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what makes a species?


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#41 Guest_mywan_*

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Posted 04 March 2011 - 09:32 AM

In your main points I agree with you almost entirely. About the only thing I can take exception to is the characterizations of points I was trying to make. My point in using set theory was to outline why such an approach is broken, as further articulated by your rejection. The main general idea I wanted to combat was the idea of the importance for biologist to come up with a species definition that lacked any degree of self contradiction. Hence I was using more concise models to illustrate how its (set theory, etc.) application to species was irrevocably broken.

With regard to "bar-coding ecologists" again you have perfectly made the point I was trying to make when you said: "demonstrated to NOT be a good approach". I was merely trying to use a comparative system to illustrate exactly why is was NOT a good approach. As well as pointing out some of the potential consequences of presuming otherwise, in agreement with your statement, "positively misleading".

Yes, I did use the idea of a definition a lot. This is because the implicit assumption when it is posited that biologist need a purely objective species definition entails it. Hence by speaking in terms of definitions I was attempting to illustrate exactly what was wrong with the implicit assumption that such a definition was either possible or needed.

Now the final point concerning statistics to come up with some estimate of species "boundaries". In fact the statistics I described does not define a boundary, but defines the loss of clear boundaries. Obviously the boundary between an armadillo and a chicken is not a problem. But between various groups of gorillas or salamanders the boundary is not always so distinct. So I was not defining a boundary, I was defining the loss of certainty in such objective boundaries. This points back to, and justifies, all the other points which we apparently agree on.

I also previously included paragraphs supporting BSC and its very real importance in spite of the lack of objective "boundaries" in many cases, or even the possibility of purely objective boundaries. That lack of possibility is why I embarked on statistically defining when that boundary likely begins to lose any objective "definition".

#42 Guest_Elassoman_*

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Posted 04 March 2011 - 01:00 PM

Behold the baby diaper;

An unnatural tool created and used by people to organize a messy natural process. It doesn't always fit perfectly, but it does the intended job for an undetermined period of time. Taxonomy is the diaper used to organize the mess of evolution into discrete packages. By asking "What makes a species?" you are essentially asking "What makes a full diaper?".

Sometimes the answer is easy; each morning the baby's diaper is inevitably full.... Equivalently, a pugnose minnow is a pugnose minnow, and a golden shiner is a golden shiner.

Sometimes it is less cut and dry. What if the baby has diarrhea? What are those fish in the grey zone between Spotted Sunfish and Redspotted Sunfish? Burgundyspotted Sunfish? The answer is not as simple as "well we need to get more data". More data will allow us to draw a finer line on a map, but until evolution stops there will ALWAYS be a grey zone.

As a parent, you will at some point face this grey zone, "should I change it now, or wait until after lunch?"... In making this decision, you can't use a single criterion, but must consider a number of factors, which need not be listed here. This is the same debate faced by the taxonomist when attempting to describe a species. How much genetic or morphological variation is enough? What if I have missed some critical piece of information? What if the species breed in captivity? etc...

Expecting a single species concept to adequately define all species is like expecting a robot to take care of your baby's excrement. Each diaper is different, and no robot could perform that function to your satisfaction. We do the best we can with the options available. Species (as genetically or morphologically definable entities) don't last forever. Most die out, others diverge into different forms, and some are assimilated with other lineages through introgression. No species concept adequately addresses the latter process, although it happens frequently.

Taxonomy and diapers, however imperfect, are worth fooling with. Putting a name on a group of distinct populations allows state agencies to develop a conservation plan, and might prevent the undetected translocation and/or exinction of native genotypes. The goals (in my mind) are to understand and protect biodiversity, which exists at all levels of biological organization. It's value can only be effectively communicated to others when we transform a continuous process into discrete classifications. So, we use diapers, a discretionary tool, to define a continuous process. If not, what is the alternative?

- By the way, this Elassoma question is particularly familiar to me. Elassoma zonatum contains at least eight distinct mitochondrial lineages. Your fish from South Carolina are not in the same lineage as the fish from Indiana. If you notice any physical differences between them, do tell.

Edited by Elassoman, 04 March 2011 - 01:02 PM.


#43 Guest_gerald_*

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Posted 04 March 2011 - 01:28 PM

Taxonomy is the diaper used to organize the mess of evolution into discrete packages.


Wow, that's as beautiful as it is profound, Mike. A great opening line for a book on evolution, a Theme for EEEF, T-shirts, or Biology Dept bathroom graffiti. I'll definitely steal it. ... and welcome back. Guess we know what's been keeping you away.

Edited by gerald, 04 March 2011 - 01:29 PM.


#44 Guest_smbass_*

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Posted 04 March 2011 - 03:19 PM

Perfectly described Mike, I really like the analogy it works very well. Then again maybe I just think so since I can relate to it so well right now...

#45 Guest_fundulus_*

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Posted 04 March 2011 - 06:24 PM

Yeah, a tour de force of conceptual reorganization. Or, I think it's really good.

#46 Guest_farmertodd_*

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Posted 04 March 2011 - 07:41 PM

I think you've also coined a new on-the-road euphemism... 'Scuse me guys, I need to go breed some golden shiner. :)

Todd

#47 Guest_mywan_*

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Posted 04 March 2011 - 07:41 PM

Behold the baby diaper;

Wow, I always did prefer the firm ones, and tended to pass the buck on the messy one. Mike cleaned up that messy one better than I ever could have.

#48 Guest_baker46947_*

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Posted 07 March 2011 - 10:51 AM

I have thought about the spread of species into and around an area/land mass. It amazes me that animals, plants and other living organisms can stay so simular so far apart and that they started as an occupant of an area so long ago. To call a specimen a species is for the accidemics. I just find them at a wonder of how life works. That is the best I can do with this. I thought that there was only Johnny Darters growing up and now it is for me, OH MY!!!!!
Please excuse my spelling

Edited by baker46947, 07 March 2011 - 10:53 AM.


#49 Guest_farmertodd_*

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Posted 07 March 2011 - 12:38 PM

Believe me, it's all about OH MY for the academics, and helping others hit those OH MY moments too :)

Todd

#50 Guest_nativeplanter_*

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Posted 07 March 2011 - 12:43 PM

To call a specimen a species is for the accidemics. I just find them at a wonder of how life works. That is the best I can do with this. I thought that there was only Johnny Darters growing up and now it is for me, OH MY!!!!!


And therein lies all the fun, doesn't it!

#51 Guest_baker46947_*

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Posted 26 September 2011 - 06:47 PM

I was reading Aquarium fish magnzine (February 2000) today and some of the points were brought up in this discussion topic. The artical was basicly about the differences between the "wild/natural" fish that came into the fish hobby, and what we have in the hobby today.
Can this lead to a new/ different species in time? Is this a possiblity?
It appears that mankind is doing what nature does, but to our choosings and not survival's. Isolate a species long enoungh and it can change?- right? That has been an arguement here that captivity changes a species from natures's form over time(spring Pygmy sunfish). Or an introduced species that can enterbreed with indemic species, Sheeshead Minnows in the Southwest water ways with other pupfish. Platty and swordtails being so close to each other and used to trasfer a color from one to the other. How long before we call this "a new species"?
How long before we have a "long fin Longear sunfish"?

#52 Guest_baker46947_*

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Posted 26 September 2011 - 07:00 PM

I was reading Aquarium fish magnzine (February 2000) today and some of the points were brought up in this discussion topic. The artical was basicly about the differences between the "wild/natural" fish that came into the fish hobby, and what we have in the hobby today.
Can this lead to a new/ different species in time? Is this a possiblity?
It appears that mankind is doing what nature does, but to our choosings and not survival's. Isolate a species long enoungh and it can change?- right? That has been an arguement here that captivity changes a species from natures's form over time(spring Pygmy sunfish). Or an introduced species that can enterbreed with indemic species, Sheeshead Minnows in the Southwest water ways with other pupfish. Platty and swordtails being so close to each other and used to trasfer a color from one to the other. How long before we call this "a new species"?
How long before we have a "long fin Longear sunfish"?

Oh by the way I want to thank you all for giving us your knowledge for this topic, as well as others, it is a privilege to learn from you.

#53 Guest_Usil_*

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Posted 26 September 2011 - 07:05 PM

I remember we argued about the definition of species in my Taxonomy class for a long long time. In the end, it has been 42 years now, I can't remember what we drew a concensus on. Even if we did, it is probably out dated by now and that is the rub. Science moves on. Grouping characteristics is defined by who characterizes the grouping. I liked the simplest definition. Ability to breed and creat viable offspring. Seemed less messy. Anything beyond that and you won't get a consensus.


Usil

#54 Guest_MichiJim_*

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Posted 26 September 2011 - 07:26 PM

This is too much fun to ignore, but there is really nothing more to add. The diaper analogy is as good as any.

Taxonomy is a necessary evil amongst biologists. We need it to provide order to that which cannot be ordered. It is totally an artificial creation, based on ongoing discovery catching up to an ongoing evolutionary process. Like the pea under the shell, its always on the move.

I love it and study it, but sometimes I would rather just watch the fish swim by.

#55 Guest_IvanMike_*

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Posted 01 October 2011 - 08:11 AM

Yeah, a tour de force of conceptual reorganization. Or, I think it's really good.


Amen. (course, I'm an agnostic or Dawkins category #6)... :tongue:

There is a use for philosophy in scientific endeavors, but strangely, you never read about their discoveries, only their critizisms (e.g., there is no such thing as math and numbers, humans made this up... :biggrin:)

Clearly the differentiation between species becomes fuzzy at times, but the nuances of the organisms in question must be taken into account. Are the various Lepomis species in their own right? I would vote yes, despite their tendency to hybridize when geographically separated populations are mixed (alas for the poor native CT pumpkinseed, who is slowly turning into a "pumpkingill". The unfortunate acceptance of ciclid hybrids such as blood parrots (the inventors of which should be strung up IMO), and Flowerhorns (which once again IMO have nothing on their parents) blurs the lines again, but just as lepomis are, many cichlids are separated geographically by genus, and hybridization is rare to non-existent in the wild, but become common in aquaria where there is no partner of your species to be had and all that food and high temps puts you in rut.

Clearly cladistics et al are in need of some tweaking, and it is true that mathematics is quite helpful (probably indispensable?) to biology, but sometimes people just like to hear themselves talk.... :wink:



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