Class Note for ECOL 182R with Professor Huxman at UA
Class Note for ECOL 182R with Professor Huxman at UA
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Date Created: 02/06/15
Posted on web 3308 at 530 pm Evolution of Photoautotrophy and Plant Diversity 301 82 34008 3 g Summary from last time We talked about Con rrols over phoTosynThesis Spa rial heir39ar39chy is impor ran r for39 unders randing pho rosyn rhe ric regulation Physicochemical cons rr39ain rs Biochemcial cons rr39ain rs Diffusive cons rr39ain rs Wholeorganism cons rr39ain rs 11a Thylakoids L1ght v Thylakoid a Arrangement of cells in a C3 leaf Upper epidermis quot 39Vem Spongy mesophy cell Lower epidermis CO exxernal air Sunlight LIFE THE SCIENCE OF BIOLOGY Samm Edilian Figum a The Ingre ianls for Phaiosynmasis 2004 STnanarAssacrahs Imam w H Freeman 5 c Factors shaping constraints over photosynthetic rates a series of heirarchical controls with multiple tradeoffs hinge P Relative allocation of Tradeoff between Leaf lifespan returns nitrogen to carboxylation exchanges of water and on C amp N investment versus light harvesting carbon Cowan 1977 reproductive timing and Field and Mooney 1986 Cowan and Farqhuar output Bloom 1986 Farqhuar et al 1980 1977 Bazzaz 1996 Other issues Phoforespir a rion Rubisco is a carboxylase adding COZ To RuBP Phofor39espir39a39l39ion and Its Consequences Photorespira on RuBP 02 gt phosphoglycola re 3P6 Glycola re diffuses i n ro peroxisomes Figure 8 5 Organelles of Photoresplratlon LIFE THE SCIENCE OF EIOLDGV Seventh Edilion Figure 315 Organslles n1 Phntolespira on Ln 2m Smausv Assnmauas W and w H Freeman E Cu Phofor39espir39a39l39ion and Its Consequences Pho ror39eSpir39a rion uses ATP and NADPH AND Rubisco ac rs as an oxygenase if COZ is very low and 02 is high Big Questions What have been the important constraints and or principles that have shaped the evolution of plants Diversi cation Form and function Important particularities on evolution and speciation in plants RA Fisher 1958 Fundamental Theorem of Natural Selection In order for there to be evolution there must be genetic variation Maj or ways genetic variation is introduced into populations 1 Mutation UV random error 2 Genetic recombination meiosis including crossingover 3 Immigration into population But plants do two additional tricks that enhance genetic variation 4 Polyploidy 5 Hybridization Multicellularity and plant evolution Multicellularity evolved more than once for plants prokaryotic unicellular algae gt multicellular algae gt embryophytes Multicellularity has several interesting advantages When is an organism multicellular When neighboring cells adhere interact and physiologically communicate Contact is achieved in four ways 1 T ighl junctions proteins in membranes that bond neighboring cells 2 Desmosomes intracellular laments that adjoin cells often creating a space for material movement 3 Gap junctions pores surrounded by transmembrane proteins direct material movement between cells Multicellular plant Single living protoplast of adjoining cells What is a plant Plants are photosynthetic eukaryotes A more derived group of plants is called the embryophytes Plants appear monophyletic forming a single branch of the evolutionary tree so says your book Please please remember these endosymbiotic events and the discussions you have had on a treelike phylogeny versus a Weblike phylogeny gt Brown plantsquot Stramenopiles J Ancestral u organism amp gt Red plants J amp ChlorophytesKm Charophytes gtquotGreen plantsquot P1 t Embryophytes an ae LIFE THE SCIENCE OF BIDLaGY Savant Edition Flglna 291 What Is a Plum r 2004 Smauar Assocrznes me am w H Freeman amp Cm Diversity of Embrophytes Embryophytes fall out into 10 phyla Three phyla liverworts hornworts and mosses derived in that order lack tracheids and are collectively referred to as the nontracheophytes Seven include members possessing welldeveloped vascular systems called the tracheophytes Table 291 in your book lists the groups and their de ning characteristics good source for important knowledge hint Unique characteristics of plants Alternation of generations is a universal feature of the life cycles of plants Life cycle includes both multicellular diploid and multicellular haploid individuals The multicellular diploid plant is called the Sporophyte The sporangia on the sporophyte produce haploid unicellular spores by meiosis The multicellular haploid plant formed by mitosis of a spore is called the gametophyte The gametophyte produces haploid gametes The fusion of two gametes results in the formation of a diploid cell the zygote and the cycle repeats Multicellular gametophyte Spore Gametes I HAPLOID n DIPLOID 2n Multicellular spoi oph y te Figure 292 in the book Sporophyte generation Gametophyte generation Charophytes a group of green algae appear to be the closest living relative of Embryophytes These organisms now occupy the margins of ponds or marshes meaning that the jump to a terrestrial environment was in close proximity a Chara sp stonewort b Coleoclzaete Sp LIFE THE SCIENCE OF BIOLOGY Savenlh Edition Figula 25311 Closasi Relatives 01 Land Flam 92001 Sinauer Assnmales inn and w H Freeman 5 Co The Conquest of the Land Embryophytes invaded the terrestrial environment approximately 400 500 mya lnvading the land is more like invading the air rather than soil Some adaptations to life on land Cuticlea waxy covering that prevents drying Gametangiaenclosure for gametes to prevent drying Embryosprotected young sporophytes Pigmentsprotection against mutagenic UV radiation Spore wall thickeningprevent drying and resist decay Mychorhizzae mutualistic association with a fungus to promotes nutrient uptake from the soil Stomata controllable pore in tissue that regulate water loss and CO2 uptake Aerenchyma invaginations in tissue that create moist internal surface area for controlled gas exchange The Conquest of the Land Evolution of specialized water conducting cells tracheids allowed for movement onto land Recall tracheophytes versus nontracheophytes The rst land plants either lacked vascular tissue or like some mosses had very simple conducting tissue that developed from dead cells Chlorophytes Ancestral alga Charophytes Liverworts Protected Hornworts embryos First true vascular Club mosses tissue Ferns and allies v v sal qdoaqaenuoN peasuoN v squad squdoaqamJ P998 a w W First seed 0 Gymno plants sperms Flowering plants squdoatpml aeluuld 1210198qu LIFE THE SCIENCE OF BIOLOGY Sammy Edition gure 294 Fran Green Algae to Phil 9 2004 Smauy Assma es mo and w H Freeman E Co Water and nutrient acquisition by non tracheophytes recall they do not have a vascular system Many grow in dense masses They have leaflike structures They are small enough a Marclmntm sp Nontracheophytes Liverworts Hornworts and Mosses Grow in dense mats in moist habitats typically they are small in size Layers of maternal tissue prevent loss of water from the embryo Have a thin cuticle though it is not highly effective in retarding water loss Nontracheophytes Visible green structure is the garnetophyte Sporophyte produces unicellular haploid spores through meiosis within sporangium or capsules Spores germinate and give rise to a rnulticellular haploid gametophyte Whose cells contain chloroplasts Gametophytes n i 9 Ar omum n Photosynthetic filament Protonema Antheridium n with bud Bud HAPLOID n Gametophyte generation Rhizoid DIPLOID 2n Sporophyte generation mari Sporophyte 2n Gametophyte 1 LIFE THE SCIENCE OF BIOLOGY Seventh Edivian Figure 295 A NDniracheophyle Lila Cycle 9 2004 Smauev Assamales me and w H Fveeman 5 Co Liverworts most ancient surviving plant clade Rhizoids absorb water with laments found on the lower surfaces gametophytes Several genera have both sexual and asexual reproduction Asexual reproduction by simple fragmentation of the gametophyte n Marclzzmtin sp Mm chantia sp I I c Lmzularia sp The hornworts phylum Anthocerophyta mosses and tracheophytes all have unique adaptations to life on land A n Ilmtcms sp LIFEWE smerEoFsrmocv Slvmlhfd fm awn 1 ngcnf lulg rm Two characteristics distinguish hornworts from liverworts and mosses Cells of hornworts contain a single large platelike chloroplast whereas liverworts and mosses contain numerous small lensshaped chloroplasts Cyanobacteria often populate internal mucilage lled cavities within hornworts These cyanobacteria are able to x atmospheric nitrogen gas into a form that can be used by the plant The phylum Bryophyta mosses are probably sister to the tracheophytes Hydroid cells in many mosses are a likely progenitor of the water conducting cells of the tracheophytes cIENcE OF BIGLK 20a Chlorophytes Ancestral alga Charophytes Liverworts Protected Hornworts embryos First true vascular Club mosses tissue Ferns and allies v v sal qdoaqaenuoN peasuoN v squad squdoaqamJ P998 a w W First seed 0 Gymno plants sperms Flowering plants squdoatpml aeluuld 1210198qu LIFE THE SCIENCE OF BIOLOGY Sammy Edition gure 294 Fran Green Algae to Phil 9 2004 Smauy Assma es mo and w H Freeman E Co The Tracheophytes The sporophyte generation of a nowextinct organism produced a new cell type called the tracheid Allowed for the radiation of a novel life form The tracheophytes have welldeveloped vasculature consisting of Phloem Xylem Nontracheophytes 39 39 39 Z 0 common Club mosses W a ancestor g E 9 Horsetalls g b g Tracheids 0 branching Whisk ferns 1 8 H independent K3 7 3 m klt n sporophyte f d r Iquot l m g quotS Multi agellate n E sperm complex 7 lt 8 leaves k a g Comfers E o m 0 m 9 Seeds R 3 H a a m 839 o Gnetophytes Flowers carpels triploid endosperm Angiosperms LIFE THE SCIENCE OF BIOLOGY Savant Edition Figure 2WThe Evolulinn o1 Tnday39s Flams 2qu Smauer Assocmes me am w H Freeman 5 Co The Tracheophytes Recall plants invaded land about 400500 million years ago During the Devonian period club mosses lycopods horsetails and ferns made the environment more hospitable to animals Trees dominated during the Carboniferous period resulting in forest that eventually become coal deposits At the end of the Permian period the ZOOmillionyear reign of the lycopod fern forests came to an end as they were replaced by forests of seed plants Introducing the Tracheophytes The rst tracheophytes were in the nowextinct phylum Rhyniophyta They had the structural features found in all other tracheophyte phyla Club mosses Lycophyta appeared in the Silurian period Ferns horsetails and whisk ferns Pteridophyta appeared in the Devonian These groups Lycophyta and Pteridophyta had true roots true leaves and a differentiation between two types of spores The Tracheophytes Roots had their origins as branches either as rhizomes or aboveground portion of stems Early roots were simple structures that penetrated soil branching and anchoring the plant absorbing water and minerals Belowground and aboveground environments are quite different Sporan gia Dichotornous quotquot branching The Tracheophytes A leaf is a attened photosynthetic structure emerging laterally from a main aXis or stem and possessing true vascular tissue There are two leaf types microphylls and megaphylls The microphyll has a single vascular strand that has departed from the stern Without disturbing the stern s vascular structure The club rnosses have rnicrophylls Microphylls may have evolved from sterile sporangia a Vascular tissue Sp0rangium Sporan gia Mlcrophy The Tracheophytes The megaphyll is larger and more complex found in ferns and seed plants May have arose from attening of stems and development of overtopping one branch differentiates from and extends beyond rest Overtopping Megaphyll Introducing the Tracheophytes Plants that bear a single type of spore are said to be homosporous The most ancient tracheophytes were all hornosporous Both the gametophyte and the sporophyte are independent and usually photosynthetic A single type of gametophyte bears both female and male reproductive organs Introducing the Tracheophytes Plants with two distinct types of spores evolved later and are said to be heterosporous In heterosporous plants the megaspore develops into a larger speci cally female gametophyte megagametophyte The microspore develops into the smaller male gametophyte microgametophyte Heterospory evolved independently and repeatedly suggesting that it affords selective advantages n Homospory Archegonium 9 Gamatophytc IL II Antheddium d Spove11 390 E Spatmm ggs H HAPLOID I J DIPLOID 2quot Spore mother cell Zn zygote 2 2 H er s 039 c o P y MegagametophyteQ Sporangium 271 Embryo 2quot S l l poggfye chmgamgffphytew mmiima umanvwmimmuruuvrnuNWym mm WWW w m x m Megaspore n Microspore n sperm 1 Eggs 390 HAPLOID I t DH LOIDZn Spore mother Spare mother ZYEOMQ cell 211 cell 2 Mcgasparangium Wdospomngium Embryo 2n 2quot 211 Sporophyke 2H Urswssarm earlmmansnwmsmbmmwnum my MM m Mature gametophyte A Rhizoids 39 Germinating spore Antheridium HAPLOID n Mature DIPLOID 2n sporophyte Archegonial wall Sporophyte Root Horizontal stem LIFE THE SCIENCE OF BIOLOGY Suanlh Edition Figure 2920 The Life Cycle 01 a Fem 2004 5mm Assncmes me and w H Freeman 1 Ca Nontracheophytes 39 39 39 Z 0 common Club mosses W a ancestor g E 9 Horsetalls g b g Tracheids 0 branching Whisk ferns 1 8 H independent K3 7 3 m klt n sporophyte f d r Iquot l m g quotS Multi agellate n E sperm complex 7 lt 8 leaves k a g Comfers E o m 0 m 9 Seeds R 3 H a a m 839 o Gnetophytes Flowers carpels triploid endosperm Angiosperms LIFE THE SCIENCE OF BIOLOGY Savant Edition Figure 2WThe Evolulinn o1 Tnday39s Flams 2qu Smauer Assocmes me am w H Freeman 5 Co
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