Example 1: The Cichlids
One day in class we had a prolonged discussion on the high levels of diversity of cichlid fishes in the Rift Lakes that have formed in eastern Africa. These fish represent a textbook example of an explosive radiation. There are estimates of nearly 1000 species of cichlids in these rift lakes, even though the rift lakes are relatively young in geologic time. The lakes formed as a result of plate tectonics because the plate that eastern Africa sits on is slowly pulling away from the rest of the continent. This has resulted in the formation of a deep valley that has filled up with water in some parts. Hence, any organisms living within these lakes had to get there within a relatively recent time frame, and the sheer number of species found there suggest that they must have evolved at an accelerated rate.
While the fish community represents a large amount of genetic diversity, the professor made the comment about how all the diversity might eventually be wiped out if the two plates separated completely. This would be because the rift valley would eventually fill up with sea water, which would obviously kill off any freshwater species. So it's a conundrum. While this system represents a classic example of rapid evolution (side note: there are fish so specialized in these lakes that they only eat the eyeballs or scales of other cichlids), it may also only be a blip on the screen of evolutionary time. That's if all these species eventually become extinct.
I'm not doing the conversation justice here, but I remember it as clearly as the day I sat in the classroom. However, here are the only notes I took during that conversation:
The second picture is the national flag for the country that will be sitting on the shoreline of the newly developed seaway: Dead Cichlid Nation*.
Example 2: Bees
We had another discussion about how we need to be mindful of changing environmental conditions when thinking about conservation and how it pertains to plant and animal distributions. Just because an organism occurs somewhere does not mean that it was always there, just like absence of an organism from a certain area doesn't guarantee that it's never occurred there. Anyone familiar with the fossil record knows that. This could be important when planning reserves. If possible, you want to conserve enough of an area that things can shift around if they need to. That usually isn't possible because of the financial obligations and politics, but it would be ideal.
The example our professor gave us when trying to illustrate this point was the continent of Antarctica. Today it is obviously covered with ice, but that hasn't always been the case. He mentioned a fairly recent study that talked about how Antarctica was once a much warmer place, and showed that bees migrated from Africa to South America across Antarctica (more recently than when all three continents were joined together to make up Gondwana).
Here are my notes from that discussion:
That would be the flag** for Frozen Bumblebee Nation.
*Incidentally, Dead Cichlid Nation would be one of George W. Bush's favorite countries because of the mass extinction rate associated with its formation - so glad that guy's not our president anymore.
**One of my lab mates looked at my notes while I was drawing these flags, and she interrupted the class by laughing too loud. The professor was not as amused. That may have been the reason why he started disliking me. I'm not sure about this.
