Temperature-related phenotypic plasticity in the green microalga Micrasterias rotata

Temperature-related morphological variation of Micrasterias rotata (Desmidiales) strain CAUP K604 was investigated using landmark-based geometric morphometrics. Cultured morphotypes were compared with natural populations of M rotata collected in different seasons at a central European lowland peat bog. In addition, we compared temperature-related variation with morphometric differentiation among other species within the genus Micrasterias. As temperatures increased, the population size of cultured M rotata generally decreased and shape of the individual temperature groups differed significantly. The high temperature (30 degrees C) population contained the vegetative diploid cells. The shape variation related to temperature was similar to the size-related change in shape. Natural populations of M rotata were consistently similar to the low temperature cultured populations throughout the season, while the high temperature morphotypes seen in culture were not present in natural samples.