Lecture 12 BIO 311D 2nd EditionOutline of Last Lecture I. MacroevolutionII. Data for Phylogenetic AnalysisIII. Human Evolution Outline of Current Lecture I. Eukaryotic diversity and the origin of plant kingdomII. Big challenge for early plants- life OUT of the waterIII. Plant vegetative organs: leaf, stem, rootCurrent LectureI. Eukaryotic diversity and the origin of plant kingdom- We classify eukaryotes into 3 major kingdoms (Fungi, Animals, Plants), plus a mixed complex known as “Protista”- Protists include amoebas, euglenas, ciliates, sporozoans, dinoflagellates, diatoms, green algae, red algae and brown algae - What traits would you use to build a phylogeny of these major eukaryotic groups?DNA sequences, life cycle, reproductive traits, etc. - Slime molds are Protists that are haploid during most of the life cycle. During their feeding stages they are single-celled amoebas. In asexual reproduction, the haploid cells aggregate and form a stalked spore-forming structure. Spores germinate into new amoebas.- Fungi are made up of elongate threads called hyphae, in a mass collectively known as myceliumThey eat through absorption; in many forms there is an “n+n” stage called the dykaryon - Comparing the multicellular eukaryote kingdoms: Plants, Animals, Fungi: Life cycles Animals: Generally haploid stage is not multicellularPlants: alternation of generations (multicellular n and multicellular 2n)- Members of the Plant Kingdom seem to form a monophyletic group, based on these shared derived traits that are not found in algae protists+ Multicellular reproductive organs+ Multicellular embryos (retained on parent)+ Apical meristem (continuous mitosis)- Which type of algae is the sister group to Plants, and how do we know?+ Traits to compare: cell wall material, food storage molecule, and specific photosynthetic pigments - Plants retain multicellular embryos on the parent plant. Plants have multicellular reproductive organs- Plants have apical meristems (zones of continuous mitosis, at tips of roots and shoots)II. Big challenge for early plants- life OUT of the water- When plants first colonized land habitats, what were the new opportunities (evolutionary advantages)?+ More sunlight, CO2 would be everywhere, less predators+ Disadvantages: lack of water, UV radiation (too hot) III. Plants vegetative organs: leaf, stem, root- Leaf: photosynthesis- Stem: transport and support- Root: anchor and
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