Dataset Information

Eggspot number and sexual selection in the cichlid fish Astatotilapia burtoni.

ABSTRACT: Sexual selection on male coloration is one of the main mechanisms proposed to explain the explosive speciation rates in East African cichlid fish. True eggspots are color patterns characteristic of the most species-rich lineage of cichlids, the Haplochromini, and have been suggested to be causally related to the speciation processes. Eggspots are thought to have originated by sensory exploitation and subsequently gained several roles in sexual advertisement. However, for most of these functions the evidence is equivocal. In addition, the genetic architecture of this trait still is largely unknown. We conducted bidirectional selective breeding experiments for eggspot numbers in the model cichlid, Astatotilapia burtoni. After two generations, low lines responded significantly, whereas the high lines did not. Body size was both phenotypically and genotypically correlated with eggspot number and showed correlated response to selection. Males with higher numbers of eggspots were found to sire larger offspring. Despite the potential to act as honest indicators of fitness, the behavioral experiments showed no evidence of a role in either intra- or inter-sexual selection. Visual-based female preference was instead explained by courtship intensity. The evolution of this trait has been interpreted in light of adaptive theories of sexual selection, however the present and published results suggest the influence of non-adaptive factors such as sensory exploitation, environmental constraints and sexual antagonism.

SUBMITTER: Henning F

PROVIDER: S-EPMC3427294 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Eggspot number and sexual selection in the cichlid fish Astatotilapia burtoni.

Henning Frederico F Meyer Axel A

PloS one 20120824 8

Sexual selection on male coloration is one of the main mechanisms proposed to explain the explosive speciation rates in East African cichlid fish. True eggspots are color patterns characteristic of the most species-rich lineage of cichlids, the Haplochromini, and have been suggested to be causally related to the speciation processes. Eggspots are thought to have originated by sensory exploitation and subsequently gained several roles in sexual advertisement. However, for most of these functions ...[more]

PMID: 22937082

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Project description:BackgroundTeleost fish have seven paralogous clusters of Hox genes stemming from two complete genome duplications early in vertebrate evolution, and an additional genome duplication during the evolution of ray-finned fish, followed by the secondary loss of one cluster. Gene duplications on the one hand, and the evolution of regulatory sequences on the other, are thought to be among the most important mechanisms for the evolution of new gene functions. Cichlid fish, the largest family of vertebrates with about 2500 species, are famous examples of speciation and morphological diversity. Since this diversity could be based on regulatory changes, we chose to study the coding as well as putative regulatory regions of their Hox clusters within a comparative genomic framework.ResultsWe sequenced and characterized all seven Hox clusters of Astatotilapia burtoni, a haplochromine cichlid fish. Comparative analyses with data from other teleost fish such as zebrafish, two species of pufferfish, stickleback and medaka were performed. We traced losses of genes and microRNAs of Hox clusters, the medaka lineage seems to have lost more microRNAs than the other fish lineages. We found that each teleost genome studied so far has a unique set of Hox genes. The hoxb7a gene was lost independently several times during teleost evolution, the most recent event being within the radiation of East African cichlid fish. The conserved non-coding sequences (CNS) encompass a surprisingly large part of the clusters, especially in the HoxAa, HoxCa, and HoxDa clusters. Across all clusters, we observe a trend towards an increased content of CNS towards the anterior end.ConclusionThe gene content of Hox clusters in teleost fishes is more variable than expected, with each species studied so far having a different set. Although the highest loss rate of Hox genes occurred immediately after whole genome duplications, our analyses showed that gene loss continued and is still ongoing in all teleost lineages. Along with the gene content, the CNS content also varies across clusters. The excess of CNS at the anterior end of clusters could imply a stronger conservation of anterior expression patters than those towards more posterior areas of the embryo.

Dataset Information

Eggspot number and sexual selection in the cichlid fish Astatotilapia burtoni.

Publications

Eggspot number and sexual selection in the cichlid fish Astatotilapia burtoni.

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