Why do mass extinctions occur?
Mass extinctions have occurred throughout history, resulting in the disappearance of countless species through a variety of extinction events. Now, a new study published in Science has shed light on why these mass extinctions happen, and how we can use this information to possibly predict upcoming ecological disasters.
Massive changes in ecological systems can occur suddenly, and often result in the extinction of the species that are a part of them, as well as the loss of biodiversity as a whole. One of the main challenges in understanding why these changes happen is that they tend to occur under what seems to be steady environmental conditions – thus, they cannot be directly linked to a specific environmental change.
Researchers from the University of Leicester investigated sudden ecological transitions that have happened throughout history, ranging from mass mortality events in the distant past to more recent extinctions that we have witness in the last few decades. Through combining empirical data, mathematical models, and insights from ecological theory, the research team found that sudden transitions in an ecosystem can occur as a result of long-term transient dynamics, which include “ghost attractors” and “crawl-bys.”
A ghost attractor is described as a special configuration of an ecosystem that exhibits “end-state” behavior, but only for a finite period of time. After that time, the system usually goes through a fast evolution or transition to another state which may have very different properties. This transition would correspond to a catastrophe or major ecological shift.
Crawl-bys occur when changes to the dynamics of an ecosystem occur slowly over a long period of time.
“An ecological catastrophe emerging from a ‘ghost attractor’ or a ‘crawl-by’ may be a debt that we have to pay for the actions or mistakes – for example unsustainable use of natural resources – made many generations ago,” explains Sergei Petrovskii, a professor at the University of Leicester. “Our research shows that a healthy ecosystem will not necessarily remain healthy, even in the absence of any significant environmental change. Therefore, better monitoring of the state of an ecosystem is required to mitigate potential disasters.”
Petrovskii also states that this research can help us look for signs of an upcoming catastrophe.
“These findings create a new paradigm as well as a powerful theoretical framework for understanding – and potentially predicting – ecological catastrophes and for their efficient management.”