Lecture 7 - Environmental Adaptations

Question 1

what must plants and animals deal with in the boreal?

Answer 1

snow
wind
drought
lack of nutrients in soil

Question 2

what happens to plant tissues when water freezes?

Answer 2

water expands in the cells and destroys living tissues

sharp ice crystals can damage and kill cells

Question 3

in what 2 ways does frozen water injure cells?

Answer 3

1. rupturing cell membranes

2. altering permeability of membranes

Question 4

what 2 methods do boreal plants escape frost damage?

Answer 4

1. extra-cellular freezing

2. supercooling

Question 5

briefly describe extracellular freezing

Answer 5

antifreeze accumulates inside cell walls allowing cells to prevent freezing.
plants encourage ice formation in between cells and prevent them in cells

Question 6

briefly describe supercooling

Answer 6

lowing temp of liquid or gas below its potential freezing point w/o becoming a solid

Question 7

how do cold temps affect animals?

Answer 7

food scarcity
metabolism is disrupted
freezing

Question 8

what are 3 broad methods of staying able 0C

Answer 8

migration
stay warm
dormancy

Question 9

what are 2 broad methods of dropping below 0C

Answer 9

Freeze avoidance

Freeze tolerance

Question 10

how does the choice of habitat reflect the difference strategies of coping with extreme temperatures?

Answer 10

above snow = accept cold temperatures and manage being cold

@ freezing zone = freeze tolerance (frogs)

below frost line = freeze avoidance

Question 11

where is the best play to go for aquatic animals?

Answer 11

deeper bc fresh water is most dense at 4C so it sinks (warmer at bottom)

Question 12

why do fish dive deep in salt water?

Answer 12

avoid ice

Question 13

what subnivean snow zone do arctic animals inhabit?

ex?

Answer 13

pukak

lemmings

Question 14

what adaptation do greenland collared lemmings have to avoid freezing?

Answer 14

grow long wide claws in winter for digging snow since there are larger crystals in the pukak layer

Question 15

acclimation vs adaptation

Answer 15

acclimation: readily and reversible modification caused by exposure to the environment (not inherited)
adaptation: accumulation of genteel changes to increase survival/reproduction. not readily reversible

Question 16

define homeotherm?

Answer 16

maintain a constant body temperature

Question 17

define endotherm

Answer 17

generates own body heat using own energy to maintain temperature

Question 18

define poikilotherm

ex?

Answer 18

animals with a variable body temp

moths/butterflies

Question 19

example of a poikilothermic endotherm

Answer 19

hibernating animals

Question 20

define ectotherm

Answer 20

generally do not produce enough heat to maintain a constant body temp. Rely on external sources of heat.
MAY have constant Tb depending on behaviour and environment

Question 21

example of a homeothermic ectotherm

Answer 21

several antarctic fish

Question 22

how do bee hives stay warm in winter?

Answer 22

bumblebees shiver to produce heat via muscle contraction. communal effort used to heat the colony and keep the queen warm

Question 23

list the general ways to reduce heat loss

Answer 23

get big (bergman's rule)
get round (allen's rule)
adjust MBR
prevent heat loss (insulate, lower conductive HL, restrict evaporative HL)

Question 24

bergmann’s rule

Answer 24

animals of larger size found in colder envr (poles)

decrease SA:V

Question 25

why doesn't bergmann's rule always hold true with arctic animals?

Answer 25

large body size means more food is required | advantages of being large outweigh the disadvantages

Question 26

allen's rule

Answer 26

roundness is most effective for SA:M

Question 27

example of allen's rule

Answer 27

arctic foxes ears, muzzle, legs, tail | ~allows them to conserve heat

Question 28

what can heat loss through conduction be prevented?

Answer 28

increase insulation | increase fur/feather thickness

Question 29

how is caribou hair adapted to cold environments?

Answer 29

hair is hollow and filled with air pockets since it's such a good insulator also increase density and thickness of fur

Question 30

what environmental variables decrease insulation through fur? example of how this is mitigated

Answer 30

water -pb fur sheds water efficiently wind - muskoxen w/ very long fur that isn't affected by high winds

Question 31

Glogers Rule

Answer 31

pigmentation declines towards to poles since black objects absorb AND radiate more heat

Question 32

briefly, why are arctic animals white?

Answer 32

- reduce heat gain from sun during activity to cool down and prevent overheating - lack of melanin increases room for air cavities (insulator) - reflect light onto black skin of the animal (doesn't reflect but scatters!)

Question 33

how do animals cope with limited food availability in winter?

Answer 33

use fat deposits

Question 34

2 methods of lowering conductive heat loss

Answer 34

insulate extremities | allow peripheral tissues to cool

Question 35

example of insulating extremities

Answer 35

underside of paw with fur in caribou, polar bears and arctic fox

Question 36

benefits of knobbly feet?

Answer 36

reduce contact (conductive heat loss) between feet and ground

Question 37

how does foot size related to latitude?

Answer 37

increases with latitude | -> better at walking through snow

Question 38

why are huskies feet maintained so cold? | what is responsible for this?

Answer 38

decreases gradient tf less heat loss cutaneous vascular plexus

Question 39

how to reduce convective heat loss? (evaporative less)

Answer 39

reindeer - conchae - increase SA - divide air flow - thick mucosal layer

Question 40

explain the process of inhaling and exhaling over conchae

Answer 40

inhale = air pass over warm mucosa, saturated with water. Mucosa cooled and warm air to lungs exhale = air passing over cool mucosa is warm and wet from lungs. water condenses and mucosa warmed. animal exhales cool "dry" air

Question 41

4 options to dealing with temp when living in cold climate

Answer 41

1. migration 2. habitat selection 3. adjust lifecycle 4. adjust body temp

Question 42

what coping strategies are used that include a reduced metabolism?

Answer 42

hibernation diapause freezing anoxia

Question 43

what are the 2 supercooling chemical categories and what habitats are each used in?

Answer 43

antifreeze proteins = subnivean habitats cryoprotectants = exposed habitats

Question 44

what do antifreeze proteins do? where are they found?

Answer 44

decrease the freezing point | in plasma

Question 45

what does glycerol (cryoprotectant) do? where is it produced from?

Answer 45

reduce the nucleation potential of seed crystals | produced from fat

Question 46

what is it called when ice crystals form?

Answer 46

seeding

Question 47

what does freezing cause in the body?

Answer 47

freezing of intracellular fluids change structure of proteins and inhibit function of enzymes cause sells to shrink

Question 48

examples of freeze tolerate species

Answer 48

``` frogs painted turtles garter snakes some lizards many insects ```

Question 49

freeze tolerance is most commonly seen in what animals?

Answer 49

those that cannot avoid coming in contact with ice

Question 50

how can wood frogs freeze without dying?

Answer 50

ice forms extracellularly but their growth it prevented. Ice nucleating proteins initiate, antifreeze proteins prevent growth. high level of polyols intracellularly to prevent ice

Question 51

define hypothermia

Answer 51

core temperature drops below that required for normal metabolism and body functions

Question 52

define torpor

Answer 52

entry of animal into hypothermia with behavioural inactivity

Question 53

define hibernation

Answer 53

sustained state of torpor, entry to and exit from which is governed by internal signals together with exclusively seasonal external cues

Question 54

examples of animals that hibernate

Answer 54

richardson's ground squirrel arctic ground squirrel little brown bat

Question 55

what are the precursors to hibernation?

Answer 55

seasonal phenomenon gain up to 40% body mass need polyundsaturated fats find hibernaculum

Question 56

what indicates timing of hibernation?

Answer 56

circannual and environmental cues

Question 57

during hibernation, what slows down?

Answer 57

``` DNA/RNA synthesis protein synthesis fuel metabolism ion pumping ATM turn over decrease to <5% normal ```

Question 58

what mechanism is used for arousal in hibernation?

Answer 58

BAT

Question 59

function of BAT vs WF

Answer 59

heat production via non shivering thermogenesis insulation, energy and storage