.the-scientist.com/?articles.view%2FarticleNo%2F34477%2Ftitle%2FPenis-Size-Matters-for-Golden-Moles%2F
Bad news guys... size does matter. Well, if you're a Hottentot golden mole, that is.

The Hottentot golden mole (Amblysomus hottentotus) makes its home in sub-Saharan Africa, where it lives in a network of tunnels feeding on earthworms and insect larvae. They are polygamous and the female is able to mate all year round, allowing males and females to reproduce whenever they meet. But given that Hottentot moles are blind, how do females determine the quality of a mate?

The evidence suggests they judge him according to his penis length. All Hottentot golden moles have small penises relative to their size (while a male measures between 74-97mm long, its penis will be in the range of 1.2-2.5mm in length). But there is great variation in length between males - much more variation than in other body dimensions - which is a strong sign of sexual selection. 

"The basic role of a penis is to put sperm as close to the site of fertilisation as possible, and perhaps to get it as far ahead of sperm of other males as possible," said Bill Bateman (University of Pretoria, South Africa). "Therefore it makes sense for males to invest, in the evolutionary sense, in big or long penises." For example, if a mole is a poor hunter he would not have the energy to invest in growing a long penis, and then female could tell he was not a great candidate for high-quality offspring. 

Photo credit: Justin Nicolau.

http://www.bbc.co.uk/nature/21321171

http://www.wired.co.uk/news/archive/2013-02/21/golden-mole-penis-size-matters

http://www.the-scientist.com/?articles.view%2FarticleNo%2F34477%2Ftitle%2FPenis-Size-Matters-for-Golden-Moles%2F

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