Wednesday, December 28, 2016

Relict Ecosystems

Part of what I like about biology is that it includes topics ranging in scale from the analysis of how a single protein functions all the way to how species and whole ecosystems change over geological time. At every level, there is dramatic complexity to be explored.

As the glaciers from the last Ice Age retreated northwards, a whole landscape of ecosystems followed them. Along the way, isolated fragments of those moving ecosystems were sometimes left behind as a species found a microclimate to their liking. The first such relict ecosystems I learned of are the Lost Pines and Lost Maples areas of central Texas. Each of these locales are known for the large numbers of a type of tree not seen over a wide area around them. More recently I learned about Texas Wild Rice, a tiny relict of the ecosystem that northern Minnesota is now known for.

If these relics persevere long enough, they may rejoin the parental populations when the next ice age happens. The relict populations may then blend back into the larger population, or (if they have fully speciated) they may retain a distinct biological identify. American Sycamore trees and their old-world cousins can hybridize, so it isn't certain the extended time apart would result in speciation.