Simple reason helps males evolve mo...(chromosome making for fewer interactions...)

In females, a dominant allele can hide the presence of a recessive allele, said Lauren McIntyre, an associate professor of molecular genetics and microbiology in UFs College of Medicine. In contrast to females, which have two X chromosomes, one inherited from each parent, males have only one X inherited only from their mother. This is a simple mechanism that could be working in cooperation with sexual selection to help males evolve more quickly.

Researchers believe this relatively uncomplicated genetic pathway helps males respond to the pressures of sexual selection, ultimately enabling them to win females and produce greater numbers of offspring.

Relationships between gene expression and modes of inheritance have been addressed before, but this study analyzed an extremely large data set that involved most of the genes in the fruit fly genome, said David Rand, a professor of biology at Brown University who was not involved in the study.

This research shows how recessive and dominant traits are important in determining variation in populations, Rand said. The best way to think of it is males play with one card, but females get to play one and hold one. If males have got a good trait, its promoted; something bad, its eliminated. In females you can have a bad card, but a good card can protect it. As a result, females can carry deleterious traits but not express them.

UF scientists analyzed 8,607 genes that are shared by both sexes of a fruit fly called Drosophila melanogaster. Of those genes, 7,617 are expressed differently -- meaning the same genes do different things -- in males and females.

Over the years, fruit fly research has helped scientists understand the role of genes in diseases, development, population genetics, cell biology, neurobiology, behavior and ev
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