Arsenic contamination, size, and complexity: A volvocine green algae case study

摘要

Evolution occurs not only through mutational changes, but also during evolutionary transitions-when groups become a new higher-level individual. The unicellular-multicellular transition was one of these important events in life. The volvocine green algae are an ideal model system to study this transition since they range from unicellular (e.g., Chlamydomonas), to undifferentiated colonies (e.g., Eudorina), to multicellular forms with complete germ-soma differentiation (e.g., Volvox). How does the evolution of traits that are necessary for multicellularity such as an extra-cellular matrix and germ-soma separation, alter the response to harmful chemicals? To test this, Volvocales of different size and complexity, but of similar cellular biology and development, were grown at different arsenic concentrations to measure their ecotoxicological response. We found evidence that Volvocales of larger size and complexity are more sensitive to arsenic contamination than their simpler and smaller counterparts.