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One Whale or Two or … ?

The Speciation of Orca Whales



Co Authors:

Celeste A. Leander
Department of Biology & Zoology
The University of British Columbia
cleander@interchange.ubc.ca

Pamela Kalas
Departments of Zoology and Botany
The University of British Columbia
kalas@zoology.ubc.ca

Abstract:

This case study focuses on the intersection of defining a scientific species and defining a legal species. The compelling story of Lolita, an orca whale in captivity, is used to highlight the legal significance of species declaration. Students will work through scientific species definitions and data on Orca whales before deciding if Orca whales should be considered as one or several species. After an introduction to Lolita and a mock town hall meeting, students are thrown into the real life situation of contemplating the fate of an Orca in captivity that suddenly has protected legal status. This case was developed for use in a first-year biology course focusing on ecology, genetics, and evolution. It also could be used in upper or lower division courses on ecology, evolution, or conservation.

Objectives:
  • Describe four species concepts and the appropriate use of each.
  • Discuss how conservation protocol can be affected by species designation decisions.
  • Evaluate phylogenies to identify closest relatives and relative branching patterns.
  • Distinguish between allopatric and sympatric speciation events.
  • Diagram and describe three modes of selection (directional, stabilizing, disruptive).
Keywords: orca; Orcinus orca; species definitions; species concept; phylogeny; ecology; morphology; conservation; directional; stabilizing; disruptive
Topical Area: N/A
Educational Level: Undergraduate lower division, Undergraduate upper division
Formats: PDF, PowerPoint
Type/Method: Directed, Discussion, Flipped
Language: English
Subject Headings: Biology (General)   Ecology   Environmental Science   Wildlife Management   Evolutionary Biology   Zoology   Marine Science / Oceanography  
Date Posted: 9/28/2017
Date Modified: N/A
Copyright: Copyright held by the National Center for Case Study Teaching in Science, University at Buffalo, State University of New York. Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work.

Teaching Notes


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Answer Key


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Supplemental Materials


The PowerPoint slides below can be used to structure the class presentation.

 

  orca_speciation_flip.pptx (~5MB)

Videos

The following video(s) are recommended for use in association with this case study.

  Blackfish
This video is a theatrical trailer for the movie, Blackfish, a documentary about orca whales in captivity. The video is intended to provoke an emotional response in the students and make them care about the topic of the case. Running time: 2:24 min. Created by Magnolia Pictures, CNN films, 2013.

  Modes of Selection
This video defines ecotypes and describes three modes of selection and how they act on different traits. Running time: 5:09 min. Created by Celeste Leander and Pamela Kalas for the National Center for Case Study Teaching in Science, 2017.

I used this case study in my class. We only got through Part I, but the students based their conclusions by relating the orca populations to different human races and thus concluded that orcas are all one species. This took me by surprise and I don't think I responded to this well in the moment. I am thinking about how to address this in my next class, any help, ideas would be appreciated.


Hattie
Biology
Normandale Community College
Bloomington MN
hattie.dambroski@normandale.edu
10/6/2017

AUTHOR’S REPLY:

This has happened in my class too (the example was about birds, not orcas, but same idea). I am happy to share how I addressed this, but I am by no means saying that this is how it should be addressed or how someone else should deal with it. Also, I don’t know in what way the commenter’s students used the human analogy, so my example may or may not be suitable.

First, I asked my students what definition(s) of species they thought were used to determine that humans are a single species. The consensus was that the concept of biological species definitely matched with humans being a single species (but whether it does for the orcas is debatable), while the morphological concept of species did not. Opinions were split for ecological and phylogenetic.

We then had a conversation about how we would proceed if we wanted to separate humans into different species using the morphological species concept, and very quickly the class realized that (at least based on their own knowledge) there was no morphological characteristic, or set of characteristics, that could define one particular human “race,” or even a population. At that point the discussion became focused on whether the two bird populations that we were discussing had morphological characteristics that definitely distinguished them from each other (in the end the class was split).

Thinking about the orcas in particular, it seems surprising that students came to the conclusion that they are all one species by analogy with humans. For example, I think that if they saw the jaw bones of 20 different orcas, with some being transients and some residents, they would be able to differentiate them and put them into two categories. However, they would not be able to do that with human bones... so how they could come to the conclusion that because humans are all one species, then orcas must all be one species?

Apologies about the lengthy reply; I hope some bits of it may turn out useful!




Pamela Kalas
Departments of Zoology and Botany
The University of British Columbia

kalas@zoology.ubc.ca
10/10/2017



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