When I first started to get into environmental issues, the first term that came to mind was “”ecology“”. Then I learned more about it and realized it was much more than a branch of biology marred with the technical language of ecology and evolution. Ecology, has a much deeper focus than just the material world of Earth. Lifeways and environments are integral parts of the whole process of life and evolution: competition for resources, mutual aid, symbiosis, interactions between life forms on Earth.
As scientists around the world start to reckon with the consequences of climate change, one subject has begun to emerge: the effects of climate change on the natural world. Just a month ago, the Nobel Prize Committee awarded the 2007 Nobel Prize in Ecology to Robert M. Burks and Svante Pääbo for their pioneering work linking the chemistry of life on Earth to the overall history of climate change. The authors are not climate scientists, but the history of ecology scholars, and they use the analysis of ancient plant and animal fossils to gain insight into the likely effects of climate change on ecological communities. By doing so, they can suggest which natural systems might be vulnerable to further climate change and the ways that humans might respond to these changes.
No other theory in the natural sciences fills in so many parts of the history of life and ecology. Instead of focusing on all the single interactions between species, the history of ecology employs a suite of models, each focusing on a different point in time. Most of these models are long-term ecological processes, of which the next important question is how all those interactions relate to the evolution of life on Earth.
Some of those interactions are relatively simple. For instance, in response to shifts in temperature and climate, fungi and certain types of bacteria begin to grow at warmer temperatures. Scientists have now identified how this process may have led to the early evolution of terrestrial plants. And there are also myriad ancient ecological interactions that can be studied using more detailed long-term histories. In doing so, we learn about how the environment changed over time. For instance, in ancient forests, the same species of trees may have grown and fruited at different times in response to changing climate and rainfall patterns.
But even some relatively simple interactions take time to play out, which is a useful thing to know when we are planning how to respond to climate change. For example, insects respond to the climate because they can adjust their strategies, from staying close to the equator to avoiding the sun in the warmer southern parts of the globe. Similarly, some animals adjust their behavior to fit their environment: birds move north to avoid the worst of winter storms, but keep their breeding grounds in the southern parts of the world, and don’t move too far north until spring. So both the ecology of a particular species and the history of that species can tell us when to expect a shift in the environment. For example, if, because of climate change, a bird moved to the northern part of its range, it might not evolve additional migratory behavior in the southern part of its range.
All of these observations explain why biodiversity continues to expand for more than a million years after the last major extinction of the evolution of life. The tree of life goes on because some species keep up with the climate. As long as some species persist, all species have a chance to continue to evolve and respond. This is one of the most powerful illustrations of the importance of understanding the history of ecology.
Of course, the ability to respond to climate change is a necessary but not sufficient condition for the existence of life on Earth. If all the species of the tree of life had been exposed to dramatic shifts in climate long before they came into existence, the tree would have ended up like a pile of matchsticks. The history of ecology can help us understand how those shifts occur. Some were the consequence of extreme meteorological events, such as hurricanes or tsunamis, which moved the pattern of species interactions across millennia. Others were changes to the landscape over a short period of time, such as a long drought or a sudden change in water flow patterns. And some change occurred over thousands of years, like the beginning of the end for several species after the demise of the ancient forests. But this description doesn’t begin to describe the richness and diversity of life on Earth. By looking at a range of models in the long history of ecology, we can learn about the richness of the evolutionary history of life on Earth. It’s this diversity, that has accumulated over millions of years of constant change in the environment, that has made Earth a hospitable place for life.
Categories: Environment and Ecology