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

Schematic of experimental cross scheme.Inbred parental strains were crossed, and individual F1 males (purple) sacrificed at between 3 and 6 months, when their sperm were subjected to a swim-up assay. Libraries were prepared from liver or tail (control; left) and sperm (experiment; right) samples, sequenced, and then aligned to a diploid reference genome; subspecies of origin was determined for as many sequences as possible.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0131933.g001: Schematic of experimental cross scheme.Inbred parental strains were crossed, and individual F1 males (purple) sacrificed at between 3 and 6 months, when their sperm were subjected to a swim-up assay. Libraries were prepared from liver or tail (control; left) and sperm (experiment; right) samples, sequenced, and then aligned to a diploid reference genome; subspecies of origin was determined for as many sequences as possible.

Mentions: Here we explore a novel approach in which we survey the genome for SD by directly sequencing viable gametes from F1 hybrid M. m. domesticus/M. m. castaneus males, allowing us to circumvent the problems outlined above. Briefly, we enrich for viable sperm in hybrids and then sequence these sperm in bulk preparations, along with control somatic tissues, to identify any skew in the representation of either parental chromosome in the viable sperm relative to the control (Fig 1). While we demonstrate via simulation that our experimental design has excellent power, we find no evidence of SD in this cross, suggesting that SDs are not a primary contributor to male infertility in M. m. castaneus and M. m. domesticus hybrids. Nonetheless, this approach has a number of advantages relative to conventional methods. Specifically, our method is more cost effective, more specific to the identification of SD, and more generally applicable to a wide variety of organisms than conventional pedigree-based approaches. We therefore expect that it will be a useful means of studying the frequency and impact of SD in other systems.


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)

Schematic of experimental cross scheme.Inbred parental strains were crossed, and individual F1 males (purple) sacrificed at between 3 and 6 months, when their sperm were subjected to a swim-up assay. Libraries were prepared from liver or tail (control; left) and sperm (experiment; right) samples, sequenced, and then aligned to a diploid reference genome; subspecies of origin was determined for as many sequences as possible.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0131933.g001: Schematic of experimental cross scheme.Inbred parental strains were crossed, and individual F1 males (purple) sacrificed at between 3 and 6 months, when their sperm were subjected to a swim-up assay. Libraries were prepared from liver or tail (control; left) and sperm (experiment; right) samples, sequenced, and then aligned to a diploid reference genome; subspecies of origin was determined for as many sequences as possible.
Mentions: Here we explore a novel approach in which we survey the genome for SD by directly sequencing viable gametes from F1 hybrid M. m. domesticus/M. m. castaneus males, allowing us to circumvent the problems outlined above. Briefly, we enrich for viable sperm in hybrids and then sequence these sperm in bulk preparations, along with control somatic tissues, to identify any skew in the representation of either parental chromosome in the viable sperm relative to the control (Fig 1). While we demonstrate via simulation that our experimental design has excellent power, we find no evidence of SD in this cross, suggesting that SDs are not a primary contributor to male infertility in M. m. castaneus and M. m. domesticus hybrids. Nonetheless, this approach has a number of advantages relative to conventional methods. Specifically, our method is more cost effective, more specific to the identification of SD, and more generally applicable to a wide variety of organisms than conventional pedigree-based approaches. We therefore expect that it will be a useful means of studying the frequency and impact of SD in other systems.

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