OPPapers.com

Key Innovations And Adaptive Radiations

An adaptive radiation was defined by Schluter (2000), as "the evolution of ecological diversity, within a rapidly multiplying lineage". Species can go through an adaptive radiation (involving a diversification of that species), in response to having invaded a vacant ecological niche. It is thought the ability to do this, can be attributed to one or more key innovations developed by this species (i.e. the species has developed a new ‘key innovation', which makes it possible to invade new niche, that was not possible before). A radiating clade, which is the original ancestral species and descendants, then has opportune to exploit the new resources that often come with this new vacant niche. (And perhaps not have to compete with other species present, for the same resources and space).

The role of a key innovation in an adaptive radiation can be thought of as a new feature which increases ecological opportunity (Schluter, 2000). This ecological opportunity, in turn, can be defined as "the wealth of different resource types under-utilized by species in other taxa" (Schluter, 2000). These two main ideas, partly make up the "ecological theory". This theory generally states that the differences in phenotype observed between populations and species, is caused directly by differences in the environment they inhabit and resources consumed (Schluter, 2000). This essay looks at some examples of adaptive radiations that have seen the arising of several new species from an ancestral group in a relatively short period of time. Each example attempts to explain how each radiating clade is the result of a key innovation. Classic examples of adaptive radiations include the Galápagos finches, the Hawaiian silversword alliance, and cichlid fishes. These examples are well covered in previous literature and this essay instead examines others. Other more unknown examples discussed include diversity of insects that feed on vascular plants, and diversity of weevils. Firstly, a...