BIOL1108L_BiodiversityWorksheet_online

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Valdosta State University *

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Biology

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Feb 20, 2024

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Purpose: The purpose of this exercise is to describe the diversity of life and the phylogenetic relationships among living organisms. This exercise will solidify your understanding of the tree of life and how to interpret phylogenetic relationships and use these relationships to identify shared derived and shared ancestral characteristics. Being able to compare living organisms in an evolutionary framework will benefit you as you move into upper division science courses and even in your daily lives. Beyond being biophilic and having a general appreciation for life, identifying the properties of different lineages, and describing the evolutionary relationships among different organisms has practical applications which can benefit humans, the society, and the biosphere. Having a foundation in interpreting evolutionary relationships will allow you to evaluate these data and figures when you come across them in your daily lives. For example, we can use this phylogenetics approach to understand the relationships among different strains of COVID-19 and track the spread of COVID-19 across the globe. We could also use this information to evaluate hypotheses regarding its origins. This exercise falls under Course Learning Objects #1 Task : Observe the specimens provided, read the descriptions for each of the major lineages of life displayed in the phylogenetic trees. Trace the phylogenetic relationships among the lineages described. Use the hyperlinks to reveal more information. Based on the information provided, answer the questions. Criteria for Success: To succeed in this assignment, you must: Read the protocol Interpret the phylogenetic trees Carefully read the descriptions of each lineage in the protocol Explore the hyperlinks The worksheet is worth 25 points (0.5-2 points per question)
QUESTIONS Use the specimens in class, the phylogenetic trees, and if necessary digital sources to answer the following questions. Clicking on the lineages on the phylogenetic trees will take you to the Wikipedia entry for that group. If typing, please use a different font color. You do not need to use complete sentences. 1. a. Which node in the 3-domain supertree (the first tree) represents the common ancestor of eukaryotes and Archaea? (0.5 pts) b. Which node in the 3-domain tree represents the common ancestor of all Eukaryotes? (0.5 pts) c. What are some characteristics that would have been present in the common ancestor of all eukaryotes? Hint: think about characteristics that are shared between your cells and the cells of all these other groups (0.5 pts). 2. Survey the links provided and read the protocol descriptions. Look carefully at the traits you see and think about the evolutionary relationships among the organisms present. Based on this, provide at least 3 nodes that represent instances where multicellularity convergently evolved. (1.5 pts). 3. Look at the images in the file labelled “Unknown Gram- Stained Bacteria” in D2L . Determine which organisms are gram-positive and which organisms are gram-negative. List the organisms by letter and state “gram-positive”, “gram- negative”, or “alive and not stained” and include a brief explanation for how you know which is which (1 pt)
4. Explore the links for the organisms in the Archaeplastida tree beginning with Rhodophyta. As part of this be sure you learn about sporophytes vs. gametophytes. Using this information, identify the node in the Archaeplastida phylogeny where the diploid sporophyte generation became the dominant stage in the life cycle (0.5 pt). 5. Look at the Archaeplastida tree links starting with Rhodophyta. Identify the node in the Archaeplastida phylogeny where “land plants” evolved. (0.5 pt) 6. Look at the Archaeplastida tree links. Which node represents the most recent common ancestor of Seed Plants ? (0.5 pt) 7. a. Find the gymnosperms in the Archaeplastida tree. Which node represents the most recent common ancestor of Gymnosperms ? (0.5 pts) b. Conifers are, by far, the most species-rich lineage of modern Gymnosperms; look at the leaf specimens provided for the conifers, other gymnosperms, and their closest relatives, do you think the most recent common ancestor of seed plants would have had needles like a pine tree or broad leaves more like most angiosperms? (0.5 pts)
8. a. Find the flowering plants in the Archaeplastida tree. Which node is the most recent common ancestor of Angiosperms (flowering plants)? (0.5 pts) b. These are now the most species-rich lineage of embryophytes by far with approximately 350,000 species. Most of these species (including all monocots) are herbaceous , meaning they don’t form a woody trunk with internal vascular rings or bark. Look at the Amborella trichopoda photo. Amborella is a shrub from New Caledonia that represents the basal branch of Angiosperms (i.e. all other flowering plants are more closely related to each other than they are to Amborella ). (Hint: Amborella have woody “trunks”) Do you think the ancestor of angiosperms was woody or herbaceous? (0.5 pts) c. Expand your research to include all other seed plant links (Both Gymnosperms + Angiosperms) What about the ancestor of all seed plants? Do you think this ancestor was woody or herbaceous? (0.5 pts) 9. Look at the animal tree links beginning with sponges. Sponges have specialized individual cells but lack true tissue (masses of coordinated cells, like muscle, nerve, etc.). At what node in the animal phylogeny did true tissues evolve? (0.5 pt)
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