BIO3132 Lecture Notes - Lecture 3: Thrombin, Arms Race, Phospholipase A2
31 May 2018
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Week 2. Adaptations to Extremes and Venomous
Vertebrates
ADAPTATIONS TO EXTREMES: TEMPERATURES AND ARIDITY
Lecture objectives:
• Wh ater alae & od teperature are iportat
• Speifi adaptatios to etrees of Ta
• Speifi adaptatios for ater balance
• Ho teperature ad ater alae adaptatios a opliet & oflit
• Importance of water and temperature:
o Organisms require water for survival
o Must maintain water balance by regulating water loss and uptake (osmoregulation)
o Why is temperature important:
Influences all chemical reaction and thus every bodily process
Can cause death – when environmental temperatures move outside of viable
body temperatures
Can influence fitness
o Combined dehydration and heat:
Heat is a factor but humidity is also very important for evaporative cooling
Australia is both hot and arid
Sweating increases water and salt loss (cramps)
Moderate stress = less effective heat loss (lose some ability to sweat heat out)
Extreme stress = anuria, explosive heat rise and death – body starts to shut
down extremities (shutting down blood flow)
find more resources at oneclass.com
find more resources at oneclass.com
• Temperature adaptations:
o 3 basic groups of how they deal with temperature:
Evaders
o Small animals (high surface to volume ratio)
o Too small for evaporative cooling (eg. sweating)
-evading rather than enduring
o Use microclimates to beat the heat through microhabitat selection (eg.
burrows)
o Often nocturnally active
Evaporators
o Size and water intake high enough to allow evaporative cooling
-usually have access to free water
o Uncommon in deserts
o Generally medium sized
o Eg. sweating, belly dipping in bats
o Eg. dingoes, rabbits
Endurers
o Large animals, cannot hide in burrows or dens
o Difficulty losing heat due to large body size (low surface to volume ratios)
o Rely heavily upon physiology
o Inactive hottest part of the day
o Eg. kangaroos
o Shuttling and posture
o Insulation:
Fur and feathers
Colour, length and thickness
Acclimatisation (shedding)
Reptiles and frogs are less protected
o Heat windows and thermal dumping:
Regional changes in blood flow to dump heat
Typically little or no insulation
Eg. rabbits ears = heat window
Something the animal can adjust in some way
o Evaporative cooling and environmental :
Environmental vs body water
Metabolically costly
Trade-off between overheating and desiccation
Types:
▪ Sweating – Important in mammals, Salts lost, two types:
1. Atrichial (primates, pads of cats and dogs) – outer hair
2. Epitrachial (other mammals) – above hair
▪ Panting – cools body by increasing air flow, no salt loss, in mammals,
reptiles and desert birds, most common, blood runs through mouth and
straight to brain
▪ Salivating – eg. lick forearms, kangaroos have heat windows on inside of
arm
▪ Gular fluttering – form of panting specific to birds eg. pelicans, birds will
often want to overheat feathers to get rid of parasites
find more resources at oneclass.com
find more resources at oneclass.com
o Regional heterothermy:
Allows core temperature to rise without overheating brain (cools brain)
Brain may be 2-3ᵒC cooler than core
Allows hyperthermia which reduces water loss
• Water adaptations:
o Means of obtaining water
Free water
o All animals accept free water
o Arid adapted animals drink large quantities
o Some travel long distances to get to
o Eg. thorny devil
-African
-sits on sand dunes
-capillary network that draws in water -> wets the whole animal (changes
colour) -> coughing action allows it to drink water
o Eg. agile wallabies
-digs holes rather than going to water because of crocodiles
Water from food
o Some animals have no access to free water
o Rely on water in food
o Meat and whole animals are high in percentage water
o Eg. mulgara – can survive never drinking water
Metabolic water
o Cellular respiration yields CO2 and water
o All animals produce some metabolic water
o Small proportion of total water even in arid animals
o Means of limiting water loss
Choice of microclimate
o Underground burrows provide moist microclimate (mammals,
reptiles, frogs)
o Shade is critical for above-ground animals (eg. most birds and large
mammals)
Activity times
o Combination of heat and aridity dictates nocturnal activity in deserts
o Others are crepuscular, early morning
Protective integument
-cocooning
o Aestivation during dry season
o Epithelial shedding
o Covers all surfaces except nares
o Eg. water holding frogs – go into hibernation state
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Lecture objectives: wh(cid:455) (cid:449)ater (cid:271)ala(cid:374)(cid:272)e & (cid:271)od(cid:455) te(cid:373)perature are i(cid:373)porta(cid:374)t, spe(cid:272)ifi(cid:272) adaptatio(cid:374)s to e(cid:454)tre(cid:373)es of ta, spe(cid:272)ifi(cid:272) adaptatio(cid:374)s for (cid:449)ater balance, ho(cid:449) te(cid:373)perature a(cid:374)d (cid:449)ater (cid:271)ala(cid:374)(cid:272)e adaptatio(cid:374)s (cid:373)a(cid:455) (cid:272)o(cid:373)pli(cid:373)e(cid:374)t & (cid:272)o(cid:374)fli(cid:272)t. Importance of water and temperature: organisms require water for survival, must maintain water balance by regulating water loss and uptake (osmoregulation, why is temperature important: Influences all chemical reaction and thus every bodily process. Can cause death when environmental temperatures move outside of viable body temperatures. Can influence fitness: combined dehydration and heat: Heat is a factor but humidity is also very important for evaporative cooling. Moderate stress = less effective heat loss (lose some ability to sweat heat out) Extreme stress = anuria, explosive heat rise and death body starts to shut. Sweating increases water and salt loss (cramps) down extremities (shutting down blood flow: temperature adaptations, 3 basic groups of how they deal with temperature:
