Field work after a Mass Extinction

The following is a guest post by Darko D. Cotoras Viedma.

Imagine that somehow you have the chance to travel to the future. A time when you will be alone on this planet and humanity is part of a history that nobody will read. Your mission is to do a biodiversity inventory and try to answer one question: What was the signature of the presence of humans on Earth?

Enclosed on its natural environment the endangered Mauna Kea silversword (Argyroxiphium sandwicense subsp. Sandwicense) is protected with a fence from introduced feral animals. South slope of Mauna Kea. Big Island, Hawai’i.

Right before that future, humanity never took real responsibility for the environment. It centered its efforts on promoting a strongly industrial development which deepened social inequalities. However, this didn’t affect every aspect of life. The interest in market expansion favored the worldwide access to a whole “family” of products and services associated mostly with entertainment and luxury. Immediate desires related to those things could be satisfied in the same way pretty much anywhere in the world. In that sense the world became more “equal”.

As many science fiction authors predicted, the world became dominated by big corporations. In some places it was easier to get access to their products and services than to any other basic needs. Also the movement of people became extremely easy; the average person lived in three different cities during his/her life and one third of world’s population owned a second house.
Humanity gained complete independence from seasonality and weather. Everybody could get any kind of vegetable or fruit year around. Cities were founded in the middle of the deserts or deep in jungles. But, this way of life couldn’t last for long. When it spread to the entire world it was a matter of a century to reach a point of no return. Hundreds of thousands of years after that event your mission starts.

The first thing you notice is the reduction in species diversity. The long announced “Sixth mass extinction” happened and an important part of the biological patrimony was lost forever. In some cases whole branches of the Tree of Life were lost, while in others only some species. But, what really commanded your attention were the survivors. You expected to find hundreds of different species that evolved from the wide spread agricultural plants and animals, however they were all extinct. The domestication of these organisms made them absolutely dependent on us. On the other hand, other organisms dispersed unintentionally by humans had the distribution pattern you expected. The New World was populated by many new species of grasses coming from Europe, while the islands in Oceania were full of new species of rats, geckos and land snails coming from Africa, South America and Asia.

At the same latitude most of the low elevation environments had a similar biodiversity. The same thing happened in shallow waters in the ocean. Everywhere between 100 meters below to 1,500 meters above sea level, you were able to describe a very well defined biological community, the “Human-impacted community”. Interestingly within this community you found some species originally endemic to those very areas. They are the result of past human conservation efforts. Somehow, by establishing biological interactions with all the rest of introduced species they managed to survive.

Outside of the “Human-impacted community” there is another kind of survival species. Those areas weren’t affected directly by humans, but because of global changes extinctions also occurred. The survival species then had very small population sizes restricted to reduced patches of habitat in comparison to their original distributions.

At some point, standing in the middle of what once was a city you look around and only see an extensive forest, a forest comprised of species that initially were on the sidewalks of the streets or in the backyards of houses. This forest is replicated in all the former cities at this latitude, but now after thousands of years, each one has its own species that evolved from once widely spread ornamental plants.

The world you saw in the future was definitely a different place. Somehow less diverse, somehow more diverse. The same as five times before, life was able to recover from a cataclysmic event. After a period of exponentially rapid change, ecosystems evolved into a new configuration that was stable over units of geologic time.

In a geologic perspective it seems clear that life followed its own course. The main consequences of our activities affected us and the unfortunate species that happened to co-exists with us. The preservation of the environment it is not only a problem of sustainability for our own benefit, it is also a matter of respect for others and I am not talking about other humans.

Darko on Molokai

Darko Cotoras, originally from Chile, is a Ph.D. candidate in the Integrative Biology dept at UC Berkeley. He is interested in the historical processes that shape biodiversity, in particular on insular environments. For his dissertation he is studying the temporal dynamic of the adaptive radiation of an endemic group spiders (genus Tetragnatha) from the Hawaiian archipelago. He has also researched terrestrial invertebrates on the Juan Fernández Islands and Rapa Nui.