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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]
The age of the Earth is about 4.5 billion years. [1] [2] [3] The earliest undisputed evidence of life on Earth dates from at least 3.5 billion years ago. [4] [5] [6] Evolution does not attempt to explain the origin of life (covered instead by abiogenesis), but it does explain how early lifeforms evolved into the complex ecosystem that we see ...
Fourth, the modern evolutionary synthesis involved agreement about which forces contribute to evolution, but not about their relative importance. [36] Current research seeks to determine this. Evolutionary forces include natural selection, sexual selection, genetic drift, genetic draft, developmental constraints, mutation bias and biogeography.
Macroevolution is guided by sorting of interspecific variation ("species selection" [2]), as opposed to sorting of intraspecific variation in microevolution. [3] Species selection may occur as (a) effect-macroevolution, where organism-level traits (aggregate traits) affect speciation and extinction rates, and (b) strict-sense species selection, where species-level traits (e.g. geographical ...
[69] [4] The pioneers of agriculture faced tooth cavities, protein deficiency and general malnutrition, resulting in shorter statures. [4] Diseases are one of the strongest forces of evolution acting on Homo sapiens. As this species migrated throughout Africa and began colonizing new lands outside the continent around 100,000 years ago, they ...
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype.It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations.
Other evolutionary forces outside of mutation and natural selection can also play a role or be incorporated into experimental evolution studies, such as genetic drift and gene flow. [3] The organism used is decided by the experimenter, based on the hypothesis to be tested.
where n=4 is the number of surviving bacteria. Mathematical models ... genetic drift) a significant driving force in the evolution of new species.