BIO 2 Lecture Notes - Lecture 2: Green Algae, Cambrian Explosion, Embryophyte
Document Summary
Many secondary plastid endosymbiosis for more photosynthetic eukaryotes. Photosynthetic eukaryotes arose ~1. 5 billion years ago. Green algae probably around by >900 million years ago: multicellularity had already evolved. Green algae & plants (diversified during the cambrian explosion) The green algae split into two major groups: chlorophytes never made it to land, charophytes freshwater algae; did get to land most closely related to all land plants. Scientists consider plants to be: green algae + land plants = green plants, or just land plants = land plants/plants. Are micro and macroscopic: ~1700 species. Colonize multiple environments: fresh and saltwater, tree trunks, soil, snow. Apart from some microbes (e. g. cyanobacteria), plants were the first organisms to invade land: ~470 mya, first jawed vertebrates existed around this time, coral reefs, many mollusks. First land plants probably occurred in seasonally dry fresh water pools. Plants set the stage for all other organisms to invade land. These features did not evolve all at once.
