Genetic
variation in
salinity tolerance of Mytilus edulis mussels
Leucine Amino Peptidase (LAP) is an enzyme
that cleaves peptide bonds adjacent to Leucine residues
in proteins. 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 optimally in saline
environments. In Long Island Sound east of New York City,
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 the lap94 allele
increases in a cline (a
steady linear change) as a function of local adaptation
to local salinity and gene flow between adjacent
locations. LAP is a well-documented case of biochemical
adaptation, in which differences among alleles at the same
locus produce different genotypes, which are expressed as
different phenotypes that are variably adaptive in different
environments.
Homework: In no more than three sentences, describe the differences between the enzyme LAP, the gene locus lap, and the allele lap94 . Is the allele lap94 part of the genotype or of the phenotype? Explain.
8), where salinity
reaches nearly the same level as that on the sea-ward side
of Long Island (sites 9
11). The frequency of the lap94 allele
increases in a cline (a
steady linear change) as a function of local adaptation
to local salinity and gene flow between adjacent
locations. LAP is a well-documented case of biochemical
adaptation, in which differences among alleles at the same
locus produce different genotypes, which are expressed as
different phenotypes that are variably adaptive in different
environments.Homework: In no more than three sentences, describe the differences between the enzyme LAP, the gene locus lap, and the allele lap94 . Is the allele lap94 part of the genotype or of the phenotype? Explain.