map unit


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map unit

Etymology: L, mappa, napkin, unus, one
an arbitrary unit of measure used to express the distance between genes on a chromosome. It is calculated from the percentage of recombinations that occur between specific genes so that 1% of crossing over represents one unit on a genetic map, or approximately the number of new combinations that can be detected. The measurement is accurate only for small distances because double crossovers do not appear as new recombinations. Also called map distance. See also morgan.

map unit

An arbitrary unit for the distance between genes, usually derived from the percentage of recombination, but also defined by the time at which the gene is transferred during conjugation. One map unit corresponds to a recombination frequency of 1%.

map unit

or

linkage unit

a unit of ‘distance’ between genes along a chromosome. The number of map units is directly correlated with the amount of RECOMBINATION between loci; 1% recombination is equal to 1 map unit. See CROSS-OVER VALUE, GENETIC LINKAGE.

map distance, map unit

the amount of recombination between two genes expressed as a percentage. See also centimorgan.
References in periodicals archive ?
Each map unit contains unmapped soil components, so linking the soil classes with the most appropriate environmental covariates within a map unit is a critical but uncertain step in building reliable soil class predictive models.
Clearly, the logistic regression procedure was very tolerant of map unit inclusions and classification errors.
Example of triangular distribution parameter calculation from Western Australian soil map unit database The areal proportion is the proportion of the Soil Group in a Zone that has a particular Qualifier.
Where map units contain inclusions (unnamed soils) that have sensitive soil parameters that contrast with the named map components, the presence of small areas of these inclusions can have significant effects on the leaching for the map unit as a whole.
The State Soil Survey Database system was based on the Soil Interpretation Record (SIR) and the attribute data, linked to the soil map units, which was identified as the map unit interpretation record (MUIR) relational database (USDA, 2002b).
All soils within map units were assigned a hazard rating: not applicable, low, moderate or high.
Statistical and geostatistical variability of the soil properties were compared for the similar delineations of the soil map unit.
Thus, it has an application in defining soil map unit composition, and therefore adds to the knowledge base of a continuous mapping system.
Only a few studies on variability of soil attributes within map units have been reported for soils in New Zealand.
A mouse click produces a black and white soils map sheet showing soil map unit polygons.
Semi-automated systems for predicting soil distribution or soil properties usually relate vegetation, landform, geology, or climate characteristics to soils in a typical area and then use these characteristics as `indicators' of soil map units present in broadly similar landscapes elsewhere.
Where map legends and map unit definitions reflect the mental models used by soil surveyors to map soils in the past, the association between soil map units and other environmental spatial data can be re-modelled to infer formal survey rules.