BIOL 1902 Lecture Notes - Lecture 5: Torpor, Ruffed Grouse, Beaver
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Astors are filled with alkaloids
Braken fern is loaded with moulting hormones –
Chemical messengers = phyto hormones
(don’t worry about learning the certain systems
Challenge 2: Environmental stress
1. Temperature extremes
Sub zero temps – water turns to ice and most things have water within their systems (water expands)
Endotherms: keeps body temperature internally through cellular metabolic activity. (warm blooded)
Ectotherms: don’t produce temp internally but rely on environment around them. (cold blooded)
3 main responses to freezing temperatures:
− Physiological and behavioural adaptations (active)
Mammals – underfur is next to body/Guard hair outside grows longer and thicker to trap heat in the
body. Traps air which is hot and keeps them more. Beaver. Otter has the densest fur ever.
Subcutaneous fat = insulation (next to skin)
Brown fat = internal for burning for warmth (don’t need to know about mitochondirea)
Birds – Grow bulkier feathers; outside layer =contour or body feathers. Chickadee 50 degree difference
Under feathers = down/under feathers.
Shivering important for thermogenesis. Subcutaneous fat = for fuel
Color can provide warmth: wind chill takes away body heat, white traps more body heat and black expels it
quicker. Bird that becomes white. Snowy owl, artic fox (gloger’s rule) = animals that shed their dark hair for
light in winter. Light hair traps air as they are empty because they lack pigment. White hairs gain 27% more
heat than when dark.
Body Shape: large ears, long legs and tail
1. shorter extremities are better (caribou)
Farther north = shorter extremities (Allen’s rule)
2. Low surface area to: volume ratio (northern animals have more round shape and not long)
The closer to 1:1 is better (Bergmann’s Rule)
• Artic fox has large tail to put over face when sleeping
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