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Friday, October 31, 2008


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Only your reliable, calm scientific voice can be trusted to deploy terms such as "wacky factor." Though I'm inclined to post a few B ericifolia flowers to illustrate, for your readers, how "dull" the eastern Banksias are. :)

Wonderful photos and narrative.


And I love the caution with which you seem to approach the B gardneri, as though it might run away.

Teresa Gilman

".....for the past 2.5 bajillion years earth's climate has swung between glacials and interglacials...."

Now, is this a trick concept or what? I looked up interglacial and it said "formed or occurring between two glacial epochs"


So, what are they saying then in their mobiusstriptalk?


Philip Gleeson

Ok, Jarrett, so eastern Australian Banksias are still rather weird, but nonetheless there isn't anything quite like Banksia coccinea and certainly nothing quite so odd as the several species of prostrate Banksia in the southwest. The point could be much more strongly illustrated with Xanthosia or Darwinia or even Eucalyptus.

Teresa, the important point to note is that during the Quaternary, due to the influence of Milankovitch cycles on the earth's climate, the earth has swung in and out of ice ages roughly every 100,000 years. Given that this period of time is relatively short compared to the lifetime of most species, which is on the order of 1 to 3 million years, then this climatic cycle is an important determinant of the earth's current biodiversity. Put another way, every species you see in existince today has to have had the ability to survive through ice ages. If they live in a part of the earth where the influence of ice ages is extreme, such as Europe or North America, this means that they have to have the ability to migrate over large distances every time the cycle changes from one to the other. However, in some climatically blessed parts of the globe, the tropics in general, but also a few odd places such as South Africa and southwest Western Australia where the surrounding oceans moderate the climate, the species don't have to move nearly so far. As a result, these parts of the earth have been able to accumulate species to become far richer in biodiversity than other parts of the globe.

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