PPT Slide

so, in general, a given area has a

richer biota if it is in humid low latitudes

WHY?

we have seen some ecological

(climate; productivity) reasons for this

but also HISTORY is relevant:

PERSISTENCE

GLACIATION

ISOLATION

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Notes:

explaining these trends:

endemism is especially enhanced by topographic diversity and other physical forms of isolation - thus Madagascar, Australia, Indonesia etc.

HOT-SPOTS are usually low-lat. (and therefore hot & humid) but also isolated from other areas which has permitted INDEPENDENT EVOLUTION OF NEW FORMS………… we shall meet this again.