SELECTION AND THE MAINTENANCE OF A COLOUR PATTERN POLYMORPHISM IN THE GREEN SWORDTAIL (XIPHOPHORUS HELLERI)

In: Behaviour
View More View Less
  • 1 Zoologisches Institut und Zoologisches Museum der Universität, Arbeitsbereich Ethologie, Martin-Luther-King-Platz, D-20146 Hamburg, Germany
  • 2 Zoologisches Institut und Zoologisches Museum der Universität, Arbeitsbereich Ethologie, Martin-Luther-King-Platz, D-20146 Hamburg, Germany
  • 3 Theodor-Boveri-Institut für Biowissenschaften der Universität, Physiologische Chemie I, Am Hubland, D-97074 Würzburg, Germany

Purchase instant access (PDF download and unlimited online access):

€25.00$30.00

Abstract

Many Xiphophorus populations include a number of individuals with black spots on body sides or fins. In many cases such spots are composed of extremely large melanophore cells, the so-called macromelanophores. Macromelanophore pattern polymorphism is known in 10 out of 22 Xiphophorus species. In at least 8 species alleles of the macromelanophore determining locus Mdl are intimately linked to a dominant oncogene, ONC-Xmrk, which can give rise to malignant skin tumors (melanoma). We present, for the first time, evidence that macromelanophore pattern polymorphisms may be maintained by selection in a seasonally variable environment. In school-choice experiments single Xiphophorus helleri females spent more time with groups of spotted females than with non-spotted females under turbid, but not under clear water conditions. Similarly, receptive females preferred spotted males in turbid, but not in clear water. Thus, in nature, when the water becomes turbid after heavy rainfalls, school mates and reproductive partners can evidently find each other more easily with the help of macromelanophore spotting patterns. Intrasexual selection seems to be irrelevant because spotted and non-spotted males were equally successful in competition experiments. A genetic hitchhiking scenario is discussed which could explain the fact that the potentially injurious tumor gene ONC-Xmrk has been maintained in the genus Xiphophorus over a period of millions of years by its close linkage to positively selected macromelanophore alleles.

Content Metrics

All Time Past Year Past 30 Days
Abstract Views 153 81 9
Full Text Views 137 10 0
PDF Downloads 17 10 0