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Plant Diversity Plant Diversity Plant Diversity (Freeman Ch 30 & 40) 25 February 2010 ECOL 182R UofA K. E. Bonine •From • Origins, Relationships,Plant Diversity Diversity 28-3, 28-5, 39-3 Videos 18 Feb KB – • Shared Derived Traits Lecture Schedule Sea to Land 23 Feb KB – ( 25 Feb KB – •NonvascularSynapomorphies 2 Mar KB – Fungi •Seedless 4 Mar KB – Prokaryotes, Ch31 & Protists Plant Diversity, Form, Function 1 9 Mar KB – 11 Mar KB – Plant Form and Function Plant Function 13-21 Mar Spring Break (middle third) Plant Ecology to Seedsto 23 Mar KB – ) Ecology Vascular 25 Mar KB - Part 2. Discussion and Review. , Ch38&39 , Ch28&29 30 Mar KB - , Ch50,52,53 Biology of the Galapagos, Ch50,52,53 , Ch36&37 Wikelski 2000 and http://livinggalapagos.org/ Plants , Ch30&40 EXAM 2 The Evolution of Land Plants Figure 29-8 Bacteria (from the edge of the swamp…) Archaea Eukaryotic Eukarya Excavata Alveolata Stramenopila Rhizaria Green stuff Discicristata Bacteria Archaea Chromalveolata 3 Diplomonads Parabasalids Euglenids Ciliates Dinoflagellates 2 Apicomplexa Oomycetes Diatoms Brown algae Plantae Opisthokonta Amoebozoa Foraminifera Chlorarachniophytes Glaucophyte algae Red algae Unikonta Green algae Land plants Fungi Choanoflagellates Green Original Land Plants Related to Algae plants Animals Land plants retain derived features they Lobose amoebae Eight major lineages Cellular slime molds of eukaryotes (protist branches are in color) Plasmodial • Chlorophyllshare with a slime molds •Starch • Cellulose 5 as a storage product a green algae ( in cell walls.and 4 b . See Figure 30.9 Charales . ): 6 1 Land Plants are Monophyletic Land Plants Comprise ~Ten Clades Nonvascular (3 clades) Land plants are monophyletic, all -paraphyletic group descendants from a single common ancestor. -liverworts, -hornworts Synapomorphy: development from an -mosses embryo protected by tissues of the parent plant. Therefore, also called Vascular plants, or tracheophytes embryophytes. (7 clades)—all have conducting cells called -tracheids. (phyton = plant) 7 -monophyletic group 8 Moving to Land Biological history Plants first appeared on land between 400–500 million years ago. Environmental Challenges: 1. d 2. transport water to all parts 3. support (fight gravity) Plants first appeared on land between 400–500 4. disperse million years ago. Some challenges met immediately, 9 10 others took millions of years Biological history Adaptations for Land Earth forms Origin of Life 1. Cuticle Oldest fossils -waxy covering thatretards water Photo- synthesis 2. Gametangia enclosing gametes evolves Eukary- Multi- 3. Embryos in a protective structure otic cellular cells Abundant 4. Pigments that protect against UV life Moss radiation 5. Spore walls containing sporopollenin -resistsdesiccation and First land Forests Birds Aquatic life plants Insects Flowering First plants 6. Mutualistic relationships with fungus Abundant mammals Rise of fossils First land animals Dinosaurs Mammals First hominids - to promote nutrient uptake from soil dominant Homo 11 12 sapiens 2 Nonvascular Plants Are Plants Help Create Soil Similar to Ancestral Land Plants Today’s nonvascular plants are Ancient plants contributed to soil thought to be similar to the formation. first land plants. Acids secreted by plants help break They grow in moist down rock. environments in dense mats Organic material from dead plants They are small, there is no contributes to soil structure. system to conduct water or Create habitat and pave way for minerals from soil to plant succession of other species. body parts. mosses 13 14 Extant Plants See Figure 30.9 Three Nonvascular Clades (paraphyletic group) Liverworts Hornworts Discuss ancestral first, Mosses then derived 15 16 Alternation of Generations Moss Lifecycle (Nonvascular Plant) Water required Size and for egg and independence of sperm to meet gametophyte or sporophyte gametophyte, 1n changes in sporangia All plants have alternation of Sporophyte (2n) sporophyte, 2n dependent on, generations and attached to, (= multicellular See Figure haploid & multicelluar 30.17 See Figure diploid) 17 18 30.16 3 Nonvascular: Gametophyte Dominates Nonvascular Plant Reproduction In nonvascular plants: Male: antheridium Female: archegonium gametophyte is larger, longer-lived, and more self-sufficient than the sporophyte. gametophyte generation is sporophyte may or may not be photosynthetic, but is always nutritionally dependent on the gametophyte, and is permanently attached. Reduction of the gametophyte generation is a major theme in plant evolution. 19 See Figure 20 30.17 Nonvascular Plant Life cycle of a moss Reproduction Base of archegonium grows to protect embryo during early development. Video 28-3 (land plants aka embryophytes) Mosses are sister group to vascular plants 21 22 Harvesting Peat from a Bog Moss… Sphagnum grows in swampy places. The upper layers of moss compress lower layers that are beginning to decompose, forming peat. Long ago, continued compression led to the formation of 23 24 4 Paleozoic: Carboniferous • Large glaciers and swamp forests of treeferns and horsetails. • Fossilized forests formed the coal we now mine for Navajo Power Plant, Page, AZ 25 26 Vascular Plants Arose from Vascular Plants Comprise Seven Nonvascular Clades 10 clades of land plants: Recently, fossilized fragments of ancient Nonvascular (3 clades) liverworts have been discovered. -liverworts, hornworts, and mosses -paraphyletic group Vascular plants, or tracheophytes (7 clades) -conducting cells called tracheids. 27 -monophyletic group 28 Extant Plants Evolution of Vascular Plants Vascular plants have a branching, independent sporophyte. Mature sporophyte is nutritionally Vascular, but independent from the Seedless gametophyte. See Fig 30.12 Still must have water for part of the life cycle— for the flagellated, swimming sperm. 29 30 5 Figure 28.17 Horsetails Evolution of Leaves Megaphylls: 31 32 The Life Cycle of Mature gametophyte Life cycle of a fern (about 0.5 cm wide) a Homosporous Archegonium Fern Egg Video Germinating Rhizoids 28-5 spore Antheridium Sperm Sporophyte and HAPLOID (n) Meiosis Fertilization Gametophyte are DIPLOID (2n) each free-living Sporangium Embryo Microsorum sp. Sporophyte Sori (clusters Mature sporophyte Roots Vascular but Seedless of sporangia) (typically 0.3–1 m tall) 33 34 Early Vascular Plants Bristlecone Pine During the Permian, the continents came together to form Pangaea. If you could imagine a living tree as old as the pyramids Extensive glaciation occurred late in of Egypt, what do you think it would look like? It would the Permian. look like a bristlecone pine, Pinus longaeva, the oldest known tree species in the world. Lycophyte–fern forests were replaced The bristlecone pine only lives in scattered, arid mountain by gymnosperms. regions of six western states of America, but the oldest are found in the Ancient Bristlecone Pine Forest in the White Mountains of California. There the pines exist in an exposed, windswept, harsh environment, free of competition from other plants and the ravages of insects and disease. The oldest bristlecones usually 35 36 grow at elevations of 10,000 to 11,000 feet. 6 Bristlecone Pine Which of the following are vascular plants? The oldest known tree is "Methuselah", which is 4,789 years old. To keep Methuselah from harm, this tree isn't labeled, as the other trees are. An older tree called Prometheus was killed shortly after it was a Juniper discovered in 1964. This happened when a geologist searching for evidence of Ice Age glaciers was taking b Sunflower some core samples from several bristlecones. Just as c Fern he realized he had found a tree over 4,000 years old, his coring tool broke. Amazingly the U.S. Forest d Moss Service gave him permission to cut down the tree. e Horsetail Prometheus turned out to be 4,950 years old. It was a 300 year old tree when the pyramids were being built f Liverwort in Egypt. g Lily Laboratory of Tree-Ring Research 37 38 http://www.ltrr.arizona.edu/ (Gymnosperms & Angiosperms) The Evolution of Seed Plants Seed Plants Late in the Devonian, some plants developed secondary growth: thickened woody stems of xylem. Small seeds Large seeds First species with secondary growth were the progymnosperms: seedless vascular plants, now extinct. Wood: proliferated xylem, gives support and Penny allows plants to grow above their competitors 39 for sunlight. 40 Figure 29.1 Highlights in the History of Seed Plants Seed Plants Took Over Surviving seed plants fall into two groups: • Gymnosperms: pines and cycads •Angiosperms: flowering plants 41 42 7 Evolution of Plants Gymnosperms Horsetails and ferns (Pteridophytes) replaced by seed plants Extant gymnosperms are probably a clade. Gymnosperm: “naked-seeded”—the ovules and seeds are not protected by ovary or fruit tissue. 43 44 Gymnosperms Living fossils: Gingko Four major groups of living gymnosperms: • Cycads: Cycadophyta—140 species • Ginkgos: Ginkgophyta—one living species, Triassic Ginkgo biloba (~200mya) • Gnetophytes: Gnetophyta—90 species in 3 genera • Conifers: Coniferophyta—600 species, the cone bearers • Cycads and Ginkgos still have 45 46 cycad conifer Cycas revoluta UA Campus gnetophyte Gingko biloba 47 Gymnosperms 48 http://arboretum.arizona.edu/plantwalks.html 8 Gymnosperm Evolution Most living gymnosperms have only tracheids for water conduction and support. Angiosperms have vessel elements and fibers alongside of tracheids. 49 50 Evolution of Seed Plants Gametophyte generation is reduced even further than it is in ferns. Haploid gametophyte develops partly or entirely while
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