- Evolutionary processes occurring above the level of a species are mostly designated as macroevolutionary processes. The action of macroevolutionary processes leads to the formation and development of higher taxa. Similarly as mutations are a source of new evolutionary features at a microevolutionary level, the individual speciations are a source of new features at a macroevolutionary level. The long-term fate of a new macroevolutionary feature, a new species, is determined by the ratio of the rate with which its and its daughter species undergo speciation and the rate at which they die out – are subject to extinction. The members of various taxa frequently differ substantially in their phenotypes. There are especially important differences in the adaptive traits that provide access to ecological niches that are not available for other taxa. For example, the existence of the photosynthetic apparatus of the plant type allows the organism to utilize carbon dioxide, water and solar radiation for synthesis of organic substances and thus to occupy ecological habitats in which there are no sources of organic substances. Study of the formation and development of new adaptive traits forms the main content of microevolutionary theory. The adaptivity (usefulness) of a trait is apparently the decisive criterion that affects the probability of whether a certain new evolutionary feature becomes fixed in the species or disappears. However, at a macroevolutionary level, aspects connected with the probability of speciation and extinctiontend to be more important. Adaptive traits are important for the course of macroevolution only if they negatively or positively affect the probability of one of these two processes. In a great many cases, a trait that is adaptive from the viewpoint of an individual is simultaneously advantageous from the viewpoint of survival of the species, as it reduces the probability of its extinction. In some cases, this need not be so and a particular trait may reduce the chances of survival of the species or higher taxon.

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The classical Darwinian theory of evolution can explain the evolution of adaptive traits only in asexual organisms. The frozen plasticity theory is much more general: It can also explain the origin and evolution of adaptive traits in both asexual and sexual organisms Read more