A Study of the ‘Escape and Radiate’ Coevolution Mechanism, between plants and animals.
The term ‘coevolution’ is a broad term used to describe the way in which two organisms of different plant or animal species influence each other’s evolutionary paths. The term was coined by Charles Mode in 1958, generally speaking, it means that organisms are dependent on each other for survival. In scientific terms, coevolution is regularly described as the way in which a change in the genetic code of an organism affects the ability to adapt in another organism. There are many different types and examples of coevolution, for example, mutualism, symbiosis, speciation and guild coevolution, but in this investigative essay, I will be discussing ‘escape and radiate’ coevolution in detail, a process outlined originally in "Butterflies and plants: a study in coevolution." (Erlich and Raven, 1964). The term ‘escape and radiate’ was not coined until it was included in the article ‘Concepts of coevolution’ (John N. Thompson, 1989). Escape and Radiate Coevolution is the method in which an organism which is undergoing restrictions from other organisms, has the ability to evolve alternative defence mechanisms so that it can escape and then radiate (the process of a single species evolving diversely into numerous forms). This is carried out by means of an organism being preyed upon, obtains a new defence and, therefore, is capable of avoiding predation and can then swiftly proliferate into new species. This form of coevolution is predominantly viewed between herbivores and its host plant.
Plant chemistry is the central dogma of escape and radiation coevolution. There are four main factors influencing the coevolution of plants and animals this way; as follows;
· Secondary chemicals are produced purely by chance and are altered under pressure from herbivores.
· Plant escape and radiation: plants with defence mechanisms escape from herbivores and radiate.
· Insect escape and radiation: insects react to the defence mechanisms of the plant and overcome these defences. They escape competition from other insects and radiate.
· Plants and Insects diversify parallelly: plants and animals affect one another’s variety and diversity harmoniously, through coevolution.
A table of plant defences and insect’s counter defences was put together by Rausher MD in his article; ‘Co-evolution and plant resistance to natural enemies.’ (2001). This table (included in diagram section) gives a list of different organisms, which are coevolving or have coevolved by the ‘escape and radiate’ procedure. Organisms have evolved strange methods to reduce predation, which includes; mimicry, chemical defense, camouflage and aposematism. Erlich and Raven (1964) theorise that a trait that influences the organism in a favourable way, and enables it to fill a niche free of predation, can advance heterogeneity. Allmon (1992) hypothesized that if plants were placed in...