Ordinary Animals and sex: choosing the right partner

The Grant Museum’s current exhibition – The Museum of Ordinary Animals: The Boring Beasts that Changed the World ­­- explores the mundane creatures in our everyday lives. Here on the blog, we will be delving into some of the stories featured in the exhibition with the UCL researchers who helped put it together.

Guest post by Professor Judith Mank (UCL Genetics, Evolution and Environment)

In many animals, females are pickier about choosing their mates than males are, since they invest more in their offspring than males do. By choosing high quality mates, females give their offspring a good chance of inheriting their fathers’ beneficial traits. This will help the young in their own search for mates, thereby increasing the chances that the original female’s genes will be passed down through the generations.

I was involved in a team of researchers at UCL and Stockholm who were studying mate choice, and we chose guppies – a very Ordinary Animal – to investigate why females some often make poor choices about whom to mate with.

We found that the size of their brains had a lot to do with it.

Female guppies with larger brains prefer males with bright orange patterns and long tails. These are traits that have been linked to good foraging ability and health: features a mother would want her young to inherit.

We gave females with large and small brains the opportunity to associate with two males, one more colourful than the other. Females in the wild need to remember what the males they have already met look like to help them decide how attractive they find new individuals by comparison. Therefore in the lab, females could swim around to spend time with either male, but they couldn’t directly compare them, instead having to use their memory to decide which one they preferred.

Females with larger brains showed strong preferences for more colourful males. Smaller-brained females showed no preference. This couldn’t be explained by differences in colour perception, as tests showed that small-brained and large-brained females could perceive and respond to colour equally as well.

This suggests that females use complex cognitive abilities to decide which males to mate with, and that females with larger brains make better mate choice decisions.

It takes brains to choose a good father for your children.

The Museum of Ordinary Animals runs until 22^nd December. A number of events accompany the exhibition: through discussions, a late opening, a comedy night and offsite events discover how boring beasts shape our relationship with the natural world. Full details are on the exhibition’s website.

Judith Mank is Professor of Evolutionary and Comparative Biology at UCL, and contributed to the Museum of Ordinary Animals.

 

References:

Corral-López A, Bloch NI, Kotrschal A, van der Bijl W, Buechel SD, Mank JE, Kolm N (2017) Female brain size affects the assessment of male attractiveness during mate choice. Science Advances 3(3): e1601990. https://doi.org/10.1126/sciadv.1601990