Sympatric speciation suggested by monophyly of crater lake cichlids

Abstract

The existence of sympatric speciation--that populations diverge into species in the absence of physical or ecological barriers--is controversial. The East African Great Lakes harbour hundreds of cichlid species representing only a few monophyletic lineages, although palaeolimnological evidence and local restrictions on species distribution suggest that speciation in these lakes could have been allopatric. The case for sympatry in restricted areas of Lakes Malawi and Tanganyika is stronger but not unassailable. A better case might be made for cichlid species flocks in small, ecologically monotonous crater lakes. Here we present a mitochondrial DNA analysis of cichlid species flocks endemic to two such lakes in Cameroon. The results suggest that the flocks in each lake are monophyletic: the implication being that each lake was colonized once only, the size and shape of each lake being such that subsequent diversification would have been sympatric.

The oldest fossil cichlids (Teleostei: Perciformes): indication of a 45 million-year-old species flock

“…The nature of a small crater lake indicates that the Mahenge cichlids may have speciated sympatrically as has been suggested for other crater lake cichlid £ocks (Schliewen et al 1994).…”

Adaptive Dynamics and Evolving Biodiversity

“…In conjunction with mounting empirical evidence that rates of race formation and sympatric speciation are potentially quite high, at least under certain conditions (e.g., Bush 1969;Meyer 1993;Schliewen et al 1994), the above considerations suggest that longer-term conservation efforts will benefit if attention is paid to how environmental change interferes with evolutionarily stable community patterns.…”

Partial island submergence and speciation in an adaptive radiation: a multilocus analysis of the Cuban green anoles

“…Classic models of allopatric divergence are often challenged by adaptive radiations occurring in small, geographically homogeneous areas where barriers to gene flow or dispersal may be lacking. In some such radiations, non-allopatric speciation is suggested: sympatric speciation, for example, is considered common in African rift-lake cichlids (Schliewen et al 1994(Schliewen et al , 2001Seehausen & van Alphen 1999;Shaw et al 2000). However, allopatric speciation also occurs in cichlids when large lakes become fragmented into smaller ones during historically dry periods (Sturmbauer & Meyer 1992;Rü ber et al 1998;Sturmbauer et al 2001).…”