Inheritance of female mating preference in a sympatric sibling species pair of Lake Victoria cichlids: implications for speciation

Abstract

Female mate choice has often been proposed to play an important role in cases of rapid speciation, in particular in the explosively evolved haplochromine cichlid species flocks of the Great Lakes of East Africa. Little, if anything, is known in cichlid radiations about the heritability of female mating preferences. Entirely sympatric distribution, large ecological overlap and conspicuous differences in male nuptial coloration, and female preferences for these, make the sister species Pundamilia pundamilia and P. nyererei from Lake Victoria an ideally suited species pair to test assumptions on the genetics of mating preferences made in models of sympatric speciation. Female mate choice is necessary and sufficient to maintain reproductive isolation between these species, and it is perhaps not unlikely therefore, that female mate choice has been important during speciation. A prerequisite for this, which had remained untested in African cichlid fish, is that variation in female mating preferences is heritable. We investigated mating preferences of females of these sister species and their hybrids to test this assumption of most sympatric speciation models, and to further test the assumption of some models of sympatric speciation by sexual selection that female preference is a single-gene trait. We find that the differences in female mating preferences between the sister species are heritable, possibly with quite high heritabilities, and that few but probably more than one genetic loci contribute to this behavioural speciation trait with no apparent dominance. We discuss these results in the light of speciation models and the debate about the explosive radiation of cichlid fishes in Lake Victoria.

Territory quality affects female preference in a Lake Victoria cichlid fish

“…In subsequent mate-choice experiments, we showed that red females prefer males of their own species in the absence of differences in territory quality (experiment II). This confirms earlier results (Seehausen and Van Alphen 1998;Haesler and Seehausen 2005). This preference changed significantly into the direction of blue (heterospecific) males when those males had a larger tube, resulting in a non-significant preference for blue.…”

Disruptive sexual selection on male nuptial coloration in an experimental hybrid population of cichlid fish

“…Heterozygous females mate at random (Haesler & Seehausen 2005). Complementary to our study, van der Sluijs et al (2008) did the first comparison of female preference functions between P. pundamilia and P. nyererei, showing preference functions in both species that were open ended over the range of male phenotypes tested, and sign inversed between the species.…”

“…Complementary to our study, van der Sluijs et al (2008) did the first comparison of female preference functions between P. pundamilia and P. nyererei, showing preference functions in both species that were open ended over the range of male phenotypes tested, and sign inversed between the species. If the absence of preferences for red or blue males observed in F 1 hybrid females by Haesler & Seehausen (2005) is because preference alleles for red and blue cancel out to make a no preference, as opposed to a yellow preference, segregation of female mating preferences in the F 2 generates some females with preference for red, some with preference for blue and a majority of females that mate at random. In a population in which female preferences segregate, more extremely coloured males are then predicted to have higher MS than males of intermediate colour.…”

“…if the effects of blue-and red-preference alleles cancel out in hybrids. Prediction (iii) then arises because in the F 2 generation female preference alleles for red and blue segregate (Haesler & Seehausen 2005). While most F 2 hybrid females carry similar proportions of the different preference alleles and are expected to mate at random just like F 1 hybrid females, segregation of preference genes also produces females carrying unequal numbers of the preference alleles with different sign, favouring either red or blue males and hence exhibiting mating preferences.…”

The diversity of male nuptial coloration leads to species diversity in Lake Victoria cichlids

“…Here, we focused on the receiver sensitivity and ambient light of two Pundamilia species. Females of Pundamilia species have heritable preferences and species-specific sensitivities to different light wavelengths (Haesler and Seehausen, 2005;Maan et al, 2006). P. nyererei (red coloration) has a low threshold for the detection of red light (high sensitivity to red light), whereas P. pundamilia (blue coloration) has a low threshold for the detection of blue light (high sensitivity to blue light) .…”