[Taxacom] FW: The 'reality' of species boundaries -- Once Again (UGHHH!)

Frederick W. Schueler bckcdb at istar.ca
Sun Sep 20 21:35:32 CDT 2009

Edwards, James wrote:
> But differing genitalia per se are not proof of reproductive isolation. You are *inferring* such isolation. Because genitalia are so closely involved with reproduction, you and most other insect taxonomists believe that they are good indicators of species boundaries. But until you have done the experiments to show that hybridization does not occur between two groups of organisms with different genitalia, you have not discovered any boundaries due to reproductive isolation. You have inferred that these boundaries exist, but you have not really shown that reproductive isolation is the cause. Instead, you have used the morphological species concept to say that you think that these morphological differences are so great that you believe that the species could not/do not interbreed. I do not find that any more "real" or non-subjective than Rich Pyle apparently does.
> The biological species concept is a great theoretical construct, but it has very little relevance, I believe, to what taxonomists do in their day-to-day work. I know of very few taxonomists who "agonise over evidence for or against reproductive isolation". Rather, we taxonomists are agonizing over where we think species-level differences fall within the diversity we see. Some of us then use the BSC to justify those decisions that we have made on morphological or genetic or other grounds. However, until and unless we have done hybridization experiments, we cannot truly assert whether or how reproductive isolation might be involved in these differences.

* see "It is certainly true that the biological species concept is not 
very operational, but, as I have argued elsewhere, no theoretically 
significant concept in science is." Hull, 1979. - 

...the BSC is a theoretical construct that guides how one thinks about 
morphological and genetic evidence, not a requirement that hybridization 
experiments be conducted to test every case of inferred reproductive 
isolation (or of hybridization).

            Bishops Mills Natural History Centre
          Frederick W. Schueler & Aleta Karstad
       RR#2 Bishops Mills, Ontario, Canada K0G 1T0
    on the Smiths Falls Limestone Plain 44* 52'N 75* 42'W
      (613)258-3107 <bckcdb at istar.ca> http://pinicola.ca
If we'd been meant to refer to species by made-up vernacular names,
God wouldn't have created Linnaeus!

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