Transcript Document
Plants, Insects and our Environment and How They Interact!!!! Photosynthesis Photosynthesis: Process by which plants capture Energy from the Sun; use it to build Carbohydrates Directly by eating the plant (lettuce) or indirectly (by eating another animal), they provide the food for the living world, including themselves Occurs in plants, algae, certain other protists, and some prokaryotes Oxygenic Photosynthesis: Produces oxygen; cyanobacteria, algae and essentially all land plants Figure 10.2 (b) Multicellular alga (a) Plants (d) Cyanobacteria (c) Unicellular protists 10 m (e) Purple sulfur 1 m bacteria 40 m Algal Groups – Green, Brown and Red Non – Vascular Plants - Mosses Number of Land Plant Species Seedless Vascular Plants - Ferns Carboniferous Plants – Coal Formation Seeds: Transforming the World Seed: Consists of an embryo and nutrients surrounded by a protective coat Seeds: Changed the course of plant evolution, enabling them to become the most Dominant Photosynthetic Producer in most terrestrial ecosystems Seed Plants: Plants and other organisms were able to move on land because of the formation of the ozone layer Originated about 360 million years ago Domestication of seed plants along with animals had begun by 8,000 years ago and allowed for permanent settlements Seed Plants Seeds provide some evolutionary advantages over Spores Producers (Ferns): May remain dormant for years until conditions are favorable for germination Have a supply of stored food – good for the plants but “Food for Us” My be transported long distances by wind or animals or water Gymnosperms: “Naked Seeds” Seeds are exposed on cones Appear early in the fossil record about 305 million years ago and dominated Mesozoic (251– 65 million years ago) terrestrial ecosystems Today, cone-bearing Conifers dominate in the northern latitude Angiosperm: Seeds are found in fruits, which are mature ovaries Began to replace gymnosperms near the end of the Mesozoic Dominate more terrestrial ecosystems Gymnosperms – Cycads Cycads: Most are tropical or subtropical with palm-like leaves Individuals have large cones (either male or female) Air or Beetles carry pollen Thrived during the Mesozoic, but relatively few species exist today Gymnosperms – Ginkgo Ginkgo: Age of the Dinosaurs Single living species, Ginkgo biloba Male is widely planted Pollinated by wind Leaves are resistant to insects, disease and air pollution Gymnosperms – Gnetophyta Gnetophyta: Genera: Gnetum, Ephedra, Welwitschia Species vary in appearance Some are tropical; others live in deserts having a deep tap root Gymnosperms – Conifers Conifers: Largest group of the Gymnosperms Many dominant the forested regions of the Northern Hemisphere Most conifers are evergreens; few are deciduous Evergreens can carry out photosynthesis year round as they retain their leaves Tallest – redwood; oldest – bristlepine cone Life Cycle - Reproduction: Development of Seeds from fertilized ovules Transfer of sperm to ovules by Wind Blown Pollen Figure 30.5e Common juniper Douglas fir Sequoia European larch Wollemi pine Bristlecone pine Angiosperms Angiosperms: Ancestors of Angiosperms and Gymnosperms diverged 305 million years ago Angiosperms originated at least 140 million years ago Comprise more than 250,000 living species Previously, Angiosperms were divided into 2 main groups; Monocots (one cotyledon) – remain as a group Dicots (two dicots) Today, Eudicot (“True” Dicots) includes most Dicots Angiosperms – Basal Basal Angiosperms: 3 small lineages: Amborella trichopoda, water lilies, and star anise Angiosperms – Magnoliids Magnoliids: Include magnolias, laurels, and black pepper plants More closely related to monocots and eudicots than basal angiosperms Angiosperms – Monocots Monocots: > 25% angiosperm species are Monocots Angiosperms – Eudicots Eudicots: > 2/3 angiosperm species are Eudicots Angiosperms Angiosperms: Greek anthos for flower Seed plants with reproductive structures called Flowers and Fruits Pollinators: animals (insects that feed on pollen) move pollen grains from male parts of one flower to female parts of another Coevolution: over time, plants and animal pollinators jointly evolved; changes in one exerts selection pressure on the other Angiosperms have 2 key adaptations Flower: Structure specialized for sexual reproduction Pollinated by insects, animals or wind Fruits: Typically consists of a mature ovary but can also include other flower parts Protect seeds and aid in their dispersal Seeds can be carried by Wind, Water, or Animals to new locations Angiosperm Flowers Flowers are the Reproductive Structure of Angiosperms: Non-Reproductive: Corolla (Petals): leaflike ring (brightly colored) that attracts pollinators Calyx (Sepal): leaf-like outer whorl at base; photosynthetic; protects ovary Receptacle: modified green base of the flower (modified leaves) Reproductive: Stamens: male parts of a flower Anther: pollen is produced by meiosis in pollen sacs Filament: veined stalk that holds the anther Carpels (Pistils): female parts of a flower Ovary: eggs developed Style: tube that connects the ovary with stigma Stigma: sticky or hairy surface where the pollen lands Figure 38.2a Stamen Anther Filament Petal Stigma Carpel Style Ovary Sepal Receptacle (a) Structure of an idealized flower Diversity of Flowers Flower Structure: adaptations to maximize Cross-Pollination between 2 different plants Regular: symmetric (identical sections) or Irregular: not radially symmetric flowers Single: 1 flower or Inflorescences: many flowers Complete: sepals, petals, stamens and carpals Incomplete: lack one or more of these structures Perfect: may be pollinated by other plants or itself Imperfect: male or female parts or cannot be pollinated by itself Monoecious: both male and female Diecious: male or female flowers on separate plants Self-Pollination has its advantages but often produces plants that are less vigorous than CrossPollinated Plants Pollination About 390 mil years ago, Seed Plants began making Pollen – at 1st, air currants may have disperse the pollen but Insects made the connection between “Plant with Pollen” and “Food” Pollination: Transfer of Pollen from an anther to a stigma by wind, water, or animals Wind-Pollinated species (grasses and many trees) release large amounts of Pollen Co-Evolution: 2 or more species jointly evolving as an outcomes of close biological interactions Heritable changes in one species affects the other so the other evolves also Pollination Vectors: Agents that deliver pollen from an anther to a compatible stigma (wind or releasing billions of pollen grains) Pollinators: Living pollination vectors (insects, birds, or other animals) Flower shape, pattern, color and fragrance are adaptations that attract sanimal pollinators Often rewarded for visiting a flower by obtaining nutritious pollen or sweet Nectar Selective advantage of Pollinators visiting flowers - bring the pollen to the next plant 90% of the 295,000 have Co-Evolved with Pollinators and do not depend on the Wind Pollinators Visual Cues: Bee pollinated flowers are often yellow, blue or purple Birds and butterflies are attracted to red and yellow flowers Olfactory Cues: Bats (nectar sipping) search for intense fruity or musty odors Beetles and flies search for fermenting fruit and drug Nectar: Sucrose rich fluid secreted by the plant Provides the food for butterflies and hummingbirds Bees collect it and bring it back to the hive to make Honey Flowers: Evolved with their Pollinator Nectar rich floral tubes are the same length as the pollinator’s feeding siphon (proboscis) Small flowers like daisies are of no interest to finches or bats Tall, thin flowers cannot support beetles Angiosperms and Their Pollinators Figure 38.4a Abiotic Pollination by Wind Pollination by Bees Common dandelion under normal light Hazel staminate flowers (stamens only) Hazel carpellate flower (carpels only) Common dandelion under ultraviolet light Figure 38.4b Pollination by Moths and Butterflies Pollination by Flies Pollination by Bats Anther Moth Fly egg Stigma Moth on yucca flower Blowfly on carrion flower Pollination by Birds Hummingbird drinking nectar of columbine flower Long-nosed bat feeding on cactus flower at night Corpse Flower Apple and Peach Flowers Cactus Flowers Hummingbirds and Flowers Fruits Fruit: Develops from the Ovary Protects the enclosed seeds and aids in seed dispersal by wind or animals May be classified as Dry, if the ovary dries out at maturity, or Fleshy, if the ovary becomes thick, soft, and sweet at maturity Fruits are also classified by their development: Simple: single or several fused carpels Aggregate: single flower with multiple separate carpels Multiple: group of flowers called an inflorescence Accessory: other floral parts contribute to the fruit; apple, ovary is embedded in the receptacle Fruit Dispersal Mechanisms include: water, wind and animals Figure 38.10 Stigma Carpels Stamen Flower Style Petal Ovary Stamen Sepal Ovule Stigma Ovule Pea flower Raspberry flower Carpel (fruitlet) Seed Stigma Ovary Stamen Pineapple inflorescence Each segment develops from the carpel of one flower Stamen Ovary (in receptacle) Apple flower Remains of stamens and styles Sepals Seed Pea fruit (a) Simple fruit Raspberry fruit (b) Aggregate fruit Pineapple fruit (c) Multiple fruit Receptacle Apple fruit (d) Accessory fruit Seeds Seed (mature ovule): Embryo and nutritious endosperm encased in a seed coat Remains dormant until conditions are right for germination and growth resumes Germination: Process by which a dormant mature Embryo in a seed resumes growth after a period of arrested growth (Dormancy) Begins when water activates enzymes in the seed Cell divide, elongate and differentiate into primary root Ends when the Primary Root breaks the seed coat Growth: Differentiation results in the formation of tissues and parts in predictable patterns Cells divide by Mitosis Figure 38.11a Dispersal by Wind Dandelion fruit Dandelion “seeds” (actually one-seeded fruits) Tumbleweed Winged seed of the tropical Asian climbing gourd Alsomitra macrocarpa Winged fruit of a maple Dispersal by Water Coconut seed embryo, endosperm, and endocarp inside buoyant husk Figure 38.11b Dispersal by Animals Fruit of puncture vine (Tribulus terrestris) Squirrel hoarding seeds or fruits underground Ant carrying seed with nutritious “food body” to its nest Seeds dispersed in black bear feces Fruit and Seed Dispersal Asexual Reproduction Many Angiosperm species reproduce both Asexually and Sexually Asexual Reproduction results in a clone of genetically identical organisms In some species, a parent plant’s root system gives rise to adventitious shoots that become separate shoot systems Bees as Pollinators in Our Food Supply