Sexual practice of polygyny skews genetic variability

Sep 26, 2008

Researchers have found DNA evidence that polygyny, the practice among males of siring children with multiple female partners at the same time or successively, has led to an excess of genetic diversity on the X chromosome relative to the autosomes. Details are published Sep. 26 in the open-access journal PLoS Genetics.

Women have been more successful on average in passing their genes on to the next
generation. "This is because a few males have fathered children with multiple females, which occurs at the expense of other less successful males", says Dr. Michael Hammer, ARL Division of Biotechnology at the University of Arizona.

The group has found DNA evidence that polygyny, the practice among males of siring
children with multiple female partners at the same time or successively, has led to an excess of genetic diversity on the X chromosome relative to the autosomes. Details are published September 26 in the open-access journal PLoS Genetics.

The X chromosome is present in two copies in females and a single copy in males. The autosomes, which are inherited equally by both sexes from each parent, are expected to have more genetic diversity than the X chromosome in a population with an equal number of breeding males and females.

The article examines potential demographic and evolutionary forces that have led to higher than expected genetic variation on the X chromosome. The research team measured levels of neutral polymorphism at 40 independent loci on the X chromosome and autosomes in ninety humans representing six populations, including: Biaka (Central African Republic), Mandenka (Senegal), San (Namibia), French Basque, Han Chinese and Melanesians (Papua New Guinea). The group contrasted alternative explanations for the higher observed levels of X-linked (versus autosomal) diversity.

Background selection, changes in population size and sex-specific migration were
all discounted as contributors to the observed patterns of genetic variability. Only the process of polygyny could by itself account for the sex ratio skew and resulting patterns of genomic variation. By this process, fewer unique male genes are being passed into the next generation.

The group's research highlights how unseen, sex-biased forces have shaped genomic patterns of variability. Over the long-term, the findings may provide lessons on the dynamics of beneficial mutations on different chromosomes as they sweep through the population.

Citation: Hammer MF, Mendez FL, Cox MP, Woerner AE, Wall JD (2008) Sex-Biased Evolutionary Forces Shape Genomic Patterns of Human Diversity. PLoS Genet 4(9): e1000202. doi:10.1371/journal.pgen.1000202 dx.plos.org/10.1371/journal.pgen.1000202

Source: Public Library of Science

Explore further: Sharks off the menu and on the tourist trail in Palau

add to favorites email to friend print save as pdf

Related Stories

Ray tracing and beyond

34 minutes ago

Ray tracing is simple to explain at one level: "We all do it all day long: That's how you navigate the world visually," Gene Tracy explains. "The fact that I know that you're sitting there and not over there is because the ...

Going to extremes for enzymes

34 minutes ago

In the age-old nature versus nurture debate, Douglas Clark, a faculty scientist with Berkeley Lab and the University of California (UC) Berkeley, is not taking sides. In the search for enzymes that can break ...

Recommended for you

An uphill climb for mountain species?

3 hours ago

A recently published paper provides a history of scientific research on mountain ecosystems, looks at the issues threatening wildlife in these systems, and sets an agenda for biodiversity conservation throughout ...

Extinctions during human era worse than thought

4 hours ago

It's hard to comprehend how bad the current rate of species extinction around the world has become without knowing what it was before people came along. The newest estimate is that the pre-human rate was ...

User comments : 0