BioScience Dictionary

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Found Evolution 63 times.

Displaying results 1 to 10.

1. 16S rRNA
A large polynucleotide (about 1500 bases) which functions as a part of the small subunit of the ribosome of prokaryote s and from whose sequence evolutionary information can be obtained; the eukaryotic counterpart is 18S rRNA.

2. Adaptation
Tendency of an organism to suit its environment; one of the major points of Charles Darwin's theory of evolution by natural selection : organisms adapt to their environment. Those organisms best adapted will have a greater chance of surviving and passing their genes on to the next generation.

3. Adaptive radiation
The evolution of new species or sub-species to fill unoccupied ecological niches.

4. Adaptive radiation
The development of a variety of species from a single ancestral form; occurs when a new habitat becomes available to a population . evolutionary pattern of divergence of a great many taxa from a common ancestral species as a result of novel adaptations or a recent mass extinction . Examples: mammals during the Cenozoic Era after the extinction of dinosaurs at the close of the Mesozoic Era flowering plants during the Cretaceous Period diversified because of their reproductive advantages over gymnosperm and non-seed plants that dominated the floras of the world at that time.

5. Allopatric speciation (geographic speciation)
The evolutionary process through which two geographically separated (and therefore non-interbreeding) population s of the same species become less and less similar to each other over time (via mutation or the success of different traits in each environment) and eventually become distinctly different species.

6. Allopatrically
An adverb refering to a specific mechanism of evolutionary divergence. A species which arose allopatrically from another diverged from the other because of evolutionary changes occurring in two different geographically separated populations. Also see allopatric and speciation .

7. Analogy (adj. analogous)
Two anatomical structures or behavioral traits within different and unrelated organisms which perform the same functions in each organism but which did not originate from an ancestral structure or trait that the organisms' ancestors had in common. Instead, the structures or traits arose separately and then later evolved to perform the same function (or similar functions). See also convergent evolution . Compare homology .

8. Anaplasia (anaplastia; adj. anaplastic)
* The loss of cellular organization and differentiation; typical of a tumor. * A phase in the evolutionary development of a species characterized by increase hardiness and diversification.

9. Big bang theory
A model for the evolution of the universe that holds that all matter and energy in the universe were concentrated in one point, which suddenly exploded. Subsequently, matter condensed to form atoms, elements, and eventually galaxies and stars.

10. Biogenetic law (recapitulation theory, "ontogeny recapitulates phylogeny")
The theory that " ontogeny recapitulates phylogeny ," which means that one can trace the evolutionary development of a species by studying the development of an individual embryo or young of that species. The theory is still used, especially in paleontology , but has been found to not be strictly true when applied to problems in biology .

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