Title

Predation and Selection in the Green Alga Chlamydomonas

Presentation Type

Presentation

Abstract

For most of the 3.5 billion year history of life on Earth, organisms were confined to a single-celled existence. When some lineages made the transition from single-celled to multicellular life, there were profound implications both for the planet and the organisms that remained unicellular. A leading hypothesis suggests that predation drove this important evolutionary transition in some multicellular lineages. In recent experiments, populations of the unicellular green alga Chlamydomonas reinhardtii evolved simple multicellular structures under selection on settling rate or from predation. C. reinhardtii is a model system for genetics, photosynthesis, circadian rhythms, flagellar motility, and sexual and asexual reproduction. I tested whether and to what degree simple multicellularity provides a viability advantage for C. reinhardtii exposed to two of its natural predators by comparing growth rates of unicellular and multicellular strains with and without predators. I found that multicellularity provides a meaningful advantage for C. reinhardtii with respect to predation under laboratory conditions. This provides support for the hypothesis that predation was an important factor in the evolution of multicellular lineages leading to the vast diversity seen in life today.

Category

Life Sciences

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Predation and Selection in the Green Alga Chlamydomonas

UC 332

For most of the 3.5 billion year history of life on Earth, organisms were confined to a single-celled existence. When some lineages made the transition from single-celled to multicellular life, there were profound implications both for the planet and the organisms that remained unicellular. A leading hypothesis suggests that predation drove this important evolutionary transition in some multicellular lineages. In recent experiments, populations of the unicellular green alga Chlamydomonas reinhardtii evolved simple multicellular structures under selection on settling rate or from predation. C. reinhardtii is a model system for genetics, photosynthesis, circadian rhythms, flagellar motility, and sexual and asexual reproduction. I tested whether and to what degree simple multicellularity provides a viability advantage for C. reinhardtii exposed to two of its natural predators by comparing growth rates of unicellular and multicellular strains with and without predators. I found that multicellularity provides a meaningful advantage for C. reinhardtii with respect to predation under laboratory conditions. This provides support for the hypothesis that predation was an important factor in the evolution of multicellular lineages leading to the vast diversity seen in life today.