Intraorganismal genetic heterogeneity as a source of genetic variation in modular macroalgae

Genetic diversity is considered a key factor of population survival and evolution, especially in changing environments. Genetic diversity arises from mutations in the DNA sequence of cell lines and from there it reaches the level of organisms, populations, and regions. However, many previous studies have not considered the organism architecture or pattern of thallus construction, ignoring the potential genetic complexities that intraorganismal genetic heterogeneity could generate in modular organisms. In seaweeds, modularity and clonality exist in many species. Modular organization has been related to advantages in terms of rapid construction and recovery after the loss of individual modules, which have their own demographic properties as they generate, mature, senesce, and die. Based on recent evidence from the literature, we suggest that modules also have their own genetic properties. Specifically, modular seaweeds have two possible sources of genetic diversity at the individual level: the heterozygosity of the genotypes composing the genet, and genetic heterogeneity among the modules within a genet (i.e., intraclonal genetic variability). Both sources of genetic diversity can have ecological and evolutionary consequences, and most of them must be considered in research on modular seaweeds. Linking intraorganismal genetic diversity with clonal architecture and propagation styles may help us to understand important ecological and evolutionary processes such as speciation modes, invasive capacities, or farming potential.