Surviving Adverse Conditions: Dormancy, Torpor, and Aestivation

1. Negative feedback Conformer Vasoconstriction Regulator Hypothalamus Homeostasis Effector Vasodilation Thermoreceptor Endotherm Ectotherm

2. Key Area 2.5 Maintenance of metabolism during environmental change • Surviving adverse conditions • Avoiding adverse conditions • Extremophiles

3. Surviving Adverse Conditions Learning Intentions • Describe the different ways organisms have of surviving adverse conditions. • Define hibernation, torpor and aestivation

4. Surviving adverse conditions • Cyclic changes in environments create conditions beyond the tolerable limits of most organisms metabolism. • What mechanisms do organisms use to survive adverse conditions?

5. Staying put: Dormancy • A reduction in metabolic rate prevents an organism expending excessive energy, this is achieved by dormancy • E.g. Staying cool in hot climate • Staying warm in a cool climate

6. Dormancy • Dormancy occurs when an organisms growth and development are temporarily arrested • Metabolic rate decreases to the minimum rate required to keep its cells alive • Energy is therefore conserved and the plant/animal is able to survive a period of adverse conditions

7. Predictive dormancy • Predictive dormancy occurs before the arrival of the adverse condition • E.g. Trees respond to decrease in photoperiod (day length) and lose their leaves before winter • Winter buds are dormant until spring • Increasing photoperiod reverses dormancy

8. Consequential dormancy • Consequential dormancy occurs after the arrival of the adverse condition • Common in regions of unpredictable climate • Advantageous as organism can exploit available resources for longer

9. Task Around the room are cards with organisms that go through a period of dormancy. Use the cards to answer the questions on your worksheet

10. Questions • Which of the animals go into Torpor to conserve energy? • Which of the animals hibernate to conserve energy? • What physiological mechanisms occur during hibernation to allow for this to happen? • What is the difference between Torpor and Hibernation? • Hedgehogs also carry out aestivation, what is this? • Why might an organism wake from torpor? • Which animal can actually give birth and nurse its young during Torpor? • Which animal can stop its heart beating, breathing and cause its blood to form ice during hibernation?  • What environmental conditions trigger hibernation and Torpor? • Which animal is the only ectotherm to go into hibernation?

11. Answers • Bears, black tailed prairie dogs, deer mice, hamsters, skunks, ground squirrels, • Bats, white tailed prairie dogs, Common poorwills, wood frogs, hedgehogs • Lowering of heart rate and breathing rate Lowering of body temperature Decreased metabolism • Torpor is a light form of hibernation. • Hibernation to avoid hot conditions or drought 6. To eat food for energy • Bears • Wood frog • Weather is too cold or food is scarce • Wood Frog

12. Hibernation • Hibernation is a form of dormancy that allows some animals (usually mammals) to survive adverse winter conditions • Before hibernating animals consume extra food to store as fat • What type of dormancy do hibernating animals display?

13. Hibernation • During hibernation • Metabolism decreases • Temperature decreases • Heart rate slows • Breathing rate slows • Minimum energy expended • If temperature is too low, the hibernating animal will increase their metabolism to increase their temperature Video clip

14. Aestivation • Aestivation is a form of dormancy that allows some animals to survive excessive heat or drought in summer • Snails retreat in their shells in a ‘safe place’ with their metabolism at a minimal rate until favourable conditions return

15. Aestivation • Also occurs in vertebrates • E.g. Tortoises, crocodiles and lungfish Video clip

16. Daily torpor • An animals metabolic rate and activity are greatly reduced as part of every 24 hour cycle • Heart rate, breathing rate and temperature decrease • Common in small birds and mammals • Small animals lose heat rapidly, why? • LARGE surface area to volume ratio.

17. Advantage of daily torpor • Decreases energy consumption when hunting would be unsuccessful or leave the bird open to danger • Hunt in evening and night when cooler Video clip

18. Homework: ERQ Write notes on: (i) endotherms and ectotherms; (ii) temperature regulation in mammals. (10)

19. Marking scheme Endotherms and Ectotherms • endotherms can regulate/control/maintain their (body) temperature (physiologically) AND ectotherms cannot/ectotherms temperature is dependent on their environment/behaviour (1) • endotherms derive (most body) heat from respiration/metabolism/chemical reactions (1) • ectotherms derive/get (body) heat from surroundings/environment OR description of behaviour (1) Max 2 (from 3)

20. Marking Scheme • temperature monitoring centre/thermoreceptors in hypothalamus OR information about temperature detected/received by hypothalamus (1) • nerve message/communication/impulse sent to skin/effectors (1) • vasodilation/widening of blood vessels to skin in response to increased temperature OR vasoconstriction/narrowing of blood vessels to skin in response to decreased temperature (1) 7. More/less blood to skin/extremities OR less/more blood in body core (1) 8. increased/more OR decreased/less heat radiated from skin/extremities (1) 9. increased temperature/body too hot leads to (increase in) sweat production OR converse (1) 10. increase in heat loss due to evaporation of (water in) sweat OR converse (1) 11. Decrease in temperature causes hair erector muscles to raise/erect hair (1) 12. traps (warm) air OR forms insulating layer (1) 13. Decrease in temperature causes muscle contraction/shivering which generates heat/raises body temperature (1) 14. temperature regulation involves/is an example of negative feedback (1) Max 8 (from 11) Total 10

21. Avoiding adverse conditions Learning Intentions • How do organisms avoid adverse conditions? • How are some organisms able to survive in extreme environmental conditions?

22. Avoiding adverse conditions • Cyclic changes in environments create conditions beyond the tolerable limits of most organisms’ metabolism • Animals are adapted to survive them or are able to AVOID them

23. Migration • Migration is the regular movement of members of a species from one place to another over a relatively long distance • e.g. Birds flying south for the winter • Migration • What advantage do you think migration offers birds and mammals?

24. Migration • Read through the article and answer the questions.

25. Questions • What is migration? • Why do animal migrate? • Which mammal has the greatest migration? • Which insect has the longest migration? • Which insect migrates from North America to overwinter in California or New Mexico? • What is special about this migration? • What triggers migration in some animals? • Name 4 methods that allow migration to be studied.

26. Answers • Migration is the regular movement of members of a species from one place to another over a relatively long distance • For food resources • Humpback Whale • Monarch Butterfly • Monarch Butterfly • The journey exceeds their lifespan, females lay new migrants during migration. • Day length, Hormones • Bird Banding, Radar/Sonar, Tracking devices, stable isotopes.

27. Studying migration • Scientists want to know: • When animals migrate • Where they overwinter • If they return to their summer territory • How long they live for. • They use specialised techniques to follow their routes over thousands of miles

28. Innate and Learned influences on Migration Innate Learned Learned influences are thought to play the secondary role in migratory behaviour Occurs as a result of trial and error and the transmission of knowledge and skills in a social group Learned behaviour begins after birth and is gained by experience • Innate influences are thought to play the primary role in migratory behaviour • This is performed the same way by every member of the species • It occurs in response to an external stimulus e.g. Change in photoperiod

29. Research • Make notes on (page 182/183 in textbook): • Displacement experiment (Starlings) • Directional tendencies (blackcap warbler) • Cross fostering experiment (Herring gulls and black-headed gulls)

30. Extremophiles • Are organisms that are able to survive in extreme conditions – that would be lethal to most others • Extreme thermophiles thrive at high temperatures (50-80°C), in hot springs and hydrothermal vents • Possess unusual enzymes that function at high temperatures

31. Extremophiles are organisms that live in "extreme environments," under high pressure and temperature. Bacteria often form on the rocks near the hydrothermal vents. Pictured is the Sully Vent in the Main Endeavour Vent Field, NE Pacific. A bed of tube worms cover the base of the black smoker.

32. Scientific use • The enzymes have been put to use by scientists e.g. Heat-tolerant DNA polymerase used in the polymerase chain reaction • Thermophiles have a unique form of energy metabolism • They are able to remove high energy electron needed to generate ATP from hydrogen sulphide.