Plant Diversity I: How Plants Colonized Land

Transcription

1 LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jae B. Reece, Lisa A. Urry, Michael L. Cai, Steve A. Wasserma, Peter V. Miorsky, Robert B. Jackso Chapter 29 Plat Diversity I: How Plats Coloized Lad Overview: The Greeig of Earth For more tha the first 3 billio years of Earth s history, the terrestrial surface was lifeless Cyaobacteria likely existed o lad 1.2 billio years ago Aroud 500 millio years ago, small plats, fugi, ad aimals emerged o lad Lectures by Eri Barley Kathlee Fitzpatrick Figure 29.1 Sice coloizig lad, plats have diversified ito roughly 290,000 livig species Lad plats are defied as havig terrestrial acestors, eve though some are ow aquatic Lad plats do ot iclude photosythetic protists (algae) Plats supply oxyge ad are the ultimate source of most food eate by lad aimals Cocept 29.1: Lad plats evolved from gree algae Gree algae called charophytes are the closest relatives of lad plats Morphological ad Molecular Evidece May characteristics of lad plats also appear i a variety of algal clades, maily algae However, lad plats share four key traits with oly charophytes Rigs of cellulose-sythesizig complexes Peroxisome ezymes Structure of flagellated sperm Formatio of a phragmoplast 1

2 Figure 29.2 Comparisos of both uclear ad chloroplast gees poit to charophytes as the closest livig relatives of lad plats Note that lad plats are ot desceded from moder charophytes, but share a commo acestor with moder charophytes 30 m Figure mm Chara species, a pod orgaism Figure 29.3a 5 mm Coleochaete orbicularis, a disk-shaped charophyte that also lives i pods (LM) 40 m Chara species, a pod orgaism Figure 29.3b Coleochaete orbicularis, a disk-shaped charophyte that lives i pods (LM) 40 m Adaptatios Eablig the Move to Lad I charophytes a layer of a durable polymer called sporopollei prevets exposed zygotes from dryig out Sporopollei is also foud i plat spore walls The movemet oto lad by charophyte acestors provided ufiltered su, more pletiful CO 2, utriet-rich soil, ad few herbivores or pathoges Lad preseted challeges: a scarcity of water ad lack of structural support 2

3 Figure 29.4 Red algae The accumulatio of traits that facilitated survival o lad may have opeed the way to its coloizatio by plats Systematists are curretly debatig the boudaries of the plat kigdom Some biologists thik the plat kigdom should be expaded to iclude some or all gree algae Util this debate is resolved, we defie plats as embryophytes, plats with embryos ANCESTRAL ALGA Chlorophytes Charophytes Embryophytes Platae Streptophyta Viridiplatae Derived Traits of Plats Four key traits appear i early all lad plats but are abset i the charophytes Alteratio of geeratios ad multicellular, depedet embryos Walled spores produced i sporagia Multicellular gametagia Apical meristems Alteratio of Geeratios ad Multicellular, Depedet Embryos Plats alterate betwee two multicellular stages, a reproductive cycle called alteratio of geeratios The is haploid ad produces haploid gametes by mitosis Fusio of the gametes gives rise to the diploid sporophyte, which produces haploid spores by meiosis Figure 29.5a The diploid embryo is retaied withi the tissue of the female Nutriets are trasferred from paret to embryo through placetal trasfer cells Lad plats are called embryophytes because of the depedecy of the embryo o the paret Gametophyte Mitosis Spore Gamete MEIOSIS Gamete from aother plat Mitosis FERTILIZATION 2 Zygote Key Haploid Diploid (2) Sporophyte (2) Mitosis Alteratio of geeratios 3

4 Figure 29.5b Figure 29.5ba Embryo Materal tissue Embryo (LM) ad placetal trasfer cell (TEM) of Marchatia (a liverwort) 2 m Embryo Materal tissue Wall igrowths 10 m Placetal trasfer cell (outlied i blue) 10 m Figure 29.5bb 2 m Walled Spores Produced i Sporagia Wall igrowths Placetal trasfer cell (outlied i blue) The sporophyte produces spores i orgas called sporagia Diploid cells called sporocytes udergo meiosis to geerate haploid spores Spore walls cotai sporopollei, which makes them resistat to harsh eviromets Figure 29.5c Figure 29.5ca Spores Logitudial sectio of Sphagum sporagium (LM) Sporophyte Gametophyte Sporophytes ad sporagia of Sphagum (a moss) Sporophyte Gametophyte Sporophytes ad sporagia of Sphagum (a moss) 4

5 Figure 29.5cb Spores Logitudial sectio of Sphagum sporagium (LM) Multicellular Gametagia Gametes are produced withi orgas called gametagia Female gametagia, called archegoia, produce eggs ad are the site of fertilizatio Male gametagia, called atheridia, produce ad release sperm Figure 29.5d Figure 29.5da Female Archegoia, each with a egg (yellow) Female Atheridia (brow), cotaiig sperm Male Archegoia ad atheridia of Marchatia (a liverwort) Male Figure 29.5e Apical Meristems Plats sustai cotiual growth i their apical meristems Cells from the apical meristems differetiate ito various tissues Apical meristems of plat roots ad shoots Apical meristem of shoot Developig leaves Apical meristem of root Root 100 m Shoot 100 m 5

6 Figure 29.5ea Figure 29.5eb Apical meristem of shoot Developig leaves Apical meristem of root Root 100 m Shoot 100 m The Origi ad Diversificatio of Plats Additioal derived traits iclude Cuticle, a waxy coverig of the epidermis Mycorrhizae, symbiotic associatios betwee fugi ad lad plats that may have helped plats without true roots to obtai utriets Secodary compouds that deter herbivores ad parasites Fossil evidece idicates that plats were o lad at least 475 millio years ago Fossilized spores ad tissues have bee extracted from 475-millio-year-old rocks Figure 29.6 Figure 29.6a (a) Fossilized spores (a) Fossilized spores (b) Fossilized sporophyte tissue 6

7 Figure 29.6b Those acestral species gave rise to a vast diversity of moder plats (b) Fossilized sporophyte tissue Figure 29.7 Figure 29.7a 1 Origi of lad plats (about 475 mya) 1 Origi of lad plats (about 475 mya) 2 Origi of vascular plats (about 425 mya) 3 Origi of extat seed plats (about 305 mya) ANCESTRAL GREEN 1 ALGA Liverworts Mosses Horworts Novascular plats (bryophytes) Lad plats 2 Origi of vascular plats (about 425 mya) 3 Origi of extat seed plats (about 305 mya) ANCESTRAL GREEN ALGA 1 Liverworts Mosses Horworts Lycophytes (club mosses, spike mosses, quillworts) 2 Pterophytes (fers, horsetails, whisk fers) Gymosperms 3 Agiosperms Seedless vascular plats Seed plats Vascular plats 2 3 Lycophytes (club mosses, spike mosses, quillworts) Pterophytes (fers, horsetails, whisk fers) Gymosperms Agiosperms Millios of years ago (mya) Millios of years ago (mya) Figure 29.7b Liverworts Mosses Horworts Lycophytes (club mosses, spike mosses, quillworts) Pterophytes (fers, horsetails, whisk fers) Gymosperms Agiosperms Novascular plats (bryophytes) Seedless vascular plats Seed plats Vascular plats Lad plats Lad plats ca be iformally grouped based o the presece or absece of vascular tissue Most plats have vascular tissue; these costitute the vascular plats Novascular plats are commoly called bryophytes Bryophytes are ot a moophyletic group; their relatioships to each other ad to vascular plats is uresolved 7

8 Seedless vascular plats ca be divided ito clades Lycophytes (club mosses ad their relatives) Pterophytes (fers ad their relatives) Seedless vascular plats are paraphyletic, ad are of the same level of biological orgaizatio, or grade A seed is a embryo ad utriets surrouded by a protective coat Seed plats form a clade ad ca be divided ito further clades Gymosperms, the aked seed plats, icludig the coifers Agiosperms, the flowerig plats Table Cocept 29.2: Mosses ad other ovascular plats have life cycles domiated by s Bryophytes are represeted today by three phyla of small herbaceous (owoody) plats Liverworts, phylum Hepatophyta Horworts, phylum Athocerophyta Mosses, phylum Bryophyta Bryophyte refers to all ovascular plats, whereas Bryophyta refers oly to the phylum of mosses Figure 29.UN01 Bryophyte Gametophytes Novascular plats (bryophytes) Seedless vascular plats Gymosperms Agiosperms I all three bryophyte phyla, s are larger ad loger-livig tha sporophytes Sporophytes are typically preset oly part of the time 8

9 2 mm 2 mm 2 mm 2 mm 2/14/2012 Figure Figure Key Haploid Diploid (2) Protoemata Bud Bud Male Key Haploid Diploid (2) Protoemata Bud Bud Atheridia Male Sperm Egg Spore dispersal Peristome Spores Gametophore Female Rhizoid Spore dispersal Peristome Spores Gametophore Female Archegoia Rhizoid MEIOSIS Mature sporophytes Seta Capsule (sporagium) Foot MEIOSIS Mature sporophytes Seta Capsule (sporagium) Foot FERTILIZATION (withi archegoium) Capsule with peristome (LM) Female s Capsule with peristome (LM) Female s Figure Figure 29.8a Key Haploid Diploid (2) Protoemata Bud Bud Atheridia Male Sperm Egg Spore dispersal Peristome Spores Gametophore Female Archegoia Rhizoid MEIOSIS Mature sporophytes Capsule with peristome (LM) Seta Capsule (sporagium) Foot Youg sporophyte (2) Female s Embryo FERTILIZATION (withi archegoium) Zygote (2) Archegoium Capsule with peristome (LM) A spore germiates ito a composed of a protoema ad gamete-producig gametophore The height of s is costraied by lack of vascular tissues Rhizoids achor s to substrate Mature s produce flagellated sperm i atheridia ad a egg i each archegoium Sperm swim through a film of water to reach ad fertilize the egg Aimatio: Moss Life Cycle 9

10 500 m 500 m 2/14/2012 Bryophyte Sporophytes Bryophyte sporophytes grow out of archegoia, ad are the smallest ad simplest sporophytes of all extat plat groups A sporophyte cosists of a foot, a seta (stalk), ad a sporagium, also called a capsule, which discharges spores through a peristome Horwort ad moss sporophytes have stomata for gas exchage; liverworts do ot Figure 29.9a Thallus Gametophore of female Marchatia polymorpha, a thalloid liverwort Marchatia sporophyte (LM) Sporophyte Foot Seta Capsule (sporagium) Plagiochila deltoidea, a leafy liverwort Figure 29.9aa Thallus Gametophore of female Figure 29.9ab Foot Seta Capsule (sporagium) Marchatia sporophyte (LM) Marchatia polymorpha, a thalloid liverwort Figure 29.9ac Figure 29.9b A Athoceros horwort species Plagiochila deltoidea, a leafy liverwort Sporophyte Gametophyte 10

11 Aual itroge loss (kg/ha) 2/14/2012 Figure 29.9c Polytrichum commue, hairy-cap moss The Ecological ad Ecoomic Importace of Mosses Capsule Seta Sporophyte (a sturdy plat that takes moths to grow) Mosses are capable of ihabitig diverse ad sometimes extreme eviromets, but are especially commo i moist forests ad wetlads Some mosses might help retai itroge i the soil Gametophyte Figure RESULTS With moss Without moss Sphagum, or peat moss, forms extesive deposits of partially decayed orgaic material kow as peat Peat ca be used as a source of fuel Sphagum is a importat global reservoir of orgaic carbo Overharvestig of Sphagum ad/or a drop i water level i peatlads could release stored CO 2 to the atmosphere Figure Figure 29.11a (a) Peat beig harvested from a peatlad (b) Tollud Ma, a bog mummy datig from B.C.E. (a) Peat beig harvested from 1 a m peatlad 11

12 Figure 29.11b Cocept 29.3: Fers ad other seedless vascular plats were the first plats to grow tall (b) Tollud Ma, a bog mummy datig from B.C.E. Bryophytes ad bryophyte-like plats were the prevalet vegetatio durig the first 100 millio years of plat evolutio Vascular plats bega to diversify durig the Devoia ad Carboiferous periods Vascular tissue allowed these plats to grow tall Seedless vascular plats have flagellated sperm ad are usually restricted to moist eviromets Figure 29.UN03 Origis ad Traits of Vascular Plats Novascular plats (bryophytes) Seedless vascular plats Gymosperms Agiosperms Fossils of the foreruers of vascular plats date back about 425 millio years These early tiy plats had idepedet, brachig sporophytes Livig vascular plats are characterized by Life cycles with domiat sporophytes Vascular tissues called xylem ad phloem Well-developed roots ad leaves Figure Sporagia Life Cycles with Domiat Sporophytes I cotrast with bryophytes, sporophytes of seedless vascular plats are the larger geeratio, as i familiar fers The s are tiy plats that grow o or below the soil surface Aimatio: Fer Life Cycle 12

13 Figure Figure Key Key Haploid Diploid (2) MEIOSIS Spore dispersal Haploid Diploid (2) MEIOSIS Spore dispersal Spore Youg Rhizoid Atheridium Sorus Mature sporophyte (2) Sorus Mature sporophyte (2) Uderside of mature Sperm Archegoium Egg FERTILIZATION Fiddlehead (youg leaf) Fiddlehead (youg leaf) Figure Key Haploid Diploid (2) Sorus MEIOSIS Spore dispersal Fiddlehead (youg leaf) Mature sporophyte (2) Spore Youg New sporophyte Rhizoid Uderside of mature Zygote (2) Gametophyte Archegoium Egg FERTILIZATION Atheridium Sperm Trasport i Xylem ad Phloem Vascular plats have two types of vascular tissue: xylem ad phloem Xylem coducts most of the water ad mierals ad icludes dead cells called tracheids Water-coductig cells are stregtheed by ligi ad provide structural support Phloem cosists of livig cells ad distributes sugars, amio acids, ad other orgaic products Vascular tissue allowed for icreased height, which provided a evolutioary advatage Evolutio of Roots Roots are orgas that achor vascular plats They eable vascular plats to absorb water ad utriets from the soil Roots may have evolved from subterraea stems Evolutio of Leaves Leaves are orgas that icrease the surface area of vascular plats, thereby capturig more solar eergy that is used for photosythesis Leaves are categorized by two types Microphylls, leaves with a sigle vei Megaphylls, leaves with a highly brached vascular system 13

14 Figure Accordig to oe model of evolutio, microphylls evolved as outgrowths of stems Megaphylls may have evolved as webbig betwee flatteed braches Vascular tissue Sporagia Microphyll Overtoppig growth Megaphyll (a) Microphylls (b) Megaphylls Other stems become reduced ad flatteed. Webbig develops. Figure 29.14a Figure 29.14b Vascular tissue Sporagia Microphyll Overtoppig growth Megaphyll (a) Microphylls (b) Megaphylls Other stems become reduced ad flatteed. Webbig develops. Sporophylls ad Spore Variatios Sporophylls are modified leaves with sporagia Sori are clusters of sporagia o the udersides of sporophylls Strobili are coe-like structures formed from groups of sporophylls Most seedless vascular plats are homosporous, producig oe type of spore that develops ito a bisexual All seed plats ad some seedless vascular plats are heterosporous Heterosporous species produce megaspores, which give rise to female s, ad microspores, which give rise to male s 14

15 1 cm 25 cm 1 cm 4 cm 1.5 cm 2/14/2012 Figure 29.15a Classificatio of Seedless Vascular Plats There are two phyla of seedless vascular plats Phylum Lycophyta icludes club mosses, spike mosses, ad quillworts Phylum Pterophyta icludes fers, horsetails, ad whisk fers ad their relatives Selagiella moelledorffii, a spike moss Isoetes guii, a quillwort Strobili (clusters of sporophylls) 2.5 cm Diphasiastrum tristachyum, a club moss Figure 29.15aa Selagiella moelledorffii, a spike moss Figure 29.15ab Isoetes guii, a quillwort Figure 29.15ac Strobili (clusters of sporophylls) 2.5 cm Figure 29.15b Athyrium filix-femia, lady fer Equisetum arvese, field horsetail Vegetative stem Strobilus o fertile stem Psilotum udum, a whisk fer Diphasiastrum tristachyum, a club moss 15

16 4 cm 25 cm 1.5 cm 2/14/2012 Figure 29.15ba Figure 29.15bb Athyrium filix-femia, lady fer Equisetum arvese, field horsetail Vegetative stem Strobilus o fertile stem Figure 29.15bc Psilotum udum, a whisk fer Phylum Lycophyta: Club Mosses, Spike Mosses, ad Quillworts Giat lycophytes trees thrived for millios of years i moist swamps Survivig species are small herbaceous plats Club mosses ad spike mosses have vascular tissues ad are ot true mosses Phylum Pterophyta: Fers, Horsetails, ad Whisk Fers ad Relatives Fers are the most diverse seedless vascular plats, with more tha 12,000 species They are most diverse i the tropics but also thrive i temperate forests Horsetails were diverse durig the Carboiferous period, but are ow restricted to the geus Equisetum Whisk fers resemble acestral vascular plats but are closely related to moder fers The Sigificace of Seedless Vascular Plats The acestors of moder lycophytes, horsetails, ad fers grew to great heights durig the Devoia ad Carboiferous, formig the first forests Icreased growth ad photosythesis removed CO 2 from the atmosphere ad may have cotributed to global coolig at the ed of the Carboiferous period The decayig plats of these Carboiferous forests evetually became coal 16

17 Figure Fer Lycophyte trees Horsetail Tree truk covered with small leaves Lycophyte tree reproductive structures Figure 29.UN02 Figure 29.UN04 Homosporous spore productio o sporophyll Sigle type of spore Heterosporous spore productio Megasporagium o megasporophyll Microsporagium o microsporophyll Megaspore Microspore Typically a bisexual Female Male Eggs Sperm Eggs Sperm Figure 29.UN05 Gametophyte Mitosis Mitosis Spore Gamete MEIOSIS Haploid Diploid Sporophyte FERTILIZATION Mitosis Zygote 1 Alteratio of geeratios Archegoium with egg 2 Atheridium with sperm Apical meristem of shoot Developig leaves 2 Apical meristems Spores 3 Multicellular gametagia 4 Walled spores i sporagia Figure 29.UN05a Figure 29.UN05b Gametophyte Mitosis Mitosis Spore Gamete Apical meristem of shoot Developig leaves MEIOSIS FERTILIZATION Haploid Diploid Sporophyte 2 Mitosis Zygote 1 Alteratio of geeratios 2 Apical meristems 17

18 Figure 29.UN05c Figure 29.UN05d Archegoium with egg Atheridium with sperm Spores 3 Multicellular gametagia 4 Walled spores i sporagia Figure 29.UN06 Figure 29.UN07 Figure 29.UN08 Figure 29.UN09 18

19 Figure 29.UN10 19