Keystone Species & their Role in an Eco-System

Thilina Jayarathne

All species play a role within an ecosystem as, (i) Primary producers (ii) Primary consumers (iii) Predators, and (iv) Decomposers. Primary producers absorb energy from the environment mainly from sun light an inorganic substances CO2 and H2O, produce Organic molecules such as C6H12O6 in their living cells which contain pigments. The primary consumers feed on them, they are herbivores. the Predators consume flesh meet on herbivores. Decomposers decompose dead organic materials in to inorganic particles and contribute for the material cycle. For many species the role is not unique. But some species play a unique & important role in ecosystem function & their removal results changes in that system.

Key Stone species is a species which affects the survival and abundance of many other species in the community in which it lives. The removal of such species can have a profound effect on the ecosystem in which they live, and sometimes even on the physical structure of the environment. And often the importance of these species is not evident until they disappear. Keystone species are less abundant, but they exert strong effects on the community they inhabit. There are Four types of Key Stone Species, (i)Organisms Controlling Dominants (ii)Resource Providers (iii)Keystone Mutualists (iv)Ecosystem Engineers.

Organisms Controlling Dominants Promote coexistence by reducing competition among other species for limiting resources in an Eco-system. Best examples are Predators which control the herbivores population and Herbivores which controls the plant composition. Resource Providers Provide continuous reliable source of food for many kinds of creatures. If it is removed unable to bridge the gap of supply. The best example is Fig tree. Mutualism is an interaction between 2 organisms. Both are inter dependent. They depend for Pollination (plants & animals) & Dispersal (plants & animals). If It fails it can be led to Reproductive failures, Loss of genetic diversity, Change in plant and animal population dynamics, Local extinctions without replacement, Loss of animal species reliant on fruits and seeds, Long terms species loss (trees). Ecosystem engineers are keystone species who physically modifies habitats. Best example is Elephants which maintain grasslands. Most exotic invasive species are ecosystem engineers in their invaded locations.

Loss of a Key Stone Species Can create a series of linked extinction events known as an extinction cascade. Returning the keystone species to the community may not necessarily restore the community, if other component species & physical environment have already lost.