Limits...
Direct Gamete Sequencing Reveals No Evidence for Segregation Distortion in House Mouse Hybrids.

Corbett-Detig R, Jacobs-Palmer E, Hartl D, Hoekstra H - PLoS ONE (2015)

Bottom Line: However, the evolutionary forces that lead to the accumulation of such incompatibilities between diverging taxa are poorly understood.Segregation distorters are believed to be an important source of Dobzhansky-Muller incompatibilities between hybridizing species of Drosophila as well as hybridizing crop plants, but it remains unclear if these selfish genetic elements contribute to reproductive isolation in other taxa.We then genotyped millions of single nucleotide polymorphisms in these gamete pools and tested for a skew in the frequency of parental alleles across the genome.

View Article: PubMed Central - PubMed

Affiliation: Department of Organismic & Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America.

ABSTRACT
Understanding the molecular basis of species formation is an important goal in evolutionary genetics, and Dobzhansky-Muller incompatibilities are thought to be a common source of postzygotic reproductive isolation between closely related lineages. However, the evolutionary forces that lead to the accumulation of such incompatibilities between diverging taxa are poorly understood. Segregation distorters are believed to be an important source of Dobzhansky-Muller incompatibilities between hybridizing species of Drosophila as well as hybridizing crop plants, but it remains unclear if these selfish genetic elements contribute to reproductive isolation in other taxa. Here, we collected viable sperm from first-generation hybrid male progeny of Mus musculus castaneus and M. m. domesticus, two subspecies of rodent in the earliest stages of speciation. We then genotyped millions of single nucleotide polymorphisms in these gamete pools and tested for a skew in the frequency of parental alleles across the genome. We show that segregation distorters are not measurable contributors to observed infertility in these hybrid males, despite sufficient statistical power to detect even weak segregation distortion with our novel method. Thus, reduced hybrid male fertility in crosses between these nascent species is attributable to other evolutionary forces.

No MeSH data available.


Related in: MedlinePlus

Minimum level of distortion that could be detected given a specified significance threshold (α, y-axis), and desired power (x-axis).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4487504&req=5

pone.0131933.g004: Minimum level of distortion that could be detected given a specified significance threshold (α, y-axis), and desired power (x-axis).

Mentions: Through simulation, we ensured that we have sufficient statistical power, given our experimental design and data quality, to detect SD if it is indeed occurring in hybrid males. We found that we have 50% power to detect SD to approximately 0.014, or 1.4% (this number reflects the positive or negative deviation from the expectation, 0.5, at α = 0.001) if distortion affects CW and WC males equally (Fig 4). In other words, we have 50% power to detect distortion that is greater than 51.5% or less than 48.5%. If there is directionality to the distortion effect (i.e. only CW or only WC males experience SD), we have 50% power to detect distortion of 0.016 for CW males and 0.018 for WC males (at α = 0.001). This significance level was selected for illustrative purposes because it is approximately what would be required for genome-wide significance given our false discovery rate correction. The slight difference in power based on cross direction reflects differences in sequencing depth between WC and CW sperm and liver samples. It is also important to note that different regions of the genome will differ slightly in power to detect distortion because read mapping and sequencing, as well as divergence between the CAST and WSB strains and their divergence from the reference, are not uniform across the genome.


Direct Gamete Sequencing Reveals No Evidence for Segregation Distortion in House Mouse Hybrids.

Corbett-Detig R, Jacobs-Palmer E, Hartl D, Hoekstra H - PLoS ONE (2015)

Minimum level of distortion that could be detected given a specified significance threshold (α, y-axis), and desired power (x-axis).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4487504&req=5

pone.0131933.g004: Minimum level of distortion that could be detected given a specified significance threshold (α, y-axis), and desired power (x-axis).
Mentions: Through simulation, we ensured that we have sufficient statistical power, given our experimental design and data quality, to detect SD if it is indeed occurring in hybrid males. We found that we have 50% power to detect SD to approximately 0.014, or 1.4% (this number reflects the positive or negative deviation from the expectation, 0.5, at α = 0.001) if distortion affects CW and WC males equally (Fig 4). In other words, we have 50% power to detect distortion that is greater than 51.5% or less than 48.5%. If there is directionality to the distortion effect (i.e. only CW or only WC males experience SD), we have 50% power to detect distortion of 0.016 for CW males and 0.018 for WC males (at α = 0.001). This significance level was selected for illustrative purposes because it is approximately what would be required for genome-wide significance given our false discovery rate correction. The slight difference in power based on cross direction reflects differences in sequencing depth between WC and CW sperm and liver samples. It is also important to note that different regions of the genome will differ slightly in power to detect distortion because read mapping and sequencing, as well as divergence between the CAST and WSB strains and their divergence from the reference, are not uniform across the genome.

Bottom Line: However, the evolutionary forces that lead to the accumulation of such incompatibilities between diverging taxa are poorly understood.Segregation distorters are believed to be an important source of Dobzhansky-Muller incompatibilities between hybridizing species of Drosophila as well as hybridizing crop plants, but it remains unclear if these selfish genetic elements contribute to reproductive isolation in other taxa.We then genotyped millions of single nucleotide polymorphisms in these gamete pools and tested for a skew in the frequency of parental alleles across the genome.

View Article: PubMed Central - PubMed

Affiliation: Department of Organismic & Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America.

ABSTRACT
Understanding the molecular basis of species formation is an important goal in evolutionary genetics, and Dobzhansky-Muller incompatibilities are thought to be a common source of postzygotic reproductive isolation between closely related lineages. However, the evolutionary forces that lead to the accumulation of such incompatibilities between diverging taxa are poorly understood. Segregation distorters are believed to be an important source of Dobzhansky-Muller incompatibilities between hybridizing species of Drosophila as well as hybridizing crop plants, but it remains unclear if these selfish genetic elements contribute to reproductive isolation in other taxa. Here, we collected viable sperm from first-generation hybrid male progeny of Mus musculus castaneus and M. m. domesticus, two subspecies of rodent in the earliest stages of speciation. We then genotyped millions of single nucleotide polymorphisms in these gamete pools and tested for a skew in the frequency of parental alleles across the genome. We show that segregation distorters are not measurable contributors to observed infertility in these hybrid males, despite sufficient statistical power to detect even weak segregation distortion with our novel method. Thus, reduced hybrid male fertility in crosses between these nascent species is attributable to other evolutionary forces.

No MeSH data available.


Related in: MedlinePlus