How Does Ultra-violet Light Influence Evolution?
The rest of the talk I'm going to really focus on UV, which is a new interest of mine. Since my first five or six years at Ames, I saw the world through elevated carbon dioxide. How could you explain evolutionary history just in terms of carbon dioxide concentration changes. And then I went to a big paradigm shift and now I'm very heavily into UV; in five years, I'll be doing oxygen or something, who knows. But today, I'm going to give you an earful on UV. Why UV? It turns out there's a lot of good reasons.
Why is UV important to Evolution?
UV is providing evolutionary challenge to life on earth. That's something that we're going to talk more about for the rest of the talk. In the last 15, 20, 25 years, there's been a lot of research on UV radiation. This is because of the concern about the ozone hole, if you will. It's always put in quotation marks in papers. What we're talking about is depletion of stratospheric ozone. Now, what's important here is that ozone protects the earth from UV-B radiation. UV-B radiation is damaging and a little bit of the depletion of ozone allows more UV-B to reach the surface of the earth. There's very little UV-B that reaches the surface of the earth compared to UV-A but because it's so much more damaging, it's very important to know about. I'll drive this point home again prior to actually giving you wavelengths and so on.