Chapter 30Overview: Feeding the WorldSlide 3Concept 30.1: The reduced gametophytes of seed plants are protected in ovules and pollen grainsAdvantages of Reduced GametophytesLE 30-2Heterospory: The Rule Among Seed PlantsOvules and Production of EggsLE 30-3Pollen and Production of SpermThe Evolutionary Advantage of SeedsConcept 30.2: Gymnosperms bear “naked” seeds, typically on conesLE 30-4aaLE 30-4abLE 30-4acLE 30-4adLE 30-4aeLE 30-4afLE 30-4agLE 30-4baLE 30-4bbLE 30-4bcLE 30-4bdLE 30-4beLE 30-4bfGymnosperm EvolutionSlide 27Slide 28A Closer Look at the Life Cycle of a PineLE 30-6_3Concept 30.3: The reproductive adaptations of angiosperms include flowers and fruitsCharacteristics of AngiospermsFlowersLE 30-7Slide 35FruitsLE 30-8Slide 38LE 30-9The Angiosperm Life CycleLE 30-10aLE 30-10bLE 30-10cSlide 44Angiosperm EvolutionFossil AngiospermsLE 30-11An “Evo-Devo” Hypothesis of Flower OriginsAngiosperm DiversityLE 30-12aaLE 30-12abLE 30-12baLE 30-12bbLE 30-12bcLE 30-12bdEvolutionary Links Between Angiosperms and AnimalsLE 30-13Concept 30.4: Human welfare depends greatly on seed plantsProducts from Seed PlantsSlide 60Threats to Plant DiversityCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsPowerPoint Lectures for Biology, Seventh EditionNeil Campbell and Jane ReeceLectures by Chris RomeroChapter 30Chapter 30Plant Diversity II: The Evolution of Seed PlantsCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsOverview: Feeding the World•Seeds changed the course of plant evolution, enabling their bearers to become the dominant producers in most terrestrial ecosystemsCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsConcept 30.1: The reduced gametophytes of seed plants are protected in ovules and pollen grains•In addition to seeds, the following are common to all seed plants:–Reduced gametophytes–Heterospory–Ovules–PollenCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsAdvantages of Reduced Gametophytes•The gametophytes of seed plants develop within the walls of spores retained within tissues of the parent sporophyteLE 30-2LE 30-2Sporophyte(2n)Gametophyte(n)Sporophyte dependent on gametophyte (mosses and other bryophytes)Gametophyte(n)Sporophyte(2n)Large sporophyte and small, independent game-tophyte (ferns and other seedless vascular plants)Microscopic femalegametophytes (n) inovulate cones(dependent)Microscopic malegametophytes (n) ininside these partsof flowers(dependent)Sporophyte (2n),the flowering plant(independent)Microscopic malegametophytes (n)in pollen cones(dependent)Microscopic femalegametophytes (n) ininside these partsof flowers(dependent)Sporophyte (2n),(independent)Reduced gametophyte dependent on sporophyte (seed plants: gymnosperms and angiosperms)Copyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsHeterospory: The Rule Among Seed Plants•Seed plants evolved from plants with megasporangia, which produce megaspores that give rise to female gametophytes•Seed plants evolved from plants with microsporangia, which produce microspores that give rise to male gametophytesCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsOvules and Production of Eggs•An ovule consists of a megasporangium, megaspore, and one or more protective integuments•Gymnosperm megaspores have one integument•Angiosperm megaspores usually have two integumentsLE 30-3LE 30-3IntegumentMegasporangium(2n)Megaspore (n)Unfertilized ovuleFertilized ovuleSpore wallMale gametophyte(within germinatingpollen grain) (n)MicropyleFemalegametophyte (n)Egg nucleus (n)Dischargedsperm nucleus (n)Pollen grain (n)Seed coat(derived fromintegument)Embryo (2n)(new sporophyte)Gymnosperm seedFood supply(femalegametophytetissue) (n)Copyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsPollen and Production of Sperm•Microspores develop into pollen grains, which contain the male gametophytes•Pollination is the transfer of pollen to the part of a seed plant containing the ovules•Pollen can be dispersed by air or animals, eliminating the water requirement for fertilization•If a pollen grain germinates, it gives rise to a pollen tube that discharges two sperm into the female gametophyte within the ovuleCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsThe Evolutionary Advantage of Seeds•A seed develops from the whole ovule•A seed is a sporophyte embryo, along with its food supply, packaged in a protective coatCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsConcept 30.2: Gymnosperms bear “naked” seeds, typically on cones•The gymnosperms include four phyla:–Cycadophyta (cycads)–Gingkophyta (one living species: Ginkgo biloba)–Gnetophyta (three genera: Gnetum, Ephedra, Welwitschia) –Coniferophyta (conifers, such as pine, fir, and redwood)LE 30-4aaLE 30-4aaCycas revolutaLE 30-4abLE 30-4abLE 30-4acLE 30-4acLE 30-4adLE 30-4adGnetum. This genus includes about 35 species of tropical trees, shrubs, and vines, mainly native to Africa and Asia. Their leaves look similar to those of flowering plants, and their seeds look somewhat like fruits.LE 30-4aeLE 30-4aeEphedra. This genus includes about 40 species that inhabit arid regions throughout the world. Known in North America as “Mormon tea,” these desert shrubs produce the compound ephedrine, commonly used as a decongestant.LE 30-4afLE 30-4afWelwitschia. This genus consists of one species Welwitschia mirabilis, a plant that lives only in the deserts of southwestern Africa. Its strap like leaves are among the largest known.LE 30-4agLE 30-4agOvulateconesLE 30-4baLE 30-4baDouglas fir. “Doug fir” (Pseudotsuga menziesii) provides more timber than any other North American tree species. Some uses include house framing, plywood, pulpwood for paper, railroad ties, and boxes and crates.LE 30-4bbLE 30-4bbPacific yew. The bark of Pacific yew (Taxa brevifolia) is a source of taxol, a compound used to treat women with ovarian cancer. The leaves of a European yew species produce a similar compound, which can be harvested without destroying the plants. Pharmaceutical companies are now refining techniques for synthesizing drugs with taxol-like properties.LE 30-4bcLE 30-4bcBristlecone pine. This species (Pinus longaeva), which is found in the White Mountains of California, includes some