Host–parasite kinship in a female‐philopatric bird population: evidence from relatedness trend analysis

Abstract

Conspecific brood parasitism (CBP), an alternative reproductive tactic where some females lay eggs in the nests of other females of the same species, occurs in many animals with egg care. It is particularly common in waterfowl, for reasons that are debated. Many waterfowl females nest near their birthplace, making it likely that some local females are relatives. We analyse brood parasitism in a Hudson Bay population of common eiders, testing predictions from two alternative hypotheses on the role of relatedness in CBP. Some models predict host-parasite relatedness, others predict that parasites avoid close relatives as hosts. To distinguish between the alternatives, we use a novel approach, where the relatedness of host-parasite pairs is tested against the spatial population trend in pairwise relatedness. We estimate parasitism, nest take-over and relatedness with protein fingerprinting and bandsharing analysis of egg albumen, nondestructively sampled from each new egg in the nest throughout the laying period. The results refute the hypothesis that parasites avoid laying eggs in the nests of related hosts, and corroborate the alternative of host-parasite relatedness. With an estimated r of 0.12-0.14, females laying eggs in the same nest are on average closer kin than nesting neighbour females. Absence of a population trend in female pairwise relatedness vs. distance implies that host-parasite relatedness is not only an effect of strong natal philopatry: some additional form of kin bias is also involved.

Kin structure and choice of brood care in a Common Eider (Somateria m. mollissima) population

“…1; Laurila and Hario 1988; see also Lehikoinen et al 2006). Thus, the overall nesting conditions also contributed to the varying availability of samples (and varying rate of parasitism; see Andersson and Waldeck 2007;Waldeck et al 2008).…”

“…Based on this finding, Andersson and Waldeck (2007) and Waldeck et al (2008) concluded that the high host-parasite relatedness among laying Eider hens is not an effect of natal philopatry alone but also forms some additional kin-biasing mechanism. This means that Eider females recognize first-order relatives (siblings, mother-daughter pairs), and possibly also maternal halfsiblings, when laying parasitically in their nests.…”

“…Molecular studies on waterfowl have established hostparasite relatedness on the one hand, and a negative relationship between female relatedness and nest distance on the other (Gibbons 1986;McRae and Burke 1996;Andersson and Å hlund 2000;Andersson and Waldeck 2007;Waldeck et al 2008;Jaatinen et al 2009). However, this duality cannot be combined into one paradigm unless there is information on the identity of the parasitic females and the whereabouts of their nests.…”

“…Using protein fingerprinting of egg albumen, Andersson and Waldeck (2007) and Waldeck et al (2008) estimated that the mean relatedness in Eiders tended to be higher among host-parasite pairs than among random pairs of spatially close neighbors. Based on this finding, Andersson and Waldeck (2007) and Waldeck et al (2008) concluded that the high host-parasite relatedness among laying Eider hens is not an effect of natal philopatry alone but also forms some additional kin-biasing mechanism.…”

“…It has been postulated that, during their 8-weeklong pre-fledging period, young Common Eiders (Somateria mollissima) might learn to recognize their broodmates and attending females (for reviews, see Ö st et al 2005;Andersson and Waldeck 2007). In cavity-nesting Goldeneyes (Bucephala spp.…”