“Trouble in Paradise” by James A. Hewlett Page 1 by James A. Hewlett ames A. Hewlett Science and Technology Department cience and Technology Department Finger Lakes Community College inger Lakes Community College Trouble in Paradise: rouble in Paradise: A Case of Speciation Case of Speciation Background As an expert in the fi eld of mammalian reproductive strategies, you have been hired by the Department of Nature and Island Resources of the West Indies. Th is organization is a cooperative of several West Indies islands concerned with the loss of biological diversity on their island nations as tourism and development continue to grow. Scientists working on the island of St. Kitts and its sister island Nevis have uncovered what appears to be a previously undiscovered species of rodent. Based on the original description of this animal, it was placed in a genus within the squirrel family. What you have been hired to do is to help save the population on St. Kitts, which is small and threatened by development. Th e population is so small that individuals are having diffi culty fi nding mates and, in many cases, the reproductive seasons are being delayed by up to one year. When you arrive in the region and begin your observations, you notice that the Nevis population is very healthy and could be used as stock for the recovery operation that you plan on the island of St. Kitts. In your recovery plan, you bring animals from Nevis into the population on St. Kitts to bolster the population numbers, ensure the availability of mates, and increase the genetic diversity within the shrinking population. As a good scientist, you observe the reproductive behaviors of this animal in the fi eld to ensure the success of your program. Within a very short time, you realize that your plan is failing. In the 240 attempts to bring a Nevis animal into the St. Kitts population, you are unable to observe a single successful reproductive event. Although these animals look identical, you are concerned that they are two distinct species. Your focus now becomes identifying the diff erences between the two populations. What follows is a brief review of the data you collected from your study. NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE “Trouble in Paradise” by James A. Hewlett Page 2 St. Kitts Rodent Nevis Rodent Average weight: 83g Average weight: 86g Average length: 21.8cm Average length: 23.3cm Average hind limb: 7.8cm Average hind limb: 4.2cm Average forelimb: 4.2cm Average forelimb: 3.9cm Top speed: 2.2 meters/second (m/s) Top speed: 0.8m/s Average leap height: 1.4m Average leap height: 0.4m Average gestation time: 29.3 days Average gestation time: 42.7 days Average time spent in courtship display: 12.6 seconds Average time spent in courtship display: 21.3 seconds Assignment Th is case study describes a recovery program for a rodent population on the island of St. Kitts in the Caribbean. After reading the case study above, your job is to formulate your own story incorporating some of the details and data provided while also drawing on several evolutionary concepts studied in class. A list of these concepts can be found at the end of this document. Th ere are no limitations on the details you can incorporate into your story, but it should follow some specifi c guidelines. Your story: • Should be 600 words or less. • Should incorporate the data supplied in the case study. • Should incorporate at least three of the concepts from the “Concept List.” As you incorporate each concept, you must demonstrate its relevance to your story. • Can be told in any form. For instance, one student presented the story as fi eld notes collected from observing the animals in their natural habitat. Another student presented the story as a series of experiments and observations made by groups of scientists over hundreds of years. Be creative. • Should account for the data on the organisms provided in the case study. It is acceptable to add more data as you develop your story as long as it fi ts into the patterns of the data provided. • Can include graphics and illustrations. Be sure to cite the source and give credit for the material, including material taken from the Internet. • Should include a scientifi c and common name for the rodent populations. In developing these names, make sure you use the rules for binomial classifi cation. In addition, make sure that you put the rodents into an existing genus. You come up with the species names. • Needs a good title. Remember that you are developing an evolutionary picture of a rodent population using data supplied with the case study. Keep in mind that in an evolutionary story you will be describing events that may have occurred over very long time periods. Important: When incorporating concepts from the “Concept List” into your story, you must elaborate on how they relate to your story. Simply including a concept word in your assignment is not acceptable. For example, stating that “the animals became two species because of genetic drift” is not suffi cient. You must also explain how genetic drift works in this process. NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE “Trouble in Paradise” by James A. Hewlett Page 3 Credit: Photo of St. Kitts coastline © Jason Ross | Dreamstime.com. Copyright 1999, National Center for Case Study Teaching in Science, University at Buff alo, State University of New York. Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work. Concept List You must include at least three of the following: • Genetic drift • Bottleneck eff ect • Founder eff ect • Gene fl ow • Mutation • Natural selection—Directional selection • Natural selection—Stabilizing selection • Natural selection—Diversifying selection • Prezygotic reproductive isolation—Habitat isolation • Prezygotic reproductive isolation—Behavioral isolation • Prezygotic reproductive isolation—Temporal isolation • Prezygotic reproductive isolation—Mechanical isolation • Prezygotic reproductive isolation—Genetic isolation • Postzygotic reproductive isolation—Reduced hybrid viability or fertility • Allopatric speciation