What is a keystone species and give an example?

What is a keystone species and give an example?

• A. A species with a disproportionate effect on ecosystem structure (for example, sea otter)
• B. A species that is the most abundant in the community
• C. A species that has no significant impact on its environment
• D. A species that possesses the most robust genome

Answer: (B)

A keystone species is defined by its disproportionate influence on the ecosystem, not by how common it is. Even if a species is relatively rare, its actions can shape community structure and resource flows in a way that supports many other organisms. For example, sea otters keep sea urchin populations in check, which allows kelp forests to flourish. Those kelp forests provide habitat and food for a wide array of species; remove the otters and urchins overgraze the kelp, causing a big drop in biodiversity and ecosystem function. So the key idea is the outsized role in maintaining the environment, rather than being the most abundant. Other options don’t fit because being the most abundant doesn’t automatically give a species that strong controlling effect, some abundant organisms don’t regulate the ecosystem in the same way. Saying a species has no significant impact is the opposite of what a keystone species does, and traits like genome robustness aren’t what define keystone status.

A keystone species is defined by its disproportionate influence on the ecosystem, not by how common it is. Even if a species is relatively rare, its actions can shape community structure and resource flows in a way that supports many other organisms. For example, sea otters keep sea urchin populations in check, which allows kelp forests to flourish. Those kelp forests provide habitat and food for a wide array of species; remove the otters and urchins overgraze the kelp, causing a big drop in biodiversity and ecosystem function. So the key idea is the outsized role in maintaining the environment, rather than being the most abundant.

Other options don’t fit because being the most abundant doesn’t automatically give a species that strong controlling effect, some abundant organisms don’t regulate the ecosystem in the same way. Saying a species has no significant impact is the opposite of what a keystone species does, and traits like genome robustness aren’t what define keystone status.