Dive Dry with Dr. Bill

048: The Eco-Evolutionary Spiral

When I first arrived on Catalina in 1969, I had grandiose ideas typical of any recent college grad. Hmmm... I guess nothing has changed. As the marine biology teacher at the old Catalina Island School for Boys at Toyon Bay, I created the "Catalina Eco-Evolutionary Studies Laboratory (CEESL)." In my correspondence with marine biologists throughout the country, that name attracted mild curiosity. Most were not quite sure what I meant at the time, although such thinking has become far more popular over the years. My students seemed intrigued by the concept of the "eco-evolutionary spiral" that I presented in my classes.

This "spiral" was a different way of looking at ecology. Many ecological studies looked at simple "time slices" of ecosystems- how the system functioned at the specific time of the study's data collection. My interest was in the dynamics of ecosystems, how they change over time. In my teaching I emphasized looking at ecosystems over longer time periods and at the changes, both ecological and evolutionary, that occured within them over those intervals.

I'm being unusually philosophical and abstract today, so let me give a very simple and concrete local example. Dive dry with me to the rocky bottom just above the wreck of the Sujac at the harbor end of the Dive Park. If we poke around a bit, we may find a moray eel in a crevice slowly breathing through its mouth. Nearby a group of blacksmith are sheltering in the rocks. This is one time slice of a small portion of the ecosystem. During the next second, one of the blacksmith wanders too close to the moray and is instantly gulped down. The chemicals released by the dying blacksmith trigger another blacksmith to defecate in the rocks out of fear. Within a second (give or take a few nannoseconds), the ecological and evolutionary state of the ecosystem has experienced a small change.

The matter that was tied up as "blacksmith" now will be incorporated into the matter known as "moray." Food chains and food webs do just this... "recycle" matter between species (giant kelp to bacteria to whales). This matter gets incorporated in new organisms. If the organisms are fairly mobile (say a black sea bass), the matter may be removed from the local ecosystem when the fish swims away. Matter is also being recycled in the blacksmith poop. This particular matter is rich in nutrients (fertilizer) and may be incorporated by the seaweeds or even giant kelp as they grow. The matter in the blacksmith "began" as plankton, was partially converted to "blacksmith" which was eaten to become "moray" while some was released in poop which became "algae." Multiply this simple example by the multitude of ecological interactions that occur daily in an ecosystem and you get the picture.

One of the courses I developed while at Toyon was astronomy. One reason for teaching it was a childhood interest in the subject, but I also saw it as a necessary component in a complete understanding of ecology. No, I wasn't thinking about alien life forms (although it certainly is an interesting question). If you understand astrophysics like I don't, you may realize that the early Universe was largely constituted of the simplest elements like hydrogen. Not much there to create life on Earth... yet. As the hydrogen and other matter coalesced into stars, nuclear reactions began which converted these simpler elements into more complex ones including carbon, oxygen and nitrogen which are necessary for carbon-based life as we know it. When these oldest stars supernovaed, their explosions released these newly-created elements into the mix and paved the way for life forms as we know them to emerge. So human beings (and other species today) are the "stuff of which stars are made."

So that's the way matter is recycled through ecosystems over time. What about the evolutionary component? Let's look again at the unfortunate "blacksmith"... er, now "moray." Prior to its being eaten, the genetic material in the blacksmith was a part of the gene pool of the blacksmith population in the Dive Park. Once the "blacksmith" became "moray," that genetic material was removed from the blacksmith population (as well as the poor "blacksmith" himself). The gene pool of the population changed, albeit ever so little. However, such changes are the stuff of which evolution occurs. If enough "blacksmith" carrying a certain set of genes become "morays," a significant change in the blacksmith gene pool may occur.

Let's carry this to its logical extreme. Years ago the "stuff of which stars are made" was concentrated into dinosaurs and other species that existed in the Mesozoic period. After many million years, that matter is now concentrated into humans, redwood trees and goldfish (as well as the rocks and fossils in the physical environment or the oxygen in our atmosphere). So we are also the stuff of which dinosaurs were made. I like to think I'm made of atoms from DaVinci and Einstein, and my future dive buddy of atoms from Lucy Liu (oops, she's still intact... wonder if she dives). All this is the result of an endless (?) spiral in which matter gets recycled through food chains and webs while the systems are undergoing evolutionary change. Does this eco-evolutionary spiral deny the existence of God (or whatever name you prefer)? Of course not, it just means She is working things out slowly and with much thought!

Think about all this next time you encounter a blacksmith or a moray, or maybe an island fox or even a pigeon (yuck)! I know I often do while underwater... sometimes forgetting to push the record button on my camera as matter gets converted from one species to another before my lens.

© 2003 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM weekdays.

Image caption: top- Matter as planktonic copepod, converted to blacksmith sheltering on rocks;
converted to moray eel; bottom- matter as bat ray, being converted to sheep crab,
converted into some mystery predator that ate the sheep crab!

This document maintained by Dr. Bill Bushing.
Material © 2003 Star Thrower Educational Multimedia