Eukarya: Land Plants Lecture 15 PDF

Eukarya: Land Plants Bacteria/Archaea worksheet review  Kingdom Plantae Monophyletic group of photoautotrophic protists and plants We will focus today on one branch of the green plant lineage → land plants green p...

Eukarya: Land Plants Bacteria/Archaea worksheet review  Kingdom Plantae Monophyletic group of photoautotrophic protists and plants We will focus today on one branch of the green plant lineage → land plants green plant lineage  Land plants General characteristics: ○ Photoautotrophs ○ Multicellular ○ Differentiated tissues The first photoautotrophic organisms that could survive completely exposed to air Why do scientists study land plants? We can’t live without them! ○ Ecosystem services - any benefit that wildlife or ecosystems provide to people Small or large Direct or indirect Some can be harmful ○ Human health hazards ○ Harmful to ecosystems ○ Harmful to crops Source Ecosystem services of land plants 1. Sequester CO2, provide O2 http://www.eschooltoday.com/photosynthesis/images/diagram-of- photosynthesis.png  Ecosystem services of land plants 1. Fix CO2, provide O2 2. Retain soil & nutrients 3.. http://health.hawaii.gov/cwb/files/2013/05/ PRC_WaimanaloStream.jpg Ecosystem services of land plants 1. Fix CO2, provide O2 2. Retain soil & nutrients 3. Buffer temperature, wind, & humidity Source Ecosystem services of land plants 1. Fix CO2, provide O2 Source 2. Retain soil & nutrients 3. Buffer temperature, wind, & humidity 4. Provide food for heterotrophs, shelter for other organisms Source Ecosystem services of land plants Source 1. Fix CO2, provide O2 2. Retain soil & nutrients 3. Buffer temperature, wind, & humidity 4. Provide food for heterotrophs, shelter for other organisms 5. Provide food, building materials, fabrics, paper, rope, drugs, recreation, etc for humans! Source Source Why do scientists study land plants? We can’t live without them! ○ Ecosystem services Some can be harmful ○ Human health hazards ○ Harmful to ecosystems ○ Harmful to crops Source Plants can be harmful Poisonous plants ○ Contact (skin) reactions ○ Systemic reactions Source Source Plants can be harmful Poisonous plants ○ Contact (skin) reactions ○ Systemic reactions Harmful to ecosystems ○ Ex: kudzu Source Plants can be harmful Poisonous plants ○ Contact (skin) reactions ○ Systemic reactions Harmful to ecosystems ○ Ex: kudzu Harmful to crops Source  How do biologists study land plants? Think-pair-share!  Land plant evolution All evidence suggests that land plants evolved from multicellular, freshwater green algae  Plant evolution Fossil record suggests that green algae evolved 700 MYA, when oxygen increased in the atmosphere.  Land plant evolution Plants then evolved from 5 major radiations starting ~475 million years ago with morphological innovations allowing them to live on land http://www.adonline.id.au/plantevol/images/ Source cookper.jpg  Land plant evolution The earliest land plants were still associated with water ○ Swampy environments, freshwater ○ Tied to tissue structure & reproduction  Land plant evolution Terrestrial environment: challenges & opportunities ○ Tissues exposed to air will dry out and die ○ Reproduction a problem ○ But - light + O2/CO2 are more plentiful! Natural selection favored plants that had solved the drying problem ○ Whole bunches of new ecospace available! Which of the following were challenges for the very first terrestrial land plants? A. More abundant O2 B. Drier conditions C. Intense light D. A lack of supporting tissues E. A&C F. B&D Based on fossil evidence, land plants were present at least 475 million years ago. A. True B. False  Origin of land plants - fossil record 475 mya - first evidence of land plants ○ Reproductive adaptations: Spores: reproductive cells with a waxy coating like sporopollenin Sporangia: spore-producing organs ○ Structural adaptations: Cuticle: watertight barrier (helps prevent drying)  Origin of land plants - fossil record 416 mya - most major morphological innovations present ○ Vascular tissue (present but rare at first) ○ Roots ○ Stomata - pore to let out water vapors/perform gas exchange ○ Leaves Plants colonized land in Source conjunction with symbiotic fungi  Origin of land plants - fossil record 359 mya - extensive coal-forming swamps developed Fossils from coal deposits ○ Lots of seedless vascular plants (ex: giant club mosses) Seeds evolve! ○ Earliest group with seeds = seed ferns http://www.bio.miami.edu/dana/pix/ lycopodium_clavatum.jpg  Giant club moss, seed fern http://www.fossilmuseum.net/plantfossils/ SeedFernFruit/WP2b.jpg http://www.fossilplants.co.uk/blog/wp-content/uploads/2013/03/5CABC158-50E9-4BAC-89C6-  Origin of land plants - fossil record Both wet & dry environments blanketed with green plants for the first time! Wind-driven pollination Gymnosperms much better at surviving dry conditions http://meyeremma.weebly.com/uploads/ 4/3/5/4/43542039/514789394.jpg  Origin of land plants - fossil record 145 mya - Diversification of flowering plants! ○ Flowers evolved ○ Animal-driven pollination Source  Recap video https://www.youtube.com/watch?v=UrwMUQbUR30  Major groups of land plants 3 major groups based on morphology:  Non-vascular plants AKA bryophytes Characteristics: ○ No vascular tissue → this is the tissue that plants use to move water & nutrients Instead, they absorb Figure 14.4a Mosses H2O & nutrients directly Need to live in moist habitats ○ No seeds → spores or asexual reproduction Table 3 Hornworts Liverworts  Nonvascular plants AKA bryophytes Habitat: moist forests & fields Life cycle: gametophyte- dominated alternation of generations Impact: among the world’s most abundant plants; responsible for peat Recall: aquatic habitats had less light & dissolved CO2 Land offered plants increased light and atmospheric CO2… …but at the risk of drying out!  Nonvascular plants - adaptations for land Land offered plants increased light + CO2, but at the risk of drying out Solution? ○ A waxy cuticle to prevent water loss + UV protection ○ But is the cuticle almost too effective? What about respiration?  Nonvascular plants - adaptations for land Land offered plants increased light + CO2, but at the risk of drying out Solution? ○ A waxy cuticle to prevent water loss + UV protection ○ But is the cuticle almost too effective? What about respiration?  Nonvascular plants - adaptations for land Stomata prevent water loss & regulate gas exchange ○ Open during the day when plant is generating energy → allow CO2 in ○ Close at night → prevent water loss  Nonvascular plants - adaptations for land Land introduced some more challenges: ○ Wind ○ Gravity ○ Need to transport water through tissues Nonvascular plants answer: simple water-conducting cells  Enter: seedless vascular plants! Evolution of vascular tissue provided plants with better support. This allowed: ○ Taller upright growth ○ More efficient transport of water upwards  Seedless vascular plants These do have vascular tissue, but no seeds Habitat: moist forests Life cycle: sporophyte-dominated alternation of generations Impact: used as food & landscaping Table 3 Club mosses Horsetail Whisk ferns Figure 14.4b Ferns s  Seedless vascular plants - life cycle Haploid (n) Diploid (2n) Spores dispersed Developing by wind (n) gametophyte (n) Spores are produced in 1 mm sporangia Mature gametophyte (n) Mature sporophyte (2n)  Seedless vascular plants - life cycle Ferns also have swimming sperm on the gametophyte Sporophy te Mobile fern sperm Gametoph yte Seedless vascular plants - life cycle On a hike in the woods, you find a plant growing in a shady, cool, relatively moist habitat that has spores growing on the underside of the leaves. You conclude that this plant is most likely a…? A. Nonvascular plant B. Seedless vascular plant C. Seed plant D. None of the above--a whole new category of plant  Activity: your local plant! Use the next 10-15 minutes to research a native plant from the state you were born, grew up in, or one you just love! I will share a google slides link with a template slide. Next time: Will explore how terrestrial plants were able to exploit drier environments through new innovations (seeds, flowers, etc.)