Predators keep the prey population under control. The prey species could achieve very high population densities and cause ecosystem instability in the absence of predators. Predators also help in maintaining species diversity in a community, by reducing the intensity of competition among competing prey species. They do so by keeping the size of species populations in check at supportable levels as "when preys are high, predators increase and reduce the number of prey by predation. When predators are high, prey decrease and thus reduce the number of predators by starvation." Predation can have large effects on prey populations and on community structure. Predators can increase diversity in communities by preying on competitive dominant species or by reducing consumer pressure on foundation species. When preys are high, predators increase and reduce the number of prey by predation. When predators are low, prey decrease and thus reduce the number of predators by starvation. These predator/prey relationships thereby promote stability in ecosystems and enable them to maintain large numbers of species. Predator-prey relationships are also vital in maintaining and even increasing the biological diversity of the particular ecosystem, and in helping to keep the ecosystem stable. This is because a single species is kept under control by the species that uses it for food. Predators keep the prey population under control. The prey species could achieve very high population densities and cause ecosystem instability in the absence of predators. Predators also help in maintaining species diversity in a community, by reducing the intensity of competition among competing prey species. 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. Predation creates stability by maintaining population levels of the prey organisms at constant levels. Predation provides energy to prolong the life and promote the reproduction of the organism that does the killing, the predator, to the detriment of the organism being consumed, the prey. Predation influences organisms at two ecological levels. Predation can directly regulate prey numbers and indirectly regulate their survival via habitat availability, individual growth, and trophic structure. They often attack different life stages of the pest, and even different pest species. Many predators are also able to supplement their diet by feeding on alternative food sources, such as nectar, pollen and fungi. They are often voracious feeders and more robust than parasites.

Dr Rana Hamza Shakil thank you for your contribution to the discussion