STRUCTURE

• Introduction – Define keystone species (15 words)    
• Body – Explain importance of keystone species ln conservation biology (120 words)
• Conclusion – Mention a short conclusion  (15 words)

ANSWER

Keystone species is a species whose addition to or loss from an ecosystem leads to major changes in abundance or occurrence of at least one other species. Certain species in an ecosystem are considered more important in determining the presence of many other species in that ecosystem.

All top predators (Tiger, Lion, Crocodile, Elephant) are considered as keystone species because it regulates all other animals’ population indirectly. Hence top predators are given much consideration in conservation.

IMPORTANCE

• There are three types of keystone species cited by many scientists: predators, ecosystem engineers, and mutualists.
  • Predators: Predators help control the populations of prey species, which in turn affects the quantity of plants and animals further along the food web. Sharks, for example, often prey upon old or sick fish, leaving healthier animals to flourish. Simply by their presence near sea grass beds, sharks are able to keep smaller animals from overgrazing and wiping out the grass. Scientists in Australia observed that when tiger sharks were not near the grass beds, sea turtles—among tiger sharks’ favorite prey—tended to decimate them. But when tiger sharks patrolled the grass beds, the sea turtles were forced to graze across a much wider region.
  • Ecosystem Engineers: An ecosystem engineer is an organism that creates, changes, or destroys a habitat. There is perhaps no clearer example of a keystone engineer than the beaver. River ecosystems rely on beavers to take down old or dead trees along riverbanks to use for their dams. This allows new, healthier trees to grow in abundance. The dams divert water in rivers, creating wetlands that allow a variety of animals and plants to thrive.
  • Mutualists: When two or more species in an ecosystem interact for each other’s benefit, they are called mutualists. Bees are a primary example of this. As bees take the nectar from flowers, they collect pollen and spread it from one flower to the next, enhancing the odds of fertilization and greater flower growth. Nectar and pollen are also the primary food sources for the bees themselves.
• Some scientists identify other categories of keystone species. One alternate list includes predators, herbivores, and mutualists. Another cites predators, mutualists, and competitors for resources.
• Keystone species can also be plants. Mangrove trees, for instance, serve a keystone role in many coastlines by firming up shorelines and reducing erosion. They also provide a safe haven and feeding area for small fish among their roots, which reach down through the shallow water.
• In many cases, the vital role of a keystone species in an ecosystem is not fully appreciated until that species is gone.
• Ecologist Robert Paine, who coined the term “keystone species” in the 1960s, observed the importance of such species in a study of starfish along the rocky Pacific coastline in Washington state. The starfish fed on mussels, which kept the mussel population in check and allowed many other species to thrive. When the starfish were removed from the area as part of an experiment, the mussel population swelled and crowded out other species.
• The biodiversity of the ecosystem was drastically reduced. Payne’s study showed that identifying and protecting keystone species can help preserve the population of many other species.