Ecological Niche and Neutral Theories

If you have studied biology at all you are probably familiar with niche theories, that all organisms fill a role within their environment that makes them all important; all organisms have evolved over time so that they can fulfil these roles more completely. The environment includes factors such as climate, weather and interactions with other organisms. Two species within an environment won’t have very similar niches as this would cause too much competition between the two species. Lions are important because as predators they ensure that zebra and wildebeest populations don’t get too big; decomposing bacteria are important they allow waste materials to be reused by the environment. These are the niches of these organisms, all organisms have them; it is one of the reasons why maintaining biodiversity is so important. Niche theory is a cornerstone of evolution and ecology.
Less well known are opposing neutral theories that use much simpler ideas to explain why organisms are found in specific environments. While niche theories suggest that environments lead to most differences between species, neutral theories suggest that the main factor driving change is luck, pure and simple. Neutral theories suggest that changes in environment don’t have a major effect on, for example, the size and shape of an organism. Neutral theories suggest that animals with bigger ears have no advantage in hot climates, this is just a trait that they inherited from ancestors who had large ears.
Examples such as the one above highlight where neutral theories are lacking. Many animals that live in hot climates have large ears as they can be used to combat overheating; and many animals that are found in cold climates have small ears to conserve heat. This example is on a very large scale, contrasting the extremes of hot and cold. Where neutral theory can sometimes be applied is on a small scale, where differences between near neighbours are examined.
Neutral theories are unpopular and controversial, science tells us the theories based on a large random element will never work but they can work on a local level. Niche theories are much more scientific, but they don’t explain all biodiversity. Both theories have their merits, and should actually be combined to try and explain the variety of life that is found on the planet. There is reason behind the changes that are found in organisms, however it is important to keep in mind that there is a random element.