Just wondering if anyone has any links or could point me in the general direction. No easy outs like "b/c God made it that way!" I want some scientific reasoning or evidence ;-)

John

In discover magizine I was reading a blip concerning how the lines are drawn between species. Generally animals and plants must breed successfully with the same species and not be able to breed with an individual of another species. After that the lines get murky.

It is my new theory the highly divided Quercus AND Acers should be listed as varieties of the same species since cross pollination is such a problem when trying to get good seeds.

My Metasequoia and Taxodium generally do not cross polinate.

Going by the oak and maple species naming plan Native Hawaiians, Native Americans and Europeans would all be different species of "Homos".

Not to mention the Fagaceae family has only but a few genus' besides quercus in America. Not much diversity in fagus, castanea, chrysolepis, and maybe a couple more I don't know about. Yet quercus has incredible species diversity comparitively.

John

Should read "...can clearly breed with other species within their genus (white with other whites, reds with other reds)..."

There are actually many reasons. Here are a few, described in an extremely cursory manner:

Taxonomy often poorly describes phylogeny: One huge one is that the whole binomial nomenclature system is a human fabrication that does a poor job, in many respects, of explaining the real nature of nature. Although phylogenetic relationships are being better understood and worked into the system, they were poorly understood in the past and often missing or misinterpreted when the various "species" were originally classified. Many relationships and mechanisms for evolutionary development are not easily accounted for in this system. Frequently, the relative closeness of species or other ranks are very poorly represented in the system.

Genetics: Genetics obviously also plays a big roll in this. Multiple factors are at work here, so I'll just leave it at that.

Adaptation to change: Evolution and adaptation are another very important area. The origin of many species (and especially biological varieties) can be traced to events or changes in conditions. Changes in climate and even where land masses were at various times in the Earth's history (can't think of the word for that right now) have obviously been key in determining what species currently exist, but even much smaller things like a mountain range can result in varying conditions and adaptations. If one group of plants experiences a broader variety of conditions than another, it would be easy to see why that would tend to encourage greater variety in the group experiencing the most change.

Distribution: If a type of plant is distributed over a broad area, one would expect to see it face a broader variety of conditions, resulting in greater biological diversity. Also, if a population is split, it's easy to see how that, at least in the mid-term, two very similar but slightly different populations can result. Consider two varieties of the same species that gradually evolve into two separate species.

Take a look at the Wikipedia article on speciation. It can shed some lot of light on this subject. While not directly addressing the question, it explains some of the mechanisms involved.

I still wonder why, for example, acers did not differentiate much (as far as forest trees are concerned) considering their massive natural range while quercus apparently did. That could be attributed to genetics. But then why did the other fagaceae members fail to achieve something similar? Are the genetics of quercus predisposed for variation? American beech has a large natural range (very similar to red maple) and is in the same family but not much in the way of nearly identical relatives. Has quercus been around so much longer that it has had time to differentiate where others did not? Maybe there are a lot of species that did differentiate but are now extinct?

I agree our naming system was not the greatest for fine details when things started getting names. Perhaps an overhaul would benefit science, but no way is that happening.

If someone has a piece of literature with more info, I would appreciate it. Something I could find at the local library perhaps... I am not curious enough to order some hulking piece of horticulture history just for this, though :-)

John

ken

Just a few thoughts. Not married to them.

Dan

A likely explanation is that the hybrids do not reproduce as fast as the purebred oaks. It would not take much of a difference in reproductive success to maintain "pure" species.

As far as the observed diversity, it's a fascinating question. Biologists long wondered why there are so many species of beetles....maybe some biologist is looking at oaks with the same question.

>Perhaps an overhaul would benefit science, but no way is >that happening.

There's a definite group of biologists that would agree, suggesting that classification systems strictly reflect phylogenetic (evolutionary) relationships. There would be some interesting changes (birds as a subset of reptiles, monocots as a subset of the dicots, the term "fish" becoming almost meaningless and so on) Changes are made to classifications all the time, but I doubt a complete overhaul would happen all at once.

Alex