Dataset Information

Gene genealogies indicates abundant gene conversions and independent evolutionary histories of the mating-type chromosomes in the evolutionary history of Neurospora tetrasperma.

ABSTRACT:

Background

The self-fertile filamentous ascomycete Neurospora tetrasperma contains a large (approximately 7 Mbp) and young (< 6 MYA) region of suppressed recombination within its mating-type (mat) chromosomes. The objective of the present study is to reveal the evolutionary history, including key genomic events, associated with the various regions of the mat chromosomes among ten strains representing all the nine known species (lineages) contained within the N. tetrasperma species complex.

Results

Comparative analysis of sequence divergence among alleles of 24 mat-linked genes (mat A and mat a) indicates that a large region of suppressed recombination exists within the mat chromosome for each of nine lineages of N. tetrasperma sensu latu. The recombinationally suppressed region varies in size and gene composition among lineages, and is flanked on both ends by normally recombining regions. Genealogical analyses among lineages reveals that eight gene conversion events have occurred between homologous mat A and mat a-linked alleles of genes located within the region of restricted recombination during the evolutionary history of N. tetrasperma.

Conclusions

We conclude that the region of suppressed recombination in the mat chromosomes has likely been subjected to independent contraction and/or expansion during the evolutionary history of the N. tetrasperma species complex. Furthermore, we infer that gene conversion events are likely a common phenomenon within this recombinationally suppressed genomic region. We argue that gene conversions might provide an efficient mechanism of adaptive editing of functional genes, including the removal of deleterious mutations, within the young recombinationally suppressed region of the mat chromosomes.

SUBMITTER: Menkis A

PROVIDER: S-EPMC2923516 | biostudies-literature | 2010 Jul

REPOSITORIES: biostudies-literature

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Publications

Gene genealogies indicates abundant gene conversions and independent evolutionary histories of the mating-type chromosomes in the evolutionary history of Neurospora tetrasperma.

Menkis Audrius A Whittle Carrie A CA Johannesson Hanna H

BMC evolutionary biology 20100731

<h4>Background</h4>The self-fertile filamentous ascomycete Neurospora tetrasperma contains a large (approximately 7 Mbp) and young (< 6 MYA) region of suppressed recombination within its mating-type (mat) chromosomes. The objective of the present study is to reveal the evolutionary history, including key genomic events, associated with the various regions of the mat chromosomes among ten strains representing all the nine known species (lineages) contained within the N. tetrasperma species comple ...[more]

PMID: 20673371

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Project description:The significance of introgression as an evolutionary force shaping natural populations is well established, especially in animal and plant systems. However, the abundance and size of introgression tracts, and to what degree interspecific gene flow is the result of adaptive processes, are largely unknown. In this study, we present medium coverage genomic data from species of the filamentous ascomycete Neurospora, and we use comparative genomics to investigate the introgression landscape at the genomic level in this model genus. We revealed one large introgression tract in each of the three investigated phylogenetic lineages of Neurospora tetrasperma (sizes of 5.6 Mbp, 5.2 Mbp, and 4.1 Mbp, respectively). The tract is located on the chromosome containing the locus conferring sexual identity, the mating-type (mat) chromosome. The region of introgression is confined to the region of suppressed recombination and is found on one of the two mat chromosomes (mat a). We used Bayesian concordance analyses to exclude incomplete lineage sorting as the cause for the observed pattern, and multilocus genealogies from additional species of Neurospora show that the introgression likely originates from two closely related, freely recombining, heterothallic species (N. hispaniola and N. crassa/N. perkinsii). Finally, we investigated patterns of molecular evolution of the mat chromosome in Neurospora, and we show that introgression is correlated with reduced level of molecular degeneration, consistent with a shorter time of recombination suppression. The chromosome specific (mat) and allele specific (mat a) introgression reported herein comprise the largest introgression tracts reported to date from natural populations. Furthermore, our data contradicts theoretical predictions that introgression should be less likely on sex-determining chromosomes. Taken together, the data presented herein advance our general understanding of introgression as a force shaping eukaryotic genomes.

Dataset Information

Gene genealogies indicates abundant gene conversions and independent evolutionary histories of the mating-type chromosomes in the evolutionary history of Neurospora tetrasperma.

Background

Results

Conclusions

Publications

Gene genealogies indicates abundant gene conversions and independent evolutionary histories of the mating-type chromosomes in the evolutionary history of Neurospora tetrasperma.

Similar Datasets

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