Figure 8 from Boyd et al. 2018
Figure 8 from Boyd et al. 2018. Analysis of algal movement due to light exposure where positive values indicate movement toward the light source and negative values indicate movement away from the light source.

Former undergraduate researcher Maggie Boyd has published her analysis of motility in experimentally evolved Chlamydomonas reinhardtii in PLoS ONE:

C. reinhardtii is capable of photosynthesis, and possesses an eyespot and two flagella with which it moves towards or away from light in order to optimize input of radiant energy. Motility contributes to C. reinhardtii fitness because it allows cells or colonies to achieve this optimum. Utilizing phototaxis to assay motility, we determined that newly evolved multicellular strains do not exhibit significant directional movement, even though the flagellae of their constituent unicells are present and active. In C. reinhardtii the first steps towards multicellularity in response to predation appear to result in a trade-off between motility and differential survivorship, a trade-off that must be overcome by further genetic change to ensure long-term success of the new multicellular organism.

Maggie is now a Ph.D. student in Northwestern University’s Biomedical Engineering program.

Boyd, M., Rosenzweig, F. and Herron, M.D. 2018. Analysis of motility in multicellular Chlamydomonas reinhardtii evolved under predation. PLoS ONE, 13: e0192184. doi: 10.1371/journal.pone.0192184