Thanks for the explanation Ricki. It is interesting that BA (and
BOCA?) seem to use the BSC concept whereas Clements and HBW use PSC. I
wonder if this is a philosophical decision on the part of BA or just
reflects that their list needs updating? Maybe someone from BA can
comment?
Another area where there is a BIG discrepancy is Albatrosses, with BA
recognising 21 species and Clements having only 13 - 2 of which (Waved
and Laysan) are not in our area at all, so he really has only 11
species where BA have 21.
On Wed, 5 Jan 2005 18:18:31 +1100, Ricki Coughlan <> wrote:
>
> Hi everyone
>
> I've been following this discussion on Rosellas with a little interest. I'm
> certainly not trying to bite anyone's head off here and I know that this is
> a bit of a can of worms and that this can has been kicked plenty of times
> before, but I am surprised that so many correspondents adhere to the old
> Biological Species Concept (BSC).This conception, which broadly states that
> if an organism can breed with another and the resultant offspring are viable
> then the organisms in question are of the same species, is largely
> discredited nowadays. This conception really doesn't work very well with
> most forms of life and certainly doesn't work well with birds at all. Its
> weakness is definitely demonstrated here in the case of Rosellas. Here, we
> have a number of very unique types of birds in the Platycercus genus and yet
> because many of them can breed with several others this old BSC is used to
> mount an argument that this group be reduced to a few species only. I can
> think of many reasons (both philosophical and practical) why such a position
> is fraught with danger but it certainly fails to adequately reflect the
> diversity of this assemblage of birds: ie. the reality.
>
> On the other hand, there is the Phylogenetic Species Concept, which states
> that if a cohesive population of organisms exhibits a distinct character or
> characters, then these can be considered to be a "type", or "species". This
> conception deals with these issues far more elegantly and in closer accord
> with our knowledge of genetics and cladistics. The boundaries are frequently
> drawn within a narrow realm of genetic variation so that we do not end up
> with "splitting" ad infinitum. This is a concept which is not only
> satisfactory at all times (try applying the BSC to many marine species!) but
> also reflects the diversity of life more precisely. The most frequent
> argument I hear against this concept is posed by folk who don't wish to have
> to deal with a greater variety of species or two volume field guides.
> Unfortunately, we have to deal with the reality of nature around us if we
> are to gain a more complete understanding of it. This should not be held
> back simply because we might desire comfort and familiarity in our
> recreational pursuit of bird watching.
>
> I think that it can therefore be easily resolved that each of these birds
> reflects the diverse genetic nature of the Platycercus genus as each
> displays distinct characteristics. The Yellow Rosella, Adelaide Rosella,
> Crimson Rosella, Green Rosella, Northern Rosella, Pale-headed Rosella,
> Eastern Rosella and Western Rosella are each distinctive types of Rosella
> and are therefore distinct species of Rosellas. That gives us eight species.
>
> Sorry if I've trodden on toes, but that's reality as I see it (and as seen
> by many who are far more learned than yours truly).
>
> Happy birding
> Ricki
>
> Broome WA
>
>
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