Sneaky exploitation in nature

In my last post I talked about females selecting certain traits in males. In these cases, the males developed a trait and the females in turn selected for it.

Well there’s actually a very controversial theory being debated in the literature that says females evolve their preferences in mates first, and then males evolve their mating display afterwards. How is this possible?

Females that are picky might have pre-existing sensory biases

It is hypothesised that this begins with a trait evolving in a non-mating context, and then is in turn exploited by the other sex to receive more mating opportunities (Ryan, M.J. 1998).

For example the female water mite Neumania papillator adopt a posture called the net stance (shown below) in order to catch copepods until it senses the vibrations in the water caused by its prey, and then proceeds to clutch at it (Proctor 1991). The male water mite has evolved to take advantage of this by finding a female (through scent) and creating vibrations in the water, causing the female to instinctively clutch onto him, which is then followed by the male releasing his spermatophores. This is a perfect example of males evolving a courtship technique that exploits the predation technique of females.

  

Sourced from Proctor 1991

Another example is female three spined sticklebacks (Gasterosteus aculeatus), where females have a preference for males with a red throat and jaw. Some have proposed that this has evolved on a runaway basis (Fisherian hypothesis), however others have tested the possibility of it originating in the context of foraging (Smith et al 2004). Red fruits fall into the streams where guppies live. As these fruits are a rare treat, guppies have adapted an ability to find them quickly, and over time developed an affinity for the colour red. Males have then taken advantage of this preference and evolved red colouration to attract mates (Smith et al 2004). Isn’t that cool!?

Red throats in male Three Spined Sticklebacks
Author unknown

If you want to check more of this out, sexual selection through pre-existing sensory biases is also evident in auklets, wolf spiders and manakins.

References 

• Smith, C. Barber, I. Wootton, R.J. & Chittka, L. 2004, ‘A receiver bias in the origin of three-spined stickleback mate choice,’ The Royal Society, no. 271, pp. 949–955
• Proctor, H.C. 1991, ‘Courtship in the water mite Neumania papillator: males capitalize on female adaptations for predation,’ Animal Behaviour, No. 42, pp. 589-598