Re: Species concepts: a newspaper essay

[John Wilkins <john.s.wilkins@gmail.com>]

I have the following:

"[Naturalists employ the term _species_ in a double sense to denote “two very 
different orders of relations”.] When we call a group of animals, or of plants, 
a species, we may imply thereby either, that all these animals and plants have 
some common peculiarity of form or structure; or, we may mean that they possess 
some common functional character. That part of biological science which deals 
with form and structure is called Morphology – that which concerns itself with 
function, Physiology – so that we may conveniently speak of these two senses or 
aspects of “species” – the one as morphological, the other as physiological." 
[T. H. Huxley, “Darwin on The Origin of Species” published in the Westminster 
Review of 1860]

"LINNEON: _to replace the term species in the Linnaean sense, and to designate 
a group of individuals which resemble one another more than they do any other 
individuals._

To establish a Linneon consequently requires careful morphological comparison 
only." [Johannes Paulus Lotsy, Evolution by means of hybridization, 1916, 27]

"A species is a community, or a number of communities, whose distinctive 
morphological characters are, in the opinion of a competent systematist, 
sufficiently definite to entitle it, or them, to a specific name." [ Regan, C. 
Tate. 1926. Organic evolution. Report of the British Association for the 
Advancement of Science, 1925:75-86, 75)

"Thus in most cases a group can be distinguished as a species on the basis of 
the following points jointly: (i) a geographical area consonant with a single 
origin; (ii) a certain degree of constant morphological and presumably genetic 
difference from related groups; (iii) absence of intergradation with related 
groups." [Huxley, Julian. 1942. Evolution: the modern synthesis. London: Allen 
and Unwin, 164]

I seem to recall that in the book

Wheeler, Quentin D., and Rudolf Meier, eds. 2000. Species concepts and 
phylogenetic theory: a debate. New York: Columbia University Press.

one of the phylospecies proponents argued that character constancy was required 
for species-hood. This would make it a morphological conception. However, given 
that the notion is either so vague as to be a part of almost all conceptions 
that require some diagnosis of species, or so specific as to be excluded from 
all employed conceptions, I think that any further definition is impossible.

Autapomorphic conceptions are, I think, not necessarily "morphological" in this 
sense (the sense of Mayr, that they must have necessary and sufficient 
characters all and only members of that species have, cf Mayr 1996:266f), 
because everyone bar a couple of weirdoes has recognised that species are 
polymorphic and variable, and so too in this case. Given that taxonomies for 
Rosen et al are "synapomorphy schemes", and these are based on a consensus of 
apomorphies, it follows that species, too, can be defined as ensembles and 
consensuses of autapomorphies. But I don't recall seeing this discussed in 
detail anywhere.

Mayr, Ernst. 1996. What is a species, and what is not? Philosophy of Science 
2:262–277.

On 23/10/2010, at 2:52 AM, Roberto Takata wrote:

> Does anybody have ever defined formally "mophological species"?
> 
> Rosen's 1979 definition of species is of a monophyletic (aka
> phylogenetic taxon) species or a diagnosable (aka autapomorphic)
> species?
> 
> []s,
> 
> Roberto Takata
> 
> On Thu, Oct 21, 2010 at 11:25 AM, John Wilkins <john.s.wilkins@gmail.com> 
> wrote:
>> They have but to ask and I can expand upon it :-)
>> 
>> On 21/10/2010, at 11:16 PM, Mike Taylor wrote:
>> 
>>> Sadly, this was not published in the actual newspaper -- just in one
>>> of the blogs associated with it.  Shame: the Guardian's science
>>> coverage is pretty good, but not THAT good.
>>> 
>>> 
>>> On 21 October 2010 14:10, Thomas R. Holtz, Jr. <tholtz@umd.edu> wrote:
>>>> http://www.guardian.co.uk/science/punctuated-equilibrium/2010/oct/20/3
>>>> 
>>>> Thomas R. Holtz, Jr.
>>>> Email: tholtz@umd.edu   Phone: 301-405-4084
>>>> Office: Centreville 1216
>>>> Senior Lecturer, Vertebrate Paleontology
>>>> Dept. of Geology, University of Maryland
>>>> http://www.geol.umd.edu/~tholtz/
>>>> Fax: 301-314-9661
>>>> 
>>>> Faculty Director, Science & Global Change Program, College Park Scholars
>>>> http://www.geol.umd.edu/sgc
>>>> Fax: 301-314-9843
>>>> 
>>>> Mailing Address:        Thomas R. Holtz, Jr.
>>>>                        Department of Geology
>>>>                        Building 237, Room 1117
>>>>                        University of Maryland
>>>>                        College Park, MD 20742 USA
>>>> 
>>>> 
>>>> 
>> 
>> --
>> John Wilkins, Assistant Professor, Philosophy, Bond Uni
>> Associate, Philosophy, University of Sydney
>> john@wilkins.id.au
>> "Correlation doesn't imply causation, but it does waggle its eyebrows 
>> suggestively and gesture furtively while mouthing 'look over there'." 
>> <http://xkcd.com/552/>
>> 
>> 

-- 
John Wilkins, Assistant Professor, Philosophy, Bond Uni 
Associate, Philosophy, University of Sydney
john@wilkins.id.au
"Correlation doesn't imply causation, but it does waggle its eyebrows 
suggestively and gesture furtively while mouthing 'look over there'." 
<http://xkcd.com/552/>