Endosymbiosis and Evolution

The mosaic of algal species has been shaped by many forces, but evolutionarily, the acquisition of prokaryotic photosynthetic machinery by eukaryotes in the sea is perhaps the most important. Subsequent endosymbiotic engulfment along with mutations, selections, genetic drift, and environmental factors have led to the radiation of species with their unique, but sometimes related, distinguishing characteristics. This chapter describes some of the early debates about endosymbiosis and introduces current hypothesis about “why the land is green and the ocean red.” Phylogenetic reconstructions are rapidly changing as new data are amassed.