Shared paternity among non-relatives is a result of an egalitarian mating system in a communally breeding bird, the pukeko

Abstract

W ith ex tra-p air p atern ity now known to be com m on am ong m any species of birds, it is not surprising th at males of most species exhibit behaviour th at minimizes the risk of losing paternity. T h e most com m on form of p atern ity assurance is m ate guarding w hereby the m ale closely follows his m ate during her fertile period and attem p ts to prevent other males from copulating w ith her. Even in com m unal or cooperative breeding species w here two or m ore males collaborate in defending a breeding territory, m ate guarding by the alp h a m ale still occurs. H ere we report th a t w ithin com m unally breeding groups of pukeko (.Porphyrioporphyrio) d o m in an t males do not guard their m ates and rarely in terru p t the copulations of unrelated rival males. This population of pukeko meets the conditions of a m odel th at predicts th at unrelated individuals who form breeding coalitions should interact in an egalitarian m anner. DNA fingerprinting revealed a tendency for alpha males to father the m ajority of offspring in a brood, but frequent, u n in terru p ted copulations by subordinate birds assured th at most males w ithin the group had at least some p atern ity . Because the tim ing of ovulation is difficult to predict in female pukeko, individual males m ay be unable to estim ate the proportion of eggs th at they have fertilized, which could explain why most males p articip ate m ore or less equally in p aren tal care.

An evolutionary theory of the family.

“…Both pukekos, Porphyrio porphyrio (an Australasian gallinule), and lions, Panthera leo, form extended families in which the group males may or may not be closely related to one another. Copulation and paternity data confirm that reproduction is shared quite equitably among males when the groups are composed of unrelated individuals, but dominants monopolize reproduction when the potential mate-sharing groups are composed of close male relatives (65,71).…”

A bare-part ornament is a stronger predictor of dominance than plumage ornamentation in the cooperatively breeding Australian Swamphen

“…At this site, Pūkeko live in permanent, mixed-sex social groups of 5-15 individuals that defend an all-purpose territory. Further details on Pūkeko social organization and reproductive ecology are published elsewhere (Jamieson et al 1994, Jamieson 1997. From 2008 to 2013, we captured adult Pūkeko during 5 sampling periods (see Table 1) using trapping procedures that are described elsewhere .…”

Living on the wedge: female control of paternity in a cooperatively polyandrous cichlid

“…Males are usually unrelated and reproduction is often evenly divided among the males ('low reproductive skew', e.g. Burke et al 1989;Jamieson et al 1994;Whittingham et al 1997;Williams 2004). In extended family groups, male offspring help their dominant parents to rear younger siblings in their natal territory and typically reproduction is highly skewed towards dominant males ('high reproductive skew ', e.g.…”