Speciation in Cichlid Fishes of East African Lakes

Trewavas, Ethelwynn

doi:10.1038/160096b0

Cited by 30 publications

(16 citation statements)

References 3 publications

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“…Possible influences of these fluctuations on the evolution of fishes were suggested by Trewavas (1947) and by Lowe (1952), and further points are mentioned by Fryer (1959). A rather important point which has not yet been sufficiently stressed is the influence of these fluctuations on the basic food supply of the littoral zone which is, faunistically, both qualitatively and quantitatively the richest zone of the lake.…”

Section: (7) the Significance Of Lake Level Fluctuationsmentioning

confidence: 96%

Some Aspects of Evolution in Lake Nyasa

Fryer

1959

Evolution

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Section: (7) the Significance Of Lake Level Fluctuationsmentioning

confidence: 96%

Some Aspects of Evolution in Lake Nyasa

Fryer

1959

Evolution

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“…Classic models emphasize adaptive divergence of populations on isolated rocky habitat patches, which are created and destroyed by changes in lake level (Trewavas 1947;Fryer 1959b). The reorganization of habitat patches by £uctuating water levels in Lake Malawi at di¡erent spatial and temporal scales has been con¢rmed by historical observations and geological evidence (Hill & Ribbink 1978;Crossley et al 1984;McKaye & Gray 1984;Scholz & Rosendahl 1988;Owen et al 1990).…”

Section: Introductionmentioning

confidence: 99%

Population structure and colour variation of the cichlid fishes Labeotropheus fuelleborni Ahl along a recently formed archipelago of rocky habitat patches in southern Lake Malawi

Arnegard

Markert

Danley

et al. 1999

Proc. R. Soc. Lond. B

111

133

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Extremely ¢ne-scale genetic partitioning has recently been detected among populations of Lake Malawi's rock-dwelling cichlids through the study of microsatellite loci. Understanding the mechanisms of genetic di¡erentiation that operate in this rapidly speciating group requires further investigation of the geographic patterns of gene £ow and the congruence between morphological and genetic divergence. In pursuit of this goal, genetic variation at four microsatellite loci and variation in male breeding coloration were examined in several populations of Labeotropheus fuelleborni from southern Lake Malawi. Signi¢cant genetic di¡erentiation exists among populations (overall F ST 0.063; p 0.0002). While migration appears unrestricted within continuous rocky patches, deep waters and sandy bays more than 2 km wide act as strong barriers to gene £ow. Dispersal of L. fuelleborni appears to follow a stepping-stone model in which the distribution of habitats often constrains migration to one dimension. It is hypothesized that clinal colour variation in the study area has resulted from the secondary contact of divergent lineages, although reproductive isolation between colour variants is not apparent. Relative to shoreline populations, reduced levels of gene £ow among populations inhabiting isolated, deep-water islands provides greater opportunities for drift, adaptation to local conditions, or sexual selection to e¡ect genetic di¡eren-tiation in this species.

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“…It is unlikely, however, that fluctuations on a realistic time scale would first establish the initial population and then not further destabilize the process of sympatric speciation. Nevertheless, temporal fluctuations merit further theoretical consideration because lake level changes are widely considered to play an important evolutionary role in the African Great Lakes (Trewavas 1947;Fryer 1959;Markert et al 2001). Turner (2002) proposed a scenario in which hybridization might establish symmetric initial conditions.…”

Section: Symmetrical Initial Phenotypic Distributions?mentioning

confidence: 99%

Sympatric Speciation by Sexual Selection Alone Is Unlikely

2004

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Abstract. According to Darwin, sympatric speciation is driven by disruptive, frequency-dependent natural selection caused by competition for diverse resources. Recently, several authors have argued that disruptive sexual selection can also cause sympatric speciation. Here, we use hypergeometric phenotypic and individual-based genotypic models to explore sympatric speciation by sexual selection under a broad range of conditions. If variabilities of preference and display traits are each caused by more than one or two polymorphic loci, sympatric speciation requires rather strong sexual selection when females exert preferences for extreme male phenotypes. Under this kind of mate choice, speciation can occur only if initial distributions of preference and display are close to symmetric. Otherwise, the population rapidly loses variability. Thus, unless allele replacements at very few loci are enough for reproductive isolation, female preferences for extreme male displays are unlikely to drive sympatric speciation. By contrast, similarity-based female preferences that do not cause sexual selection are less destabilizing to the maintenance of genetic variability and may result in sympatric speciation across a broader range of initial conditions. Certain groups of African cichlids have served as the exclusive motivation for the hypothesis of sympatric speciation by sexual selection. Mate choice in these fishes appears to be driven by female preferences for extreme male phenotypes rather than similaritybased preferences, and the evolution of premating reproductive isolation commonly involves at least several genes. Therefore, differences in female preferences and male display in cichlids and other species of sympatric origin are more likely to have evolved as isolating mechanisms under disruptive natural selection.

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Speciation in Cichlid Fishes of East African Lakes

Cited by 30 publications

References 3 publications

Some Aspects of Evolution in Lake Nyasa

Some Aspects of Evolution in Lake Nyasa

Population structure and colour variation of the cichlid fishes Labeotropheus fuelleborni Ahl along a recently formed archipelago of rocky habitat patches in southern Lake Malawi

Sympatric Speciation by Sexual Selection Alone Is Unlikely

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