Use of isozymes (including allozymes) in studies of population genetics and systematics of seaweeds has increased sufficiently in the last
decade to allow some generalization. Only a single locus has been observed for about half the enzymes analysed in seaweeds, compared
with 29% in vascular plants. Compared with higher plants, macroalgal species generally have low amounts of electrophoretically
detectable genetic variation; the lowest levels of genetic variation found in natural populations are those reported for seaweeds.
Nonetheless, seaweeds show an association between levels of genetic diversity as revealed by isozymes and species-specific attributes,
such as mating system and predominance of asexual versus sexual reproduction. In systematic studies, isozymes have revealed cryptic
species and identified pairs of sibling taxa. The quaternary structure of enzymes appears to be conserved at the phylum level. With the
current availability of improved techniques for enzyme electrophoresis and for data interpretation, we expect future studies utilizing
isozyme electrophoresis to provide further insight into population and evolutionary processes in seaweeds.