Super Enzyme Regulates Testosterone Levels In Male Ruffs

A single gene in the shorebird species known as ruffs controls the blood concentrations of testosterone in males, and this in turn affects their appearances and behavior.

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Three adult male Ruffs (Calidris pugnax) are watching a female (out of the picture). The two males with colorful neck plumage are dominant “Independents” whereas the one with white neck plumage is a less dominant “Satellite”. (Credit: Frans Vandewalle / CC BY-NC 2.0)

Ruffs, Calidris pugnax, are medium-sized Eurasian sandpipers that get their common name from the large ruff of feathers that adorn the males’ necks. When raised, this feathery ruff is integral to the males’ ostentatious lekking displays that are intended to attract the attention of the females.

Leks are small areas where groups of males display to watching females and where strong female mate choices are exerted. Leks confer indirect benefits to males and reduced costs to females.

In short, leks are like comparison window shopping for your future childrens’ father. Especially because the males are not choosy with whom they mate with — whereas females most certainly are.

“Females provide all incubation and parental care, so males are just trying to mate with as many females as possible,” said one of the study’s co-authors, David Lank, a research fellow and adjunct professor of biology at Simon Fraser University. “It is a highly polygynous species. Males are half again as large as females … except for the [smaller] female mimics.”