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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 ...
Richard Lenski's classic E. coli long-term evolution experiment is an example of adaptation in a competitive environment, ("improvement in fitness" during "survival of the fittest"). [65] The probability of a beneficial mutation occurring on some member of the lineage to give improved fitness is slowed by the competition.
A deeper understanding of developmental biology shows that common morphology is, in fact, the product of shared genetic elements. [5] For example, although camera-like eyes are believed to have evolved independently on many separate occasions, [6] they share a common set of light-sensing proteins , suggesting a common point of origin for all ...
More recently, the merge between biological science and applied sciences gave birth to new fields that are extensions of evolutionary biology, including evolutionary robotics, engineering, [2] algorithms, [3] economics, [4] and architecture. [5] The basic mechanisms of evolution are applied directly or indirectly to come up with novel designs ...
For example, there is a trade-off between maximizing body size and maximizing lifespan, and between maximizing offspring size and maximizing offspring number. [5] [6] This is also sometimes seen as a choice between quantity and quality of offspring. [7] These choices are the trade-offs that life history theory studies.
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.
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 ...