29 March 2013
There is much to learn from nature. Are ducks racist? I have been asking this for a long time and Mallards seem to happily cross with a variety of Domestic ducks producing hybrids. for an introduction to the topic I suggest reading Paul R. Ehrlich's essay. http://www.stanford.edu/group/stanfordbirds/text/essays/Sexual_Selection.html
What about species not semi-domesticated? What about Widgeons. Well I got a great opportunity to see what is most likely the answer and even managed a picture. A male Eurasian widgeon was feeding along with Canadian Widgeons or Baldpates in the Grand hotel moat area and when he got too close to a female Balpate who had a mate already she let him know what she thought of his European attire. Check the action.
Feeding happily on new grass in tolerated communal setting. Male and female Baldpates nearby no conflict.
Standing side shot.
The racist snub. He gave her a look of interest sidling over but she had already picked a dapper dabbler of her own species. She turned on him with a vicious low head scowl and then a scolding. She seems to be saying, "Don't give me that look buster, you got no chance."
There you have it. Was it a racist snub or was he simply too far out. I observed him later and his luck still hadn't changed even thought there were many females around. This is all about sexual selection. A look is programmed into females and they are not prepared to tolerate anything vastly different. Behaviour patterns that have proven survival value are echoed by the colour patterns and females know this and choose accordingly (my opinion). Widely different variants would have different habitats and adaptations and lower her offspring's chances of survival except for the hybrid vigour outside genes bring. However hybrid vigour may extend physical prowess it may not translate into social prowess, a consideration for social birds.
From the female's perspective she has to weigh potential increased hybrid vigour against risking her eggs on failure due to the male possibly not producing viable offspring due to mutational or expression differences between their genes.
I watched a show on Oasis TV about Marine Iguanas on Galapagos and their adaptations to El Nino'. Seems El Nino' causes severe loss of marine algae and edible sea weed and besides shrinking their bodies with some mystery hormones others opted for breeding with Land Iguanas with their hybrid progeny turning into terrestrial vegans.
The male hybrids however, were not accepted by the female marine Iguanas but if there were more of them they would cross with each other and possibly gradations of hybrids would be created that would be accepted. There is precedent far back in evolutionary history for hybridization as an evolutionary adaptive device to foster increased fitness from exploitation of alternate habitats but fertility had to a factor in the offspring which suggests they weren't quite good species differences anyway. More on Iguanas. http://www.arkive.org/galapagos-marine-iguana/amblyrhynchus-cristatus/
I have seen hybrids of mallards with other domestic duck species and they are for the most part shunned by wild populations.
True species cannot by definition cross with other species. Sexual selection in birds is one of the most finely tuned attributes of the Class from my own experience. Nothing else could account for the huge diversity of colours and patterns we observe. This is a huge topic and a great source of interesting questions can be posited about the mechanics involved.
Apparently, racism is natural in birds despite our political correctness views on the world. Species differences translate into hybridization barriers in some cases early in divergence but in others like mallards and domestic ducks much later.
Copyright 2013 Jorma Jyrkkanen. All rights reserved.
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