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TOPIC: Splitters and Lumpers
http://groups.google.com/group/entstrees/browse_thread/thread/64ea62681f5a0ae2?hl=en
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== 1 of 5 ==
Date: Sun, Aug 24 2008 12:32 pm
From: "Edward Forrest Frank"


ENTS,

A friend of mine constantly uses the phrase "Splitters and Lumpers" when talking about how people classify things in general and trees in particular. Splitters break down a set into numerous separate categories each based upon the slightest differences between individuals. Lumpers tend group things together in broad all encompassing categories based upon the assumption that this simplified classification has some redeeming characteristics. I recently heard one of his college professors make the same comment. Clearly when talking about trees some of these characteristics can be seen at work. There has been over a thousand varieties of hawthorn described in North America alone based upon minor variations in their form http://dnr.wi.gov/forestry/TreeID/OtherKeys/crataeguskey.htm . The University of Wisconsin is working to eliminate synonyms and merge this cacophony of redundant names into a reasonable listing without so many members http://wisplants.uwsp.edu/scripts/SearchResults.asp?Genus=Crataegus . There should be a degree of reasonableness when working at classifications. Within a specific population there is typically some degree of variation in the make-up of the overall genetic pool and this can result in slightly different forms in different individuals. This does not mean that they are different organisms. Likewise even of there are two individuals with exactly the same genetic make-up the local environmental conditions can cause the individuals to express their genetic make up differently.

Carolus Linneaus proposed the first classification for biological organisms in the 18th century. This taxonomic classification was designed to simplify the complexity of nature by lumping together living species that shared common traits. The purpose of a classification system is to be able to group individuals based upon their similarities and differences into categories, so that comparisons and contrasts can be made within these categories and between these categories. If the grouping is too large, too simplistic, then there is little that can be learned from the category. Say we looked at all the trees in Bob's backyard, if we lumped them all together, what could be said about the group? You could say they were all trees. Little else could be said about the group that would be true for all members. If you treat each tree as a separate category, then there is nothing you can say about what they have in common, and as for differences you can say they are all different in different ways. Neither of these extremes is helpful in understanding the relationships and differences between the trees present.

The categories need to be broad enough and yet distinct enough that in a given population several different groups can be created. Then you can start making comparisons about what members in one group have in common, and how they differ from those members in another group. It allows you to begin to learn about the populations you are studying It allows you to draw initial conclusions about relationships between members of each group based upon their characteristics. The size of each group is also dependant on what information you are trying learn and the size of the population you are examining. Even in a bad classification, the process of dividing the overall population set into smaller categories is a learning tool. If there are mistakes in the initial ordering, then the information you learn by this process can allow you to do a better job during the next iteration of the classification system.

How do you determine the boundaries of the categories? As I said, that may depend on what you are trying to learn from he process. In natural systems there is often a lumping of characteristics. There is a large group of the population that has this characteristic, there is a large group that has another characteristic. Ideally the breaks between categories should coincide with these naturally occurring clusters of characteristics. In other cases there is a more gradational change between one form and another. In these cases if the populations need to be subdivided, then an arbitrary point needs to be chosen. As it is arbitrary, one choice is as good as another, so choosing a practical point is often the best. In a discussion about where we as ENTS should mark the dividing line between different areas of the country -NE vs. SE vs. Midwest, one of the suggestions was to break them along the boundaries of various forest classification systems. That was reasonable. Another suggestion was to break them along purely political boundaries. That was practical. Since the change between two forest classifications may be gradational and indistinct, and may vary depending on the source of the classification system, a compromise position would be to mark the dividing lines along the state boundaries that best match the majority of the general forest classification boundaries.

The overall point to this discussion is that I think whoever came up with the concept of "Lumpers and Splitters" was a lumper. There may be some truth to the statement, but it oversimplifies the problems of classification and misrepresents the efforts of people trying to devise a workable classification scheme for any natural system. Still, the next time I hear the phrase, I will grit my teeth and try to agree...

Ed

== 2 of 5 ==
Date: Sun, Aug 24 2008 12:43 pm
From: DON BERTOLETTE


Ed-
Probably the take-home lesson is that it's good that somebody has studied the species sufficiently that even small differences have been noticed...it's then up to the user to choose what level of accuracy to use for the purpose at hand.
-DonRB

== 3 of 5 ==
Date: Sun, Aug 24 2008 3:27 pm
From: "Edward Forrest Frank"

Don,

The thing is with the hawthorns, when there are these vast numbers of different varieties described for a single group, I must wonder at the validity of the descriptions. I must wonder at possibility or likelihood of multiple names for the same variety. Too much of a good thing is not that great if you can't count on the veracity of the information. The individual variety descriptions do not appear to be ordered into a hierarchy, but are presented as stand alone descriptions done by a number of competing sources. There is no way to tell what is meaningful or not. I did not looked at many of them, but I gave up the task as pointless. I felt a better way to go was with sources that tried to consolidate the multitude into a smaller number of "species" or varieties.

Ed

== 4 of 5 ==
Date: Sun, Aug 24 2008 6:45 pm
From: turner

ENTS and ED

I just used the term 'splitters and lumpers' a few hours ago when I
discovered that Northern Red Oak has been "split" into two varieties
acording to USDA Plants. Q. rubra var. rubra and Q. rubra var ambigua.
I have not made a search yet but can anyone point out some references
that spells out the differences. And this was a species I thought I
knew.
TS

== 5 of 5 ==
Date: Sun, Aug 24 2008 7:05 pm
From: "Edward Forrest Frank"

Turner,

Interesting, http://plants.usda.gov/plantguide/pdf/cs_quru.pdf
Variation within the species: There are different interpretations of variation patterns among trees of northern red oak. A single species without formally variants is sometimes recognized, or two varieties may be recognized.

Quercus rubra var. ambigua (A. Gray) Fernald

SY= Q. borealis Michx. f.

SY= Q. rubra var. borealis (Michx. f.) Farw.

Quercus rubra var. rubra

SY= Q. maxima (Marsh.) Ashe

SY= Q. borealis var. maxima (Marsh.) Ashe

Var. rubra has a shallow cup, to 3 cm wide, enclosing 1/4-1/5 of the nut. Var. ambigua has a deeper cup, to 2 cm wide, enclosing 1/3 of the nut. McDougal and Parks (1984, 1986) found evidence of correspondence between morphological types and flavonoid chemotypes but the evolutionary status and geographic distribution of these have not been worked out in detail.

Ed