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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.
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 ...
The success of this theory raised awareness of the vast scale of geological time and made plausible the idea that tiny, virtually imperceptible changes in successive generations could produce consequences on the scale of differences between species. [13]
Sexual selection acts to refine secondary sexual (i.e. non-genital) phenotypes, such as the morphological differences between males and females (sexual dimorphism), or even differences between species of the same sex. [18] As a refinement to Darwin's theory of selection, Trivers (1974) observed that: [18] [20]
The neutral theory of molecular evolution, proposed by Motoo Kimura in 1968, holds that at the molecular level most evolutionary changes and most of the variation within and between species is not caused by natural selection but by genetic drift of mutant alleles that are neutral.
The gene-centered view of evolution is a synthesis of the theory of evolution by natural selection, the particulate inheritance theory, and the rejection of transmission of acquired characters. [ 6 ] [ 7 ] It states that those alleles whose phenotypic effects successfully promote their own propagation will be favorably selected relative to ...
Evolutionary progress as a tree of life. Ernst Haeckel, 1866 Lamarck's two-factor theory involves 1) a complexifying force that drives animal body plans towards higher levels (orthogenesis) creating a ladder of phyla, and 2) an adaptive force that causes animals with a given body plan to adapt to circumstances (use and disuse, inheritance of acquired characteristics), creating a diversity of ...
The Baldwin effect compared to Lamarck's theory of evolution, Darwinian evolution, and Waddington's genetic assimilation. All the theories offer explanations of how organisms respond to a changed environment with adaptive inherited change. In evolutionary biology, the Baldwin effect describes an effect of learned behaviour on evolution.