Meiotic drive in Drosophila subobscura
I am trying to understand the population dynamics of the selfish X chromosome SRS in the European fruit fly Drosophila subobscura, with my PhD student Rudi Verspoor, and my postdoc Sarah Forrester. In Tunisian populations about 20% of flies carry a driving X chromosome called SRS. Normal X chromosomes are passed on to half a male’s offspring, while the other halfinherits his Y chromosome. But when males carry the SRS chromosome all their Y bearing sperm die and all their offspring inherit the SRS X chromosome. This allows the SRS chromosome to spread as it is passed on to more offspring that the normal X, but it also causes male carriers to only have daughters, and to produce less sperm than normal males. This can cause populations to mostly consist of females, and potentially could wipe entire populations out due to a total lack of males. Work in related species has shown that if females mate with multiple males the small amounts of sperm produced by carrier males is usually swamped by the large amounts of sperm transferred by normal males, and the driving X cannot spread. But in D. subobscura, SRS is only found in the Southern populations where females remate, and is never found in the Northern populations where females mate once. It’s a bit of a mystery.
I am trying to understand the molecular and genetic basis of the drive mechanism in this species, and releted ones. Ultimately, if we can understand sex chromosome drive, we might be able to use it to control pest species, or to modify the sex ratio of important agricultural animals. But our understanding of how these mechanisms work, how they evolve, and how they persist, is still at a very early stage.
My research involves a lot of work in the flylab, often watching flies mating (as those two Drosophila pseudoobscura are)
Polyandry in Drosophila pseudoobscura
I collaborate with Michelle Taylor and Nina Wedell (at the University of Exeter) to try to understand the reasons for variation in remating rate by females in the Northern American fruit fly Drosophila pseudoobscura. Females of some species only mate once in their lives, while others may mate with hundreds of males. This can have huge consequences for everything from their physiology and behaviour, to how their social systems are arranged and their population dynamics. But despite decades of research and plentiful between-species variation, we still don’t really understand why these differences have evolved. Fortunately Drosophila pseudoobscura is pretty easy to work with, and females vary in their propensity to remate. We have been observing and collect flies in nature to find out how they live, and are trying to replicate these conditions in the laboratory to work out the circumstances under which females benefit from mating with many males.
Cannibalism in mantids
My new PhD student Adam Fisher and I are trying to understand the ecological consequences of sexual cannibalism in spiders and praying mantises, with help from Stephen Cornell and Greg Holwell. Sexual cannibalism, where females typically eat males after or during mating, is bizarre and fascinating stuff. But no one really knows whether it has consequences for the survival of the cannibalistic species. It might increase population survival, because the eaten male results in more offspring. But it could potentially lead to a severe lack of males in a population, driving that populations towards extinction. We are using experiments and mathematical models to try to understand all this.
(image from mantisonline)
Masturbation in birds
I am working with Chloe Heys and Kevin Arbuckle here at Liverpool to try to understand why there seems to be such a lot of variation in masturbation between different species of birds. We are interested in whether masturbation is adaptive, or whether it is an unimportant side effect of sex. Does it correlate with mating system, social system or intelligence? Although there is a lot of data on masturbation in mammals, there is very little information on it in birds, despite the huge numbers of youtube videos of masturbating parrots. We are currently trying to compile data from zoos, aviaries, and scientists around the world in an effort to get a picture of how birds masturbate, so that eventually we can work out why they do it too. Please check out the Masturbation in Birds page for more information.