Recurrent origin of a sexually selected trait in Xiphophorus fishes inferred from a molecular phylogeny

Darwin believed that sexual selection accounts for the evolution of exaggerated male ornaments, such as the sword-like caudal fin extensions of male fishes of the genus Xiphophorus, that appear detrimental to survival. Swordtails continue to feature prominently in empirical work and theories of sexu...

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Bibliographic Details
Published in:Nature (London) 1994-04, Vol.368 (6471), p.539-542
Main Authors: Meyer, Axel, Morrissey, Jean M, Schartl, Manfred
Format: Article
Language:English
Subjects:
Agnatha. Pisces
Animals
Base Sequence
Bias
Biological and medical sciences
Biological Evolution
Cyprinodontiformes - classification
Cyprinodontiformes - genetics
Cyprinodontiformes - physiology
Cytochrome b Group - genetics
Deoxyribonucleic acid
DNA - genetics
DNA Primers
Ecology
Evolution
Female
Fish
Freshwater
Fundamental and applied biological sciences. Psychology
Male
Males
Mitochondria
Molecular Sequence Data
Origins
Phylogeny
Pisces
Protein-Tyrosine Kinases - genetics
Selection, Genetic
Sensation
Sex Characteristics
Survival
Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution
Xiphophorus
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Summary:Darwin believed that sexual selection accounts for the evolution of exaggerated male ornaments, such as the sword-like caudal fin extensions of male fishes of the genus Xiphophorus, that appear detrimental to survival. Swordtails continue to feature prominently in empirical work and theories of sexual selection; the pre-existing bias hypothesis has been offered as an explanation for the evolution of swords in these fishes. Based upon a largely morphological phylogeny, this hypothesis suggests that female preference to mate with sworded males arose in ancestrally swordless species, thus pre-dating the origin of the sword itself and directly driving its evolution. Here we present a molecular phylogeny (based on mitochondrial and nuclear DNA sequences) of Xiphophorus which differs from the traditional one: it indicates that the sword originated and was lost repeatedly. Our phylogeny suggests that the ancestor of the genus is more likely to have possessed a sword than not, thus questioning the applicability of the pre-existing bias hypothesis as an explanation for the evolution of this sexually selected trait.
ISSN:0028-0836
1476-4687
DOI:10.1038/368539a0