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Interactions between sperm and the female reproductive tract (FRT) are critical to reproductive success and yet are poorly understood. Because sperm complete their functional maturation within the FRT, the life history of sperm is likely to include a molecular “hand-off” from males to females. Although such intersexual molecular continuity is likely to be widespread among all internally fertilizing species, the identity and extent of female contributions are largely unknown. We combined semiquantitative proteomics with sex-specific isotopic labeling to catalog the posttesticular life history of the sperm proteome and determine the extent of molecular continuity between male and FRTs. We show that the Drosophila melanogaster sperm proteome undergoes substantial compositional changes after being transferred to the FRT. Multiple seminal fluid proteins initially associate with sperm, but most become undetectable after sperm are stored. Female-derived proteins also begin to associate with sperm immediately after mating, and they comprise nearly 20% of the postmating sperm proteome following 4 d of storage in the FRT. Female-derived proteins that associate with sperm are enriched for processes associated with energy metabolism, suggesting that female contributions support sperm viability during the prolonged period between copulation and fertilization. Our research provides a comprehensive characterization of sperm proteome dynamics and expands our understanding of the critical process of sperm–FRT interactions. 

Evolution explains both the unity and the diversity of all organisms, and developing students' ability to represent and communicate evolutionary relationships is an important component of a complete biology education. We present a series of student-centered, exploratory activities to help students develop their tree-thinking skills. In these activities, students use complementary phenotypic and molecular data to explore how to build phylogenetic trees and interpret the evolutionary relationships they represent. This learning module is designed to engage students in the process of science, provide them with active learning experiences using online bioinformatics tools, and foster their appreciation for the evolutionary connections across the tree of life.