Question

Define and discuss the concept of a keystone species. Use at least one example that is NOT the beaver, prairie dog, or sea otter (those we went over in class). For full credit, be sure you discuss the conservation implications of keystone species as they pertain to “trophic cascades.”

Answer 1

Keystone species is whose presence and role within an ecosystem has a disproportionate effect on other organisms within the system. A keystone species is often a dominant predator whose removal allows a prey population to explode and often decreases overall diversity.

A common example of keystone species in the context of conservation biology is the predator-prey relationship. Small predators that consume herbivorous species prevent such herbivores from decimating the plant species in the ecosystem, and are considered keystone species. In this scenario, despite the low number of predators required to maintain a low population of herbivorous species, without this keystone species, the herbivore population would continue to grow, and thus consume all of the dominant plant species in the ecosystem.

The sea otter is considered a keystone species as their consumption of sea urchins, preventing the destruction of kelp forests caused by the sea urchin population. Kelp forests are a critical habitat for many species in nearshore ecosystems. In the absence of sea otters, sea urchins feed on the nearshore kelp forests, thereby disrupting these nearshore ecosystems. However, when sea otters are present, their consumption of sea urchins restricts the sea urchin population to smaller organisms confined to protective crevices. Thus, the sea otter protects the kelp forests by reducing the local sea urchin population.

While small predators are important keystone species in many ecosystems, large mammalian predators are also considered keystone species in larger ecosystems. For example, the lion, and gray wolf and jaguar are considered keystone species as they help balance large ecosystems (e.g., Central and South American rainforests) by consuming a wide variety of prey species.

Sea stars are another commonly recognized keystone species as they consume mussels in areas without natural predators. In many cases, when the sea star is removed from an ecosystem, the population of mussels proliferates uncontrollably, and negatively effects the resources available to other species within the ecosystem.

Unlike most keystone species, snowshoe hares are prey for a lot of predators in the Canadian Boreal forests. It is the biggest source of food for carnivals in the forest. Consequently, its extinction would have adverse effects on the ecosystem. The snowshoe hare is in large populations in the forests, contrary to other keystone species.It becomes a keystone species in its ecosystem because it holds the balance of the prey and the predator. Its presence ensures thriving of the ecosystem whereas its extinction would subsequently lead to the end of the ecosystem.

Keystone species are integral to their specific ecosystem and habitat, as they play a role deemed vital to the existence of the species which share their home. They define an entire ecosystem. Without its keystone species, ecosystems would be dramatically different or cease to exist altogether.Some conservation strategies have now shifted focus to the Keystone Species. As ecological systems are the more prone to disturbances, the effects may sometimes further accelerate a series of events, affecting the stability of the system as a whole.Keystone Species can be targeted for conservation approaches to maintain diversity, and used to retain the community structure intact. Coral, for example, is not only prone to extinction itself, but also can be inhabited by species prone to extinction. This Keystone Species is integral to the existence of coral cities, and we are only now learning the catastrophic effect of the decline of a particular Keystone Species.Keystone Species play a central role in nature cycles, helping keep order in their ecosystems. They are proof that everything must have a balance, and conservation efforts are more needed than ever not only to protect single species, but entire ecosystems and habitats.The elimination of keystone species destabilizes ecosystems, setting off chain reactions that eventually cascade down the trophic ladder (or food web) to the lowest rung, often reducing habitat complexity and species diversity. Ecologist Robert Paine coined the term trophic cascade to describe such multi-level trophic interactions.