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Professor of biology Jerry Coyne sums up biological evolution succinctly: [3]. Life on Earth evolved gradually beginning with one primitive species – perhaps a self-replicating molecule – that lived more than 3.5 billion years ago; it then branched out over time, throwing off many new and diverse species; and the mechanism for most (but not all) of evolutionary change is natural selection.
The hypothesis contends that the mechanism of clinal variation through a model of "centre and edge" allowed for the necessary balance between genetic drift, gene flow, and selection throughout the Pleistocene, as well as overall evolution as a global species, but while retaining regional differences in certain morphological features. [1]
In the so-called modern synthesis of the early 20th century, between 1918 and 1930 Ronald Fisher brought together Darwin's theory of evolution, with its insistence on natural selection, heredity, and variation, and Gregor Mendel's laws of genetics into a coherent structure for evolutionary biology. Biologists assumed that an organism was a ...
The mechanisms of evolution focus mainly on mutation, genetic drift, gene flow, non-random mating, and natural selection. Mutation: Mutation [12] is a change in the DNA sequence inside a gene or a chromosome of an organism. Most mutations are deleterious, or neutral; i.e. they can neither harm nor benefit, but can also be beneficial sometimes.
Objections to evolution have been raised since evolutionary ideas came to prominence in the 19th century. When Charles Darwin published his 1859 book On the Origin of Species, his theory of evolution (the idea that species arose through descent with modification from a single common ancestor in a process driven by natural selection) initially met opposition from scientists with different ...
Neutral theory – Theory of evolution by changes at the molecular level; Shifting balance theory – One version of the theory of evolution; Price equation – Description of how a trait or gene changes in frequency over time; Coefficient of relationship – Measure of biological relationship between individuals
Evolution provides the field of biology with a solid scientific base. The significance of evolutionary theory is summarised by Theodosius Dobzhansky as "nothing in biology makes sense except in the light of evolution." [78] [79] Nevertheless, the theory of evolution is not static. There is much discussion within the scientific community ...
Evolutionary thought, the recognition that species change over time and the perceived understanding of how such processes work, has roots in antiquity. With the beginnings of modern biological taxonomy in the late 17th century, two opposed ideas influenced Western biological thinking: essentialism, the belief that every species has essential characteristics that are unalterable, a concept ...