Search results
Results From The WOW.Com Content Network
Alternatives to Darwinian evolution have been proposed by scholars investigating biology to explain signs of evolution and the relatedness of different groups of living things. The alternatives in question do not deny that evolutionary changes over time are the origin of the diversity of life, nor that the organisms alive today share a common ...
In biology, polymorphism [1] is the occurrence of two or more clearly different morphs or forms, also referred to as alternative phenotypes, in the population of a species. To be classified as such, morphs must occupy the same habitat at the same time and belong to a panmictic population (one with random mating).
Phenotypic variation (due to underlying heritable genetic variation) is a fundamental prerequisite for evolution by natural selection. It is the living organism as a whole that contributes (or not) to the next generation, so natural selection affects the genetic structure of a population indirectly via the contribution of phenotypes.
Stephen Jay Gould and Richard Lewontin used the architectural term spandrel (the triangular gap at the corner of an arch) to describe a byproduct of evolution. Basilica di San Marco , Venice . In evolutionary biology , a spandrel is a phenotypic trait that is a byproduct of the evolution of some other characteristic, rather than a direct ...
Similar genotypic changes may result in similar phenotypic alterations, even across a wide range of species. [1] The genotype–phenotype distinction is drawn in genetics. The "genotype" is an organism's full hereditary information. The "phenotype" is an organism's actual observed properties, such as morphology, development, or behavior.
The repeated evolution of similar phenotypic characteristics or traits in different organisms at different times during the evolutionary history of a clade, [1] a phenomenon which can result in the seeming de-extinction of an organism previously considered extinct. iteroparity
These phenotypic differences undergo selection; as genotypic differences narrow, the trait becomes: Genetically fixed (non-responsive to environmental conditions) Polyphenic (responsive to environmental conditions) Evolution of novel polyphenisms through this mechanism has been demonstrated in the laboratory.
Genetic variation can be identified at many levels. Identifying genetic variation is possible from observations of phenotypic variation in either quantitative traits (traits that vary continuously and are coded for by many genes, e.g., leg length in dogs) or discrete traits (traits that fall into discrete categories and are coded for by one or a few genes, e.g., white, pink, or red petal color ...