Genetic flexibility in the convergent evolution of hermaphroditism in Caenorhabditis nematodes.
The self-fertile hermaphrodites of C. elegans and C. briggsae evolved from female ancestors by acquiring limited spermatogenesis. Initiation of C. elegans hermaphrodite spermatogenesis requires germline translational repression of the female-promoting gene tra-2, which allows derepression of the three male-promoting fem genes. Cessation of hermaphrodite spermatogenesis requires fem-3 translational repression. We show that C. briggsae requires neither fem-2 nor fem-3 for hermaphrodite development, and that XO Cb-fem-2/3 animals are transformed into hermaphrodites, not females as in C. elegans. Exhaustive screens for Cb-tra-2 suppressors identified another 75 fem-like mutants, but all are self-fertile hermaphrodites rather than females. Control of hermaphrodite spermatogenesis therefore acts downstream of the fem genes in C. briggsae. The outwardly similar hermaphrodites of C. elegans and C. briggsae thus achieve self-fertility via intervention at different points in the core sex determination pathway. These findings are consistent with convergent evolution of hermaphroditism, which is marked by considerable developmental genetic flexibility.
Hill
Robin Cook
RC
Department of Biology, University of Maryland, College Park, 20742, USA.
de Carvalho
Carlos Egydio
CE
Salogiannis
John
J
Schlager
Benjamin
B
Pilgrim
Dave
D
Haag
Eric S
ES
D000818:Animals; D002107:Caenorhabditis / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics; D002478:Cells, Cultured; D012734:Disorders of Sex Development / Q000235:genetics*; D019143:Evolution, Molecular; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D009154:Mutation; D010749:Phosphoprotein Phosphatases / Q000235:genetics; D011110:Polymorphism, Genetic; D000071636:Protein Phosphatase 2C; D013045:Species Specificity; D013091:Spermatogenesis / Q000235:genetics
D029742:Caenorhabditis elegans Proteins; C075059:fem-3 protein, C elegans; C097435:Fem-2 protein, C elegans; D010749:Phosphoprotein Phosphatases; D000071636:Protein Phosphatase 2C