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basic rest-activity cycle

A biological rhythm of waxing and waning alertness with a period of approximately 90 minutes in humans. During sleep it controls the cycles of REM and slow-wave sleep. Also called the ...

Bacteria and Archaea

Bacteria and Archaea   Reference library

Encyclopedia of Evolution

Reference type:
Subject Reference
Current Version:
2005
Subject:
Science and technology, Life Sciences, Social sciences, Anthropology
Length:
3,133 words
Illustration(s):
2

...number of microbes deriving their existence from coupling the oxidation-reduction reactions is incredibly important for the cycling of elements on earth. Global cycles, including those of carbon, nitrogen, and sulfur, are driven primarily by the metabolic activity of microbes, and it is these activities that support plant and animal life on the planet. Most of what we know about microbes and their contribution to global cycles is derived from studies of microbes that have been isolated from all other organisms and grown in “pure cultures.” Growing a...

Plants

Plants   Reference library

Encyclopedia of Evolution

Reference type:
Subject Reference
Current Version:
2005
Subject:
Science and technology, Life Sciences, Social sciences, Anthropology
Length:
4,987 words
Illustration(s):
4

...plant morphology; excellent on life cycles. Graham, L. E. Origin of Land Plants . New York, 1993. A synthetic treatment of charophytes and the origin of land plants. Heywood V. H. , ed. Flowering Plants of the World . New York, 1978. A thoroughly illustrated compendium of information on angiosperm diversity. Judd, W. S. , C. S. Campbell , E. A. Kellogg , and P. F. Stevens . Plant Systematics. A Phylogenetic Approach . Sunderland, Mass., 1999. A phylogenetically oriented systematics textbook emphasizing basic principles and an overview of angiosperm...

Primates

Primates   Reference library

Encyclopedia of Evolution

Reference type:
Subject Reference
Current Version:
2005

...mating, and show opportunistic sexual proceptivity when encountering new males, even if ovarian activity is impossible, such as during pregnancy. Mating among prosimians approaches that of the estrous cycles of many other mammals, but New World monkeys have longer and more opportunistic mating periods. Females of Old World primates (Catarrhini) have taken this one step further, often mating during half or even all of an ovarian cycle. Their cycles have follicular phases twice as long as those of other primates and are of unusually variable duration,...

Viruses

Viruses   Reference library

Encyclopedia of Evolution

Reference type:
Subject Reference
Current Version:
2005

...genomes composed entirely of RNA, whereas others have genomes of only DNA. Although fundamental, the division between RNA and DNA genomes is not always clear-cut, because some viruses, like HIV and other retroviruses, have both RNA and DNA genomic stages in their life cycle: the genome that rests in the virus particle is composed of RNA, and a DNA copy is inserted into the host genome. Within both RNA and DNA viruses further subdivisions can be made according to the number of strands of nucleic acid that make up the genome and their orientation. Most RNA...

Optimality Theory

Optimality Theory   Reference library

Encyclopedia of Evolution

Reference type:
Subject Reference
Current Version:
2005
Subject:
Science and technology, Life Sciences, Social sciences, Anthropology
Length:
7,452 words
Illustration(s):
2

...of the species under consideration.) An example of an instructive use of a general model is provided by Abrams' work on the sensitivity of an optimum to various costs. It is sometimes argued that if the cost or benefit associated with an activity is very high, then there will be strong selection acting on the activity and hence we might expect behavior to be close to an optimum. Abrams ( 2001 ) shows that this view is not correct. He considers a general model in which the value of a trait determines more than one cost e.g., foraging behavior might determine...

Antibiotic Resistance

Antibiotic Resistance   Reference library

Encyclopedia of Evolution

Reference type:
Subject Reference
Current Version:
2005
Subject:
Science and technology, Life Sciences, Social sciences, Anthropology
Length:
8,300 words
Illustration(s):
1

...include use of disposable gowns and gloves by health care personnel to avoid contamination, procedures to screen patients for resistant bacteria and “cohort” or isolate those who carry them from the rest of the population, and frequent hand washing. Controlling transmission of resistant organisms in the community (outside of hospitals) is more difficult, but basic hygiene measures in other settings where resistant organisms are present, such as day care centers and nursing homes, serve similar purposes. In an effort to control the spread of penicillin-resistant...

Mate Choice

Mate Choice   Reference library

Encyclopedia of Evolution

Reference type:
Subject Reference
Current Version:
2005

...in a mate would act so as to enhance the chance of conceiving with such a male. Such an expectation is consistent with the finding that only fertile women prefer men with low FA, that women are more likely to seek extrapair partners when they are in the fertile phase of their cycle, and that single women in their fertile phase are more likely to engage in such mate-seeking behaviors as wearing revealing clothes. One (as yet unreplicated) study has claimed that female orgasms at or after ejaculation retain more sperm, and that women having extrapair...

Development

Development   Reference library

Encyclopedia of Evolution

Reference type:
Subject Reference
Current Version:
2005
Subject:
Science and technology, Life Sciences, Social sciences, Anthropology
Length:
11,771 words
Illustration(s):
2

...Yet a modest new synthesis has emerged, one not so much of new principles, but rather of new possibilities. Ecological geneticists need not rest with estimating heritabilities; they can hope to clone the genes that cause phenotypic variation. Paleontologists cannot merely revel in stratigraphy; they must stay au courant with gene expression patterns as well. This is just part of a more profound revolution in the rest of biology. The deep homologies of animal development mean that worms, flies, chickens, mice, and humans are no longer studied in isolation...

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