Genetic
cline in salinity tolerance of Mytilus
edulis mussels
Leucine Amino Peptidase (LAP) is an enzyme
that cleaves protein peptide bonds adjacent to Leucine
residues. In the Blue
Mussel (Mytilus edulis), the
electrophoretic allele lap94
at the leucine amino peptidase (lap)
locus produces a form of the enzyme that has
been shown experimentally to function best in saline
environments. In Long Island Sound, there is a strong
salinity gradient beginning with freshwater in more westerly
locations through increasingly brackish sites eastward
(sites 1
8), where salinity reaches nearly
the same level as that on the sea-ward side of Long Island
(sites 9
11). The frequency of lap94
increases in a cline as a function of
local adaptation to local salinity and gene flow
between adjacent locations.
Note the distinction between the enzyme LAP, the gene locus lap, and the allele lap94 . As with other enzymatic environmental adaptations, differences among alleles at the same locus produces enzymes with different biochemical phenotypes. Adaptation involves changes in allele frequencies according to their effect on enzymatic and organismal phenotypes.
8), where salinity reaches nearly
the same level as that on the sea-ward side of Long Island
(sites 9
11). The frequency of lap94
increases in a cline as a function of
local adaptation to local salinity and gene flow
between adjacent locations.Note the distinction between the enzyme LAP, the gene locus lap, and the allele lap94 . As with other enzymatic environmental adaptations, differences among alleles at the same locus produces enzymes with different biochemical phenotypes. Adaptation involves changes in allele frequencies according to their effect on enzymatic and organismal phenotypes.