BIOL 102 Lecture 11: Chapter 29
20 Nov 2016
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For much of earth"s history, terrestrial surface was lifeless. Cyanobacteria and protists likely existed on land 1. 2 bill yrs ago. Around 500 mil yrs ago, small plants, fungi, and animals emerged on land. Plants have diversified into 290,000 living species. Plants supply oxygen and are the ultimate source of most food eaten by land animals. Land plants are defined as having terrestrial ancestors, even tho some are now aquatic. La(cid:374)d pla(cid:374)ts do(cid:374)"t i(cid:374)clude photosy(cid:374)thetic protists (cid:894)certai(cid:374) algae(cid:895) Green algae called charophytes are the closes relatives of land plants (charophytes=stoneworts) Comparisons of both nuclear and chloroplast genes point to charophytes as the closes living relatives of land plants. Note that land plants did not descend from modern charophytes, but share a common ancestor w/ modern charophytes. Many characteristics of land plants also appear in some algae. Land plants share the following traits w/ only charophytes (shared ancestral characters) Rings of cellulose-synthesizing proteins= (enzyme rosette)(non-morphological character)
