Extra-pair paternity and the opportunity for sexual selection in a socially monogamous bird (Dendroica petechia)

Abstract

We used multi-locus DNA fingerprinting to characterise the genetic mating system of the socially monogamous yellow warbler (Dendroica petechia).Over 2 years there were no instances of brood parasitism, but 59% of families (n = 90) contained extrapair sired young and 37% of offspring (n = 355) were of extra-pair paternity. Most hypotheses for extra-pair mating in monogamous species assume a paternity benefit to extra-pair sires, and focus on the benefit(s) to females. However, the assumption of male benefit has been little tested. Among yellow warblers, known extra-pair sires were just as likely to be cuckolded as any male in the population, and there was at least one reciprocal exchange of extra-pair paternity. Nevertheless, among known extra-pair sires, the paternity gains from extra-pair paternity were, on average, greater than the losses in their own families. These results show there is a paternity benefit to certain males. However, the benefit is not absolute but relative and therefore more difficult to measure. The results also suggest that patterns of extra-pair fertilisation are not determined by female choice alone. Most confirmed extra-pair mates were territorial neighbours, but some resided as far as three territories apart, and greater spatial separation was implied in other cases. Thus, the opportunity for extra-pair mating is great. We estimate that as a result of extra-pair fertilisations, variance in male mating success is increased somewhere between 3-fold and 15-fold over that which would result from withinpair reproduction alone. These findings affirm the potential importance of extra-pair reproduction for sexual selection in monogamous species and they support earlier suggestions that extra-territorial forays by male yellow warblers are for the purpose of extra-pair mating.

Extra–pair mating, male plumage coloration and sexual selection in yellow warblers (Dendroica petechia)

“…Variation in parentage (the proportion of the brood sired by the social father) was independent of clutch size and changes in clutch size of renests (Yezerinac et al 1995(Yezerinac et al , 1996. Parentage increased with male size, but was unrelated to plumage streaking or estimated age (table 1), consistent with results from 1992 and 1993 only, that showed parentage and estimated age were unrelated (Yezerinac et al 1995(Yezerinac et al , 1996. Paternity was assigned, respectively, to 17 %, 43 % and 57 % of extra-pair sired young from 4 of 19, 14 of 34 and 11 of 16 nests that contained extra-pair offspring in 1992, 1993 and 1994.…”

“…Paternity assignment was incomplete in 1994, despite all territorial males on the study area being fingerprinted, indicating that some extra-pair sires did not reside within the study area. Non-resident males and perhaps the 5 % unsampled territorial males accounted for unassigned young in 1993 (Yezerinac et al 1995).…”

“…We studied yellow warblers at three sites between 2 and 8 km apart near the ueen's University Biological Station in eastern Ontario, Canada (44m 34h N; 76m 20h W ; described in Yezerinac et al 1995). Colour banding and blood sampling of adults was begun in 1991, when 30-70 % of territorial males at these sites were captured.…”

“…Southern blots were probed with per, effre s' 33.15 and an in-lane lambda size marker. Bands not found in either social parent (novel genetic markers) and band-sharing coefficients between nestlings and the female and male were used to establish parentage as described in Yezerinac et al (1995). These two criteria were never in contradiction.…”

Neighbours vs. strangers discrimination in Water Rail (Rallus aquaticus)

“…They are competing for space, food and fertilization resources (Yezerinac et al, 1995;Webster et al, 2001;Segelbacher et al, 2005;Akçay et al, 2009). In 76 many species, individuals manifest less aggressively towards their neighbours, a phenomenon called "Dear Enemy Effect" (DEE) or Fisher Phenomenon -Dear Enemy (Temeles, 1994).…”