The Developmental and Genetic Architecture of the Sexually Selected Male Ornament of Swordtails

Manfred Schartl, Susanne Kneitz, Jenny Ormanns, Cornelia Schmidt, Jennifer L. Anderson, Angel Amores, Julian Catchen, Catherine Wilson, Dietmar Geiger, Kang Du, Mateo Garcia-Olazábal, Sudha Sudaram, Christoph Winkler, Rainer Hedrich, Wesley C. Warren, Ronald Walter, Axel Meyer, John H. Postlethwait

Research output: Contribution to journalArticlepeer-review


Sexual selection results in sex-specific characters like the conspicuously pigmented extension of the ventral tip of the caudal fin—the “sword”—in males of several species of Xiphophorus fishes. To uncover the genetic architecture underlying sword formation and to identify genes that are associated with its development, we characterized the sword transcriptional profile and combined it with genetic mapping approaches. Results showed that the male ornament of swordtails develops from a sexually non-dimorphic prepattern of transcription factors in the caudal fin. Among genes that constitute the exclusive sword transcriptome and are located in the genomic region associated with this trait we identify the potassium channel, Kcnh8, as a sword development gene. In addition to its neural function kcnh8 performs a known role in fin growth. These findings indicate that during evolution of swordtails a brain gene has been co-opted for an additional novel function in establishing a male ornament. Schartl et al. study the sexually selected ornament of male Xiphophorus fish. Combining expression profiling and genetic mapping they find the sword-like extension of the tail fin develops on a non-sex biased pre-pattern of transcription factors. A potassium channel specifically expressed in males is identified as main regulator of sword outgrowth.

Original languageEnglish (US)
Pages (from-to)911-922.e4
JournalCurrent Biology
Issue number5
StatePublished - Mar 8 2021


  • QTL-mapping
  • bioelectric signaling
  • fin development
  • ornamental trait
  • potassium channel
  • sexual selection
  • swordtail
  • transcription factor pre-pattern

ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology
  • General Agricultural and Biological Sciences


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