Skip to content. | Skip to navigation

Personal tools

 
 
 
 

 
                 
You are here: Home / Associated publications / Belgian Journal of Zoology / Bibliographic References / Can ancient colour polymorphisms explain why some cichlid lineages speciate rapidly under disruptive sexual selection?

O Seehausen, JJM Van Alpen and F Witte (1999)

Can ancient colour polymorphisms explain why some cichlid lineages speciate rapidly under disruptive sexual selection?

BELGIAN JOURNAL OF ZOOLOGY, 129(1):43-60.

It is not sufficiently understood why some lineages of cichlid fishes have proliferated in the Great Lakes of East Africa much more than anywhere else in the world, and much faster than other cichlid lineages or any other group of freshwater fish. Recent field and experimental work on Lake Victoria haplochromines suggests that mate choice-mediated disruptive sexual selection on coloration, that can cause speciation even in the absence of geographical isolation, may explain it. We summarize the evidence and propose a hypothesis for the genetics of coloration that may help understand the phenomenon. By defining colour patterns by hue and arrangement of hues on the body, we could assign almost all observed phenotypes of Lake Victoria cichlids to one of three female (''plain'', ``orange blotched'', ``black and white'') and three male (''blue'', ``red-ventrum'', ``red-dorsum'') colour patterns. These patterns diagnose species but frequently co-occur also as morphs within the same population, where they are associated with variation in mate preferences, and appear to be transient stages in speciation. Particularly the male patterns occur in almost every genus of the species flock. We propose that the patterns and their association into polymorphisms express an ancestral trait that is retained across speciation. Our model for male colour pattern assumes two structural loci. When both are switched off, the body is blue. When switched on by a cascade of poly morphic regulatory genes, one expresses a yellow to red ventrum, the other one a yellow to red dorsum. The expression of colour variation initiates speciation. The blue daughter species will inherit the variation at the regulatory genes that can, without new mutational events, purely by recombination, again expose the colour polymorphism, starting the process anew Very similar colour patterns also dominate among the Mbuna of Lake Malawi. In contrast, similar colour polymorphisms do not exist in the lineages that have not proliferated in the Great Lakes. The colour pattern polymorphism may be an ancient trait in the lineage (or lineages) that gave rise to the two large haplochromine radiations. We propose two tests of our hypothesis.

5th Benelux Congress of Zoology, GHENT, BELGIUM, NOV 06-07, 1998
BJZ

ISSN 2295-0451 (online version)
ISSN 0777-6279 (printed version)
impact factor 2015: 0,87.

Editor-in-Chief:
Prof. Dr. Isa Schön
Royal Belgian Institute of Natural Sciences
Vautierstraat 29
1000 Brussels, Belgium

 



1863-1903
Annales de la Société malacologique de Belgique
 
1903-1923
​Annales de la Société royale malacologique et zoologique de Belgique
 
1923-1989
Annales de la Société Royale Zoologique de Belgique
 
1989-
Belgian Journal of Zoology