The Species Balancing Act

By April 8, 2022 No Comments

One of the most common messages in conservation is that we need to protect species; from polar bears in Canada’s arctic to tigers in India, the focus on species is prevalent internally in the conservation world and also in the mainstream media. Many people believe that we should protect species because they have an intrinsic right to exist. This is a compelling and logical argument, but there is also a compelling scientific basis for species-based conservation.

Species are the basic units of an ecological community. In nature, a community is made up of all the living things (plants, animals, bacteria etc.) in a given area and the ways in which they interact. Often, communities are very complex, and the number of interactions between species is nearly impossible to count. Some familiar interactions in communities are predator-prey relationships, herbivory, and symbiosis.

In a community, each species interacts with at least one other species, and a sudden change in the presence of a species can have rippling effects through the entire community. For example – imagine a simple community that consists of blueberry bushes, deer, and mountain lions. The deer eat the blueberries, and the mountain lions eat the deer. Imagine if the mountain lions (currently an endangered species) suddenly go extinct. Now, the deer have no predator to keep their population in check. This will lead to a sharp increase in the deer population, which may sound like a big win for the deer! All of those deer, however, will need to eat. This means that more deer will be eating blueberries, and the blueberries may not be able to keep up with this increased herbivory. Eventually, the large deer population may eat all the blueberries in the community. This causes a severe lack of the resources needed to support such a large deer population, who will begin to experience starvation. Eventually, the deer will literally eat themselves to extinction, and the whole system will collapse. This phenomenon is called a “trophic cascade” as the effects of losing the mountain lions cascade through the trophic levels, or levels of the food chain.

Thankfully, real-world communities are far more complex, with manymore interactions. Additional predators for the deer will help keep their population down after the loss of mountain lions. Extra sources of food for the deer will keep their population safe from starvation if their numbers do increase sharply. Typically, the more interactions a community has, the more resistant it is to species loss.

This doesn’t mean that communities can endure species loss regularly – many communities have highly important keystone species. A keystone species interacts with many of the other species in the community, and thus their loss would cause large-scale damage in the community regardless of how many other interactions that community has. One well-known example of a keystone species is Canada’s national animal – the beaver, known to scientists as Castor canadensis. Beavers create ponds by building dams, which create habitats for all sorts of native species. If the beavers are lost, the dam could burst, and the entire community would suffer as the pond dries up; no amount of extra interactions within the community would mitigate the effects of losing the beavers. This makes conserving the beavers extremely important to the health of the community and the ecosystem it exists in. Unfortunately, many keystone species are naturally rare or vulnerable to human disturbance, so special care must be taken to conserve their populations.

 Ultimately, an ecological community is like a machine, with each species being one of the machine’s parts. Losing or damaging one part can cause the entire machine to stop working, and unfortunately, fixing ecosystems is much harder than fixing machines. Our ecosystems exist in this delicate balance, and while they can be very good at adapting to change, every ecosystem will have its breaking point. This is why individual species must be conserved – each is a component of a system that is greater than the sum of its parts.

Of course, the best way to protect species is to conserve their habitat. TIWLT works tirelessly to ensure that high-quality habitat is available for our region’s species, and our donors make all of this work possible. Make a donation today and join our community of passionate people working to conserve species, so that our ecosystems may persist in our area 4ever.