There are two major components in Darwin's theory of evolution: The "theory of descent with modification" or "theory of evolution by common descent" essentially postulates that all organisms have descended from common ancestors by a continuous process of branching. In other words, all life evolved from one kind of organism or from a few simple kinds, and each species arose in a single geographic location, from another species that preceded it in time.
A phenotypic characteristic, acquired during growth and development, that is not genetically based and therefore cannot be passed on to the next generation for example, the large muscles of a weightlifter.
Any heritable characteristic of an organism that improves its ability to survive and reproduce in its environment.
Also used to describe the process of genetic change within a population, as influenced by natural selection. A graph of the average fitness of a population in relation to the frequencies of genotypes in it.
Peaks on the landscape correspond to genotypic frequencies at which the average fitness is high, valleys to genotypic frequencies at which the average fitness is low. Also called a fitness surface.
A behavior has adaptive logic if it tends to increase the number of offspring that an individual contributes to the next and following generations. If such a behavior is even partly genetically determined, it will tend to become widespread in the population.
Then, even if circumstances change such that it no longer provides any survival or reproductive advantage, the behavior will still tend to be exhibited -- unless it becomes positively disadvantageous in the new environment.
The term can also be applied to larger groups of organisms, as in "the adaptive radiation of mammals. A mode of coping with competition or environmental conditions on an evolutionary time scale. Species adapt when succeeding generations emphasize beneficial characteristics. A person who believes that the existence of a god or creator and the nature of the universe is unknowable.
An umbrella term for various simple organisms that contain chlorophyll and can therefore carry out photosynthesis and live in aquatic habitats and in moist situations on land. The term has no direct taxonomic significance. Algae range from macroscopic seaweeds such as giant kelp, which frequently exceeds 30 m in length, to microscopic filamentous and single-celled forms such as Spirogyra and Chlorella.
One of the alternative forms of a gene. For example, if a gene determines the seed color of peas, one allele of that gene may produce green seeds and another allele produce yellow seeds.
In a diploid cell there are usually two alleles of any one gene one from each parent. Within a population there may be many different alleles of a gene; each has a unique nucleotide sequence. The relation between the size of an organism and the size of any of its parts. For example, an allometric relation exists between brain size and body size, such that in this case animals with bigger bodies tend to have bigger brains.
Allometric relations can be studied during the growth of a single organism, between different organisms within a species, or between organisms in different species. Speciation that occurs when two or more populations of a species are geographically isolated from one another sufficiently that they do not interbreed.
Living in separate places. The unit molecular building block of proteinswhich are chains of amino acids in a certain sequence. There are 20 main amino acids in the proteins of living things, and the properties of a protein are determined by its particular amino acid sequence.
A series of amino acids, the building blocks of proteinsusually coded for by DNA.Neo-Darwinism can rebut this line of criticism in two ways: 1) almost any gene will work — a "many-worlds" theory of biology, or; 2) there is an easily-found mutational pathway, as Manfred Eigen described in , leading from the first set of primitive genes to all of the genes subsequently used in feelthefish.com, since , Eigen's model has not been fleshed out.
In some circles, however, opposition to the concept of evolution has persisted to the present. The argument from design has recently been revived by a number of academics with scientific credentials, who maintain that their version of the idea (unlike Paley’s) is .
Charles Darwin - Evolution by natural selection: the London years, – With his voyage over and with a £ annual allowance from his father, Darwin now settled down among the urban gentry as a gentleman geologist.
He befriended Lyell, and he discussed the rising Chilean coastline as a new fellow of the Geological Society in January (he was secretary of the society by ).
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This article lays out the land for evolutionists and creationists alike, presenting the concepts of and the evidence for biological evolution. The previous three editions of BIOLOGY, written by Dr. Rob Brooker, Dr.
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The author team is dedicated to producing the most engaging and current text that is available for undergraduate. and Evolution Links to our Past News of the Present Insight for the Future Alfred R.
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