BIOL 230 Chapter Notes - Chapter #3: Continental Drift, Indo-Pacific, Palearctic Realm
Document Summary
Pre reading 3: biogeography (ch 18 pg 402-422) China, southeast asia), and australasian (australia, indo-pacific and new. Species diversity greatest at tropics and decreases towards the poles. Vicariance: evolutionary separation of species due to barriers like those made by continental drift. Rece(cid:374)tl(cid:455), (cid:396)esea(cid:396)(cid:272)he(cid:396)s ide(cid:374)tified 11 (cid:271)iogeog(cid:396)aphi(cid:272) (cid:396)egio(cid:374)s (cid:894)i(cid:374)stead of walla(cid:272)e"s o(cid:396)igi(cid:374)al. Suggests that additional isolation mechanisms beyond continental drift are responsible for different regions. Oceans also have barriers like thermal, currents, salinity, oxygen gradients, difference in water depth. Not all groups of organisms show decrease ins species richness at higher latitudes. Sea birds have highest diversity at temperate and polar latitudes. Species diversification = speciation rate extinction rate. 3 broad categories of hypotheses to explain latitudinal gradients in species richness: based on assumptions that rate of species diversification in tropics is greater than in temperate regions. (species diversification rate. ) Theses two factors combine to decrease extinction rate and increase speciation rates.
