White-Striped_Clover - Im Looking Over a White-Striped...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
“I’m Looking Over a White-Striped Clover” by Evarts, Krufka, & Wilson Page  Case Objectives By the end of this case, you will: Understand the process of natural selection and the importance of environment-specific adaptations. Be able to use the terms variation, adaptation, natural selection, and evolution as they apply to this and other scientific studies. Gain experience with the scientific method and be able to propose hypotheses and justifications to explain the distribution of the two variants of white clover. Design experiments to test hypotheses and describe data that would support these hypotheses. Understand and synthesize information in figures and tables. P ART I—“I’ M L OOKING O VER …” White clover (Trifolium repens) , a small perennial plant, is found throughout the world, and has two forms. One variant has entirely green leaves (plain) and the other has green leaves with a prominent white stripe (striped). Both variants of white clover (plain and striped) are found along the coast of Long Island, New York. Most of Long Island is only a few feet above sea level. A series of low grass-covered hills separated by shallow depressions covers the area behind the oceanfront dunes. The shallow depressions reach to the water table, so they tend to be permanently moist year round and do not freeze in winter. Water drains away quickly from the low hills, which tend to dry out many times over the year and freeze in the winter. The habitat in the shallow depressions is more hospitable to molluscs (snails and slugs) that feed on clover. One type of clover is more common in shallow depressions while the other type is more likely to be found on low hills. At the end of the case, we will come back to New York and ask you to predict which type of white clover is most abundant in each microhabitat. But first, let’s consider the abundance of these two types of clover on a larger scale. Figure , below, shows the relative frequency of white clover variants in Minnesota and North Carolina. by Susan Evarts , Department of Biology, University of St. Thomas Alison Krufka , Department of Biological Sciences, Rowan University Chester Wilson , Department of Biology, University of St. Thomas I’m Looking Over a White-Striped Clover: A Case of Natural Selection
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
“I’m Looking Over a White-Striped Clover” by Evarts, Krufka, & Wilson Page  Table  provides additional information on Minnesota and North Carolina. Table 1 Minnesota North Carolina Latitude 43–49° N 34–36° N Mean elevation 0.365 km 0.213 km Ave. monthly temp. range −19.4° to 28.6° C −2.6° to 31.3° C High temperature 45.6° C 43.3° C Low temperature −51° C −37° C Mean # days with high above 32° C* 14 38 Mean # of days with low below 0° C* 154 75 Ave. yearly precipitation 66–76 cm 107–117 cm Presence of herbivores (molluscs such as snails, slugs) smaller population, not present in winter larger, more active population, present all year Data from Netstate.com and National Oceanic and Atmospheric Administration.
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern