[Taxacom] Fwd: Re: Metapopulation lineage species concept

Daniel Janzen djanzen at sas.upenn.edu
Sun Oct 18 09:36:46 CDT 2009 

If history becomes an issue, let me just add that when I was a 
graduate student in Berkeley Department of Entomology in 1963-1965, 
the notion of species as "separate evolutionary trajectory" was 
rampant among us as basic speciation and definition fabric (without 
thinking of it as having an origin in any particular person or 
writing, but rather as simply "logical"), which is why when Mayr's 
book appeared on our desks (1964 I think) it was gobbled up and 
happily used as a thinking device about the real world we were 
seeing.  Equally history, at that time the ICZN was one of the 
chapters of the Bible and we carefully read it sentence by sentence, 
marveling as to could the French version really say the same thing. 
Finally, for fun, I was severely chastized for attending seminars in 
the Botany Department.

Dan Janzen, UPenn



>From: <Don.Colless at csiro.au>
>To: <Richard.Zander at mobot.org>
>Date: Sun, 18 Oct 2009 17:34:58 +1100
>Thread-Topic: [Taxacom] Metapopulation lineage species concept
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>Subject: Re: [Taxacom] Metapopulation lineage species concept
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>Maybe my memory, like other organs, is wearing out; but I seem to 
>recall that the notion of a species defined by having a "separate 
>evolutionary trajectory" goes back to George Gaylord Simpson, some 
>time in the 40's or 50's. If so, it would be nice to acknowledge the 
>priority.
>
>Donald H. Colless
>CSIRO Div of Entomology
>GPO Box 1700
>Canberra 2601
>don.colless at csiro.au
>tuz li munz est miens envirun
>
>________________________________________
>From: taxacom-bounces at mailman.nhm.ku.edu 
>[taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Richard Zander 
>[Richard.Zander at mobot.org]
>Sent: 18 October 2009 02:56
>To: Jody Haynes; taxacom at mailman.nhm.ku.edu
>Subject: Re: [Taxacom] Metapopulation lineage species concept
>
>A small splash, a wavelet:
>
>Just because there are many alternative species concepts does not 
>throw doubt on the One True Species concept (which in my opinion is: 
>there isn't any, and systematics exists to classifiy species, not 
>necessarily to figure out how they variously originated).
>
>The phrase "separate evolutionary trajectories" is loaded. If you 
>feel that all (molecular or morphological) lineage splits are 
>followed by gradualist accumulation of important traits in the 
>daughter lineages, then you have separate evolutionary trajectories, 
>but gradualist evolution in all taxa (based on expressed traits) is 
>contradicted by fact. Taxa commonly remain in expressed-trait stasis 
>for hundreds of thousands or millions of years. An ancestral taxon 
>theoretically might have many daughter taxa that have separate 
>evolutionary trajectories, but remain static. In any cladogram, you 
>can have n minus 1 ancestral taxa.
>
>Practically, two isolated populations may not have separate 
>evolutionary trajectories if stabilizing selection is the same for 
>both. Suggesting that neutral traits can accumulate differentially 
>in each is an okay explanation for some situations of geographically 
>isolated species-pairs, but many long-isolated populations stay 
>identical (in expressed traits, though accumulating non-coding 
>traits) for geologically long periods. The observation for these 
>should be that neutral traits do not accumulate for some reason 
>(e.g. for that particular habitat, any neutral traits possibile 
>within phyletic contraint of structure and habitat are quickly 
>stomped on).
>
>Sometimes, sometimes a new approach simplifies scientific work, 
>reveals a True Path based on fact, betters facility of reason, and 
>is celebrated. Most times, new approaches are quick fixes or 
>cartoons.
>
>_______________________
>Richard H. Zander
>Missouri Botanical Garden
>PO Box 299
>St. Louis, MO 63166 U.S.A.
>richard.zander at mobot.org
>
>
>________________________________
>
>From: taxacom-bounces at mailman.nhm.ku.edu on behalf of Jody Haynes
>Sent: Wed 10/14/2009 7:43 AM
>To: taxacom at mailman.nhm.ku.edu
>Subject: Re: [Taxacom] Metapopulation lineage species concept
>
>
>
>Thanks, Alex. Point taken.
>
>As a non-taxonomist who has described new species and who has 
>struggled his entire professional life with various species 
>concepts, I find de Queiroz's simplistic and elegant explanation of 
>"the species problem" both refreshing and illuminating. 
>Specifically, according to my understanding of the "general 
>metapopulation lineage concept of species," the fact that two groups 
>of connected populations are evolving separately is sufficient for 
>them to be considered separate species, regardless of whether the 
>two groups have acquired any or all of the properties that those who 
>adhere to any of the 20+ contemporary species concepts would 
>consider as 'necessary' for the two groups to be considered valid 
>species (i.e., intrinsic reproductive isolation, monophyly, 
>ecological distinctness, diagnosability, etc.). The actual 
>'contingent' properties involved (or recognized as 'important') are 
>irrelevant; rather, it is the very fact that the two groups 
>currently have separate evolutionary tr
>  ajectories that is sufficient for them to be considered distinct 
>species. From a conceptual standpoint, this generalized species 
>concept represents a significant paradigm shift away from the 20+ 
>myopically focused (and admittedly biased) 'species concepts' and 
>toward a unified concept that is more inclusive and more 
>general-with the 20+ myopic concepts now appropriately relegated to 
>nothing more than specific examples of the general concept. In 
>application, I see this as a significant advance as well. because 
>now one simply needs to present (and justify) a testable hypothesis 
>as to how any given group (metapopulation lineage) is distinct from 
>other such groups as a means of identifying (or circumscribing) a 
>species. Different approaches of study (and types of data gathered) 
>will obviously focus on different 'contingent' properties, but the 
>ultimate goal is simplified because one simply needs to show how a 
>given group of populations are connected genetically and evolving 
>separ
>  ately from other such groups.
>
>
>
>Bracing for the tsunami...
>
>
>
>Jody
>
>
>
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