Module 4: Simple to complex
In this module, students will examine prepared slides of 6 algae differing in morphology and complexity. The Volvocine algae lineage offers a model of increasing complexity for eukaryotic cells. Chlamydomonas reinhardtii, being single celled, is the simplest organism compared to the multicelluar Volvox carteri with cell specialization and increased size and extracellular matrix volume.
Volvocine algae
The volvocine green algae (Volvox and its close relatives) are a model system for understanding the origins of multicellularity. Although they diverged from unicellular ancestors around 220 million years ago, large, complex forms such as Volvox still coexist with smaller, less complex forms. This diversity makes the volvocine algae ideal for understanding the morphological and developmental changes by which a single-celled organism can evolve into a complex, multicellular one. This module uses the volvocine algae to illustrate the steps involved in this transition.