1442 Laboratory 2

1. 1442 Laboratory 2 Classification and Taxonomy Heather M Hawkins MICHAELL@uta.edu Office Hours: 11-2 LS 464

2. Tuesday Choose 5 questions to answer: • 1. True/False Within an experiment the independent variable is measured. • 2. The first step in testing a hypothesis is making a ___________________about the observations one would expect to make if the hypothesis is correct. • 3. True/False Systematics is the science of using phylogenetic relationships to classify organisms. • 4. The basic units of mass in the metric system is____________________. • 5. What is the name of the prefix for 10^-6 that is applied to all SI units? • 6. List two of the principle parts of the microscope we studied?

3. Wednesday Choose 5 questions to answer: • 1. True/False Within an experiment the independent variable is manipulated. • 2. The first step in testing a hypothesis is making a ___________________about the observations one would expect to make if the hypothesis is correct. • 3. True/False Taxonomy is the science of naming organisms. • 4. The basic units of volume in the metric system is____________________. • 5. What is the name of the prefix for 10^-9 that is applied to all SI units? • 6. List two of the principle parts of the microscope we studied? • 7. Magnification is determined by this formula: _____ X objective = total magnification.

4. Today’s Outline • Levels of Classification • Dichotomous Key • Definition of Species • Today’s Experiment

5. Levels of Classification • Carolus Linnaeus (1707-1778) a Swedish physician and botanist contributed two fundamental ideas to science: • Developed a two part system (binomial) of naming organisms according to genus and species. • Also developed a system to group similar species into a hierarchy of increasing general categories.

6. Levels of Classification • Taxonomy: the science of naming and classifying organisms • Systematics: the science of using phylogenetic relationships to classify and name organisms • Phylogenetics: the study of evolutionary relatedness among various groups of organisms

7. Levels of Classification • Common names: Can vary with culture/region, names familiar to most laymen • Scientific names: Unique to each organism • Binomial system first employed by Linnaeus in the 18th Century (Genus species)

8. Levels of Classification

9. Taxonomic Keys • Used to identify organisms within a set • Usually limited to region or taxa • Examples: • Key to the trees of New England • Key to Lizards of Texas • Example in your lab manual (pp 20-23) • Dividing organisms based upon phenotypic characteristics • Dichotomous keys are arranged choices with two alternatives

10. Dichotomous Key Examples

11. Dichotomous Key Examples

12. Leaf Morphology • Blade (or leaf) is connected to the branch at the node. • Internode defines the space between nodes. • A simple leaf had only one blade per auxiliary bud, while a compound leaf has several.

13. Leaf Morphology • Margins or leaf edges: entire (smooth), serrate (toothed), or lobed • Leaf attachments to the branch: opposite (nodes are directly across from each other), alternate (nodes are offset), or whorled (greater than three nodes are attached to one position on a branch) • Venation patterns: pinnate (feather like pattern) or palmate (hand like)

14. Leaf Morphology

15. What is a Species? • Species is a Latin word meaning “kind” and “appearance.” • Linnaeus described species in terms of their physical form. • Basic concept: group of organisms and a single species represents all the individuals make that group • Most common definition from Ernest Mayr (1942): Species are a group of actually or potentially interbreeding natural populations which are reproductively isolated from other groups. (Biological Species Concept)

16. What is a Species? • Biological Species Concept: Can be defined in another way, a species represents a population whose members can interbred in nature to produce viable offspring but cannot with other species. • This concept is more interested in reproductive compatibility rather than physical similarities and hinges on reproductive isolation. • Limitations: How do you group extinct life forms, normally they are grouped based on physical characteristics? Definition based on interbreeding, how do you group organisms that reproduce asexually?

17. What is a Species? • Morphological species concept: Species are defined by measurable physical attributes, not by reproductive isolation. • Recognition species concept: Species are defined by molecular, morphological, and behavioral characteristics that maximize successful mating, these characteristics are affected by natural selection. • Ecological species concept: Species are defined by where they live and what they do, morphology is irrelevant.

18. What is a Species? • Evolutionary species concept: Species are defined as a sequence of ancestral and descendant populations that are evolving independently of other groups. • Many more species concepts exist than presented here. • Unlikely that a single definition can be created to define all species. • Remember, in defining a species we are talking about a genetically discrete unit in nature. To create these units processes must occur to initiate and perpetuate the isolation of the population’s gene pool from others.

19. Today’s Experiment • Construct your own Dichotomous key for the shapes on the handout. • Use page 29 in your text for help. • Have a classmate check your key.

20. Assignment • Complete Web Assignment 1 from the IntroLabs website for next week. • Print out Web Assignment 2 • Study for next week’s quiz (this week’s material and new material)

21. Homework Help • What is a species? Review the various species concepts presented attempt to merge two or three of them into a single definition. • Dichotomous Key for Leaves: Try beginning with dividing between simple and compound leaves? See page 20-22 in the text for ideas.