1. Ecology Lecture 6 Ralph Kirby

2. Adaptation of Animals to their environment The environments on Earth vary greatly. See earlier lectures Therefore animals (and all other living organisms) need to adapt to fit their environment |Obtaining nutrients is probably one of the most important –Input into system is the plants –Plants consumed by herbivores –Herbivore animals eaten by carnivores –Omnivores use both sources but may have a preferred one

3. Herbivores –Grazers (Ruminants) Leafy material Ruminants chew the cud Non ruminants are less efficient Coprophagy –High in cellulose and some lignin –Use specialized microorganisms in gut to help digest the difficult carbohydrate molecules in ruman or cecum or redigestion –Microorganisms produce proteins, lipids etc –Browsers Woody material Termites –High in lignin and cellulose –Use specialized microorganisms in gut to help digest the difficult carbohydrate molecules –Microorganisms produce proteins, lipids etc –Granivores Seeds –Crop with specialized enzymes –Gizzard for grinding –Frugivores Fruit

4. Carnivores –First level feed directly on herbivores No cellulose Rapid digestion and easy assimilation Hunting is energy consuming –Second level feed on first level carnivores Omnivores –Food eating habits vary with season, life cycle and their size Fox –Preferential carnivore Insects, small mammals and birds but eats berries, fruit, grass Bear –Preferential herbivore Buds, leaves, berries, fruit, etc Supplemented by insects, fish and small to medium mammals

6. Animals need –Essential amino acids (14) –Other amino acids –Minerals Herbivores need high nitrogen help microorganisms in the digestion of cellulose and lignin However, season is very important Herbivores get more high nitrogen food in Spring and therefore they reproduce at that time Availability is very important for a carnivore or omnivore

7. Minerals Animals need specific minerals such as sodium, magnesium, etc Sodium can be hard to obtain and can be a problem –Kangaroos –Rabbits in Australia Overgrazing of sodium rich plants can cause population collapse –Elephants See preference for sodium rich water hole in Wankie National Park, Zimbabwe High potassium can cause magnesium deficiency in goats, cattle and sheep

8. Deer need lots of calcium, phosphorus and protein to grow antlers, which are needed for reproductive success –Deficiency results in stunted antlers

9. Animals need to use aerobic respiration Therefore need to have excellent oxygen uptake system Small animals –Diffusion Insects –Diffusion and spiracles Amphibians –Vascularised skin –Simple lungs Mammals –Lungs Birds –Anterior and posterior air sacs Fish –Gills Aquatic mammals –Lungs –Special haemoglobin oxygen storage systems

10. Homeostasis To stay alive, animals need to keep their body within certain limits –Temperature –Water balance –pH –Salt balance Fedback systems to help to keep within specific limits Outside limits – death –Dehydration –Heat shock –Salt imbalance

11. Temperature –Insulation –Boundary layer –Core temeprature –Surface temeprature Ears Fingers Toes

13. Animals have different methods of maintaining their body temperatures Endothermy resulting in homeothermy –Use of internal heat source Mammals and birds Dinosaurs? Ectothermy resulting in poikilothermy –Use of external heat sources Reptiles, amphibians, fish, insects and invertebrates Dinosaurs?Heterothermy –Uses both endothermy and ectothermy Bats, bees and hummingbirds Dinosaurs?

14. Poikilotherms on Land –As the temperature increases, so does the metabolic rate –Therefore these animals are more active during the day –Every 10 o C doubles metabolic rate –Naturally low metabolic rate and high conductivity –Activities also control temperature –Upper and lower limits vary Lizards and snakes have a 5 o C Amphibians have a 10 o C Hibernation

15. During the day, the snake can maintain a fairly constant temperature by adjusting it’s environment During the night, it has few options –Temperature drops 10-15 degrees –Become torpid (slow moving) –Restricted by environment –Maximum size due to need for surface area to gather heat –No minimum size

16. Poikilotherms in water –No insulation –Match of body temperature to water temperature –Water temperature normally only changes slowly with season –Poikilotherms can adjust slowly to a wide range of temperatures –Adjust over wider range than land poikilotherms –Stressed by rapid temperature changes –Smaller change than reptiles over much longer period

17. Note that homeotherms are not restricted by their environment –Move at same rate in tropics and at poles Homeothermy needs energy Therfore homeotherms use large amounts of glucose etc to maintain temperature Need insulation in cold Need cooling mechanisms in heat Faster Move for longer periods Stronger More environments But limited in size –Too big? Core temperature build up Dinosaurs? –Too small Need to much energy to keep temperature stable 2 gm limit Solex spp eats own body weight in food every day to maintain temperature

18. Insects can be ectotherm and endotherm –Ectotherm for take off (30 o C) –Endotherm for flight (not more than 44 o C) Torpor –Small homeothemic animals Become heterothermic Body temperature drops to ambient at night Inactive –Bats, Some mice, kangaroos Hibernation –Many poikilotherms and some mammals have winter torpor to save energy –Selective advantage when resources are few –Mammals Heart rate, respiration fall Temperature drops to ambient Groundhogs, chipmonks Not bears –No temperature change –Just long sleep with no eating, drinking, defecating or urinating –Females give birth and feed young in this period –Can wake up easily –Do not visit a bear cave in winter!

19. Homeotherms and some poikilotherms use insulation to minimize temperature changes –Fur and fat in mammals –Feathers in birds, note water repellant feathers in water birds –Blubber in aquatic mammals such as seals –Water repellant fur in polar bears –Can also work in hot environment, see camels –Shivering in emergency –Burn highly vascular brown fat to produce heat, see groundhogs and human babies Terrestrial poikilotherms use microenvironments to change their temperature –Basking of reptiles followed by cooling in shade can give a fairly stable temperature during the day –Changing shape to increase or decrease convection and radiation –Note that basking can increase water loss

20. Cooling in birds, mammals and some insects uses evaporation –Only certain mammals have sweat glands Horses and man. Dogs pant Pigs wallow Camels can store body heat –34 o C in morning –41 o C by late afternoon Counter current flow can also be used to reduce temperature –Porpoise –Gazelle

21. Controlling water balance Aquatic –Freshwater Prevent excess uptake of water Remove excess water –Retain salt in special cells –Large amounts of very dilute urine –Saltwater If salt concentration very similar to cells –Limited problems If salt concentration is higher –Ion pumps –Kidneys –Salt secreting glands in birds Terrestrial –Input DrinkingEating Produced by metabolism –Output – Need to control in extreme environments Urine –Concentrated to avoid water loss FecesEvaporation –No sweat glands in some mammals Breathing

22. What happens to ungulates in a hot dry climate like Africa

23. Biological clocks have adaptive value –Used to change behavior DailySeasonally Mammals use melatonin to maintain biological clock –Produce by pineal gland at night –Used to get over jetlag

24. Seasonal Changes for male deer Only needed during mating season Can be damaged and need replacing Melatonin linked

25. Seasonal changes for squirrels When will you find food at different times of the year? Melatonin linked Note also Seasonal Affected Disorder (SAD) in humans –Why you have a very high suicide rate in Norway, Sweden and Finland

27. Crabs from a tidal estuary retain timed activities in a fixed environment –Color change –Activity –Two clocks Tidal Solar Redunancy is probably present in most organisms

28. Aquatic animals need to move up and down in water Buoyancy aids Shark –Large fatty liver –Must swim to not sinkFish –Gas bladder –Used to move up and downSeal –Blubber –Can float on surface with air in lungs