Speciies? you gotta be kidding.

[luckyme]

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Would it help the debate at all to come to a compromise whereby the idea of species is useful and explanatory but the edges are blurry? In other words, it's hard to actually draw distinct lines at the borders of each species, but the concept describes a very real distinction between animals?

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That's essentially a watered down version of what I've been stating, other than the last point which overstates the position 'species' can possibly hold.

A) In many lifeforms there is only an arbitrarily chosen difference between variety and species or any other split you want to make.

B) In lineage studies, changing 'species' every 27 paces or some arbitrary point will add nothing to what you learn or can teach.

C) In those lifeforms , such as mammals, where the ability to interbreed plays a large role in evolution it is still 'just' a major constraint on their future path and not 'the' only influence and it still faces ring species type issues.

C seems the sticking point, but surely ABC make "a VERY REAL distinction" a tough claim to make, unless species were simply built on "the ability to interbreed" and then it would serve the limited ( but important) role that Rduke correctly stresses. Obviously that restricted definition doesn't apply in A and B and is not the lone factor in C.

My split puppy litter on two islands touches on some of that. If one island looks like Hawaii and the other Greenland will the driving force in their evolution be the environment or the isolated gene pool. I asked "have I created two species by splitting them" because they certainly can't interbreed to try and bring down interbreeding to the constraint that it is.

Let's say every 100 years we exchange 1 puppy between islands to slow down the loss of the ability to interbreed. That would modify how they evolve also, but are we going to wait until it's 100% before we call them a new species. WHen it finally happened that mean that a new species appeared in less than 100 years?

I've quoted Dawkins to try and keep myself on target, I'll add a quote from Prof of Genetics, Steve Jones of University College London in his book "Darwins Ghost" p.48 discussing variation and labels -
"For plants and animals - unlike cheese labels - even to discuss whether a particular form is a species or a variety is, quite often, vainly to beat the air."

If species were a cleaned up version of (C) where rings species and hybrids didn't occur then it would serve those restricted areas of biology as the clean, natural joint that Rduke argues for. But they don't and in a large part of nature the more holistic flow arises from genetic study serves much better. Evolution is after all about small changes and slipping 'clean joint species' in places it isn't even helpful needs attention ( as comments by Dawkins and Jones point out).

I 'spose a nutshell of the two positions is that I think evolution could be studied without the concept of species at all ( to take it to the extreme for illustration). We'd study the flow of changes over time and note all the factors driving them including the role isolation of a group plays, whether isolated by islands, mountains or infertile breeding. That is the direction that DNA knowledge tends to send us in anyway. We could computer model evolution without having to teach the computer 'species' ( I'm only guessing but I suspect that's how it is done).

hope that's clearer, luckyme