Fundamentals of Ecology Class Meetings
February 2013

Physiological Ecology

Announcements:

• Homework for next Tuesday: 
  • read Willette et al. turtle article, & bring a copy to class! (in O: drive, Readings folder)
  • be able to address all the questions related to the article (outlined below, as well as on
    homework page)
  • COME PREPARED to discuss the article in class on Tuesday!!!

Thursday 2/21-

Outline of Main Objectives:

1. Adaptations
2. Physiology
3. Constraints

Question 1:  What do we mean by "adaptations?"

• what are they?

   

  • Adaptations are characters that allow organisms to thrive in a given environment

• how do they arise?

• Natural Selection

  • product of 3 conditions of organisms...  what are they?

   

   

   

  ---

  • product of 3 conditions of organisms:

  1. variation (what are the sources of variation - how do they arise in a population?)

  2. heritability of the trait

  3. differential survival & reproduction  (what do we call this?)

  "hvf"

  ---

   

   

• what are some examples of ways organisms can adapt to their environment?

Physiology - Biology of individual organisms; study of individual function

Physiological Ecology - Performance of individuals within the constraints of the abiotic environment  (e.g., what kinds of factors might form such constraints?).
... in other words, adaptations to the environment, at the physiological level!

Question 2: The African Baobab

• Study area: Tsavo National Park, Kenya
• Climate:
•  
• What Biome do you think Tsavo occupies?

• What plant growth forms should dominate in this habitat?

• Details of Tsavo's climate -
  •  semi-arid
  • scarce water & seasonal precipitation
  • punctuated by multi-year droughts

   

• Specific Baobab adaptations (2)

• Physiological Mystery: Why are baobabs not found within some of the area of Tsavo National Park?

1. Constraints
   • Homeostasis - define
      

      

      

     
     
      

     ---

   • "Master Factors" - for different types of ecosystems,  major environmental factors that play a role in:
     • survival
     • growth
     • reproduction
       
        

        

       
       
        

       ---

   • The Niche
     • Fundamental
     • Realized
     • Hierarchy of constraints - e.g. for Baobab

• Constraints on Animals - Thermoregulation:
  • Ectotherms
  • Endotherms
  • Trade-offs & limitations
  • Production efficiency (energy loss in food chains, re-visited)
  • Thought question - behavioral thermoregulation: fish feeding zones

1. Animal Thermoregulation:
   • Ectotherms vs. Endotherms
   • 2 Groups: Why be an Ecto- or Endotherm???              

• List reasons
• Address questions:

• Food for Thought - Behavioral Thermoregulation:
  • For fish living in a lake, where the temperature is warm near the surface and cold near the bottom...
  • where should a fish spend more time when food is plentiful?  (assume even food distribution throughout the water column)
  • where should fish spend more time when food is scarce?

Tuesday 2/26-

1. Climatic impacts on physiology:
   • Willette article - turtle physiology & climate
   • individual quiz!
   • Jigsaw/break-out groups
   • Discussion - major points of paper
   • Group quiz

    

Read Willette et al. article on climate & physiology in turtles.

Be able to respond to these questions, & come to class prepared for an individual quiz followed by a group quiz & discussion.  Individual assignment.

1. What is the main question being addressed in this article?

2. How are water and temperature likely to affect hatchling size & residual yolk size?

3. What are the 2 critical life-history stages for turtles discussed by the authors?

4. What are the implications of temperature for turtle nestlings, since they are ectotherms?

5. What is "empirical" documentation? (p.846)

6. Be prepared to discuss biology & ethics in light of this study.

7. What are the climatic variables the authors studied?

8. What phenotypic measurements did they make?

9. What were their main results?

10. Which hypotheses could they reject, & which did they not reject?

11. What is the influence of climatic variables on turtle physiology?

12. How might climatic change affect a population like this one?  How generalizable do you think their results are?

13. Would you expect changing climate to affect endotherms in the same way?

Climate & Physiology - Example

Question:

Sometimes in coastal areas, well-meaning people dig up eggs laid by sea turtles on beaches and re-bury them further inland where the eggs are better protected.  What impact do you think this has on the sexual development of these turtles?

• Sex determination in reptiles & amphibians
• Role of temperature
• Temperature-Dependent Sex Determination (TSD) - In turtles, most common for males to be produced at lower incubation temperatures, & females at higher temps.  The change can occur over ranges as little as 1-2^o C!  For lizards & crocodilians the pattern is reversed.
• Environmental influences
• Role of EDC's - Endocrine Disrupting Chemicals
  • PCBs, DDT, PAHs, polycarbonate plastics (Nalgenes!)
  • produce estrogenic, antiestrogenic & other effects
•  Compounds are ubiquitous in environment
• High levels of these compounds in blood & body fats of humans & wildlife  (bioaccumulation)
• Uncertainty:  What health effects do they have on humans?  on other species?  How can we be certain of the impacts of EDCs on wildlife?.......