2. What is Adaptation ? Inherited traits that increase the chances of Inherited traits that increase the chances of 1. Survival 1. Survival 2. Reproduction 2. Reproduction of an organism in a particular environment of an organism in a particular environment

3. Desert in southwest Africa Wetland Microsoft Encarta Encyclopedia Deluxe 2004 North Pole Forest Savanna Different Habitats

4. How Does Evolution Work Natural selection leads to adaptation Natural selection leads to adaptation Natural selection involves genetic variation and selection among variants present in a population Natural selection involves genetic variation and selection among variants present in a population

5. Misunderstanding on Adaptation Myth: organism selects suitable environment for them to live in. Myth: organism selects suitable environment for them to live in. Fact: Environment selects suitable organisms to live in it. Fact: Environment selects suitable organisms to live in it.

6. Use of Phylogeny to Understand Adaptation Phylogeny is a method to classify organisms by natural evolutionary relationships Phylogeny is a method to classify organisms by natural evolutionary relationships Organisms should be grouped together on the basis of shared specializations or shared-derived features Organisms should be grouped together on the basis of shared specializations or shared-derived features

7. Phylogenetic Tree of Bears Asiatic black bear (Ursus thibetanus) Polar bear (Ursus maritimus) Brown bear (Ursus arctos) Black bear (Ursus americanus) Sun bear (Ursus malayanus) Sloth bear (Ursus ursinus) Spectacled bear (Tremarctos ornatus) Giant Panda (Ailuropoda melanoleuca) # Base on their genetic similarity

8. Ursidae Family Giant panda Sun bear Sloth bear Brown bear Polar bear Spectacled Bear Asiatic Black Bear Black Bear Black Bear Microsoft Encarta Encyclopedia Deluxe 2004

9. What Problems Do Polar Bear Face ? Cold Cold Unstable food source Unstable food source Geographical change (melting ice) Geographical change (melting ice) Over heat Over heat

10. Three Major Types of Adaptation Morphological Adaptation Morphological Adaptation Physiological Adaptation Physiological Adaptation Behavioral Adaptation Behavioral Adaptation

11. Morphological Adaptation High-mobility long neck High-mobility long neck Low surface area to volume ratio (m 2 vs m 3 ) Low surface area to volume ratio (m 2 vs m 3 ) Slip resistant footpad Slip resistant footpad Teeth pattern with flat skull Teeth pattern with flat skull www.ngo.grida.no/.../ characteristics.html

12. Adaptation for Carnivore Diet and lifestyle will exert selective pressures upon skull morphology ! Polar bearBrown bearGiant panda Coronoid process 下顎齒骨冠突

13. Physiological Adaptation Thick pelt Thick pelt Fat storage Fat storage Blubber system Blubber system Haemoglobin Haemoglobin

14. Thick Pelt Inner short fur Inner short fur Outer long transparent fur Outer long transparent fur Black skin Black skin

15. Fur Two types (long / short) Two types (long / short) Translucent ( 半透明的 ) hairs can: Translucent ( 半透明的 ) hairs can: (a) Reflect visible light back to the environment (b) Absorb UV light to warm up its body Water repellant Water repellant Sun light Hollow Reflection Structure of outer fur

16. Fat Storage Mainly as Triacylglycerols in adipose cells Mainly as Triacylglycerols in adipose cells Constitute 84% of stored energy Constitute 84% of stored energy Convert energy source from white adipose to brown adipose Convert energy source from white adipose to brown adipose White adipocyte Brown adipocyte

17. Special Character of Brown Adipose

18. Blubber System The insulation afforded The insulation afforded by blubber can be bypassed when the need for heat dissipation increases. Fur outside the skin Fur outside the skin surface and its insulation value cannot be drastically changed by a bypass Animal Physiology 5/e (Cambridge university press) p263

19. Oxygen Binding Affinity under Different Temperature High temperature: Low affinity High temperature: Low affinity Low temperature: High affinity Low temperature: High affinity

20. Haemoglobin Contain special Cl - binding site Contain special Cl - binding site Lower ∆H of oxygenation Lower ∆H of oxygenation Lower the oxygen binding affinity Lower the oxygen binding affinity Easier to release oxygen to tissues Easier to release oxygen to tissues

21. Behavioral Adaptation Posture Posture Swimming Swimming Annual migration Annual migration Hibernation (Denning) Hibernation (Denning)

22. a b c Use different postures to regulate heat lost Posturing

23. Swimming Polar bear as marine mammal Polar bear as marine mammal Ursus means bear maritimus means sea Ursus means bear maritimus means sea Swim long time and distance (60miles) Swim long time and distance (60miles) To avoid over heating To avoid over heating Source: Polar bear pres

24. Two types of habitats for polar bears (1) Drift ice habitat (ice moved by wind or current) Drift = pelagic (2) Land-fast ice habitat (ice surrounding islands) http://seis.natsci.csulb.edu/rmorris/seaice/drift.htm What causes ice-drift ? Types of Polar Bear Habitats

25. Annual Migration Pelagic polar bears move northwards (summer) when ice melting at the ice edge to counteract a continuous southwards ice drift. Pelagic polar bears move northwards (summer) when ice melting at the ice edge to counteract a continuous southwards ice drift. While it moves southwards (autumn) during sea ice advance While it moves southwards (autumn) during sea ice advance

26. Hibernation True hibernation (does not occur in polar bears) Body-core temperature close to freezing Body-core temperature close to freezing Walking hibernation (denning for pregnant female) When no food is available When no food is available In order to save energy In order to save energy Using fat as the major energy source in order to preserve essential protein and carbohydrate

27. Aerobic Respiration Energy

28. Molecular Bases of Hibernation Triggered by pyruvate dehydrogenase kinase 4 Triggered by pyruvate dehydrogenase kinase 4(PDK-4) A major effect on pyruvate metabolism A major effect on pyruvate metabolism Allows modification of the pathways involving fatty acid production through acetyl co-A, and the tricarboxylic acid cycle to be markedly changed. Allows modification of the pathways involving fatty acid production through acetyl co-A, and the tricarboxylic acid cycle to be markedly changed. energy

29. Quick Summary Environment selects the suitable guests to live in its room. Environment selects the suitable guests to live in its room. Only organisms with suitable characters can survive in a particular habitat. Only organisms with suitable characters can survive in a particular habitat. Environment does change thus population changes as well. Environment does change thus population changes as well.

30. Why Is This Bear Green? Symbiosis: Algal growth inside the hollow hairs of polar bears in warm climates causes the pelt to have a green appearance Symbiosis: Algal growth inside the hollow hairs of polar bears in warm climates causes the pelt to have a green appearance

31. How Do Polar Bears Relate to Us ?

32. Enjoy the Nature

33. Acknowledgements Prof. K.L. CHOW Prof. K.L. CHOW Prof. WONG Prof. WONG Prof. SO Prof. SO Dr. T.K. GOH Dr. T.K. GOH Dr. Maggie LI Dr. Maggie LI Dr. Ice KO Dr. Ice KO Dr. Y.Y. REN Dr. Y.Y. REN Mr. Wilfred LEUNG Mr. Wilfred LEUNG Mr. Jack LI Mr. Jack LI Center for Enhanced Learning and Teaching Center for Enhanced Learning and Teaching This project is supported by the funding from Center for Enhanced Learning and Teaching

34. HKUST http://www.ust.hk http://www.ust.hk Way: bo_lkwag@stu.ust.hk Way: bo_lkwag@stu.ust.hk John: bo_ssl@stu.ust.hk John: bo_ssl@stu.ust.hk