adaptations & communication

ectothermy

• obtain heat from environment

• use behavioral adjustments

endothermy

• produces own heat

• uses physiological mechanisms

homeothermy

maintain relatively constantly body temp

fluctuations in internal body temp

• prototherians - most variable

• metatherians - internal temperature variability

• eutherians - least variable (best thermoregulator)

thermoneutral zone

a range of environmental temperatures within which the metabolic rate is minimal

if it drops below, hypothermia can lead to death

if rises above, hyperthermia can lead to death

rate of conductive heat loss

H = SA x C(T_b - T_a)

where H is conductive heat loss

SA is surface area/volume

C is thermal conductance

T_b is body temperature

T_a is ambient temperature

body size relationship to heat

large animals lose heat less quickly than small animals

volume/surface area effect on heat exchange in small mammals

• lose heat rapidly

• require intensely high metabolic rates and constant food consumption to fuel internal thermogenesis

volume/surface area effect on heat exchange in large mammals

• retain heat efficiently

• advantageous in cold but risk overheating in hot climates

• require specialized cooling mechanisms

• high thermal inertia (heats up and cools down slowly)

bergmann’s rule

body size increases in cold climates (lowering SA:V to retain heat) and decreases in warm climates (increasing SA:V to shed heat)

moderate to high support; exceptions

allen’s rule

appendices (ears, limbs) are shorter in cold climates to prevent heat loss/frostbite and longer in hot climates to act as heat-dissipating radiators (heat windows)

strong support; exceptions occur

gloger’s rule

species living in dry areas have darker pelage than their relatives in humid areas

aids in concealment, communication, and pysiological processes

mixed support; often fail statistical tests

regional heterothermy

adaptation where an animal allows different parts of its body to maintain significantly different temperatures simultaneously, rather than keeping entire body at uniform tempeature

countercurrent heat exchanges

arrangement of blood vessels that allows peripheral cooling particularly of appendages and at the same time maintains an adequate blood supply without excessive heat loss

form of regional heterothermy

countercurrent heat exchance in cetacea

blubber acts as a thick, static thermal blanket

torpor

• temperature not lowered below 15 C

• body temp, metabolic rate, respiration, heart rate

• can be daily

• ex: marsupials, rodents, insectivores, bats, some primates

hibernation

• profound dormancy

• animal remains at a body temp ranging 2-5 C for weeks during winter

• ex: hedgehogs, bats, ground squirrels, marmots

lethargy

• shallow torpor decrease in temp of only 5-7 C below active level

adaptations to cold

• increased body size

• decrease SA:V

• increased insulation

• communal nesting, foraging zones

• food hoarding

• reduction in level of activity (dormancy)

adaptations to heat

• temperature and water regulation

• dissipate heat or avoid heat

• conserve water - concentrated urine and feces; get it from plants or prey

• panting

sweating and panting advantages/disadvantages

downsides

• lose water with both

• sweating loses electrolytes

• panting uses muscular activity

upsides

• both promote evaporate heat loss

• panting combined with countercurrent exchange can help keep brain cool

estivation

• type of dormancy induced by hot/dry conditions; lack of water, food, or high temperatures trigger it

• more lethargic than torpid

intraspecific communication

between individuals of same species

interspecific communication

between different species

visual signals

• morphological features like markings (focus attention on head; increase effectiveness of the visual sign of a weapon)

• behavioral expression (like snarling)

• moderate effective distance, high localization, poor ability to go around obstacles, fast speed of transfer, high complexity, variable persistence

olfactory (chemical) signals

• used for territory, dominance, sexual receptivity, reproductive, social behavior

• pheromones are intraspecific

• allomones are interspecific

• long effective distance, variable localization, good ability to go around obstacles, slow speed of transfer, low complexity, high persistence

auditory signals

• maintain integrity of group

• predator startle/warn

• individual recognition

• stimulate reproductive behavior

• long effective distance, moderate localization, good ability to go around obstacles, fast speed of transfer, high complexity, low persistence

tactile signals

• sexual behavior (courtship) ex: Kob kobus kob

• social group structure (grooming) ex: bonobo Pan paniscus

• short effective distance, high localization, fast speed of transfer, moderate complexity, low persistence