Question

Explain the importance of biodiversity with respect to ecosystem stability, and include discussion of genetic diversity and species functional redundancy.  Explain the relationship between biodiversity and trophic cascades.

Answer 1

Ans ) Biodiversity is the variety of life across all of the different levels of biological organization. It refers to all the populations, species, and communities in a defined area. Biodiversity helps in stabilizing an ecosystem. Ecosystem stability is the maintenance of a steady-state in an ecosystem even after a disturbance or fluctuation has occurred. An ecosystem with a high level of species diversity such as a rainforest is much more stable than an ecosystem with low biodiversity such as a desert. Presence of multiple species in a community helps stabilize ecosystem if species vary in their responses to environmental fluctuations. In this case, decreased abundance of one species is compensated by an increased abundance of another. Moreover, a diverse community will have many varieties of food webs and biotic interactions. Communities with high biodiversity may contain some species that confer resilience to that ecosystem by having traits that enable them to adapt to a changing environment. Such species can buffer the system against the loss of other species.

Relationship between biodiversity and trophic cascades:
Trophic cascades occur when predators limit the density and behavior of their prey and thus enhance survival of the next lower trophic level. This helps in maintaining the biodiversity at different trophic levels. Trophic cascades are powerful interactions that strongly regulate biodiversity and ecosystem function. Adding or removing one trophic level (usually the topmost) can cause a state change in the entire system. An example of this is the replacement of high-diversity kelp forests by low-diversity sea urchin barrens in the absence of sea otters, thus leading to loss of biodiversity. A trophic cascade can help in maintaining biodiversity from the mere presence of a predator, such as a tiger, when the fear of being preyed on keeps herbivores on the move. This prevents overgrazing and thus keeping the biodiversity.