title: Co-option of alternate sperm activation programs in the evolution of self-fertile nematodes.
abstract: Self-fertility evolved independently in three species of Caenorhabditis, yet the underlying genetic changes remain unclear. This transition required that XX animals acquire the ability to produce sperm and then signal those sperm to activate and fertilise oocytes. Here, we show that all genes that regulate sperm activation in C. elegans are conserved throughout the genus, even in male/female species. By using gene editing, we show that C. elegans and C. briggsae hermaphrodites use the SPE-8 tyrosine kinase pathway to activate sperm, whereas C. tropicalis hermaphrodites use a TRY-5 serine protease pathway. Finally, our analysis of double mutants shows that these pathways were redundant in ancestral males. Thus, newly evolving hermaphrodites became self-fertile by co-opting either of the two redundant male programs. The existence of these alternatives helps explain the frequent origin of self-fertility in nematode lineages. This work also demonstrates that the new genome-editing techniques allow unprecedented power and precision in evolutionary studies.
authors.affiliation: Graduate School of Biomedical Sciences, Rowan University SOM, B303 Science Center, 2 Medical Center Drive, Stratford, New Jersey 08084, USA.
authors.forename: Qing
authors.initials: Q
authors.lastname: Wei
authors.affiliation: 1] Department of Molecular Biology, Rowan University SOM, B303 Science Center, 2 Medical Center Drive, Stratford, New Jersey 08084, USA [2] Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Yanmei
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: 1] Department of Molecular Biology, Rowan University SOM, B303 Science Center, 2 Medical Center Drive, Stratford, New Jersey 08084, USA [2] Syracuse University, 107 College Place, Syracuse, New York 13244, USA.
authors.forename: Yiqing
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Graduate School of Biomedical Sciences, Rowan University SOM, B303 Science Center, 2 Medical Center Drive, Stratford, New Jersey 08084, USA.
authors.forename: Julie
authors.initials: J
authors.lastname: Stomel
authors.affiliation: Graduate School of Biomedical Sciences, Rowan University SOM, B303 Science Center, 2 Medical Center Drive, Stratford, New Jersey 08084, USA.
authors.forename: Ryan
authors.initials: R
authors.lastname: Stires
authors.affiliation: 1] Graduate School of Biomedical Sciences, Rowan University SOM, B303 Science Center, 2 Medical Center Drive, Stratford, New Jersey 08084, USA [2] Department of Molecular Biology, Rowan University SOM, B303 Science Center, 2 Medical Center Drive, Stratford, New Jersey 08084, USA.
authors.forename: Ronald E
authors.initials: RE
authors.lastname: Ellis
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002107:Caenorhabditis / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism; D005260:Female; D005298:Fertility; D008297:Male; D008969:Molecular Sequence Data; D013094:Spermatozoa / Q000254:growth & development* / Q000378:metabolism
chemical_list: D029742:Caenorhabditis elegans Proteins