M. Raymond et al., HETEROZYGOTE DEFICIENCY IN THE MUSSEL MYTILUS-EDULIS SPECIES COMPLEX REVISITED, Marine ecology. Progress series, 156, 1997, pp. 225-237
In order to understand the phenomenon of heterozygote deficiency (F-is
) in marine molluscs, all the relevant literature concerning this phen
omenon in the Mytilus edulis species complex was reviewed. Due to larg
e heterogeneity in methods of data analysis, in particular for the cho
ice of the estimator measuring heterozygote deficiency and for the cho
ice of the testing procedure, no clear overview was possible. To overc
ome this problem, similar estimators and tests were used to analyze or
re-analyze some additional large data sets from the Baltic (M. trossu
lus), France (M. galloprovincialis), England (M. edulis), Atlantic USA
(M. edulis) and Pacific USA (M. trossulus). Large and significant het
erozygote deficiencies exist in these data sets. Estimated F-is ((F) o
ver cap(is)) values are generally higher for Lap than for other loci,
consistent with an effect of selection. No other significant variation
of F,, values across loci within each data set or across data sets fo
r each locus was detected, however no specific test has been designed
for this null hypothesis. The possible contribution of a Wahlund effec
t to explain the heterozygote deficiency is discussed. It is likely th
at there is no unique explanation of heterozygote deficiency (such as
a Wahlund effect or selection) in M. edulis or in other organisms, and
that species-specific, locus-specific or population-specific explanat
ions are to be sought.