Dataset Information

Evolution of Tandem Repeat Satellite Sequences in Two Closely Related Caenorhabditis Species. Diminution of Satellites in Hermaphrodites.

ABSTRACT: The availability of the genome sequence of the unisexual (male-female) Caenorhabditis nigoni offers an opportunity to compare its non-coding features with the related hermaphroditic species Caenorhabditis briggsae; to understand the evolutionary dynamics of their tandem repeat sequences (satellites), as a result of evolution from the unisexual ancestor. We take advantage of the previously developed SATFIND program to build satellite families defined by a consensus sequence. The relative number of satellites (satellites/Mb) in C. nigoni is 24.6% larger than in C. briggsae. Some satellites in C. nigoni have developed from a proto-repeat present in the ancestor species and are conserved as an isolated sequence in C. briggsae. We also identify unique satellites which occur only once and joint satellite families with a related sequence in both species. Some of these families are only found in C. nigoni, which indicates a recent appearance; they contain conserved adjacent 5' and 3' regions, which may favor transposition. Our results show that the number, length and turnover of satellites are restricted in the hermaphrodite C. briggsae when compared with the unisexual C. nigoni. We hypothesize that this results from differences in unequal recombination during meiotic chromosome pairing, which limits satellite turnover in hermaphrodites.

SUBMITTER: Subirana JA

PROVIDER: S-EPMC5748669 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature

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Publications

Evolution of Tandem Repeat Satellite Sequences in Two Closely Related Caenorhabditis Species. Diminution of Satellites in Hermaphrodites.

Subirana Juan A JA Messeguer Xavier X

Genes 20171128 12

The availability of the genome sequence of the unisexual (male-female) <i>Caenorhabditis nigoni</i> offers an opportunity to compare its non-coding features with the related hermaphroditic species <i>Caenorhabditis briggsae</i>; to understand the evolutionary dynamics of their tandem repeat sequences (satellites), as a result of evolution from the unisexual ancestor. We take advantage of the previously developed SATFIND program to build satellite families defined by a consensus sequence. The rel ...[more]

PMID: 29182550

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Project description:BackgroundWhy most organisms reproduce via outcrossing rather than selfing is a central question in evolutionary biology. It has long ago been suggested that outcrossing is favoured when it facilitates adaptation to novel environments. We have previously shown that the experimental evolution of increased outcrossing rates in populations of the male-hermaphrodite nematode Caenorhabditis elegans were correlated with the experimental evolution of increased male fitness. However, it is unknown whether outcrossing led to adaptation, and if so, which fitness components can explain the observed increase in outcrossing rates.ResultsUsing experimental evolution in six populations with initially low standing levels of genetic diversity, we show with head-to-head competition assays that population-wide fitness improved during 100 generations. Since outcrossing rates increased during the same period, this result demonstrates that outcrossing is adaptive. We also show that there was little evolution of hermaphrodite fitness under conditions of selfing or under conditions of outcrossing with unrelated tester males. We nonetheless find a positive genetic correlation between hermaphrodite self-fitness and population-wide fitness, and a negative genetic correlation between hermaphrodite mating success and population-wide fitness. These results suggest that the several hermaphrodite traits measured are fitness components. Tradeoffs expressed in hermaphrodites, particularly noticed between self-fitness and mating success, may in turn explain their lack of change during experimental evolution.ConclusionsOur findings indicate that outcrossing facilitates adaptation to novel environments. They further indicate that the experimental evolution of increased outcrossing rates depended little on hermaphrodites because of fitness tradeoffs between selfing and outcrossing. Instead, the evolution of increased outcrossing rates appears to have resulted from unhindered selection on males.

Dataset Information

Evolution of Tandem Repeat Satellite Sequences in Two Closely Related Caenorhabditis Species. Diminution of Satellites in Hermaphrodites.

Publications

Evolution of Tandem Repeat Satellite Sequences in Two Closely Related Caenorhabditis Species. Diminution of Satellites in Hermaphrodites.

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