Sex and the Komodo Dragon

By Fiona E. Rawle, Marc Dryer, Joan Sharp

Abstract

In this clicker case study for a flipped classroom, students familiar with the stages of meiosis work in small groups to determine the predicted genetic makeup of the parthenogenetic offspring of a Komodo dragon, based on four different types of parthenogenesis. Students then learn about the actual genetic makeup of the offspring and determine how meiosis was modified to allow parthenogenesis in this fascinating lizard. The sex of the offspring is explained, based on ZW/ZZ sex determination. A video specifically made for this case prepares students for the in-class activities, which are guided by a PowerPoint presentation. The case also examines how facultative parthogenesis may be adaptive in Komodo dragons and the implications of facultative parthogenesis to conservation of these vulnerable lizards. The case was developed for a general biology class, but could also be used in an introductory course on conservation or cell biology.

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Date Posted

10/26/2017

Overview

Objectives

Describe the sources of variation in daughter cells produced by meiosis.
Explain the process of oogenesis, a form of meiosis that produces haploid eggs.
Explain how alterations in the events and products of oogenesis may alter the genetic makeup of the resulting daughter cells.
Describe the basis of ZW/ZZ sex determination.
Explain how facultative parthenogenesis may be adaptive in Komodo dragons.
Explain the implications of facultative parthenogenesis to conservation of these lizards.

Keywords

asexual reproduction; parthenogenesis; meiosis; oogenesis; genetic variation; sex determination; adaptation; conservation; komodo dragon

Subject Headings

Biology (General)

Cell Biology

Evolutionary Biology

Zoology

EDUCATIONAL LEVEL

Undergraduate lower division, Undergraduate upper division

FORMAT

PDF

TOPICAL AREAS

N/A

LANGUAGE

English

TYPE/METHODS

Clicker, Discussion, Flipped

Teaching Notes & Answer Key

Teaching Notes

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Answer Key

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Materials & Media

Supplemental Materials

Videos

Phases of Meiosis
This video explains the major phases of meiosis including: interphase, prophase I, metaphase I, anaphase I, telophase I, cytokinesis, interphase II, metaphase II, anaphase II, and telophase II. Also explains how variation is created in the next generation through meiosis and sexual reproduction. Running time: 8:25 min. Created by Paul Anderson. Produced by Bozeman Science.
Parthenogenesis
This video animation on parthenogenesis shows the normal events of meiosis and explains four different types of parthenogenesis in which the events of meiosis are modified to produce offspring that develop from an egg that has not been fertilized by a sperm. Students are asked to predict the sex and genetic makeup of each type of parthenogenetic offspring. Students should be directed to think carefully about the questions posed in this video, but they do not have to bring written answers to class. Their understanding of this material will be probed in the pre- and post-case questions. Running time: 8:45 min. Created by Marc Dryer, Fiona E. Rawle, and Joan C. Sharp for the National Center for Case Study Teaching in Science, 2016.