Week 03

Link to slides forthcoming.

Overview

In lecture this week, we will continue to learn how using age- or stage-structured matrices can help better project population dynamics and help in population management. For example, some populations may have many individuals, but if most individuals are very old and have low reproductive output, the population may nevertheless decline to extinction in the long-term. On the other hand, small populations may eventually grow to be big if they mostly comprise individuals with high survival rates and high fecundity (reproductive rates).

Outside-of-class activities

Prior to class on Wednesday, please read the 1987 paper “A Stage-Based Population Model for Loggerhead Sea Turtles and Implications for Conservation” by Deborah Crouse et al. ( Link to paper). Also, listen to the episode “The Riddle of the Ridley” from the Sea Change podcast from WWNO (New Orleans) about the current status of sea turtle populations: link. (This episode is also available on most podcast apps).

On Wednesday in class, we will discuss the paper according the following questions:

Discussion questions for Crouse et al.

1. As of the time when this paper was written (1987), what was the primary focus of turtle conservation efforts? Why was this the primary focus of conservation activity?

2. The authors simplify the turtle life cycle, which can extend more than 50 years, into just 7 different stages. Explain in your own words (a) why they chose to do this, (b) what these stages represent, and (c) the reproductive dynamics of these stages.

3. In your own words, what does the “Elasticity” of a stage represent? What does Figure 4A tell us about the elasticity of different life stages?

4. If the authors had to pick a single life stage that should be the target of conservation, which one do you think they would advocate for? Why?

5. According to the authors, what is an uncomfortable possibility that conservation biologists needed to address about turtle conservation efforts? Where else do you think such lessons are applicable in our contemporary lives? (1 point) :::

Submissions

On Friday Sept 12th, students will complete their first in-class activity submission. The activity will focus on material covered in the first three weeks of class (mark-recapture methods for assessing population size; dynamics of exponential population growth; and dynamics of structured populations)

Self-reflection

There is no self-reflection due this week, but please return to your Week 1 self-reflection on Moodle and assign yourself a grade via the comments/feedback feature. Note that students who do not leave a score will be marked 5/10 on default, though this number will be revised should the student return and leave a thoughtful comment.