File Name: micro and macro evolution .zip
Louis, Missouri. Last reviewed: September Large-scale patterns and processes in the history of life, including the origins of novel organismal designs, evolutionary trends, adaptive radiations, and extinctions. Macroevolutionary research is based on phylogeny, that is, the history of common descent among species Fig. The formation of species and branching of evolutionary lineages mark the interface between macroevolution and microevolution, which addresses the dynamics of genetic variation within populations.
Microevolution is the change in allele frequencies that occurs over time within a population. This change happens over a relatively short in evolutionary terms amount of time compared to the changes termed macroevolution. Population genetics is the branch of biology that provides the mathematical structure for the study of the process of microevolution. Ecological genetics concerns itself with observing microevolution in the wild. Typically, observable instances of evolution are examples of microevolution; for example, bacterial strains that have antibiotic resistance.
At its simplest, evolution is any change in heritable traits in a population of organisms across generations. These changes may be the result of natural selection, genetic drift, mutation, etc — processes that we will consider in depth later in the course. All populations experience evolutionary change, as influenced by their environment, their interactions with other organisms, and random chance. Like ecology, we can consider evolution at different scales. Microevolution is genetic change that occurs over small timescales and results in small changes in heritable traits.
Macroevolution refers most of the time, in practice to evolutionary patterns and processes above the species level. It is usually contrasted with microevolution, or evolutionary change within populations. Some evolutionary processes, such as the spread of a trait from one population to another, might count as within-species processes but not within-population processes. Population genetics see entry , which emerged during the modern synthesis of the early- to mid-twentieth century, explains within-population microevolutionary change in terms of natural selection , genetic drift , mutation, and migration. One question that looms over philosophical work on macroevolutionary theory is how macroevolution and microevolution are related.
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