Classification of Organisms

1. Classification of Organisms Chapter 16

2. Why is it important for organisms to be scientifically classified? • 1. To avoid confusion that would result from only using vernacular names • Vernacular name: (aka “common name”) The nonscientific name used by the general public. (i.e. “pine tree”, “daisy”, etc…) • Often different vernacular names for the same plant. (Vernacular names vary person to person, region to region, and country to country.) • One common name could represent many different species (i.e. “daisy” or “sunflower”, “pine”)

3. Why is it important for organisms to be scientifically classified? • 2. Classification systems reflect hypotheses about evolutionary relationships between organisms. • i.e. the potato, tomato, pepper, and tobacco are all in the same family because they are evolutionarily related. • i.e. Just because a group of plants has, say, red fruit, doesn’t mean they’re all in the same family even though they share that characteristic. (i.e. strawberry, tomato, cranberry are all in different families). So a lot of thought and research goes into determining which plants are truly related genetically.

4. “Systematics” & “Taxonomy” • Systematics: The scientific study of the evolutionary relationships between organisms. • Taxonomy: the naming and classifying of species. (from the Greek taktos, ordered, and onoma, name). • (Taxonomy is included within the study of systematics.)

5. What determines how it is classified? • Systematists use a variety of characters to classify organisms. Some include: • Morphology: the form and structure of an organism (i.e. presence/absence of flowers, form and structure of flowers and fruit, microscopic design on seed coats and pollen, etc…) • Life stages (i.e. embryo development, means of reproduction, etc…) • Molecular data (i.e. genetic material such as DNA)

6. Modern Taxonomy • Throughout time, different methods of naming and classifying plants have been attempted, but Carl Linnaeus’ binomial system of classification was the one that “stuck”. • Carl Linnaeus (1707-1778) was a Swedish professor of botany and medicine.

7. Binomial Nomenclature • Linnaeus began assigning two names (bi = two, nomial= name) to plants. • Consists of a Genus and species name, usually written in Latin. • These “binomials”, usually summarized the general characteristics of the plant • i.e. Digitalis purpurea(foxglove): • Digitalis derived from Latin word for finger (flowers resemble thimbles) • purpureaLatin for purple.

8. What is the correct way to write scientific binomials? • Always italicized or underlined • Genus (the first name) is always capitalized. • Species epithet (a.k.a. specific epithet) is the second name and is always lowercase. • So when referring to a “species”, you need to refer to the whole binomial, not just the “species epithet” • i.e. Malus domestica vs. Musca domestica, these are two totally different species that share the same “species epithet”

9. Liriodendron tulipifera (“Tulip tree”, aka “Yellow Poplar”, “White Poplar”, Whitewood”, etc…

10. Organisms are classifiedinto a hierarchy of categories Domain Kingdom Phylum (some botanists use “Division”) Class Order Family Genus Species “Do Kings Play Chess On Fine Grained Sand?”

12. The Major Lineages of Life (Prokaryotes) (Prokaryotes) Prokaryotic: Cells do not have a membrane-bound nucleus Eukaryotic: Cells have a membrane around nucleus

13. Every living thing consists of at least one cell. • Based on the characteristics of these cells, they are categorized into one of 3 domains. • Two of the 3 consist of microscopic organisms The six-kingdom system The three-domain system Plantae Protista Animalia Archaea Fungi Bacteria Eukarya Archaea Bacteria

14. Cladogram: a tree-like branching diagram that shows evolutionary relationships.

16. Kingdom PlantaeWhat is a Plant? • Retention of embryo • Make organic molecules by photosynthesis • Roots that provide anchorage and absorb water and mineral nutrients from the soil. • Most have stems, leaves, cuticles, and stomata • ie: Mosses, ferns, trees, grasses, pine trees, and flowers belong to the Plantae Kingdom

17. Va Simplified cladogram with major distinguishing characteristics Algae Flowers and Fruit Seeds Vascular Tissue Embryo retention (true plants)

18. What distinguishes Plants from Algae? • True plants (i.e. Kingdom Plantae) are “Embryophytes” • After fertilization, the zygote develops into a multicellular embryo while still enclosed in the female reproductive structure. • Definitions: • Fertilization: union of sperm and egg • Zygote: cell resulting from the union of the sperm nucleus and egg nucleus (nucleus contains the genetic material, DNA) • Embryo: baby plant that hasn’t left mom yet. It even has an umbilical cord and belly button!

19. ALGAE are cool, but they’re not plants!

20. Va Simplified cladogram with major distinguishing characteristics Algae Flowers and Fruit Seeds Vascular Tissue Embryo retention (true plants)

21. Vascular tissue • Vascular tissue: plant tissue that transports water, nutrients, and hormones throughout the plant. (like our veins do!) • Provide strong support, enabling stems to stand upright and grow tall on land. • Ferns have vascular tissue, but produce no seeds, only spores.

22. Va Simplified cladogram with major distinguishing characteristics Algae Flowers and Fruit Seeds Vascular Tissue Embryo retention (true plants)

23. Seeds • A Seed consists of a plant embryo packaged with a food supply within a protective covering.

24. Va Simplified cladogram with major distinguishing characteristics Algae Flowers and Fruit Seeds Vascular Tissue Embryo retention (true plants)