While it is known that mutations in DNA are the source of genetic variation in natural populations, it is unclear how changes in genes translate into the diverse forms seen in nature. To address this, the proposed research focuses on a recently evolved unique trait, a reproductive foam produced by male Japanese quail. This study will characterize gene sequences and expression patterns for genes that encode foam proteins. Data will be obtained for multiple tissues from the Japanese quail and related species. The findings will address what types of genetic changes are responsible for unique traits and how genes underlying novel structures evolve.
The Japanese quail is an economically important domesticated poultry species raised globally for meat and eggs. It is important to understand the fertilization biology of poultry to design efficient and effective breeding programs. When foam is added to semen, it extends the life of sperm and simulates natural fertility levels. Characterizing foam genes will increase our knowledge of the fertilization biology of quail, provide targets for selection of more fertile males, and provide insight into improving sperm function across other poultry species. Additionally, understanding the evolution of reproductive proteins may inform us about the causes of infertility.
The earth’s biota is characterized by incredible diversity of form and function. While it is known that mutations in DNA are the ultimate source of variation among organisms, it is unclear how changes in DNA translate into the diverse forms seen in nature. To address this issue, our research focused on a recently evolved novel trait—a reproductive foam produced by the foam gland of male Japanese quail. This project’s specific objectives were to investigate 1) what types of genetic changes are responsible for novel traits and 2) how genes underlying novel structures evolve. To this end, we sequenced all of the genes expressed by the foam gland and used modern molecular techniques to identify which of those genes make proteins found in the foam. We then investigated the rate at which foam genes evolve and evaluated how these genes change in expression (i.e., amount of product produced) when males do and do not produce foam. We found that 1) the novel foam is comprised largely of proteins encoded by genes that also have other functions, but includes a small number of proteins encoded by "new" genes, 2) foam genes evolve more rapidly than other kinds of genes, and 3) changes in the expression levels of both ancestral and new genes are important to producing foam. Our results suggest that novel traits arise via multiple pathways including changes in protein sequence and gene expression levels, reuse of ancestral genes, and generation of new genes. This project has potential practical implications. The Japanese quail is an important domesticated poultry species, raised globally for both meat and eggs. Of all poultry, quail sperm have the shortest lifespan following artificial insemination. Therefore, breeders attempt to find ways to increase male fertility. When foam is added to the semen, it extends the life of sperm and effectively simulates natural fertility levels. By characterizing foam proteins, we identify proteins that may improve quail sperm lifespan, knowledge which may be useful to breeders as they attempt to improve fertility.
