Variation in the peacock's train shows a genetic component.

Area of Science:

• Evolutionary Biology
• Behavioral Ecology
• Genetics

Background:

• Female peafowl (Pavo cristatus) exhibit strong mating preferences for males with elaborate trains.
• This preference presents the 'lek paradox': intense sexual selection should reduce genetic variation in male ornaments, yet variation persists.
• Theoretical expectations suggest low heritability for traits under directional selection, such as peacock trains.

Purpose of the Study:

• To estimate the narrow-sense heritability of male ornaments and other morphometric traits in peafowl.
• To investigate the genetic basis of traits involved in female mate choice.
• To address the lek paradox by examining heritability in secondary sexual traits.

Main Methods:

• Two independent breeding experiments were conducted.
• A total of 42 sires and 86 male offspring were analyzed.
• Narrow-sense heritability was estimated for train length, tarsus length, body weight, and spur length.

Main Results:

• Significant heritability was found for train length, a key trait in female mate choice.
• No significant heritability was detected for non-fitness related traits: tarsus length, body weight, or spur length.
• Findings contradict the expectation of low heritability in traits under directional selection.

Conclusions:

• High levels of additive genetic variance can exist in secondary sexual traits subjected to directional selection.
• The study supports evidence for heritable variation in elaborate male ornaments.
• The primary question of what maintains this genetic variation in the face of sexual selection remains an open challenge.