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A unit of selection is a biological entity within the hierarchy of biological organization (for example, an entity such as: a self-replicating molecule, a gene, a cell, an organism, a group, or a species) that is subject to natural selection. There is debate among evolutionary biologists about the extent to which evolution has been shaped by ...
There are numerous species of cichlids that demonstrate dramatic variations in morphology. Given the right circumstances, and enough time, evolution leads to the emergence of new species. Scientists have struggled to find a precise and all-inclusive definition of species. Ernst Mayr defined a species as a population or group of populations ...
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]
Also called an antibacterial. A type of antimicrobial drug used in the treatment and prevention of bacterial infections. Archaea One of the three recognized domains of organisms, the other two being Bacteria and Eukaryota. artificial selection Also called selective breeding. The process by which humans use animal breeding and plant breeding to selectively control the development of particular ...
Retrogenes generally insert into new genomic locations, lack introns. and sometimes develop new expression patterns and functions. Chimeric genes form when duplication, deletion, or incomplete retrotransposition combine portions of two different coding sequences to produce a novel gene sequence.
Natural selection is ubiquitous in all research pertaining to evolution, taking note of the fact that all of the following examples in each section of the article document the process. Alongside this are observed instances of the separation of populations of species into sets of new species .
Also called functionalism. The Darwinian view that many or most physiological and behavioral traits of organisms are adaptations that have evolved for specific functions or for specific reasons (as opposed to being byproducts of the evolution of other traits, consequences of biological constraints, or the result of random variation). adaptive radiation The simultaneous or near-simultaneous ...
In a single lineage, when an old chronospecies (A) is judged to have changed into a new species (B) by anagenesis, the old species is deemed phyletically extinct. Pseudoextinction (or phyletic extinction) of a species occurs when all members of the species are extinct, but members of a daughter species remain alive. The term pseudoextinction ...