Brood parasitism as an alternative female breeding tactic is particularly common in ducks, where hosts often receive eggs laid by parasitic females of the same species and raise their offspring. Herein, we test several aspects of a kin selection explanation for this phenomenon in goldeneye ducks (Bucephala clangula) by using techniques of egg albumen sampling and statistical bandsharing analysis based on resampling. We find that host and primary parasite are indeed often related, with mean r ‫؍‬ 0.13, about as high as between first cousins. Relatedness to the host is higher in nests where a parasite lays several eggs than in those where she lays only one. Returning young females parasitize their birth nestmates (social mothers or sisters, which are usually also their genetic mothers and sisters) more often than expected by chance. Such adult relatives are also observed together in the field more often than expected and for longer periods than other females. Relatedness and kin discrimination, which can be achieved by recognition of birth nestmates, therefore play a role in these tactics and probably influence their success.

Conspecific brood parasitism occurs in many birds and some insects, fishes, and amphibians. Here, we develop and test a novel molecular technique for ecological analysis, protein fingerprinting (PF), based on isoelectric focusing electrophoresis (IEF) in immobilized pH gradients. It is applied here to albumen from birds' eggs and permits accurate identification of eggs laid by different females. This technique greatly clarifies female alternative reproductive tactics and laying patterns in brood-parasitic Common Goldeneye ducks Bucephala clangula.A small, nondestructive sample of albumen is taken through a hole drilled through the eggshell, which is then sealed with superglue, preserving egg hatchability. IEF yields a rich pattern of albumen bands with extensive variation among females. Observation and video recording of egg-laying by 21 color-marked females showed that they had unique band patterns, which were fully repeatable within and between years.Brood parasitism occurred in two-thirds (13 of 19) of the video-recorded nests of colorringed females, with up to five parasitic females per nest. Of 234 eggs, 36% were laid by females other than the incubating host. These results suggest that intraspecific brood parasitism is more common and important than suggested by earlier studies using traditional methods.Protein fingerprinting yields individual resolution similar to that of a DNA multilocus fingerprinting probe, and has several advantages. The albumen band pattern represents only the laying female, not her mate(s), making it easy to determine the maternity of eggs, and to identify a parasite that spreads her eggs among a number of nests. Albumen can be sampled as soon as the egg is laid, before predation or other losses occur, maximizing sample size and minimizing bias. Protein fingerprinting is relatively inexpensive and easy. It is also useful for several purposes other than maternity determination, such as relatedness estimation for categories of individuals.

No abstract

Conspecific brood parasitism occurs in many birds and some insects, fishes, and amphibians. Here, we develop and test a novel molecular technique for ecological analysis, protein fingerprinting (PF), based on isoelectric focusing electrophoresis (IEF) in immobilized pH gradients. It is applied here to albumen from birds' eggs and permits accurate identification of eggs laid by different females. This technique greatly clarifies female alternative reproductive tactics and laying patterns in brood‐parasitic Common Goldeneye ducks Bucephala clangula. A small, nondestructive sample of albumen is taken through a hole drilled through the eggshell, which is then sealed with superglue, preserving egg hatchability. IEF yields a rich pattern of albumen bands with extensive variation among females. Observation and video recording of egg‐laying by 21 color‐marked females showed that they had unique band patterns, which were fully repeatable within and between years. Brood parasitism occurred in two‐thirds (13 of 19) of the video‐recorded nests of color‐ringed females, with up to five parasitic females per nest. Of 234 eggs, 36% were laid by females other than the incubating host. These results suggest that intraspecific brood parasitism is more common and important than suggested by earlier studies using traditional methods. Protein fingerprinting yields individual resolution similar to that of a DNA multilocus fingerprinting probe, and has several advantages. The albumen band pattern represents only the laying female, not her mate(s), making it easy to determine the maternity of eggs, and to identify a parasite that spreads her eggs among a number of nests. Albumen can be sampled as soon as the egg is laid, before predation or other losses occur, maximizing sample size and minimizing bias. Protein fingerprinting is relatively inexpensive and easy. It is also useful for several purposes other than maternity determination, such as relatedness estimation for categories of individuals.

No abstract