Lecture 7: Temperature and Light

Question 1

What is range of tolerance?

Answer 1

The range of an environmental condition in which an organism can survive. The organisms performance is negatively affected the further away it is from the range of optimal performance.

Question 2

What is the optimal range of performance?

Answer 2

The range of an environmental condition in which an organism performs best in the absence of interactions with other species

Question 3

What is the link between range of tolerance and the fundamental niche?

Answer 3

Environmental conditions that limit growth also affect the abundance and distribution of organisms. Organisms experience physiological stress at the niche margins of a limiting factor

Question 4

What is the law of tolerance?

Answer 4

Species have optimal survival conditions within environmental thresholds, and beyond the optimum, survival decreases (forming a bell curve)

Question 5

What is the difference between macroclimate and microclimate:

Answer 5

Macroclimate: large-scale climactic patters that prevail over entire regions, are determined by climate cells and topography (BIOMES)
Microclimate: small scale climate patterns, can deviate from macroclimate, due to small scale topography, landscape, vegetation

Question 6

Do water temperatures fluctuate more or less than air?

Answer 6

LESS, especially in large water bodies, they only fluctuate between (-4) - 32 degrees.

Question 7

What are three properties of water?

Answer 7

Higher capacity for absorbing heat energy (with intermittent stable temperatures between phase changes)
Heat is absorbed by water as it evaporates
Water gives up heat to the environment when it freezes

Question 8

What is the principle of allocation?

Answer 8

Organisms have a limited amount of energy, and when energy is allocated to one function it reduces the energy available to other functions, and this has costs and benefits

Question 9

What is an evolutionary tradeoff?

Answer 9

Adapting to one set of environmental conditions (within the range of tolerance) which generally reduces fitness in other environments

Question 10

What are the four strategies for when you are at the margins of your tolerance?

Answer 10

1. die
2. migrate
3. acclimate
4. adapt to extreme temperatures

Question 11

Why is death a viable solution to being at the outskirts of the range of tolerance?

Answer 11

You avoid extreme temperatures by funneling all your energy into reproduction, and thus your offspring have a better chance of survival

Question 12

Why is migration a viable solution?

Answer 12

Avoid extreme temperatures by migrating to warmer regions, and the advantages outweigh the costs (birds, mammals, insects)

Question 13

What is acclimation?

Answer 13

Physiological or morphological changes in an organism in response to changes in the environment.
NOT AN ADAPTATION (the ability to acclimate is an adaptation)
Phenotypic plasticity

Question 14

What are some examples for adaptations to extreme environments”

Answer 14

Thick fur, short appendages, body fat, cryoprotection, prolonged state of metabolic activity (hibernation, estivation)

Question 15

What does the heat equation consist of?

Answer 15

Hs: total heat stored is equal to
Hm: heat gained by metabolism
Hcv: heat gain/lost from convection (winds)
Hcd: heat gain/loss from conduction (roots)
He: heat loss by evaporation
Hr: heat gain/loss by radiation (sun)

Question 16

What is the consequence of losing too much heat to evaporation?

Answer 16

DEHYDRATION, it is not the heat that kills you, it is the resulting dehydration that damages the body systems until death

Question 17

What is the water budget equation for aquatic organisms?

Answer 17

Wi: internal water
Wd: water gained by drinking
Ws: water loss by secretion
Wo: water gain/loss by osmosis

Question 18

What are diffusion and osmosis? What is the difference?

Answer 18

Diffusion is the movement of soluble salts or water due to random movement of particles, until salt concentrations are equalized in a solution
Osmosis is the movement of water through a semi-permeable membrane

Question 19

What is osmolarity? What are the three types?

Answer 19

Osmolarity: amount of solute/water in a solution in relation to a reference (in this case it is the amount of solute/water in an organism in relation to its environment
Hypoosmotic: too much water in the fish and less solute compared to the environment, therefore the fish LOSES more water
Hyperosmotic: too much solute in the fish and not enough water, therefore the fish has a tendency to gain water
Isosmotic: equal concentration of solute across fish and environment

Question 20

Most marine organisms have what type of osmolarity? What do other marine animals have?

Answer 20

Most are isosmotic
Others are hypoosmotic: not enough solute in the body and too much water, thus water leaves and salt comes in, leads to low osmotic pressure in the blood, and high risk or dehydration

Question 21

What are 3 solutions to hypoosmotic issues in marine animals?

Answer 21

Drink constantly to counteract dehydration (increased Wd), low urination rates and volumes (decreases Ws), and get rid of excess salt through specialized chloride cells in the gills (to reduce water loss by osmosis)

Question 22

Most freshwater animals have what type of osmolarity?

Answer 22

Hyperosmotic, they have a higher saly concentration in their blood compared to the environment. Have high osmotic pressure in blood, and they risk too much water entering the body and to many salts leave

Question 23

What are three solutions to hyperosmotic in freshwater fish?

Answer 23

Do not drink much
Produce highly dilute urine in large amounts
Replace salts by absorbing sodium chloride in gills by ingesting food

Question 24

What is is called when fish adapt to the salinity of their new environment?

Answer 24

ACCLIMATION

Question 25

What is an anadromous fish?

Answer 25

These fish are born and then spend that majority of their lives in marine environment, and then they migrate to back to freshwater to breed again. Salmon cope with this via taking more salt in when in fresh and excreting more salt when in salt water

Question 26

What is a catadromous fish?

Answer 26

born in the ocean, spend most of their lives in freshwater and then migrate BACK to saltwater to breed/spawn

Question 27

What is the water equation for terrestrial plants?

Answer 27

Wi: internal water
Wr: water gained from roots
Wa: water gained from air (diffusion)
Wt: water loss from transpiration (evaporation)
Ws: water loss from secretion

Question 28

What is the water equation for terrestrial animals?

Answer 28

Wi: internal water
Wd: water gained from drinking
Ws: water loss from secretion
Wf: water gain through food
Wa: water gain from air
We: water loss from evaporation

Question 29

What is water potential, how does it move, and how is it different from osmosis?

Answer 29

It is water’s ability to do work, water moves from high water potential to low water potential therefore if there is differences in water potential it will move, and it includes pressure and therefore it is different from osmosis

Question 30

What is the equation for water potential:

Answer 30

Ψ= water potential
Ψ0= water potential of a reference solution
Ψg= force of gravity pulling water down
Ψs= osmotic pressure
Ψh= water vapour pressure (pull by air, strongest in dry/warm condition
Ψm= matric pressure (pull through adhesion)
Ψp= sum of extraneous pressures (evapotranspiration)

Question 31

Is water pressure usually positive or negative? What is the range?

Answer 31

It is usually negative and ranges from 0-(-100) and pure water is 0 and hot/dry air is -100

Question 32

What is water vapor density? What is saturation water vapour density?

Answer 32

The amount of water vapour that air ACTUALLY holds, and the other one is the amount of water vapour that air can POTENTIALLY hold

Question 33

Does warm or cold air have a higher saturation water vapour density?

Answer 33

WARM AIR can hold more water vapour and thus has high water vapour pressure

Question 34

What is the relative water potential in soil, roots, tree truck, and tree canopy?

Answer 34

SOIL: high water potential (high Ψs)
ROOTS: medium high water potential (Ψs is lower than soil)
TREE TRUNK: low to moderate water potential (Ψs and Ψm are low, due to small tubes increasing capillary pull)
TREE CANOPY: lowest water potential Ψp and Ψh are very low because the leaf surface interfaces with the air causing evaporation and transpiration

Question 35

What are some ways that terrestrial animals and plants prevent water loss?

Answer 35

Waxy cuticle, or protective/hard layers covering epidermis, store water in reserves and release when in drought, conservation of urine, feces, and sweat to prevent water loss, behavioural adaptations (burrows where it is more moist and cooler)