Competition and Niches: Get in where you fit in

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Students will be able to describe the significance of competition in determining realized niches and be able to compare and contrast the three types of symbiotic relationships.

Big Idea

A species' occupied niche is often the result of adapting to very specific constraints imposed by both the non-living and living components of the ecosystem they inhabit.


This lesson covers ecological relationships and species interactions including niches and competition.  The different kinds of symbiotic relationships are also covered to introduce the following lesson examining the case study of moths and sloths.


The lesson essentially consists of two parts:

1. A pre-class textbook reading and homework assignment focused on close reading techniques, critical-thinking questions, and content vocabulary development.

2. An in class presentation that provides supplementary examples to review the concepts and vocabulary from the chapter along with a class discussion seeking to draw students into more critical examination of the topic at hand and assist in their ability to connect the concepts to their personal experiences. 

The textbook reading comes from Environmental Science: Your World, Your Turn by Jay Withgott.

If you do not have that particular textbook, I would recommend finding a similar chapter or chapters and modifying the lesson accordingly.  

Alternately, the powerpoint attached to the Direct Instruction section covers most of the same concepts and vocabulary as the chapter.  If you have a shorter class period, you may want to skip the reading assignment and assign the discussion questions as homework.  You could then hold the class discussion on the following day.       

In my case, I assign the textbook reading on the meeting previous to this lesson.  In that way, students will have already covered the concepts on their own and the powerpoint presentation will be less of a lecture and more of an opportunity for students to ask questions and clarify their understanding. 

Connection to Standard:

In this lesson, students will prepare for class by reading and determining the central idea of a text, establish familiarity with relevant scientific vocabulary, and then draw evidence from the text to support arguments and opinions presented as part of their participation in a group discussion.  


Direct Instruction

30 minutes

Like I mentioned above, I assign the textbook reading as a homework assignment to be completed upon arrival to this class period.  The powerpoint presentation is then more of a review and an opportunity for students to ask questions.  


Wondering WHY I use lectures as a pedagogical strategy?  Watch this video.

Wondering HOW I use the Powerpoint to differentiate instruction? Watch this video.

Wondering why I choose to have a reading assignment AND a lecture on the same content?  Read this rationale.

Wondering how you might use this lesson's resources if you don't plan on presenting a lecture? Read this reflection.


When class begins, I ask students to get their homework out and first give them about 10 minutes to discuss the critical thinking questions with their group members.  During this time, I walk around and put a stamp on completed homework and answer any questions that students bring up.  If students bring up a good question or insightful comment, I ask them to please remember to bring that up in the larger class discussion to follow the presentation.  

Affording this time before the presentation allows students to "field test" their answers with a smaller group, increasing their confidence to participate in the larger discussion.  Also, because the discussion is graded by groups, it allows the ideas of individual members to influence the thinking of their peers which may lead to greater insights or even new questions.  Finally, while I walk around, I listen to the nature of student discussions and get a better sense of what kinds of questions may be floating around the room, allowing me to emphasize certain aspects of the lesson or offer more detailed examples to scaffold the instruction.

After I have stamped all the homework assignments, I distribute the note sheet that accompanies the presentation.  As I've mentioned in previous lessons, offering students a note sheet provides a readymade study guide for later and allows students to focus on their thoughts and the concepts being discussed as opposed to focusing all of their attention on copying down copies amounts of notes.   


Please Note: This lecture covers a lot of material that students may already be familiar with from previous science classes or biology class.  With that being said, I find it important to really do thorough checks for understanding on a few points:

  1. Contrasting realized and fundamental niches and understanding that competition reduces the range of resources an individual or species can exploit.  This is especially important as this comes up again in the next lesson.
  2. Understanding the difference between the different kinds of symbiotic relationships.  "Symbiotic" as it is commonly used generally means only mutualistic relationships where both species benefit.  It is important to distinguish this from commensalistic and parasitic relationships which are also symbiotic because they are physically close relationships between two species where at least one benefits.  I discuss a strategy for further reinforcing this distinction in the discussion section of this lesson.


30 minutes

Following the presentation, I let students know that we will wrap up by having a class discussion to review the concepts of the lesson.  Again, depending on your class length, it may be preferable to have this follow-up discussion on the following day.  

The discussion protocol for this lesson:

  1. all groups are required to participate in the discussion and will receive a “participation” grade for the day

  2. groups with more than one member that participate will receive a higher participation grade

  3. groups that participate more frequently will receive a higher grade


These criteria make the group collectively responsible for their grade and accountable to each other. If no one in the group participates, the group as a whole will receive a failing grade.  If only one member of the group participates, regardless of how often, the group can’t receive any grade higher than a C.  


To keep track of participation, I begin by making a map of the class with the group tables labeled by group name.  Since there are four students at each table, as a student from a particular group participates, I make a tally mark in the position of that student in their group.  In this way, I can tally how often the group participates, which members are participating, and how often.  To determine "average" participation, I add up all tally marks and divide by the number of groups, rounding down.  I then use this rubric to determine their participation grades.


See this discussion guide for specific strategies for this discussion, but I would bring your attention to two key points from the guide that may guide how you lead the discussion:

  1. On the question of whether humans are generalists or specialists, it may be helpful for students to come up with specific examples of each.  Most of my students seemed to agree that we are both specialists and generalists.  An example may be that we are generalists in that we can eat many different types of plants, but we are specialists in that we can cook and combine certain plants and ingredients of a specific region for a very specific regional cuisine.
  2. On the question regarding giving examples of the different types of symbiotic relationships (mutualism, commensalism, and parasitism), I suggest assigning one type of relationship to each group (there will likely be repeats depending on the number of groups in your class) and then having them do a quick, 5 minute "smart phone research" to find specific examples of that kind of relationship.