Abstract
Cryptic female choice and sperm competition cooperate with each other could result in conspecific sperm precedence (CSP). While the premating isolation between two sympatric populations is not complete, CPS is important to maintain species as distinct entities. Most of previous experimental designs are focus on genetic variations among males contributing to the consequence of sperm competition. However, because the arena of sperm competition is within the female reproductive tract, thus the cryptic female choice determines the fate of sperm. How does the cryptic female choice dictate the rules of sperm competition? What are the underlying genes? In order to investigate the genetic basis of cryptic female choice and its role in conspecific sperm precedence, I perform quantitative trait loci analysis between Drosophila simulans and D. mauritiana. Two significant QTLs on X chromosome are detected that associated with BC1 (backcross generation one) female fecundity and may involve hybrid female sterility genes. One significant and one marginal significant QTLs on third chromosome are associated with cryptic female choice. Focusing on genes within these two intervals might be a good first step in approaching the basis of cryptic female choice. Potential candidate linked to the intervals may be olfactory receptors. Olfactory receptor may express on the sperm, ovary and/or female reproductive tract that could response to chemicals and/or hormones and allow female to bias the paternity. By comparing previous genetic studies, it also indicates the overlapping between QTLs of male traits and female mate choice. Linkage disequilibrium between male traits and female mate choice and female mate choice driven by postcopulatory process will be an interesting topic and could be further revealed in the two QTLs on the third chromosome.