[Taxacom] Justifying species?
releech at telusplanet.net
Sat Feb 16 22:27:55 CST 2008
Read this to mean, "something for everyone (read critic)."
It is certainly overkill.
----- Original Message -----
From: "Bob Mesibov" <mesibov at southcom.com.au>
To: "TAXACOM" <taxacom at mailman.nhm.ku.edu>
Sent: Saturday, February 16, 2008 7:47 PM
Subject: [Taxacom] Justifying species?
> In this recent paper:
> Palmer, C.M., Trueman, J.H. & Yeates, D.K. 2007. Systematics of the
> Apteropanorpidae (Insecta : Mecoptera) based on morphological and
> molecular evidence. Invertebrate Systematics 21(6): 589-612.
> the authors report what seems to be a routine systematic exercise:
> cladistic analysis of a 36-character morphology dataset, COI sequence
> data, and a combined morph/mol dataset, from 21 sampled populations of a
> genus with two described species.
> My query for the TAXACOM list is: is what follows also becoming routine
> in systematics, or is it unusual?
> What the authors do next is review their results in the light of at
> least 6 different species concepts. For example, cladistic analysis
> identifies a lowland clade of this mainly mountain-dwelling taxon. These
> lowland populations have a distinct genitalic morphology, which 'agrees
> with the potentially interbreeding biological species criterion of de
> Queiroz (1988)'. 'As members of this clade also form a distinct cluster
> of haplotypes, and form a diagnosable monophyletic group, this clade
> also conforms to the genotypic cluster species definition of Mallet
> (1995), and the autapomorphic (Donoghue 1985) and diagnosable
> phylogenetic (Eldredge and Cracraft 1980; Cracraft 1983; Nixon and
> Wheeler 1990) species concepts. These populations also inhabit a
> different altitudinal range from all other members of the family, and
> are therefore congruent with the ecological species concept of Van Valen
> (1976), and the adaptive zone criterion of de Queiroz (1998). These
> populations are therefore regarded as a distinct, undescribed species'
> which the authors go on to describe in the formal taxonomic section of
> their paper. They also describe a second new species because
> 'Adults of the population from Hartz Peak possess a unique combination
> of morphological characters... Males from Hartz Peak also possess
> distinct, readily diagnosable, genitalic autapomorphies... These
> features of the genitalia indicate that this population is
> reproductively isolated from all others. The haplotype of the Hartz Peak
> population is also different from that of all other members of the
> family, and constitutes its own, well-supported clade. The Hartz Peak
> population therefore meets the biological species concept, autapomorphic
> and diagnosable phylogenetic species concepts, and genotypic species
> definition, and is regarded as a separate, undescribed species.'
> Some (fill in the number of your choice here) years ago, a
> morphology-only taxonomist presented with the same 21 samples might have
> erected the two new species on genitalic differences alone, either
> without worrying about species concepts or by assuming that genitalic
> difference means reproductive isolation means two new BSC species.
> Here we have taxonomists explicitly considering varied species concepts
> and using their character evidence to build what I might call a
> 'defense' of their decision to erect new species. *In other words, the
> more species concepts the taxon fits, the greater the justification for
> naming it a Linnean species.*
> I haven't seen this philosophical approach to erecting new species
> before. Is it becoming more common now?
> Dr Robert Mesibov
> Honorary Research Associate, Queen Victoria Museum and Art Gallery
> and School of Zoology, University of Tasmania
> Contact: PO Box 101, Penguin, Tasmania, Australia 7316
> (03) 64371195; 61 3 64371195
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