> What definition for species is used in the taxonomy of birds?
The notion of a species is a much vexed question of which there
are wildly differing opinions.
One of the best known species defintion is Ernst Mayr's
biological species concept. In short:
"A species is a group of interbreeding natural populations that is
reproductive isolated from other such groups"
This reproductive isolation need not be absolute. I'm not sure how you
decide when interbreeding becomes significant but Mayr believes his
approach is almost unambiguous for birds. Anyway, his book
"Towards a New Philosphy of Biology" is worth reading.
Even for birds, I'm sure you can find plenty of people to disagree with
Mayr. In fact my theory, is that just as (supposedly) no two snowflakes
are alike, no two biologists have exactly the same view of the species
concept.
You can get a good taste of this in the introduction to Christidis and
Boles' The Taxonomy and Species of Birds of Australia and its Territories.
They describe various problems delinating species and cite differing
views and never, as far as I can see, say actually what species
concept they have used :-)
If you want a very different views talk to a botanist. Reproductive-based
definitions are much more problematic for many plants. Or if you want
a real headache add the dimension of time and think about defining
chronospecies.
If you want an easy life, you can adopt an authority-based species
concept, e.g its a species if Boles & Christidis say it is.
Andrew Taylor
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