Biology Reference
In-Depth Information
Glossary
Additive genetic variation.
Va r iability on which selection can progres-
sively modify a quantitative characteristic by increasing the frequency of
particular alleles.
Agroecotypes.
Weedy races of a crop or noncrop plant that are confined
to the cropland habitat.
Allee effect.
A reduction in population growth rate at densities below
some optimum.
Allelopathy.
Inhibition of the growth of one species by chemical agents
released into soil or water by another species.
Allopatric speciation.
See
speciation
.
Allopatry.
Occurring in nonoverlapping geographical ranges.
Allopolyploidy.
See
polyploidy
.
Allozyme.
Different forms of an enzyme coded by different alleles at a
particular genetic locus.
Amensalism.
A symbiotic relationship that is detrimental to one mem-
ber but harmless to the other.
Allozymes.
Different forms of an enzyme coded by different alleles at a
single genetic locus.
Anadromous.
Aquatic organisms, usually fish, that lay eggs in fresh water
but migrate to the ocean for much of their prereproductive life.
Apomixis.
Production of seeds without pollination.
Assortative mating.
Interbreeding of individuals having more traits in
common than expected by chance.
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