Posted by Michael Gilligan on 24/11/2017 07:00:35:
This story, on today's BBC News, rather surprised me: **LINK**
http://www.bbc.co.uk/news/science-environment-42103058
The headline is "Galapagos finches caught in act of becoming new species" … But it would perhaps be more true to say "Researchers caught in the act of re-defining terminology, to suit their own agenda"
MichaelG.
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[quote]
In the past, it was thought that two different species must be unable to produce fertile offspring in order to be defined as such. But in more recent years, it has been established that many birds and other animals that we consider to be unique species are in fact able to interbreed with others to produce fertile young.
"We tend not to argue about what defines a species anymore, because that doesn't get you anywhere," said Prof Butlin. What he says is more interesting is understanding the role that hybridisation can have in the process of creating new species, which is why this observation of Galapagos finches is so important.
[/quote]
The poor professor is rather clumsily expressing something that is not 'new' at all.
In the early 80s I was taught that 'species' is a human concept we use to classify living things into useful, homogenous groups, and that as far as nature is concerned it is wholly artificial.
The 'interbreeding' definition was a convenience that has little meaning if applied strictly. To defend its use as well as genetic barriers between species (i.e. they simply cannot interbreed – goats and giraffes) one must resort to brining in other rules such as 'behavioural barriers', 'geographical barriers' and 'well in practice they don't interbreed very often'.
Of course this was more plainly obvious to botanists at the time, but it's plainly nonsense if any thought is given to the methods by which evolution takes place.
Ultimately 'species' is simply a label to help us distinguish individuals from two similar but distinct populations (with little or no gene flow between them) of living creatures when placed side-by side.
The distinction 'sub-species' is even more tenuous and might apply when there is 'limited gene flow between the populations'.
If sepcies wasn't so damn useful for classifying things it would have been abandoned as a concept decades ago. To understand evolution and genetics it is far more useful to think in terms of populations (of individuals that interbreed within themselves and may have different levels of genetic exchange with other populations) and clades (of individuals with a common ancestor). Even these concepts are stained by the realisation that DNA can make dramatic leaps between hugely distinct populations.
Neil
Edited By Neil Wyatt on 24/11/2017 08:41:14