evolution

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evolution

 [ev″o-lu´shun]
the process of development in which an organ or organism becomes more and more complex by the differentiation of its parts; a continuous and progressive change according to certain laws and by means of resident forces.
convergent evolution the development, in animals that are only distantly related, of similar structures or functions in adaptation to similar environments.

ev·o·lu·tion

(ev'ō-lū'shŭn),
1. A continuing process of change from one state, condition, or form to another.
2. A progressive distancing between the genotype and the phenotype in a line of descent.
3. The liberation of a gas or heat in the course of a chemical or enzymatic reaction.
[L. e-volvo, pp. -volutus, to roll out]

evolution

/evo·lu·tion/ (ev″ah-loo´shun) a developmental process in which an organ or organism becomes more and more complex by differentiation of its parts; a continuous and progressive change according to certain laws and by means of resident forces.
convergent evolution  the appearance of similar forms and/or functions in two or more lines not sufficiently related phylogenetically to account for the similarity.
organic evolution  the origin and development of species; the theory that existing organisms are the result of descent with modification from those of past times.

evolution

(ĕv′ə-lo͞o′shən, ē′və-)
n.
1. A continuing process of change from one state, condition, or form to another.
2. Change in the genetic composition of a population during successive generations, often resulting in the development of new species. The mechanisms of evolution include natural selection acting on the genetic variation among individuals, mutation, migration, and genetic drift.

evolution

[ev′əlo̅o̅′shən]
Etymology: L, evolvere, to roll forth
1 a gradual, orderly, and continuous process of change and development from one condition or state to another. It encompasses all aspects of life, including physical, psychological, sociological, cultural, and intellectual development, and involves a progressive advancement from a simple to a more complex form or state through the processes of modification, differentiation, and growth.
2 a change in the genetic composition of a population of organisms over time.
3 the appearance over long periods of time of new taxonomic groups of organisms from preexisting groups. Kinds of evolution are convergent evolution, determinant evolution, emergent evolution, organic evolution, orthogenic evolution, and saltatory evolution. evolutionist, n.

ev·o·lu·tion

(ev'ŏ-lū'shŭn)
1. A continuing process of change from one state, condition, or form to another.
2. A progressive distancing between the genotype and the phenotype in a line of descent.
[L. e-volvo, pp. -volutus, to roll out]

evolution

The theory that all living organisms have developed in complexity, from a simple life form. Evolution occurs by the natural selection of those who, by the fortune of spontaneous random changes (mutations), happen to be best suited to their contemporary environment, to survive and reproduce. It does not occur by the passing on to offspring of characteristics acquired during the lifetime of an individual. Characteristics are passed on by the transmission of DNA from parents to offspring and, unless mutation has occurred, this DNA is an identical copy of the DNA of preceding generations.

evolution

an explanation of the way in which present-day organisms have been produced, involving changes taking place in the genetic make-up of populations that have been passed on to successive generations. According to DARWINISM, evolutionary MUTATIONS have given rise to changes that have, through NATURAL SELECTION, either survived in better adapted organisms (see ADAPTATION, GENETIC), or died out. Evolution is now generally accepted as the means which gives rise to new species (as opposed to SPECIAL CREATION) but there is still debate about exactly how it has taken place and how rapidly changes can take place. See LAMARCKISM.

evolution

the process of development in which an organ or organism becomes more and more complex by the differentiation of its parts; a continuous and progressive change according to certain laws and by means of resident forces.

convergent evolution
the development, in animals that are only distantly related, of similar structures or functions in adaptation to similar environment.
divergent evolution
the development of different characteristics in animals that were closely related in response to being placed in different environments.

Patient discussion about evolution

Q. How the bacterias are produced?

A. The Bacteria are a large group of unicellular microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals. (The name comes from the Greek bakterion, meaning small staff.) Bacteria are ubiquitous in every habitat on Earth, growing in soil, acidic hot springs, radioactive waste,[2] water, and deep in the Earth's crust, as well as in organic matter and the live bodies of plants and animals. There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water; in all, there are approximately five nonillion (5×1030) bacteria on Earth,[3] forming much of the world's biomass.[4] Bacteria are vital in recycling nutrients, with many important steps in nutrient cycles depending on these organisms, such as the fixation of nitrogen from the atmosphere and putrefaction. http://en.wikipedia.org/wiki/Bacteria Hope this helps.

More discussions about evolution
References in periodicals archive ?
The theory of evolution by natural selection provides a unifying framework for understanding and integrating the immense body of knowledge available on biological systems.
The third chapter explains how evolution by natural selection actually works, using as an example the evolution of the fictitious "wafflesmoozers.
Charles Darwin's theory of evolution by natural selection is a cornerstone concept in biology (White, 2007).
He said: "Although he never used the term, Hutton clearly articulated the principle of evolution by natural selection.
The first place to look for a record of the role of Darwin's finches in Darwin's thinking is in his published works, especially The Voyage of the Beagle (2) and The Origin of Species (3) where he argued for evolution by natural selection, an analogy for formation of new species.
The requirements for evolution by natural selection
Before Simpson began his work in the mid-1930s, the great majority of paleontologists did not accept Charles Darwin's theory of evolution by natural selection.
After years of research, he published his theory of evolution by natural selection in his 1859 book The Origin Of Species.
Misunderstandings about the role of variation, fitness effects, and inheritance in evolution by natural selection usually surface as well.
On the Origin of Species by Charles Darwin (1859) - The first work to suggest evolution by natural selection.
The definition of nature includes evolution by natural selection, which obviously entails change.