Cover Image   View/Hide Left Panel  opportunities, these plants
maintained their tropical physiological tolerances and moved out
of northern regions as climates shifted, as opposed to adapting
to colder, seasonal climates and maintaining a northern
distribution. The same sort of explanation, involving tropical
niche conservatism, applies to other major tropical
disjunctions, including subgroups within Melastomataceae (Renner
et al., 2001) and Lauraceae (Chanderbali et al., 2001), the
latter probably moving from east to west through the
boreotropics [for possible additional examples see Krutzsch
(1989), Lavin and Luckow (1993), Richardson et al. (2004),
Pennington et al. (2006)].  A second example is in some ways a
mirror image of the first. This concerns plants that were able
to adapt to cold, highly seasonal environments in the north. The
lineages that did manage this transition were able to move
(often repeatedly and at different times) around the Northern
Hemisphere, especially as a major corridor through