Posted: Sat Dec 27, 2014 6:21 pm
by KoutaR
Lee,

Thank you for the comments and article recommendation! I will read it.

I have always doubted the often-claimed hypothesis that much of the northern temperate angiosperm flora has an Asian origin. How would it be possible that Asia creates more new taxa than other continents? But then I read that there were a connection between the tropics and the temperate zone only in Asia for long time, at least in the Cretaceous. The Tethys Ocean separated Europe and Africa, and there was no connection between North and South America. See a map, for example, in Latham & Ricklefs, p. 302. As the angiosperms have a tropical origin this makes clear that the ~only place to give birth to temperate angiosperm taxa was in Asia.

Larry,

Enlarging the study to the Southern Hemisphere would be interesting. Let's see if I have enough energy to make it. Till now, I have only searched for species congeneric to the northern ones. In western South America the 13.5°C point is somewhere in central Chile and in Australia in southern Victoria. In Africa no coastal place is so cool. In the 168 genera of my material, Chile only has two species of Podocarpus, one Persea and four Prosopis. Victoria has one Podocarpus, two Elaeocarpus, one Ficus, one Symplocos and one Trema. (Sources: http://www.chileflora.com and http://www.rbg.vic.gov.au). Apparently, the tropical zone has been a much better “insulator” between the northern and southern temperate floras than the vast oceans between continents. Continents have broken up, moved and merged but the tropical zone has always been there. I guess southern Australia would win Chile thanks to the large genus Eucalyptus. Also Acacia are numerous in Australia.