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Lecture 5


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Carleton University
BIOL 1902

Biology 1902After MidtermGavni KharmandarianStaringLecture 5b12bndSub Zero Temperatures 2 problem for winteractive animals MobilityThe ability to move freely and easily because of high snow snow builds up and gets to deep to walk throughPhysical Adaptations Long legs Eg Moose have very long legs 2 m high at the height of your shoulderBig feet Eg Snow Shoe Hares have bigger hind feet but their tracks look like their front feet are bigger because when they jump they bring their hindbackfeet to the front Large surface area of feet more contact with the snow surfaceDeers Moose and Caribous have a wide surface area on their feetCaribous have short legs and huge feetMany northern animals such as Fisher also have large hind feetMartens have large hind feetBirds also have snowshoes Eg Northern grouse have feet that have feathers on their feetRuffed Grouse grow snowshoes every autumnBehavioural AdaptationsSubnivean SpaceWhitetailed Deer move to a sheltered area with less snow They form YARDS Deer yardsa brows line identifies a DeeryardWolves Travel in a pack and a straight lineone wold breaks track and the other followOtters have short legs but they slid on their belliesthey tobbaggan down hills MInks also use their bodies to tobbagganMigrationMany other animals escape subzero temperatures for migratingAnimals that migrateMonarch butterfliesSome dragonflies migrate Green Darner BirdsMigrationMost our birds migrate and travel very long distancesWhat is a champion Migrator Artic Tern exWorld Champion Migratory Bird 20000 km roundtrip each yearBirds store fat not carbohydrates fat powers flight the more weight you have the more energy you need to fly Semipalmated Sandpipers double their body weight in just 10 days of feedingMost small birds like Songbirds travel at night Advantages of traveling at night 1 No overheating cooler at night Colder air will air cool their engines 2 Less wind journey is calmer at night and it takes less energy from fighting winds3 SaferHawks Some birds migrate in daytime and still conserve energyThermal Hop eagles and hawks do this Soaring rising upGliding coming down Bounding Flight going up and downThermal HoppingHummingbirdsBlackbirds also migrate in the daytimeOnly 50 of the birds return the next yearStarvation being killed Mortality rate for young birds are way higher than adult birdsHow do they find the way Visual Cues oceans sun mountains landforms and other visual cuesNocturnal migrants use visual cues too constellations moon the sky Both day and night migrants use Earth Magnetic Field unknown mechanism Rhodopsin is a photopigment in the retina is likely involved with electromagnetic interactionSandpipers fly both daynightRed Knot put a geotracker and found out they flew 5100 km in 8 days straightBanding reveals migration secretscaptures birds in Mist nets dont hurt the birdanalyze itlet it gowait for it to die and when someone finds and calls the number to return it they analyze it again hence bandingbands on the legGeese fly in Vs WhyTo conserve energyGeese fly day and night birds flying behind one another use less energy to lift their wingMigration is very complex can be learnedprogrammedin by set Subzero problems for PlantsWater becomes ice ice inside the cells kills plantsPhysical AdaptationsGoing dormant in the groundPlants become Cold Hardy1 Excess water is withdrawn from leaves and twigs evaporate 2 water is drawn out of the cells which increases solute concentration less waterwhich less freezing occurs 3 Protective sugars added to cells increasing solute concentration 4 Unsaturated fatty acids added to cell membranes to increase flexibilityplants have a cell wall which animals dont have inside there is a membrane that has a special chemical that can bend to stay away from ice membrane has to stay intact5 Antifreeze proteins to suppress ice formation and proteins to resist dehydration are made Plants become Cold Hardy through acclimationAcclimationis a 2 step processThe first stage of acclimation is triggered by a change in the photoperiod 1Phytochromeslightsensitive photo pigments cause cells to go dormant make plant sensitive to low temperatures2Second stage is triggered by cold temperatures by cold temperatures0 to 10 degreesSome trees are cold hardy to 80 degreesKeeping needles little leaves creates new problemSkunk Cabbage turns up the heat during the winter and melt snow around it generates heat which keeps the plant safe and in the summer it cools downDesiccation is the next problemdries outcalmsunny days are the worstA calmer sunny day makes the tree all dried upit absorbs all the solar energyConifers retain their leaves so size and shape is very important Leaf surface area is small Close stomatathick cuticles thick laye that captures waterHairy underside of leaveshelp trap moisture and keep it inside Behavioural AdaptationsFerns curl up for the winter helps them retain the surface area reduce the surface area by curling upDeciduous trees have large leaves with a large surface areathey just drop their leaves A tree that turns red in the fall Red Maple not always red can be yellow sometimesseparate sexesFemales turn yellow in the fall Males turn red Red helps heat wave lengths an adaptive colourationRed is not present leaves produce anthocyaninAposematic coloration Theory that the red is warning the insects not to eat the leavesLeaf loss helps solve a second problem associated with subzero temps the weight of snow not much room for snow to settle on the leavesConifers retain their leaves so size and shape is very important The boreal forest is dominated by spindly and spireshaded treesBalsam Fir have a SPIRE shape like a spyroBlack Spruce are spindly short branches
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