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Chapter 29 Plant Diversity: How plants colonized land Euglenozoa Parabasala Diplomonadida Alveolata Stramenopila Radiolaria Cercozoa Amoebozoa Plantae Chlorophyta Rhodophyta Animalia Choanoflagellates Fungi Plant Origins Ancestral eukaryote Figure 28.4 Angiosperms Gymnosperms Pterophyte (ferns, horsetails, whisk fern) Lycophytes (club mosses etc.) Mosses Hornworts Liverworts Land plants Charophyceans Land plants evolved from Charophyceans (multicellular, eukaryotic, greenalgae protists) Origin of land plants (about 475 mya) Ancestral green alga Hashed lines indicate uncertainties See Fig. 29.7 Angiosperms Gymnosperms Pterophyte (ferns, horsetails, whisk fern) Lycophytes (club mosses etc.) Mosses Hornworts Liverworts Land plants Charophyceans Land plants evolved from Charophyceans (multicellular, eukaryotic, greenalgae protists) Origin of land plants (about 475 mya) Chara (a Charophycean pond alga) Ancestral green alga Hashed lines indicate uncertainties See Fig. 29.7 Angiosperms Gymnosperms Pterophyte (ferns, horsetails, whisk fern) Lycophytes (club mosses etc.) Mosses Hornworts Liverworts Land plants Charophyceans The evidence consists of many derived homologies of cellular microstructure and biochemistry (DNA, chlorophyll, etc.) Origin of land plants (about 475 mya) Ancestral green alga Hashed lines indicate uncertainties See Fig. 29.7 Evolutionary innovations: Land plants Angiosperms Gymnosperms Pterophyte (ferns, horsetails, whisk fern) Lycophytes (club mosses etc.) Mosses Hornworts Liverworts Colonization of land by the first bryophytes Charophyceans Bryophytes (nonvascular plants) Origin of land plants (about 475 mya) Ancestral green alga Hashed lines indicate uncertainties See Fig. 29.7 Evolutionary innovations: Land plants Vascular plants Angiosperms Gymnosperms Pterophyte (ferns, horsetails, whisk fern) Seedless vascular plants Lycophytes (club mosses etc.) Mosses Hornworts Liverworts Advent of a vascular system with the origin of vascular plants Charophyceans Bryophytes (nonvascular plants) Origin of vascular plants (about 420 mya) Origin of land plants (about 475 mya) Ancestral green alga Hashed lines indicate uncertainties See Fig. 29.7 Evolutionary innovations: Land plants Vascular plants Angiosperms Seed plants Gymnosperms Pterophyte (ferns, horsetails, whisk fern) Seedless vascular plants Lycophytes (club mosses etc.) Mosses Hornworts Liverworts Origin of seeds (embryo packaged with a supply of nutrients inside a protective coat) Charophyceans Bryophytes (nonvascular plants) Origin of seed plants (about 360 mya) Origin of vascular plants (about 420 mya) Origin of land plants (about 475 mya) Ancestral green alga Hashed lines indicate uncertainties See Fig. 29.7 Evolutionary innovations: Land plants Vascular plants Angiosperms Seed plants Gymnosperms Pterophyte (ferns, horsetails, whisk fern) Seedless vascular plants Lycophytes (club mosses etc.) Mosses Hornworts Liverworts Evolution of flowers (seeds develop inside chambers called ovaries, which originate in flowers that mature into fruits) Charophyceans Bryophytes (nonvascular plants) Origin of seed plants (about 360 mya) Origin of vascular plants (about 420 mya) Origin of land plants (about 475 mya) Ancestral green alga Hashed lines indicate uncertainties See Fig. 29.7 Evolutionary innovations: Land plants Vascular plants Angiosperms Seed plants Gymnosperms Pterophyte (ferns, horsetails, whisk fern) Seedless vascular plants Lycophytes (club mosses etc.) Mosses Hornworts Liverworts Alternation of generations Charophyceans Bryophytes (nonvascular plants) Origin of seed plants (about 360 mya) Origin of vascular plants (about 420 mya) Origin of land plants (about 475 mya) Ancestral green alga Hashed lines indicate uncertainties See Fig. 29.7 Review of chromosome number • A diploid nucleus (2n) has two of each kind of chromosome • A haploid nucleus (n) has only one of each kind of chromosome Human chromosomes from a diploid cell Animal Life Cycle: No alternation of generations Diploid phase is dominant See Fig. 13.5 Animal Life Cycle: No alternation of generations Key Haploid Diploid Diploid phase is dominant n n Gametes n Meiosis Diploid multicellular organism See Fig. 13.6 Fertilization Zygote 2n 2n Mitosis Fungal Life Cycle (shared by some protists): No alternation of generations Haploid phase is dominant Haploid multicellular organism n Mitosis Mitosis n n Gametes or hyphae n Spores Meiosis Plasmogamy & Karyogamy 2n Zygote-like cell Key Haploid Diploid See Fig. 13.6 n Plant Life Cycle (shared by some algae): Alternation of generations Haploid or diploid phase is dominant, depending on the lineage See Fig. 13.6 Haploid multicellular organism (gametophyte) Mitosis Spores n n n Meiosis Diploid multicellular organism (sporophyte) 2n Key Haploid Diploid Mitosis Gametes n n Fertilization Mitosis 2n Zygote Plant Life Cycle (shared by some algae): Spore = reproductive cell that can develop into a new organism Haploid multicellular organism (gametophyte) Mitosis Spores n n Meiosis Diploid multicellular organism (sporophyte) 2n Key Haploid Diploid See Fig. 13.6 n Mitosis Gametes n n Fertilization Mitosis 2n Zygote Plant Life Cycle (shared by some algae): Gamete = reproductive cell that must fuse with another gamete Haploid multicellular organism (gametophyte) Mitosis Spores n n Meiosis Diploid multicellular organism (sporophyte) 2n Key Haploid Diploid See Fig. 13.6 n Mitosis Gametes n n Fertilization Mitosis 2n Zygote Alternation of generations Mitosis results in gametophyte growth Mitosis occurs in specialized cells to produce gametes Fertilization Meiosis occurs in specialized cells to produce spores Mitosis results in sporophyte growth If humans had alternation of generations Further Adaptations of Land Plants Apical meristems Shoot See Fig. 29.5 Root Further Adaptations of Land Plants Multicellular, dependent embryos with placental transfer cells Embryo Maternal tissue See Fig. 29.5 Further Adaptations of Land Plants The spore mother cells of diploid sporangia produce protected (walled) haploid spores Spore See Fig. 29.5 Sporangium Further Adaptations of Land Plants Multicelluar, haploid gametangia produce gametes (in all but angiosperms) Egg Archegonium: female gametangium Archegonium See Fig. 29.5 Further Adaptations of Land Plants Multicelluar, haploid gametangia produce gametes (in all but angiosperms) Sperm Antheridium: male gametangium Antheridium See Fig. 29.5 Further Adaptations of Land Plants Characters for conserving water Waxy cuticle coating the epidermis Further Adaptations of Land Plants Characters for moving water Lignified vascular tissues (found in all but bryophytes) Lignin Further Adaptations of Land Plants Characters for moving water Phloem and xylem Angiosperms Gymnosperms Lycophytes (club mosses etc.) Mosses Hornworts Liverworts Bryophytes (nonvascular plants) Pterophyte (ferns, horsetails, whisk fern) Dominant plants on Earth through the first 100 million years of land plants’ existence Land plants Charophyceans I. Non-vascular Plants (Bryophytes) Origin of seed plants (about 360 mya) Origin of vascular plants (about 420 mya) Origin of land plants (about 475 mya) Ancestral green alga Hashed lines indicate uncertainties See Fig. 29.7 Dominant plants in Carboniferous, i.e., today’s fossil fuels Land plants Vascular plants Angiosperms Gymnosperms Pterophyte (ferns, horsetails, whisk fern) Seedless vascular plants Lycophytes (club mosses etc.) Mosses Hornworts Liverworts Bryophytes (nonvascular plants) Charophyceans I. Non-vascular Plants (Bryophytes) II. Vascular Plants A. Seedless Origin of seed plants (about 360 mya) Origin of vascular plants (about 420 mya) Origin of land plants (about 475 mya) Ancestral green alga Hashed lines indicate uncertainties See Fig. 29.7 Dominant plants on Earth today Land plants Vascular plants Angiosperms Seed plants Gymnosperms Pterophyte (ferns, horsetails, whisk fern) Seedless vascular plants Lycophytes (club mosses etc.) Mosses Hornworts Liverworts Bryophytes (nonvascular plants) Charophyceans I. Non-vascular Plants (Bryophytes) II. Vascular Plants A. Seedless B. Seed Plants Origin of seed plants (about 360 mya) Origin of vascular plants (about 420 mya) Origin of land plants (about 475 mya) Ancestral green alga Hashed lines indicate uncertainties See Fig. 29.7 Land plants Vascular plants Angiosperms Seed plants Gymnosperms Pterophyte (ferns, horsetails, whisk fern) Seedless vascular plants Lycophytes (club mosses etc.) Mosses Hornworts Liverworts Bryophytes (nonvascular plants) Charophyceans I. Non-vascular Plants (Bryophytes) II. Vascular Plants A. Seedless B. Seed Plants i. Gymnosperms ii. Angiosperms Origin of seed plants (about 360 mya) Origin of vascular plants (about 420 mya) Origin of land plants (about 475 mya) Ancestral green alga Hashed lines indicate uncertainties See Fig. 29.7 Bryophytes Gametophyte dominant; sporophyte dependent; gametophyte independent See Fig. 29.8 Bryophytes Key Haploid Diploid Gametophytes produce gametes by mitosis Male gametophyte Female gametophyte Antheridia Sperm (flagellated) Archegonia Egg Fertilization Meiosis See Fig. 29.8 Bryophytes A zygote begins the sporophyte generation Mature sporophytes produce spores by meiosis Key Haploid Diploid Male gametophyte Antheridia Sperm (flagellated) Spores Female gametophyte Archegonia Egg Sporangium Fertilization Meiosis Sporophytes Zygote See Fig. 29.8 Bryophytes Moss gametophytes and sporophytes Bryophytes Thin structure allows distribution of materials without vascular system Rhizoids anchor, but do not play a primary role in water and nutrient uptake Bryophytes Phylum Hepatophyta - liverworts P. Anthocerophyta hornworts P. Bryophyta mosses Bryophytes Ball or Spanish “moss” – an Angiosperm Seedless vascular plants Sporophyte dominant; sporophyte initially dependent; gametophyte independent See Fig. 29.12 Seedless vascular plants Gametophytes produce gametes by mitosis Key Haploid Diploid Antheridium Meiosis Gametophyte Sperm (flagellated) Archegonium Egg Fertilization See Fig. 29.12 Seedless vascular plants Gametophytes produce gametes by mitosis Fern prothallus = gametophyte Seedless vascular plants Gametophytes produce gametes by mitosis Key Haploid Diploid Antheridium Meiosis Gametophyte Sperm (flagellated) Archegonium Egg Fertilization See Fig. 29.12 Seedless vascular plants A zygote begins the sporophyte generation Key Haploid Diploid Antheridium Meiosis Gametophyte Sperm (flagellated) Archegonium Mature sporophytes Egg Young sporophyte Fertilization Zygote Gametophyte See Fig. 29.12 Seedless vascular plants Mature sporophytes produce spores by meiosis Key Haploid Diploid Antheridium Spores Meiosis Gametophyte Sperm (flagellated) Sporangium Archegonium Mature sporophytes Sorus Egg Young sporophyte Fertilization Zygote Sporophyll Gametophyte See Fig. 29.12 Seedless vascular plants Sori = clusters of sporangia Seedless vascular plants See diagram on pg. 586 Homosporous spore production (most seedless vascular plants) Sporangium in sporophyll (2n) Single type of spore (n) Bisexual gametophyte Heterosporous spore production (some seedless vascular plants; all seed plants) Eggs Sperm Seedless vascular plants Key Haploid Diploid Antheridium Spores Meiosis Gametophyte Sperm (flagellated) Sporangium Archegonium Mature sporophytes Sorus Egg Young sporophyte Fertilization Zygote Sporophyll Gametophyte See Fig. 29.12 Seedless vascular plants See diagram on pg. 586 Homosporous spore production (most seedless vascular plants) Sporangium in sporophyll (2n) Single type of spore (n) Bisexual gametophyte Eggs Sperm Heterosporous spore production (some seedless vascular plants; all seed plants) Megasporangium in megasporophyll (2n) Megaspore (n) Female Gametophyte (n) Eggs (n) Microsporangium in microsporophyll (2n) Microspore (n) Male Gametophyte (n) Sperm (n) Seedless vascular plants Evolution of: Leaves (principal photosynthetic organs of vascular plants) Seedless vascular plants Evolution of: Roots (principal organs that anchor vascular plants and absorb water & nutrients) Seedless vascular plants Evolution of: Vascular tissues (conduits that distribute water & nutrients within vascular plants) Seedless vascular plants Phylum Lycophyta “Club mosses” Seedless vascular plants Phylum Pterophyta Horsetails E.g., Equisetum Seedless vascular plants Phylum Pterophyta Horsetails Strobilus – a group of sporophylls forming a cone Seedless vascular plants Phylum Pterophyta Whisk ferns Seedless vascular plants Phylum Pterophyta Ferns Terrestrial species are found on the ground Seedless vascular plants Phylum Pterophyta Ferns Resurrection fern is an epiphytic species, i.e., it grows on other plants Seedless vascular plants A modern community Seedless vascular plants A diorama of an ancient community Seedless vascular plants A fossil stump of a seedless vascular plant Land plants Vascular plants Angiosperms Seed plants Gymnosperms Pterophyte (ferns, horsetails, whisk fern) Seedless vascular plants Lycophytes (club mosses etc.) Mosses Hornworts Liverworts Bryophytes (nonvascular plants) Charophyceans I. Non-vascular Plants (Bryophytes) II. Vascular Plants A. Seedless B. Seed Plants i. Gymnosperms ii. Angiosperms Origin of seed plants (about 360 mya) Origin of vascular plants (about 420 mya) Origin of land plants (about 475 mya) Ancestral green alga Hashed lines indicate uncertainties See Fig. 29.7 The Life Cycle of Animals – Illustrated for Humans Generation 1 Generation 2 Specialized cells undergo meiosis to produce gametes Gametes fuse during fertilization to become a zygote AA XX Gen. 3 A X Aa XX AA XY a X A Y Aa XY a X From the single-celled zygote stage onward, cells undergo mitosis to increase the number of cells in the maturing individual. Aa XX Multicellular individuals; Diploid (2n) cells Aa XY Unicellular gametes; Haploid (1n) cells Unicellular zygote; Diploid (2n) cell Muticellular individuals; Diploid (2n) cells The Life Cycle of Fungi – Illustrated for Bread Mold Several generations Multiple rounds of asexual reproduction possible; all cell divisions occur by mitosis. A + Brief intergenerational zygote stage Fusion of compatible hyphae to form a zygote Several generations Zygotic meiosis Aa a +- - Multiple rounds of asexual reproduction possible; all cell divisions occur by mitosis. a - Multiple rounds of asexual reproduction possible; all cell divisions occur by mitosis. Multiple rounds of asexual reproduction possible; all cell divisions occur by mitosis. a - a + Haploid (1n) cells of hyphae Diploid (2n) zygote Haploid (1n) spore Haploid (1n) cells of hyphae The Life Cycle of Plants (Alternation of Generations) – Illustrated for a Dioecious Flower Generation 1 Specialized cells undergo meiosis to produce spores AA bb A b Gen. 4 Generation 3 Generation 2 Gametes fuse during fertilization to become a zygote Pollen grain a B aa BB A b Aa Bb a B Aa Bb Multicellular sporophyte Diploid (2n) cells Embryo sac A b Aa Bb a B Single-celled spores undergo mitosis to increase the number of cells in the maturing gametophyte. Mature gametophyte produces gametes by mitosis Unicellular spores Multicellular gametophyte Haploid (1n) cells Unicellular gametes Specialized cells undergo meiosis to produce spores Unicellular zygote Multicellular sporophyte Diploid (2n) cells Unicellular spores of gametophyte Haploid (1n) cells