Are UK bird feeders causing Incipient Speciation in Blackcaps?

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Offline AllenG

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The split that the researchers observed followed the recent establishment of a migratory divide between southwest- and northwest-migrating blackcap (Sylvia atricapilla) populations in Central Europe after humans began offering food to them in the winter. The two groups began to follow distinct migratory routes wintering in Spain and the United Kingdom and faced distinct selective pressures. Under that pressure, the two groups have since become locally adapted ecotypes. (Ecotypes represent the initial step of differentiation among populations of the same species, the researchers explained. If ecotypes continue down that path, they can ultimately become separate species.)


It seems that a sub population of blackcaps are migrating to the UK about ten days before the rest of the population and breeding before the rest wing in from Spain.  The two populations can be distinguished visually about 85% of the time.
The "new" species have rounder wings and smaller beaks.

Pretty neat.


Offline litespeed

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Allen - RE Speciation

This is a very interesting topic. For instance, it is clear that certain moths change their coloration within a few generations depending upon the back drop colors they live in.  The study I am aware of [but don't have reference too] is from the UK.

If I recall correctly, in the old days - with lots of coal burning - certain trees were darker in color as a result of the soot. The moths were brown. Later, after coal soot became controlled, the trees reverted to their more natural grayish color as did the moths.

The problem I have is the definition of species. Different species can breed together. Dogs and Wolves, for instance. Polar Bears are simply white colored Brown [Grizzly} bears that can perfectly interbreed. Some species such as donkeys and horses can interbred, but their progeny can not. Thats sort of where I draw the evolutionary line.

Accordingly, the genetic difference between Poodles and Grey Wolves is little more then appearance and temperment.  And the only difference between a Pit Bull and Poodle is little more then appearance and temperment. Whats the big deal. 

The only apparent importance of one animal over the other in this area is what the hell it LOOKS like and what it might prefer to eat.  I sort of find this intrinsically offensive. Accordingly, if bird feeders help select for a certain bird with a bit different migratory pattern, and a certain differentiation in diet, to me that is simply a curiosity niche organization of biologic creatures.

However, I can just SEE the US EPA becoming horrified that people have given up bird feeders and this New Species is now endangered.