One Fish, Two Fish, Red Fish, Blue Fish: Geography, Ecology, Sympatry, and Male Coloration in the Lake Malawi Cichlid Genus Labeotropheus (Perciformes: Cichlidae)

Michael J Pauers

doi:10.4061/2011/575469

Abstract

While sexual selection on male coloration has been important in haplochromine cichlid speciation, few studies to date have examined potential environmental influences on color pattern evolution. Data from multiple sources on male nuptial coloration of the Lake Malawi endemic genus Labeotropheus were used to examine the relationship between color patterns and the environments in which these patterns were found. Red- or carotenoid-pigmented males were concentrated in the northwestern portion of Lake Malawi and were also associated with increasing depth. Further, the presence or absence of L. fuelleborni influenced the coloration of L. trewavasae populations; when L. fuelleborni was present, L. trewavasae males were more likely to exhibit some degree of red coloration. While these results support the idea that sexual selection on male coloration is an important factor in the haplochromine speciation, they also underscore the importance of environmental influences on the evolution of color patterns.

Highlights

An organism’s color can serve an adaptive function in numerous ecological contexts, including crypsis, communication, and thermoregulation [1, 2]
The set correlation analysis performed on the Labeotropheus biogeographical dataset recovered several correlations between coloration and environment, as well as some predictive relationships among the color and environmental variables
It is not surprising that this analysis recovered the welldocumented relationship between L. trewavasae and depth; L. trewavasae is found most frequently at and prefers water depths of typically more than 15 meters [32]

Summary

Introduction

An organism’s color can serve an adaptive function in numerous ecological contexts, including crypsis, communication, and thermoregulation [1, 2]. Lake Malawi is a large and heterogeneous lake, which suggests that isolated populations of Labeotropheus may experience unique visual environments that could influence the evolution or development of their visual systems [24, 31, 36] Since both intra- and intersexual selection have been demonstrated to play important roles in the evolution of male nuptial coloration in the mbuna in general and in the Labeotropheus in particular [15, 16, 37], differing spectral environments among populations could, in turn, have an effect on male nuptial coloration.

Methods

Within-Independent Set Correlations

Within-Dependent and Between-Set Correlations

Regression Analysis

Discussion

A Postscript