Organizing Life’s Diversity

1. Organizing Life’s Diversity Chapter 18

2. Classification • Grouping objects or organisms based on a set of criteria • Aristotle – plants and animals, “red blooded and bloodless.” • Further grouping based on physical characteristics • Did not account for evolutionary relationships

3. Carolos Linnaeus • Based on morphology and behavior – five kingdoms • First formal system of taxonomy • Identifying, naming, and classifying species

4. Binomial Nomenclature • Genus + Specific epithet = Species • Drosophilia melanogaster • Homo sapiens • Up to whoever discovers it! • Why do we use scientific names? • Today we use evolutionary relationships to classify organisms

5. Taxonomic Categories • Taxon – named group of organisms • Examples of taxa: • Domain - Eukarya • Kingdom - Animalia • Phylum - Chordata • Class - Mammalia • Order - Cetartiodactyla • Family - Balenopteridae • Genus - Balenoptera • Species – B. musculus • Who studies this? Systematists

6. What’s a species? • Typological species concept – based on physical similarities, assumes species are not evolving. • Biological species concept – able to interbreed and produce fertile offspring in a natural setting • Are exceptions (dogs and wolves) • Phylogenetic species concept – classification is determined based off evolutionary history • Is this knowledge complete?

7. Characters • Scientists use characters, or inherited features, to construct patterns of descent • Morphological characters – homologous ones • Birds and dinosaurs both have hollow bones! • Biochemical characters – amino acids and nucleotides • Broccoli, cauliflower, and kale all look different, but have almost identical chromosome structure! • Molecular clocks – can compare two DNA sequences and their rate of mutation to determine how fast they’ve been evolving!

9. Cladistics • Classifies organisms in order of their divergence from a common ancestor • Cladograms – use derived characteristics!

10. Tree of Life, then and now

11. Domains and Kingdoms • In 1990, five kingdoms were reclassified due to the diversity in Bacteria • Domain Bacteria – peptidoglycan in cell wall • Kingdom Eubacteria • Domain Archaea – no peptidoglycan in cell wall • Kingdom Archaebacteria • Domain Eukarya – eukaryotes! • Kingdom Protista • Kingdom Fungi – are fungi considered autotrophs? • Cell Walls made of Chitin (different from plants and bacteria) • Kingdom Plantae • Kingdom Animalia • What about viruses?

12. Eukarya

13. Basic Vocabulary/History • Producer/Autotroph – makes its own food, usually via photosynthesis • Produces oxygen that many other organisms need • Was oxygen always present on Earth? • Consumer/Heterotroph – get food by consuming other organisms • Decomposer/detritivore – breaks down materials • Gets food and recycles nutrients • All organisms go through cellular respiration

14. Kingdom Plantae Comparing Features of Seed Plants Feature Seeds Reproduction Examples Gymnosperms Angiosperms Bear their seeds on cones Can reproduce without water; male gametophytes are contained in pollen grains; fertilization occurs by pollination Conifers, cycads, ginkgoes, gnetophytes Bear their seeds within flowers Can reproduce without water; male gametophytes are contained in pollen grains; fertilization occurs by pollination Grasses, flowering trees and shrubs, wildflowers, cultivated flowers

15. Kingdom Animalia - Phylums • Phylum Porifera – sponges • Phylum Cnidaria – jelly fish, hydra, anenomes, coral • Phylum Platyhelminthes – flat worms (planaria) • Phylum Nematoda – round worms • Phylum Annelida – segmented worms (earth worms) • Phylum Mollusca – snails, clams, oysters, octopuses • Phylum Arthropoda - -pedes, insects, crabs • Phylum Echinodermata – sea stars, sea urchins

16. Phylum Chordata • Includes humans! (in addition to many other organisms) • At some stage of life has… • hollow nerve chord- becomes and spinal chord • notochord – functions like a backbone (replaced by backbone in vertebrates) • Pharyngeal pouches (gills, we have them as embryos) • Tail beyond anus • Bilateral symmetry