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It defines evolution as the change in allelic frequencies within a population caused by genetic drift, gene flow between sub populations, and natural selection. Natural selection is emphasised as the most important mechanism of evolution; large changes are the result of the gradual accumulation of small changes over long periods of time. [39] [40]
On February 19, 2008, the Florida State Board of Education adopted new science standards in a 4–3 vote. The new science curriculum standards explicitly require the teaching of the "scientific theory of evolution," [46] whereas the previous standards only referenced evolution using the words "change over time." [47]
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.
Evolution is the change in the heritable characteristics of biological populations over successive generations. [1] [2] It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, resulting in certain characteristics becoming more or less common within a population over successive generations. [3]
Habitats and biota do frequently change over time and space. Therefore, it follows that the process of adaptation is never fully complete. [ 57 ] Over time, it may happen that the environment changes little, and the species comes to fit its surroundings better and better, resulting in stabilizing selection.
A recent survey lists practical tools and online systems for investigating semantic change of words over time. [12] WordEvolutionStudy is an academic platform that takes arbitrary words as input to generate summary views of their evolution based on Google Books ngram dataset and the Corpus of Historical American English.
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D is the proper distance (which can change over time, unlike the comoving distance, which is constant) from the galaxy to the observer, measured in mega parsecs (Mpc), in the 3-space defined by given cosmological time. (Recession velocity is just v = dD/dt). Hubble's law is considered a fundamental relation between recessional velocity and ...