- Research Associate, Molecular Biology and Genetics (MBG), College of Agriculture and Life Sciences (CALS)
Quantitative genetics of Drosophila sperm competition
Sexual reproduction is a unique phenomenon in which males and females can have differing interests. It is to the male’s advantage to sire as many offspring as possible, while the female, often limited by gamete number, must choose to invest in a limited number of high quality offspring. In many species, males compete with each other via a process known as sperm competition. Two or more males will mate with a single female and the proportion of offspring each male sires defines his sperm competitive ability. This, however, is not a female-passive event. It is thought that females play an active role in preferentially using certain sperm over others (aka cryptic female choice).
Sperm competition is facilitated by both sperm and proteins that are transferred from the male to the female. Accessory proteins (ACPs) are transferred with the seminal fluid and can induce many physiological and behavioral changes in the female, including increase in egg production, ovulation and oviposition, increased feeding, changes in the reproductive tract, and reduced receptivity to remating. Indeed, some ACPs can also be toxic to females. However, all these effects occur within the female and there are ‘receptors’ and molecular pathways that have to be receptive to these proteins.
With such intricate male x female interactions, sexual conflict is expected to be a driving force of male and female evolution. This means that evolution may not be able to optimize functions for either sex and instead maintains a high level of variation. In fact, ACPs and other genes influencing sperm competition have high levels of variation and positive selection.
I am investigating three aspects of this complex system in drosophila melanogaster:
1) Quantifying male x female interactions in natural isolates of Drosophila. How do these interactions vary within geographic populations and between these populations?
2) Identifying functional interaction of natural female variation with male ACP knockdowns. Identifying new interactions and genes that may facilitate a female’s response
3) Identifying functional interaction of natural male variation with female response gene knockdowns. Identifying new interactions and genes that may allow a male to bypass certain female responses.
While the Clark and Wolfner labs have extensively studied the genetic architecture of male and female components of sperm competition, little is known about the interaction between male and female genotypes. My work seeks to shed light on the genetic interactions between males and females.
Human population genetics:
I will be working on analyzing various aspects of the 1000 genomes project. More to come....
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