Dear all,

It would be nice to quote Mayr (1963). He writes:
The modern definition of the subspecies is exceedingly different fromthat
of the Linnean geographic variety. It (...) may be worded as follows: "A
subspecies is an aggregate of phenotypically similar populations of a
species inhabiting a geographic subdivision of the range of the species and
differing taxonomically from other populations of the species" (1963: 210)
Mayr book is called: Populations, species and evolution (an abridgement of
animal species and evolution).
This definition does not automatically imply geographic separation or
isolation by some obstacle, like a sudden rise of an isthmus (like the
Panama landbridge did) dividing a population into two populations, or the
first colonisation by e.g. birds of an island.
Ponder advocated that there are no differences between Xenophora
conchyliophora from the Caribbean and the ones from the Panamic province,
named X. robusta, and also that this species came into existance somewhere
in the Eocene.
This is based on morphological characters, and not yet (as far as I know)
by DNA analyses.
I do not agree with the phrase:
> To be more than a synonym a subspecies must be consistently different
from
> the other subspecies. If they intergrade they are synonymous, no more
than
> ecomorphs or local variations.
The approach by Man in 't Veld & Visser in their revision of Doxander, i.e.
distinguishing three geographic subspecies of Strombus vittatus, viz. S.
vittatus vittatus from northern Australia, Papua New Guinea and surrounding
areas; D. v. entropi from the Philippines northward to Taiwan and the coast
of the mainland of China; and D. v. apicatus from the Andaman Sea, western
coast of Thailand and connecting part of Malaya and western Indonesia makes
sense to me. They considered S. campbelli and S. japonicus as distinct
species.
> In the case of punctuated
> equilibrium a new species arises geologically suddenly from its parent
> species, without apparent intermediate forms.
This is true, in the case of punctuated equilibrium. But recently it has
been advocated that both gradual changes and the sudden changes occur
(Vaupel Klein, J.C. von, 1994: Punctuated equilibria and phyletic
gradualism: even partners can be good friends. Acta Biotheoretica, 42:
15-48 [I haven't seen this paper but it was referred to by Prof. Dr. E.
Gittenberger, authority on some landsnail families, he is curator of the
Mollusc division of the Nation museum of Natural History from the
Netherlands]), and parapatric speciation -which might very well be the case
in the S. vittatus s.l.- cannot be excluded. And why not break "break such
an evolutionary lineage
into a series of subspecies; they intergrade." into succeeding (sub)species
when through time there is a gradual change from "morph A" via "morph B"
into "morph C"?

Gijs C. Kronenberg


----------
> Van: Andrew Grebneff <[log in to unmask]>
> Aan: [log in to unmask]
> Onderwerp: Subspecies are valid!
> Datum: woensdag 11 augustus 1999 23:12
>
> Gijs, Peter, Paul, Art...
>
> Oops, I goofed! I was listening to a taxonomist, who will remain unnamed,
> about subspecies, without checking it out. But no excuses. Yes,
subspecies
> ARE of course valid, as even  a quick peek into the ICZN code will show.
>
> To be more than a synonym a subspecies must be consistently different
from
> the other subspecies. If they intergrade they are synonymous, no more
than
> ecomorphs or local variations. Thus gradual evolution from one species to
> another does not involve anything that could be called subspecies; we
must
> arbitrarily draw a line and say "before this line all are Species A,
after
> the line all are Species B". We don't break such an evolutionary lineage
> into a series of subspecies; they intergrade. In the case of punctuated
> equilibrium a new species arises geologically suddenly from its parent
> species, without apparent intermediate forms.
>
> Chronostratigraphic or geographic distributions are not reasons for
naming
> subspecies (or species). If fossil shells of different ages are
> indistinguishable they must be considered to be conspecific. Some species
> have a very long timerange (Divaricella huttoniana from New Zealand
springs
> to mind, with a range of middle Eocene to Recent, 45 million years);
> however some such long-lived species might be subdivided on anatomical,
DNA
> etc grounds if the animals of fossil specimens were available for study.
> Without the soft tissues such studies cannot be made and we must go by
> shell features alone. Most species seem to last only about 1.5 million
> years before extinction or evolution into a new species.
>
> Now please excuse me while I go wipe the egg off my face...
>
> Andrew