Meeting Abstract
For species with internal fertilization, the complex interactions between the female reproductive tract (FRT) and male ejaculate(s) are critical to fertility, influence intraspecific variation in reproductive outcomes, and contribute to reproductive barriers between species. In contrast to the extensively studied male traits of sperm and seminal fluid proteins, the FRT, and particularly the molecular relationships among the discrete tissues within this system, remains poorly characterized. In order to develop a more complete understanding of FRT contributions to ejaculate-female interactions, we have taken a systems-level approach to characterize the spatio-temporal transcriptome of the Drosophila melanogaster FRT. The FRT is composed of 5 tissues which have a combination of distinct and redundant functions such as ejaculate processing, sperm storage, ovulation, and oviposition. We identified gene expression signatures that distinguish the FRT tissues and provide molecular support for their specific physiologies and functions. We further found that genes with tissue-specific expression and secretion signal annotation were more rapidly evolving. The characteristics of these genes resemble those found in accessory gland proteins of male seminal fluid and thus are likely candidates for their female counterparts. We also examined the expression of sex-biased genes within the FRT. Although we did find support for a small number of somatic reproductive female-biased genes unexpectedly, the greater trend was for FRT enriched genes to be male-biased. We hypothesize that this expression pattern is indicative of a molecular and biochemical continuity between the male and female reproductive environments.
