Mick Todd wrote:
>After all, isn't the standard definition of a species -
>reproductively isolated populations? Therefore, if it is
>believed that two taxa overlap and don't interbreed or
>wouldn't interbreed if they did overlap then the taxa are
>different species. To carry this argument through, if two
>populations call differently to each other there would be
>every chance that they wouldn't respond to each other
reproductively.
Ah ... you've stumbled into the great debate in modern
ornithology! This is all about species limits, and the over-
arching philosophy you select to set them. The "standard
definition" you use above is generally referred to these
days as the Biological Species Concept (BSC). Coming up
quickly on the inside lane, and gaining a lot of support, is
the Phylogenetic Species Concept (PSC).
Whereas the BSC uses classic criteria such as you quoted
above, the PSC is more concerned with taxa which have
discrete phylogenetic lineages - usually determined or
confirmed by molecular genetics methods. Under the PSC the
three shrike-tits would almost certainly qualify as separate
species - though for various reasons they may just qualify
under the BSC as well. Any taxon which satisfies both BSC
and PSC criteria these days is almost certain to be
accepted "officially" as a new or separate species.
This story is of course much more complex than my mangled
summary suggests, but time is getting away ....
=================================
Lawrie Conole
Senior Zoologist
Ecology Australia Pty. Ltd.
Flora and Fauna Consultants
88B Station Street
FAIRFIELD VIC 3078 Australia
E-mail:
Internet: http://www.ecologyaustralia.com.au/
Ph: (03) 9489 4191; Mob: (0419) 588 993
Fax: (03) 9481 7679
ABN 83 006 757 142
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