Dataset Information

Phenotypic integration of brain size and head morphology in Lake Tanganyika Cichlids.

ABSTRACT:

Background

Phenotypic integration among different anatomical parts of the head is a common phenomenon across vertebrates. Interestingly, despite centuries of research into the factors that contribute to the existing variation in brain size among vertebrates, little is known about the role of phenotypic integration in brain size diversification. Here we used geometric morphometrics on the morphologically diverse Tanganyikan cichlids to investigate phenotypic integration across key morphological aspects of the head. Then, while taking the effect of shared ancestry into account, we tested if head shape was associated with brain size while controlling for the potentially confounding effect of feeding strategy.

Results

The shapes of the anterior and posterior parts of the head were strongly correlated, indicating that the head represents an integrated morphological unit in Lake Tanganyika cichlids. After controlling for phylogenetic non-independence, we also found evolutionary associations between head shape, brain size and feeding ecology.

Conclusions

Geometric morphometrics and phylogenetic comparative analyses revealed that the anterior and posterior parts of the head are integrated, and that head morphology is associated with brain size and feeding ecology in Tanganyikan cichlid fishes. In light of previous results on mammals, our results suggest that the influence of phenotypic integration on brain diversification is a general process.

SUBMITTER: Tsuboi M

PROVIDER: S-EPMC4015177 | biostudies-literature | 2014 Mar

REPOSITORIES: biostudies-literature

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Publications

Phenotypic integration of brain size and head morphology in Lake Tanganyika Cichlids.

Tsuboi Masahito M Gonzalez-Voyer Alejandro A Kolm Niclas N

BMC evolutionary biology 20140304 1

<h4>Background</h4>Phenotypic integration among different anatomical parts of the head is a common phenomenon across vertebrates. Interestingly, despite centuries of research into the factors that contribute to the existing variation in brain size among vertebrates, little is known about the role of phenotypic integration in brain size diversification. Here we used geometric morphometrics on the morphologically diverse Tanganyikan cichlids to investigate phenotypic integration across key morphol ...[more]

PMID: 24593160

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Project description:BackgroundThe tribe Lamprologini is the major substrate breeding lineage of Lake Tanganyika's cichlid species flock. Among several different life history strategies found in lamprologines, the adaptation to live and breed in empty gastropod shells is probably the most peculiar. Although shell-breeding arose several times in the evolutionary history of the lamprologines, all obligatory and most facultative shell-breeders belong to the so called "ossified group", a monophyletic lineage within the lamprologine cichlids. Since their distinctive life style enables these species to live and breed in closest vicinity, we hypothesized that these cichlids might be particularly prone to accidental hybridization, and that introgression might have affected the evolutionary history of this cichlid lineage.ResultsOur analyses revealed discrepancies between phylogenetic hypotheses based on mitochondrial and nuclear (AFLP) data. While the nuclear phylogeny was congruent with morphological, behavioral and ecological characteristics, several species--usually highly specialized shell-breeders--were placed at contradicting positions in the mitochondrial phylogeny. The discordant phylogenies strongly suggest repeated incidents of introgressive hybridization between several distantly related shell-breeding species, which reticulated the phylogeny of this group of cichlids. Long interior branches and high bootstrap support for many interior nodes in the mitochondrial phylogeny argue against a major effect of ancient incomplete lineage sorting on the phylogenetic reconstruction. Moreover, we provide morphological and genetic (mtDNA and microsatellites) evidence for ongoing hybridization among distantly related shell-breeders. In these cases, the territorial males of the inferred paternal species are too large to enter the shells of their mate, such that they have to release their sperm over the entrance of the shell to fertilize the eggs. With sperm dispersal by water currents and wave action, trans-specific fertilization of clutches in neighboring shells seem inevitable, when post-zygotic isolation is incomplete.ConclusionFrom the direct observation of hybrids we conclude that hybridization between distantly related gastropod-shell-breeding cichlids of Lake Tanganyika follows inevitably from their ecological specialization. Moreover, the observed incongruence between mtDNA and nuclear multilocus phylogeny suggests that repeated hybridization events among quite distantly related taxa affected the diversification of this group, and introduced reticulation into their phylogeny.

Dataset Information

Phenotypic integration of brain size and head morphology in Lake Tanganyika Cichlids.

Background

Results

Conclusions

Publications

Phenotypic integration of brain size and head morphology in Lake Tanganyika Cichlids.

Similar Datasets

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