Origin and Diversification of Life:

Origin and Diversification of Life: PLANTS & FUNGI

Unit 13 – Concepts • Role of Fungi (I) • Plant Phylogeny (E) • Primitive Plants • Modern Plants • Scientific Keys (I) • Coevolution (plants and animals) (C)

Essential Question 1.1 • What role has fungi played in the colonization of terrestrial environments?

Fungal Phylogeny Aquatic fungi (oldest) Black bread mold Yeasts, truffles and morels Mushrooms, toadstools and rusts • It is hypothesized that ancestors to the kingdom Fungi diverged from protists as early as a billion years ago. Divergence from a common ancestor to animals occurred around 600MYA. The first fungi to appear distinctly in the fossil record are around 450MYA. This is due in part to the difficulty in creating a fossil from a fungus.

Protists and fungi demonstrate simple multicellularity. • Distinct types of cells with a common structure and function are called tissues(photosynthetic, attachment, reproductive, etc.) • Tissues help to organize labor into specified areas. • Most multicellular organisms have only a few tissue types. Hyphae with spores Nonseptate hypha Septate hypha SEM 330X

Fruiting body Fungal structures Spores Produced Hyphae • When you think of a fungus you probably picture the cap (thallus or body) that protrudes from the ground. • This structure is the fruiting body(reproduction) of the mycelium and represents just a small portion of the organisms total surface area. • Mycelium are a network of fungal filaments known as hyphae. Mycelium

Fungi gain nutrition by secreting digestive enzymes, and then absorbing the resulting organic compounds. • Some fungi are major decomposers. • Others parasitize living organisms. “Ring worm” infection

Mycorrhizae • One of the most import roles fungi play is the mutualism they display with plants. Plants grow more successfully when their root cells are infiltrated by hyphae(mycorrhizae). • The fungi extract minerals from the environment that plants need; plants generate sugars that fungi need.

Lichens • Lichens represent an important symbiotic relationship between protists and fungi. Originally thought to be a mutualism due to its similarities with mycorrhizae but now the fungi are thought to be more of a parasite of the algae cells.

Lichens as Pioneers • Lichens are excellent pioneer species due to the ability to grow on bare rocks. • This association is thought to be the critical link in life's establishment of terrestrial environments.

When the underground network (mycelium) sends up fruiting bodies you can see the size of the whole organism. When mushrooms appear in arrangements like this people call them fairy rings.

Question:How were fungi critical in the movement of life to land? How are they still critical to terrestrial life? • Fungi formed mutualistic and parasitic associations with plants and protists that allow for the harvesting and sharing of nutrient resources and organic products to survive on this harsh new environment. • Over time the importance of fungi has increased as they have joined bacteria and the archaea as a major source of decomposition and recycling of materials in natural food webs.

Unit 13 – Concepts • Role of Fungi (I) • Plant Phylogeny (E) • Primitive Plants • Modern Plants • Scientific Keys (I) • Coevolution (plants and animals) (C)

Essential Question 2.1 • How did the adaptations of primitive plants allow them to colonize the land?

What is a Plant? According to the chart of characteristics we used to identify the kingdoms, a plant is a multicellular autotroph with cell walls made of cellulose. In this unit we will focus on how plants have used these characteristics to colonize the land and diversify into Flora we see around us each day. *Sessile – fixed in one place; immobile

PlantPhylogeny:Phylogeny is the evolutionary relatedness amongst groups of organisms. The major groups shown below indicate how plants have developed over time to become increasingly independent of water and successful in reproduction despite their inability to move.

If you’re going to live on land… • The ancestral protists that led to plants (green algae) were bound to aquatic environments. • Moving to the land required new characteristics. • Why is living on land different?

Leaving the water:In the water, cells do not need to conserve water due to it surrounding the cell at all times. Organisms also do not need to pump supplies against the pull of gravity in an aquatic environment. Both are challenges to living on the land.

Bryophytes • The first land plants appeared about 475MYA. They were non-vascular, seedlessand most closely resemble todays mosses and liverworts. • Water and nutrients are absorbed and passed only by diffusion. This limits the height and distance away from sources of water. • Mosses and liverworts will be found in cool, moist environments and will only grow to be a few cm tall.

Ferns and horsetails Vascular Seedless Plants • Tubes for transport of materials = vascular tissue. • Allows faster / farther movement of water/nutrients than diffusion. • Allows for deeper roots. • Support for taller plants. • Access to more water between rain storms. 430MYA

Unit 13 – Concepts • Role of Fungi (I) • Plant Phylogeny (E) • Primitive Plants • Modern plants • Scientific Keys (I) • Coevolution (plants and animals) (C)

Essential Question 2.2 • How did the adaptations of modern plants allow them to outcompete primitive plants in terrestrial environments?

What is a seed? • Seeds developed about 300MYAand represent a major adaptation in the colonization of plants. • Seeds are comprised of several parts. • Sporophyte(diploid)embryo • Endosperm– source of nutrition for embryo until roots are established. • Drought resistant protective cover that allows the seed to wait for good environmental conditions prior to germination.

There are 2 major groups of seed bearing plants: Gymnosperms & Angiosperms • Gymnosperm [Gk. gymnos, naked, and sperma, seed] • Seeds are not enclosed by fruit. • Gymnosperms contain four groups; conifers, cycads, ginkgoes and gnetophytes.

Gymnosperms

Wind dispersal, while being inefficient (think about all the pollen that settles on your cars)has the advantage of not requiring water for fertilization. • Conifers avoid self fertilization by having male cones lower on the tree than female cones.

Angiosperms • Angiosperms appeared about 130MYA and are the most dominant terrestrial plants today(90% of all plants). • Virtually all of our food is derived from angiosperms. Over 50% of these calories are from only 3 plants: rice, corn and wheat. • Angiosperms successfully meet the last challenge of living on the land: the inherent conflict between the need to obtain nutrients(solved by roots) and the need to find mates.

Angiosperms • Angiosperms have seeds covered by a fruit that entices animals to aid in seed dispersal. • Flowers attract insects to aid in avoiding self fertilization.

Flowers • Flowers are the reproductive organs of angiosperm plants. • The employment of bright colorsto attract the attention of insects, sweet nectars to induce the insect to enter the flower, andstructures to coat the insect with pollenwhile visiting so that it can carry the pollen to another flower. Gymnosperm pollen Angiosperm pollen

Female Male

Fruits • A fruit is a mature, ripened ovary containing seeds. • Fruits provide angiosperms a way of dispersing seeds other than by wind. Just as in pollination they employ the use of animals. • Seeds are resistant to chewing and digestion so they will pass through the animals digestive tract unharmed and be deposited with feces at a location far from the parent.

Question:In what way did the gymnosperms not fully overcome the need to find mates? How did the angiosperms solve this issue? • Gymnosperms have pollen that is carried passively by the wind on the chance that they might by luck encounter a female cone. This is very inefficient. • Angiosperms have flowers that attract insects to carry pollen to different plants. Additionally they have fruits with seeds that can be carried off by water, wind and animals to aid in dispersion.

Plant Phylogeny As plants have adapted to a life on land they have changed reproductive strategies from having haploid spores to dispersing diploid seeds.

Essential Questions 3.1-3.2: 1. How are dichotomous keys used to identify the classification of organisms? 2. How can a dichotomous key be made for the purpose of identifying members of given groups?

A dichotomous key is used to identify previously classified organisms. • Akey consists of a series questions regarding the organism, such as... • “Insect has wings” • “Insect has no wings” • Depending on the answer given, the key directs you to new location within the key. • “go to 2” • “go to 15” • Each pair must always be a couplet of two.

A sample dichotomous key

Use the key provided by your teacher to identify the trees on the MASH campus. Some characteristics that may be helpful are below and on the next slide.

http://www.dcnr.state.pa.us/forestry/commontr/

Essential Question 4.1 • How do plant and animal species respond to each other in a way that demonstrates coevolution?

Coevolution The relationship between plants and animals is complex. Because of this interdependence between kingdoms, we can see countless examples of how many plant/animal pairs have coevolved over time. • Plants use animals to… • Pollinate flowers to avoid inbreeding. • Disperse seeds to avoid competition. • Provide nutrition. • Animals use plants for… • Food • Shelter

Coevolution How insects and birds see a flower Ludwigiaperuviana • Insects eyes are more sensitive to wavelengths of light on the blue end of the spectrum than are our eyes. To see the world as an insect you need to use ultra violet vision. • Plants have evolved to match their insect pollinators vision by highlighting landing zones or the locations of pollen and nectar. Normal light UV filtered light

Question:Can seeds survive digestion? • Yes!!Seeds will make it through your digestive tract and still sprout (experimentation at home is not recommended!!!) • Seeds not only survive being eaten by animals—some seeds will not germinate unless they are eaten. The pulp that surrounds seeds in some fruit inhibits germination and must be digested before the seed will sprout. Other seeds have chemicals in the seed coats that must be removed by the acidity of an animal’s stomach before the seeds will germinate. • Another plus to this system:the seeds are deposited in a new location where they are not going to compete with the parent for nutrients and light; not to mention the manure that provides instant nutrient for the seedlings to start growing.

Origin and Diversification of Life: