Re: Naming [Was:Re: Reproductive Selection]

In message <f7a7d245-49d4-49ef-8977-2b2379012696@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>, Mike L <mike_lyle_uk@xxxxxxxxxxx> writes
On Dec 18, 4:22pm, John Harshman <jharshman.diespam...@xxxxxxxxxxx>
wrote:
Rupert Morrish wrote:
> John Harshman wrote:
[...]
>>No reason not to either. There are no rules for assigning species to the
>>same genus or to different genera. You can do what you like for any
>>reason or no reason. That's what "arbitrary" means.

>>>Likewise, the first members of Hominidae (great apes) and the first
>>>members of Hylobatidae (gibbons) would have been very similar shortly
>>>after the speciation event that separated them. You would certainly not
>>>assign them to different families.

>>Unless you happened to feel like it, for whatever reason. Then you would.

> I know that cladists rule the world now, and that all other forms of
> taxonomy have gone the way of leechcraft, but surely there were *some*
> limits on how dissimilar two species had to be before being assigned
> into different genera?

Nothing that was explicitly stated. If you're satisfied with some vague
language like "species can't be put in the same genus if they're all
that different", without specifying what "all that different" means,
then you are welcome to it.

> Humans were probably a bad example. I doubt one could define a
> consistent taxonomic system that would have Homo as a genus.

How would you define a consistent taxonomic system at all, in that
sense? What rules would you advance for defining the limits of genera?
[...]

OK, I'll be the fall guy. As is obvious, I'm not a zoologist, so be
gentle. Could you explain what's going on here, please? To my inexpert
eye, there seem to be systematic differences, not only between, let's
say, mackerel and bananas, but between members of groups resembling
tunny and those of other groups resembling trout and salmon. It seems
reasonable to me to represent those differences and similarities in
the names we give the things, because it carries information. Do you
mean that that information is of no interest or use to a
biologist? ... Or that it is in some sense /false/ information, or not
really even information at all? That science has "grown out of" asking
that kind of question?

I realise that I'm in some danger here of trespassing on the malarial
linguistic swamps which Backspace and UC have made their own, but
those gentlemen need have no fear of a permanent occupation.

Species are generally excepted to be 'real' entities. So are clades. What is not generally accepted is that the *ranks* assigned to taxa above the rank of species are objective. You can look at a clade, and say, yes this is a clade (pace the status of any unexamined species). But, you can't just look at a clade and say, yes this is a genus, or yes this is a family.

For example, what are the objective grounds for placing humans, chimpanzees and gorillas in three genera rather than one?

--
Mike.


--
Alias Ernest Major

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