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TTU / Biology / BIOL 1404 / how do c4 plants avoid photorespiration

how do c4 plants avoid photorespiration

how do c4 plants avoid photorespiration

Description

School: Texas Tech University
Department: Biology
Course: Biology 2
Professor: Micheal dini
Term: Spring 2017
Tags: Biology and Ecology
Cost: 25
Name: BIOL 1404
Description: Notes covering all material on first two tests with Dr. Schwilk
Uploaded: 05/03/2017
118 Pages 261 Views 0 Unlocks
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o If you were dying of thirst in the desert and decided to squeeze water from parenchyma of a barrel cactus, at what time of day would you want to do this?




o What makes corn (maize) and sugarcane such productive crops?




o What is the most abundant enzyme on the planet?



4 Photosynthesis II: Photosynthetic strategies 4.1 Rubisco and photorespiration ∙ Questions o What is the most abundant enzyme on the planet? o What makes corn (maize) and sugarcane such productiveDon't forget about the age old question of ucr psychology courses
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 crops? o If you were dying of thirst in the desert and decided to squeeze water from parenchyma of a barrel cactus, at what time of day would you want to do this? ∙ Rubisco o note Fixes C02 to RuBP ∙ Limitations on photosynthesis∙ Carboxylase and Oxygenase Rubisco is also an oxygenase — when O2 concentration is high compared to CO2,  rubisco binds to RuBP and O2 ∙ Content of atmosphere This is the problem: o 78.1% N2 o 20.9% O2 o 0.9% Ar o 0.04% CO2 o 0.002% Ne ∙ Atmospheric CO2 concentration through time∙ Photorespiration: chloroplast ∙ Photorespiration: perixosome and mitochondria4.2 C4 Photosynthesis ∙ How to avoid photorespiration? o Increase CO2 concentration around rubisco By using a non oxygenase in initial carbon acquisition step: PEP carboxylase  (Phosphoenolpyruvate carboxylase) ∙ C4Gurevitch et al 2004 ∙ Anatomy of a C3 leaf Gurevitch et al 2004 ∙ Anatomy of a C4 leaf∙ C4 Plants: Sugarcane ∙ C4 Plants: Maize∙ C4 Plants: Blue grama Copyright Curtis Clark o Image copyright note: "Bouteloua gracilis 2004­08­22" by Copyright by Curtis Clark, licensed as noted ­ Photography by Curtis Clark. Licensed under CC BY­SA 2.5 via Commons  ­ ∙ Advantages of C4: o Higher maximum rates of photosynthesiso Higher temperature optimum o Higher water use efficiency o Higher N use efficiency ∙ C4 CO2 response ∙ C4 light response ∙ C4 photosynthesis o evolved up to 50 times independently o present in 19 angiosperm familieso only 3% of angiosperm species are C4 o But they account for 20% of earth's total primary  production ∙ Where does one find C4 plants? o Warm, productive systems o But not so productive that trees overtop grasses! o So landscapes like the southern High Plains where there is  a warm and reasonably wet summer, but rainfall variability limits  trees o Or semi-tropical grasslands where fire limits trees ∙ Distribution of C4 grasses in North America Figure: Gurevitch et al 2004 ∙ When did C4 evolve?Figure: Osborne and Sack 2012 o Note  See https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3248710/ 4.3 CAM Photosynthesis ∙ Crassulacean Acid Metabolism (CAM) o Problem  CO2 acquisition leads to water loss  Daytime air is dry (low relative humidity).  Arid environments  o Solution  Store carbon to separate light reactions and Calvin  cycle in time. ∙ Temporal separation: night∙ Temporal separation: day ∙ Where do you find CAM plants? Over 30,000 species o Desert succulents (Cactaceae, Agavaceae, Euphorbiaceae)o Tropical epiphytes (Bromeliads, some orchids) o Some aquatic plants (??!!) ∙ CAM plants: Euphorbia tetragona ∙ CAM plants: Cactaceae (Echinocactus texensis) ∙ CAM plants: Agave neomexicana∙ CAM plants: Bromeliads Tillandsia in Florida ∙ CAM plants: Aquatic? IsoetesFigure: Wikimedia commons AHR 2013 o Note CAM photosynthesis has also been found in a few aquatic plants. What value would  it serve for such plants? See http://www.jstor.org/stable/4354319 5 Water Relations I 5.1 Key Concepts ∙ Questions o Why can trees be taller than 9.8 m high? And why might  this be surprising? o How can leaves that have positive turgor pressure pull  water from the xylem that is under tension (negative pressures)? o Why did junipers throughout west Texas die back from the  branch tips back in 2011–2012? ∙ Key concepts o Water moves down concentration gradients o Terrestrial plants (and animals) must balance water loss  with water acquisition ∙ Major forces moving watero Loss to dry air ∙ Driven by Vapor Pressure Deficit (VPD) o Osmotic gradients (solute potential)  Semipermeable membrane   Stop when forces are balanced o Pressure gradients  Both positive (pressure) and negative (tension). Hydrogen bonds  allow adhesion, cohesion and surface tension.  Pressure from air pressure and gravity ∙ Plants balance root water acquisition with transpiration o Through the stomata or leave surface o Nearly all water loss is to the atmosphere o Nearly all water gain is via roots o All other sources negligible (metabolic water gain, loss in photosynthetic  reaction) 5.2 Water in air ∙ Water in air: saturation vapor pressure o Water vapor pressure  Denoted e. partial pressure of water vapor in atmosphere  o Saturation vapor pressure  Denoted e0.   Partial vapor pressure when liquid and gas water are at  equilibrium.   Temperature dependent ∙ Water is pulled from the leaves o Water is pulled from the leaves o Water in a plant is like a stick being pulled apart ∙ Why is water pulled from leaves? o Vapor pressure deficit o Difference between saturated vapor pressure and actual vapor pressure.  Depends on actual amount of water in air and on temperature o Relative humidity= e/e0 X 100 ∙ Whenever VPD is non zero (when RH < 100%), then atmosphere is pulling water  from leaves! 5.3 Water potential ∙ Water Potential  o The potential energy of water in a particular environment (temperature,  pressure, solutes) relative to pure water at atmospheric pressure o Differences in water potential  determine how water moves: Water always flows from higher to  lower water potential (closer to 0 to more negative places) ∙ water pressure is in units of pressure  ∙ Water potential from soil through plant o Pure water= 0 o Dry air = very low (negative)  o Soil = driven by matric forces (attraction of soil particles to water) o Plant = varies and at any point is sum = solutes + pressure  ∙ Water potential through a plantGradient within plant only occurs when water is moving ∙ Water potential through a plant ∙ Turgor pressure When pressure inside the cell (turgor pressure) increases, the cell wall pressure is  induced. A cell that is firm is turgid∙ Wilting ∙ Measuring water potential ∙ "Pressure Bomb"5.4 Water movement ∙ Symplast and apoplast o Remember that xylem tissue is primarily dead cells o And live plant cells have plasmodesmata o Symplast ∙ Everything within the cell membrane o Apoplast ∙ Almost everything outside the cell membrane (xylem, water space in cell walls,  water­filled spaces between cells). ∙ All about water  ∙ Water entry into roots o Water must get from soil, through epidermis and cortex tissue to vascular  tissue o Vascular tissue surrounded by endodermis  ∙ The Casparian strip o Narrow band of wax on endodermal cells. Composed of  suberin. o Forces water into symplast at endodermis o Allows plants to control ion uptake∙ The Casparian strip water can flow from the outside in, allows plants to control ion uptake  6.1 Soil water ∙ Questions o Why did junipers throughout west Texas die back from the  branch tips in 2011? o How can you determine differences in rooting depth of two  plants side-by-side? ∙ The water potential gradient ∙ Water moves from one part of the plant to another down a water potential  gradient. Different components of water potential are important at different stages. o Soil to roots: osmotic (and matric) potential. Potential lower in roots  than soil  o Roots to stems: pressure potential (tension).  o Stems to mesophyll cells: osmotic potential.  o Cells to stomata to atmosphere: vapor potential. ∙ Soil water: matric forces gravity drains soil out, depending on adhesion of water to particles (in upper  division), wilting cant hold anymore water and maintain turgor pressure   ∙ Salt scalding ∙ Salt scalding ∙ Predawn vs midday water potential o During the night, VPD drops and stomata are closed (for C3/C4)  No water loss, all potential is the same throughout the plant o Therefore, flow stops and   equilibrates Ψo Predawn water potential then indicates something about soil water  potential o Midday measurement is only the leaf while predawn is probably  whole plant  ∙ Example: Mesquite ∙ Example: Juniper ∙ Water potential question: During late summer you measure leaf water potential pre­dawn in a juniper and mesquite  growing side by side. You find that the predawn water potential for the juniper is ­5 MPa  and for the mesquite it is ­2 MPa. ∙ Which has deeper roots? o A) Mesquite o B) Juniper 6.2 Xylem and cavitation these are all for safety of the plant  ∙ Xylem tracheidso Tracheids are pipes that are long, tapered, and have pits o All vascular plants have this o Dead at maturity  o Pits are valve’s, water can flow through, unless air embolism, then trachea closes off, but only that one   ∙ Xylem vessel elements ∙ Wider and shorter ∙ Huge openings­ perforation plate  ∙ Vessels aren’t continuous throughout the whole plant  ∙ Very little resistance to flow o Note B: Shows early vessels (Magnolia) to more derived on right (oak). Trend is towards  wider. ∙ Besides wilting, what happens when water potential gets too  low?∙ Can crack apart if water is still flowing  ∙ Difficult for bubbles to form, need very low water potential  ∙ Tiny explosions  ∙ Drought dieback: Davis Mtns, Texas tension strongest at leaves, lowest water potential, that’s why leaves die first  ∙ Drought mortality: Santa Rosa Mtns, California 6.3 Plant adaptations to drought ∙ Whole plant adaptations o Drought avoidance whole plant (desert annuals)  Seed waiting for a good year to produceo Drought avoidance through phenology: drought deciduous  (deserts and Mediterranean shrublands) o Drought tolerance:  Desiccation avoidance: High root-shoot ratios,  succulents  Desiccation tolerance requires specific xylem  anatomy) ∙ Whole plant adaptation examples ∙ Anatomical adaptations o Desiccation avoidance:  Stomatal number, size and arrangement, control  Isobilateral leaves (symmetrical internal architecture, amphistomatous: stomata on both sides of leaf  Waxy cuticle or hairs  Curl or fold leaves o Desiccation tolerance:  Extreme xylem resistance to cavitiation  Narrow vessels?  Ability to resprout following dieback ∙ Nerium oleander ∙ Anatomical adaptation example: stomatal crypts6.4 Drought in West Texas ∙ Quercus hypoleucoides ∙ Quercus grisea ∙ Xylem vulnerability curves ∙ ∙ Remember: 1 MPA = 145 PSI! 7 Sex 7.1 Water and sugar∙ Phloem o Translocation is the movement of sugar through the plant o Occurs via phloem sieve-tube elements and companion  cells. o In vascular bundles next to xyelm ∙ Compartmentalized in vascular bundles o Damage plant on one side, that side will die o Source leaves send sugar to tissues on same end of plant  ∙ Pressure-flow o Not due to tension ∙ Phloem parasites o Make honey dew  o Note Aphids pierce phloem and pressure pushes sap through them. Honeydew is sap  excreted. Some ants "tend" aphids (clip wings, produce chemical intoxicant to drug  them). 7.2 What is sex? ∙ What is sex? Sex is meiosis followed by fertilization o note  Meiosis reduces the number of chromosomes to half  (=N, haploid)  Fertilization restores the number to full (= 2N,  diploid)∙ Asexual reproduction ∙ Asexual reproduction: Larrea tridentata ∙ Asexual and sexual reproduction o Text  Asexual reproduction:  Most animals reproduce this way:  Plants reproduce this way: o FiguresMost animals  reproduced this  way o Notes Alternation of generations ∙ Sexual reproduction o Sex has inherent cost  Half of genes from another individual (except in  selfing) ∙ Fitness cost  o When is it valuable  Especially under changing environments  Provides variation ∙ Alternation of generations: mosses o Rain washes sperm  o Cant function in dry areas  ∙ Alternation of generations: angiosperms o Sporophyte is large and long lived; gametophytes are  small, short lived, and nutritionally dependent on the  sporophyte o Double fertilization  7.3 Flowers and pollen ∙ Angiosperm reproduction I ∙ Angiosperm reproduction II∙ Angiosperm reproduction III ∙ Angiosperm reproduction IV∙ Pollen Pollen grains are basically spores that grow into tiny sperm­making organisms ∙ Start as pore, time it grows it is 2­celled ∙ Pollen grain ∙ Pollen: surface∙ Pollen tubes ∙ Pollen tubes 7.4 Pollination ∙ Wind pollination o grasses, rushes, many temperate trees (all conifers, oaks,  maples, elms, willows, etc) o Produce a LOT of pollen, but don't have showy flowers o Light, non-sticky pollen. ∙ Pollination by animalso Showy flowers are an advertisement — but they may  involve false advertising. o Colors vary according to visual system of animal o Whole inflorescence structure may contribute to  pollination. o Floral odors ∙ Pollination: beetle ∙ Pollination: hummingbird ∙ Limiting unwanted visitors ∙ Plant mating systemso Some plants self-fertilize o Some species outcross ∙ Flowers: perfect or imperfect Perfect flower functional stamens and functional stigmas Staminate flower functional stamens only Carpellate flower functional stigmas ∙ Plant sexes: which means that plants have several combinations Hermaphroditism perfect flowers only Monoecy staminate and carpellate flowers on same plant Dioecy Separate male and female individuals Ex- cannabis sativa  ∙ A dioecious plant: Cannabis sativa ∙ More complicated types: A,B C?8 Roots and nutrition 8.1 Roots ∙ Questions o Which has more fertile soils, deserts or rainforests? o N2 is useless to plants, so how do they obtain N? o How do plants such as the heaths, which lack fine roots,  survive? ∙ von Helmont's experiment 1648 o Portrait Jean­Babtiste von Helmont o Experiment (Actually he set out to prove that plant mass came from water) o Notes Book presents it as if von Helmont wast testing for soil contribution. But he was  convinced of water. Disproven by Woodward in 1690s but Woodward also failed to  measure dry mass. ∙ What are plants made of? o Carbon, hydrogen, oxygen (96% of dry weight) o Macronutrients. Most important are N, P and K. Also  calcium, magnesium, sulfuro Micronutrients: zinc, iron, copper, etc ∙ All but CO2 obtained through roots o Anions (- charge)  Usually water soluble and easily available  (NO3-,SO42-)  BUT easily lost through leaching o Cations (+ charge)  Less easily available  Bind well to clay particles ∙ Cations such as K+, NH4+, Ca2+ o Notes And roots exude protons CO2 to release cations bound to clay particles Phosphate ions form insoluble complexes ( HPO42­ ) ∙ Roots: obtaining what is needed and excluding the rest o Root hairs provide needed surface area o Casparian strip forces pathway through plasma membrane o membrane transporters (ion channels) are specific to  particular ions o Proton pumps "pump" ions against the concentration  gradient (low in soil, high in plant) 8.2 Soil ∙ Soil types Sand.02 to 2.0 mm. Large spaces between particles give good air  movement, poor water and mineral-holding capacity (poor  fertility) Silt .002 to .02 mm. Silt has texture of flour. Good for fertility Clay  <.002 mm. Small spaces give poor air movement, good water and  mineral holding capacity (good fertility). ∙ Soil type depends upon distribution of particle sizes ∙ Soil fertility o Low in areas of high rainfall o tropical rainforest: leaching o Boreal forest: acidic, podzols o Best: loams, grasslands, some temperate forests. 8.3 Nitrogen and Rhizobium ∙ Nitrogen ∙ Single most limiting nutrient for plant growth ∙ Inorganic N not useful to plants! They need NO3­ or NH4+ ∙ Nitrogen fixation by prokaryotes o N2 NH3 Catalyzed by nitrogenase. Requires ENERGY∙ Symbiotic nitrogen fixation o Nodulated legumes (Rhizobium)  Mutualism with beans and peas  Bacteria gets energy, plant gets nitrogen   Plants cannot fix their own nitrogen  o Nodulated non-legumes (Frankia) o plant-cyanobacteria symbiosis and lichens (fungal cyanbacteria symbiosis) ∙ Rhizobium ∙ Legumes in crop rotation: Alabama cotton experiment o Notes ∙ Oldest continuous cotton study in the world∙ Nitrogen limitation ∙ Plot on right only grows cotton, plot on left grows legumes in offseason of cotton  ∙ Obtaining nitrogen: carnivory 8.4 Mycorrhizae ∙ Mycorrhizae o Plant-Fungal mutualism  Both benefit (mutualism)  Fungus gets carbon (energy)  Plant gets increase access to inorganic nutrients  (especially phosphorous) and water ∙ Mycorrhizae o text  Endomycorrhizae (specifically this image: arbuscular  mycorrhizae, penetrate root cells).  Ectomycorrhizae (mantle around roots)  forests o text ∙ Mycorrhizae important for Ericaceae Arbutus xalapensis∙ Important for conifers Pinus ponderosa ∙ Important for temperate forest trees ∙ Flowering plant which is a root parasite o photo o text Sarcodes sanguinea: Steals energy from pine trees through mycorrhizae!9 Plant Diversity I: Origin of land plants 9.1 Phylogenies ∙ Questions o When did plants invade the land? o What allowed them to do so? o What major innovations have allowed plants to spread and  radiate? ∙ Tree of life: Eukaryotes ∙ Phylogenetic terms o Phylogeny (the tree) o branch o node o leaf (or tip)  taxa or individual species/ populations  o polytomy (node with more than two descendant branches)  o monophyly / monophyletic (group that contains all the  descendants of a common ancestor and no others) ∙ Phylogenetic taxonomy o Common ancestor of crocodilians, dinosaurs, and birds o Reptiles aren’t monophyletic  9.2 Major events in plant evolution ∙ Phylogeny and traditional names in plants∙ Major groups of land plants o Nonvascular plants ("bryophytes") ∙ Lack vascular tissue o Seedless vascular plants ∙ Reproduce via spores (eg ferns) o Seed plants ∙ This is a monophyletic group. Includes:  non-flowering (naked seed) plants - "gymnosperms"  Flowering plants: Angiosperms ∙ Plantae phylogeny o Can flip any node, order not important but left to right is∙ Major events in Earth history ∙ Major events in plant evolution 700 mya Green algae 475 mya Plants invade land ~400 mya The Silurian-Devonian explosion — roots, vascular tissue,  overtopping growth ~350 mya Wood (unifacial and then bifacial cambium), seed plants 300-100 mya Diversification of the gymnosperm lineages 150 mya origin of angiosperms 100 mya Diversification of the Angiosperm 9.3 Innovations I: life on land ∙ Invasion of land ≈ 475 mya Group = the embryophytes.o Protected gametes, retained offspring (embryophytes) o Evolution of a cuticle (key innovation, waxy coat) o Stomata o Way to protect spores from desiccation (sporopollenin) o Upright growth (dichotomous branching-had to branch into  2) ∙ Reproduction in green algae ∙ Reproduction in early land plants ∙ Pattern in alternation of generations o More derived lineages reduce gametophyte generation and sporophyte becomes dominant ∙ Reduction of gametophyte ∙ Upright growth and branching o Early land plants did not branch  o Middle image- could not grow much, bad set up  o Third image- more closely to today’s plants  FIGURE 4. A comparison of sporophyte branching among early­branching lineages  of land plants. In the bryophytic (moss) lineages (left) the sporophyte is unbranched; dichotomous branching evolved at the base of the polysporangiophytes (center);  overtopping (or pseudo­monopodial growth) evolved at the base of the euphyllophytes (right). Insets at the top represent these differences in branching at  the level of the apical meristem. (Drawings at the bottom are from Stewart and  Rothwell 1993.) 9.4 Innovations II: Vascular tissue ∙ Pattern in xylem evolution o Note Importance of lignoin in secondary cell walls: phenolic compound built from six carbon rings. ∙ Early vascular plants: Lycophytes o Don’t have true seconday growth  o Couldn’t get very tall  Selaginella (Resurrection plant) ∙ Devonian lycophytes: unifacial cambiumo Notes FIGURE 6. A sample of growth forms in extinct lycophytes. Two drawings on the  left (from Phillips and DiMichele 1992) show early stages in the life cycle— establishment of the stigmarian "root" system with possibly photosynthetic  "rootlets" prior to rapid stem elongation. Three drawings on the right (from Stewart  and Rothwell 1993) show reconstructed forms of the determinate stems (not drawn  to the same scale); from left to right: Sigillaria, Pleuromeia, and Lepidodendron. ∙ Early vascular plants: Ferns o Note Cyathea dregei in Cape Town, South Africa. No true wood, supported by mass of fibrous roots. ∙ When did these innovations occur? ∙ Unifacial vs bifacial cambiumFIGURE 5. Differences between the bifacial cambium in the lignophyte lineage  (including seed plants) and the unifacial cambium found in extinct tree lycophytes  (e.g., Lepidodendron). The bifacial cambium produces both secondary xylem and  secondary phloem, and the cambial initials are able to divide both periclinally  (producing cells that differentiate in secondary tissues) and anticlinally (producing  new cambial initials). The unifacial cambium produced only secondary xylem and  the cambial initials divided only periclinally, limiting expansion of the cambial  cylinder and the production of wood. These seemingly minor differences translated  into major differences in evolutionary flexibility and "success" (see text). ∙ "Trees" of the Devonian and Carboniferouso Notes FIGURE 7. Diversity of form among extinct treelike plants from the Devonian and  Carboniferous (not drawn to the same scale). From left to right: Archaeopteris (an  early lignophyte); Calamites (an equisetophyte); Psaronius (a marattialean "fern"), in which the trunk was formed by a mantle of adventitious roots; Tempskya (a  filicalean "fern"), in which the trunk was formed by numerous smaller stems  embedded in a tangle of adventitious roots. 10 Plant Diversity II: Seed plants 10.1 Seed plants ∙ Key innovations o Seed plants  Bifacial cambium and wood  Heterospory (but also evolved in some other  lineages)   Seed (embryo + nutrient packet)  Animal pollination is rare-gymnosperms  o Angiosperms  xylem vessels (but also evolved in Gnetophytes)  flowers  fruits(maternal tissue, surrounds seed, aid in  dispersal)  10.2 Seed plants ∙ Gingkos (Gingkophyta) One extant species: Gingko biloba ∙ Gingko biloba male cones ∙ Gingko biloba female cones∙ Cycads (Cycadophyta) ∙ Cycads in Australia: Cycas brunnea ∙ Cupressophyta (Cuppressus, Juniperus, etc) o Photo o Text Giant Sequoia (Sequoiadendron gigantium) ∙ Giant sequoia cones #+BEAMER" \tiny Photo: Didier Descouens∙ Juniper and pinyon pine in New Mexico ∙ Pinophyta (Pines, firs, spruce) ∙ Lodgepole pine (Pinus contorta) cones o Photo: ∙ Gnetophyta: Ephedra ∙ Gnetophyta: Ephedra sp in Arizona∙ Gnetophyta: Welwitschia o Note Welwitschia is named after the Austrian botanist and doctor Friedrich Welwitsch  who discovered the plant in 1859 in present­day Angola. Welwitsch was so  overwhelmed by the plant that he, "could do nothing but kneel down and gaze at it,  half in fear lest a touch should prove it a figment of the imagination." Welwitsch abandoned medicine to study botany full time in 1839. ∙ Pinus and fire∙ Pinus and fire∙ Longleaf pine (Pinus palustris) grass stage o Resprout after fires (rare) o Shoots up to escape fire  ∙ Longleaf pine forest ∙ Longleaf pine forest fire 10.3 Angiosperms ∙ Angiosperms ∙ Over 250,000 species of angiosperm ∙ Two major groups: monocots and "dicots"o Monocots  One cotyledon   Vascular tissue scattered  Parallel veins   Petals in multiples of 3 o Dicots  Two cotyledon  Vascular tissue in circular arrangement   Branching veins  Petals in 4s or 5s  ∙ Dicot seedling (Castor bean, Ricinus communis) ∙ Monocot seedling: Agave parryi ∙ Angiosperm diversification in the CretaceousBond and Scott, New Phytologist 2010 Fig. 5 The Cretaceous angiosperm–fire cycle showing the processes influencing the  opening of gymnosperm­dominated forests and the incursion of low­growing  angiosperms. 10.4 Evolution of C4 ∙ When is C4 favored? Figure: Ehleringer et al 1997 ∙ Atmospheric CO2 concentration through time∙ Spread of C4 delayed well after evolution of C4 Higher δ13C values indicate organic material created by C4 photosynthesis o Note Barry, J.C., Morgan, M.E., Flynn, L.J., Pilbeam, D., Behrensmeyer, A.K., Raza,  S.M. et al. (2002). Faunal and environmental change in the late Miocene Siwaliks of northern Pakistan. Paleobiol. Mem., 28, 1–55. Rubisco prefers ^{12}C more strongly than does PEP carboxylase ∙ What happened during Miocene? o CO2 fell (low by 30 mya) o Seasonality increased (≈ 8 mya) o FIRE o C4 grasses spread ≈ 8 mya11 Ecology: Introduction 11.1 What is Ecology? ∙ When did ecology emerge as a science? o 18 and 19th centuries: Age of exploration. o Massive collections of plant and animal specimens o Vegetation patterns emerged that indicated the earth was a very "patchy"  place. ∙ Maps of vegetation types ∙ Vegetation types, formations and biomes Some of the first "ecology" questions had to do with these types or "formations" o How many formations existed? o Could one predict where they would occur (from soil, climate, etc?) ∙ BiomesWe now call these  "biomes" ∙ "Pre ecology" Linnaeus, 1707­1778 In 1749 Linnaeus published The Oeconomy of Nature: nature may seem chaotic and unpredictable, but actually existed in a balanced state of order as designed  by the creator. von Humboldt, 1769­1859 Alexander von Humboldt argued that the world was not as static as Linaeus  suggested and that organisms were interconnected. Darwin, 1809­1882 Charles Darwin's theory of evolution by natural selection ( On the Origin of  Species 1859) provided a mechanism for interpreting patterns in the distribution and abundance of species. ∙ von Humboldt: organizing geography and science o NoteDistribution of vegetation on the Peak of Teneriffe in the Canary Islands. This  was one his first attempts to draw a scientific concept. He wanted to demonstrate  the relationship between elevation and the distribution of plant life. ∙ Ecology as a recognized science Haeckel, 1834­1919 Ernst Haeckel was the first to provide a name for the science in (Morphology of Organisms 1866). 1885 First book with "oekology" in the title published in Germany by Hans Reiter 1895 Term starts being used in the United States and the term and ideas are quickly  adapted especially by botanists. ∙ Origin of the word oikos the family household logy the study of ∙ Definitions: o Ernst Haeckel 1866: " By ecology we mean the body of knowledge concerning the economy of Nature  — the investigation of the total relations of the animal to its inorganic and organic environment." o Our definition The interrelationships of organisms and their environment 11.2 Questions in ecology ∙ It is about solving problems and solving mysteries o What will happen to the forests of the southwestern US under a changing  climate? o How can we manage agriculture on the southern High Plains under  increasing drought?o Why did giant sequoia regeneration fail for 100 years in Sequoia National  Park? o How does the community of microbial species in our gut influence human  health? ∙ Types of studies in ecology Controlled experiments Isolate a portion, limit factors, manipulate conditions Observations Go into the field and see what's happening. We may use statistical controls. We may use forensic techniques. Mathematical models Describe population/community/ecosystems through equations or through  computer simulation. Test against data. ∙ Levels of organization in ecology Organism Physiological ecology Population Birth and death rates, population dynamics Community All populations in a given area, interactions among species Ecosystem Community and the non­living environment. Nutrient cycles, carbon and  nitrogen flux. Earth (Biosphere) Global ecology. Global energy budgets, vegetation­climate interactions. ∙ Ecological studies may concentrate on a taxonomic level. o Taxa: Domain, kingdom, phylum, class, order, family, genus, species,  variety o Family ends in "­idae" (animals) or "­aceae" (plants) o But don't worry about ranks! Properly, they are just names for nodes on a  phylogeny. o Scientific name = genus and specific epithet. Italicized o Examples: Plants in a marsh (kingdom)  Woodpeckers in a forest (family Picidae)  Oaks in west Texas (Quercus, genus)  Coyotes on the High Plains (Canis latrans, species) 11.3 Climate ∙ Weather vs Climate Weather The temperature and moisture conditions for a specific place and time. Climate The long-term pattern of weather in a locality, region, or even  over the entire globe. o Note Note that, unlike many definitions of weather, there is no mention of averages. This  is not to exclude averages from the description of climate, as they are important  descriptors of climate Maximum and minimums are also important. Extreme events  may also be important. Hurricanes are very important components of the climate of  the Gulf Coast but they do not affect long­term averages very much. ∙ How to describe climate? o Averages  Average pattern of precipitation through the year  Average pattern of temperature through the year o Extremes  Average hottest and coldest temps (per month, per  year, per decade)  Inter-annual variation: Occurrence of major droughts. major rainfall events, blizzards ∙ Climate diagramsGraphically show monthly pattern of precipitation and temperature o Lubbock o Houston o Note Climate diagrams were invented by Heinrich Walter (another German ecologist) When I was thinking of moving to Lubbock I went and made a climate diagram.It turns out that a good rule of thumb is that plant growth needs 20\,mm of  precipitation for every 10C average annual temperature. When precipitation is above this line, shading is blue. Often indicate freezing months (minimum daily temps  below freezing) below the graphs. ∙ Climate diagram annotated o diagram o parts 1. Station name and elevation 2. Mean annual temperature 3. Total annual precipitation 4. Mean monthly precip. curve 5. Mean monthly temp. curve 6. Frost period (based on daily min.) 7. Mean daily min. temp. of coldest month 8. Mean daily max. temp. of warmest month 12 Climate 12.1 Seasonality∙ Questions o Why do we have summer rain in Lubbock? o What aspects of climate are not captured by a climate  diagram? ∙ Seasonality: tilt of Earth's axis Tilt is 23.5° ∙ Earth's tilt and temperature o Near the poles:  Photon density of solar radiation spread over greater  area at high latitudes  Light passes through a thicker layer of atmosphere -  more energy scattered  More energy is reflected due to the angle at which it  strikes the atmosphere and the Earth. o Winter vs summer: Area of direct (vertical) sunlight closer to one pole or another ∙ Tilt divides up the earth ∙ Circles of latitudeArctic and Antarctic Circles Dividing line between those regions that get 24 hr of sunlight at  height of summer, 24\,hr of darkness in depths of winter and  those regions that get some dark and light periods every day  (66.5°) Equator Circumference midway between N and S poles Tropics Where the sun is directly overhead at least once a year: from  23.5° N (Tropic of Cancer) to 23.5° S (Tropic of Capricorn) o Note The main long­term cycle causes the axial tilt to fluctuate between about 22.1° and  24.5° with a period of 41,000 years. Currently, the average value of the tilt is  decreasing by about 0.47″ per year. As a result, (approximately, and on average) the  Tropical Circles are drifting towards the equator (and the Polar Circles towards the  poles) by 15 metres per year. ∙ Solstice and Equinox Solstices shortest and longest days of the year Equinoxes days on which there are 12 hrs of sunlight and 12 hrs of darkness ∙ Rainy and dry seasons Tropics have "rainy" vs "dry" seasons o Heavy rains at the Solar Equator  which moves between -23.5° S to 23.5° N  Northern tropics near Tropic of Cancer: Rainy season  in July  Near Tropic of Capricorn: rainy season in January  Near equator: two rainy seasons ∙ Two tropical climates o 1weto 2 wet o To get from the left to the right hand climate, you would  need to travel: A) North, B) East, C) South, E) West 12.2 Winds and currents ∙ Hadley, Farrel and Polar cells o Hadley cell o Warm air rises and cools, dropping rain o Cooled air is pushed polewardo Dense, dry air descends warms and absorbs moisture  o At higher altitudes, 3 circulation cells in the northern  hemisphere  o Also 3 circulation cells in the southern hemisphere  o Sets up components for prevailing winds ∙ Winds o Earth is rotating at 465 m/s at equator, 223 m/s at 60°,  poles much slower o Convection cells set up the north-south movement, Coriolis effect sets up east-west o Due to the rotation of the earth wind (and water) currents  are deflected to the right (clockwise) in the Northern Hemisphere  and to the left (counter clockwise) in the Southern Hemisphere. ∙ Winds: Coriolis effect ∙ Prevaling winds Winds are named by the direction from which they originate. o In the northern hemisphere:  Trade winds: southward flow of surface are from  Hadley cell deflected right  Westerlies: Northward flow deflected to right.  Polar easterlies: Southward flow defected to right.o note Horse latitudes 30­35 degrees, doldrums right around equator – intertropical  convergence zone. ∙ Ocean currents o West coast cold currents-drier o East coast warm currents-storms 12.3 Continental and montane effects ∙ Water is a reservoir of heat Continental Effect At the center of continents, the summers heat and winter's cold  are not moderated by proximity to the ocean Oceanic Effect Oceans cool more slowly than land in Fall and warm adjacent  land, heat more slowly in Spring and cool adjacent land ∙ Continental effect: Lubbock o Lubbocko Houston ∙ Montane effect ∙ Adiabatic cooling o cooling of air as it rises -— caused by expansion as  pressure is reduced — air is cooler at top of mountains. Dry adiabatic rate is about 1°C per 100m (slows down when  dew point reached) ∙ Rain shadow o Adiabatic cooling causes rain to fall on side of mountains  where moist surface air is pushed up the mountain and  causes rain shadows on the side of mountain where air is  descending after being pushed over the mountain∙ Rain shadow ∙ Example: Sierra Nevada of California ∙ From the air ∙ Sierra Nevada transect∙ Rainshadow: Sierra Nevada ∙ Valley: Visalia ∙ Foothills: Three Rivers∙ Valley and foothills ∙ Grant grove ∙ Sequoiadendron giganticum∙ Sequoiadendron giganticum and fire ∙ Lodgepole ∙ Independence (east side of mountains)∙ The Owens Valley near Independence 13 Biomes 13.1 Biomes ∙ Questions o If you were to be parachuted to a location at 35° N on west side of a continent, how would you pack? What types of food would you be able to find once you arrived? o What about at 60° N in the center of a continent? ∙ Biomes o Broad grouping of biological communities which share  dominant plant forms o Determined primarily by climate, but with contributions by  fire, herbivores, topography and soil o Not a perfect classification (what is?), but useful. ∙ Rainfall and precipitation on the Earth∙ "Whittaker Biomes" Robert Whittaker, 1970s13.2 Tropical and subtropical biomes ∙ Tropical rain forest two peaks, earth crosses the equator  o Note  Abundant rainfall in all seasons and warm  temperatures.  High rate of photosynthesis (primary productivity  high). Competition for light leads to tall forest trees.  Litter does not accumulate on forest floor as the rate  of decomposition is high under warm, moist conditions.  High diversity of plant and animal life ∙ o Note  Little seasonality  Soils are thin, bedrock not far below surface. Most inorganic  nutrients are part of the biomass (both living and decomposing).  Laterization: most bases and silicate minerals leached out. Oxides  of Fe, Al, quartz sands, and stable clays remain.  Canopy is closed layer of leafy portions of trees that are exposed to sunlight. Emergent Trees: stick up above the canopy Understory Trees: trees that are not tall enough to be part of the  canopy  Shrub Understory: ground Layer of herbs  Litter does not accumulate on forest floor as the rate of  decomposition is high under warm, moist conditions  Epiphytes (plants that grow on other plants) and lianas (vines that  grow on trees so they can get to the light) are common. Many  species of all kingdoms and high biomass/ha.  Animals: many arboreal species. Ground dwellers generally not  super large. EG central America: Kinkajou (honey bear), Tapir. ∙ Tropical seasonal forest and savanna one peak when sun is overhead, summer  ∙ o Notes on tropical seasonal forest Abundant rainfall only in one season and warm temperatures,  shorter growing season than rain forest, little seasonal variation in temperature dry period increases as the latitude increases (up to 8 months).  Trees are drought deciduous, dropping their leaves when the soil  dries out.  High rate of photosynthesis (primary productivity high) during wet season.  High diversity of plant and animal life Found in Central and South  America, northern Australia, India, Africa (south of rain forests) and portions of  southeast Asia.  Agriculture has replaced much of the Tropical Deciduous forest  where rainfall is sufficient or other water sources are available. ∙ Tropical seasonal forest and savanna ∙ Tropical seasonal forest and savanna ∙ Tropical seasonal forest and savanna ∙ o Notes on savanna

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