Animals in the winter environment. Source:

Transcription

1 Animals in the winter environment Source:

2 The big challenge

3 Options for overwintering success Migration Hibernation Resistance

4 Homeotherms

5 Modes of energy transfer Heat in = Heat out

6 Heat in = Heat out M = ka*(tb Ta)/d M = heat produced by metabolism k = thermal conductivity (W/cm C ) A = surface area of exposure (cm2) Ta = outside temperature Tb = animals core temperature d = thickness of insulating layer

7 Task (30 minutes, groups of 4) Which of the two furs provided by the instructor are better insulators and why? Test your hypothesis by putting the furs outside and use a Vernier with a surface temperature sensor to log the surface temperature change of heat packs underneath the furs for 10 minutes in 10 second intervals. Graph the data on your Vernier and share your graph with the class. What might explain some of the differences in insulating properties between furs?

8 Task (30 min, groups of 4) Use the heat packs and a Vernier with a surface temperature probe to determine the rate of temperature change over a period of 10 minutes above and at the base of the snow pack (i.e., subnivean zone). Graph the data on your Vernier and share your graph with the class.

9 Thermoregulation in animals M = ka*(tb Ta)/d Physiological thermoregulation Physical thermoregulation

10 Task (30 minutes, individual) Given that: M = ka*(tb Ta)/d What physical options does a homeotherm have to keep a constant metabolic rate? Please create some pencil-scetches that illustrate physical options hometherms have to keep the metabolic rate constant.

11 Art by Marina Stevenson

12 Non-shivering thermogenesis Source: Charmeine et al., 2012 Source:

13 Shivering thermogenesis

14 Fat and feathers aren t enough Source:

15 Controlled hypothermia

16 Task (20 minutes, groups of 2) The text below is from a kids book called Winter Bees & other poems of the cold by Joyce Sidman and Rick Allen. Please expand upon this text by providing some more detail/technical information e.g., from the Life in the Cold book.

17 Task (45 minutes, groups of 4) How do animals keep extremities from freezing without constantly draining heat from the body (see page )? To answer this question refer to pages in Life in the Cold and build a model with materials supplied by the instructor that helps explain the solution to this problem. Create a video to explain your model.

18 The problem with appendages Arterial blood Venous blood

19 Task (20 min, groups of 4) Which of the two heat packs provided by the instructor will lose heat faster and why? Test your hypothesis by putting the heat packs outside for 10 minutes and use a Vernier with a surface temperature sensor to log their surface temperature change in 10 second intervals. Graph the data on your Vernier and share your graph with the class.

20 Bergmann s rule

21 Problem with the Bergmann s rule

22 Gloger s rule

23 Poikilotherms

24 Task (15 min, groups of 4) Look at the time-lapse video you produced. Which liquids started to freeze faster and slower and why? Why is this important for the winter survival of poikilotherms?

25 Insects in the winter Insects Freeze avoidance Freeze tolerance

26 Freeze avoidance Lower supercooling and freezing point by: o Excreting particles that could be nucleation sites o Mask particles (i.e., nucleators) within cell organelles and membranes o Decrease body water content o Produce cryoprotectants (e.g., polyohydric alcohols such as glycerol, sorbitol, and glycol)

27 Freeze tolerance Extracellular ice formation and cell dehydration Freezing point depression by cryoprotectants (e.g., polyols, sugars)

28 Freezing in Frogs Video

29 Freezing in frogs (cont.)

30 Hibernation

31 Task (20 min, each) Read Bears in the Winter by Bernd Heinrich. Based on the reading write a short narrative similar to text out of Winter Bees.

32 Migration

33 Migration (cont.)

34 Movement data - examples Ebird site Cornell site

35 Animal on the move Blog