Genetic population structure as indirect measure of dispersal ability in a Lake Tanganyika cichlid

Abstract

Diversification and speciation processes are influenced by intrinsic (ecological specialization, dispersal) and extrinsic (habitat structure and instability) factors, but the effect of ecological characteristics on dispersal is difficult to assess. This study uses mitochondrial control region sequences to investigate the population structure and demographic history of the endemic Lake Tanganyika cichlid Neolamprologus caudopunctatus with a preference for the rock-sand interface along two stretches of continuous, rocky shoreline, and across a sandy bay representing a potential dispersal barrier. Populations along uninterrupted habitat were not differentiated; whereas, the sandy bay separated two reciprocally monophyletic clades. The split between the two clades between 170,000 and 260,000 years BP coincides with a period of rising water level following a major lowstand, and indicates that clades remained isolated throughout subsequent lake level fluctuations. Low long-term effective population sizes were inferred from modest genetic diversity estimates, and may be due to recent population expansions starting from small population sizes 45,000-60,000 years BP. Comparisons with available data from specialized rock-dwelling species of the same area suggest that habitat structure and lake level fluctuations determine phylogeographic patterns on large scales, while fine-scale population structure and demography are modulated by species-specific ecologies.

Competition-driven speciation in cichlid fish

“…The population genetic data are consistent with a pattern of genetic isolation by distance, which is not unusual for hard substrate-associated cichlids of the region, and has been shown in other lamprologines (Variabilichromis moorii 27 and Neolamprologus caudopunctatus 28 ). The population genetic data suggest that the selective processes that have led to diversification have taken place over local spatial scales.…”

Species-Specific Population Structure in Rock-Specialized Sympatric Cichlid Species in Lake Tanganyika, East Africa

“…In particular, a strong phylogeographic pattern disrupted by the occasional presence of closely related and even identical haplotypes on opposite sides of the lake found in Tropheus, Eretmodus, and another highly structured rock-dweller, Variabilichromis moorii, suggests incidental gene flow in association with periods of low lake level (Sturmbauer et al 1997Duftner et al 2006). Furthermore, this and other recent population genetic analyses of sympatric species indicate that speciesspecific differences in traits related to dispersal superimpose on extrinsic forces and create variable patterns of population structure and diversity (this study; Duftner et al 2006;Koblmu¨ller et al 2006).…”

Phylogeny and phylogeography of Altolamprologus: ancient introgression and recent divergence in a rock-dwelling Lake Tanganyika cichlid genus

“…Differentiation is lower and only occurs on a larger geographic scale in less specialized species and species that inhabit the intermediate habitat, i.e. the transition between rocky and sandy habitat surrounding the rocky habitat patches (Koblmüller et al, 2007aSefc et al, 2007;Kotrschal et al, 2012). Finally, the sandy and the open-water habitat contain virtually no barriers to dispersal, and cichlid species specialized to these habitats show little if any population genetic structure at all (Shaw et al, 2000;Pereyra et al, 2004;Genner et al, 2008Genner et al, , 2010aAnseeuw et al, 2011;Koblmüller et al, 2015a).…”