I came across this request on my "inter-web" journey last night and asked permission to post it here for more exposure. I did post it in the HH but I thought this forum would also be a good place to put it.
Why do we see hybrids between so many ducks? Mallard x Pintail hybrids are regular, and Mallard x Green-wing Teal and Gadwall x Green-wing Teal are shot every season. The list goes on and on…. Wild hybrids between distantly related species are much more common in waterfowl than in other groups of birds. But they are rare enough that assembling a sample for scientific study is impossible without the cooperation of hunters. Thus this plea! Yes, I know the season is over, but hybrids may be lurking in freezers, and this late announcement may help bring us birds from next year’s season.
Hybrid waterfowl are thought to result from forced copulations (rapes) occurring between species or, for a few species, from interspecific brood parasitism (with parasitic young preferring to mate with their host species). Forced copulation in waterfowl is a tactic by which males sire offspring outside their pair bound. But females vigorously resist forced copulations, making haste, aggression, and an explosive penis key to successful rapes (Check out this dorkey video for an overview of duck sex: http://modernfarmer.com/2014/02/fasc...ture-duck-sex/). Presumably the very haste and aggression leading to success in forced copulations sometimes results in males attacking female of other species, thus generating hybrids.
Surprisingly, neither rape nor brood parasitism are well tested as explanations for the high frequency of hybrids in waterfowl, but modern DNA analyses make strong tests possible. The parentage of hybrids can be determined from nuclear genes and the mother and father species of hybrids can be determined from mitochondrial genes. Then, differences between species pairs that produce hybrids can be used to predict their sires. By the rape hypothesis, the father species of a hybrid is likely related to size differences between the parentals and whether one or both parental is characterized by male rape. By the parasitism hypothesis, the sire should depend on whether one or both parental is a brood parasite.
The rub is getting the samples. Birders post hundreds of photos of hybrids but photos are short on DNA, and hybrid waterfowl are far too rare for a duck hunter and museum scientist like me to collect and study. To investigate the origin of waterfowl hybrids we need specimens of hybrids with associated tissue samples for genetic analyses. Crowdsourcing through North American duck hunters seems like the only way to study their origin!
Ideally, we would like to receive whole birds to be preserved as scientific specimens at the University of Washington Burke Museum, where they always would be available for use by researchers, students, and artists. For each hybrid we would save a study skin, a fully extended wing, and a sample of tissue for DNA analysis. Although the skin and wing specimens would be invaluable additions to the science community, I understand that many hunters will not be willing to give up a hybrid they want to mount. When good photos allow us to determine the bird’s parentage, just a tissue sample, taken when the bird is being mounted, will allow us to include it in the study. However, for the interesting case of hybrids themselves producing young (mostly backcrosses), photos are proving to be insufficient to determine parentage, so we much prefer to receive whole birds for detailed study.
If you have taken a hybrid that we can include in this study, please contact me (firstname.lastname@example.org) or Burke Collections Manager, Chris Wood (email@example.com; cell 253-740-1071) directly, and not through this forum. Chris will arrange shipping and can provide tissue vials for hybrids that are going to mounts.
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