Michaels' Temperature Lectures

Question 1

Temperature

Answer 1

Temperature governs all processes that have a flow of energy. Temperature is the property of a body that determines whether is gains or loses energy relative to its surroundings. Or, a measure of the mean transactional kinetic energy of constituent atoms or molecules.

Question 2

Temperature influence on water

Answer 2

Influences ionisation/pH, viscosity, surface tension, solubility of gases and of calcium carbonate.

Question 3

Temperature to metabolism

Answer 3

Temperature -> molecular kinetic energy -> enzymatic reactions -> metabolic rates.

The warmer, the more kinetic energy from the particle vibrations, this increases the rate of successful reactions to an enzymatic way, that can be then compared to the metabolism.

Organisms are open systems, exchanging energy and matter with their environment. They also become waste through that process, temperature can control the rate at which this happens.

Question 4

Laws of thermodynamics

Answer 4

Energy can neither be created nor destroyed, every energy transfer increases the entropy of the universe. Entropy refers to chaos.

Question 5

Global Sea Surface Temperature

Answer 5

Global SST (sea surface temperature) has changed over geological time (temporal variability). There have been periods of heat and colder times, however the temperature change is. Much faster now.

For life, it is important how fast they can adapt. Whether they can change before the climate.

Question 6

Thermal variability

Answer 6

Temperate regions are thermally variable environments, whereas the tropic have a lot less seasonal variation, and there is also more stability at the poles. Daily variations can also be extreme since air is very thermally variable compared to water.

Question 7

Climate Variability Hypothesis

Answer 7

Links temperatures species experience to their physiology. Variation in traits is associated to the variation in the environment.

Question 8

Polar vs tropical species

Answer 8

Polar species tend to be used to a stable, cold environment so they tend to stay the same and have much lower thermal limits.

Whereas tropical species have high temperature limits. But temperate species can undergo many seasonal shifts and a wider range of temperatures.

Question 9

Compton et al. 2007

Answer 9

Studied mollusc species between western Australia and north western Europe. Those is Europe had much higher upper and lower limits, they also had a broader thermal window. Whereas the tropical species had a narrower temperature range and lower thermal limits.

Question 10

Prediction of global SST

Answer 10

The more emissions, the warmer the SST. Predicted to increase by 3 degrees by the end of the century. The higher the RCP, the higher the emission scenario.

Predicted extinction risks from climate change accelerate with the global temperature rise.

Question 11

Organism response to climate change

Answer 11

Move (shift in distribution), or stay which means they either die and we see local extinctions, or they cope through tolerance or phenotypic plasticity. They could also adapt through a shift in population genetic.

Migration- as climates get warmer, species may redistribute. Example; the topicalization of temperate reefs (Verges et al. 2014), or the climate-driven range expansion in sea urchins during their larval phases (Ling et al. 2009).

Stay and die- direct effects of temperature includes increases temperature and coral bleaching at the high latitude coral reefs (Adbo et al. 2012), and the local extinction of Oxymonacanthus longirostris after coral bleaching, knock-on effects (Brooker et al. 2014).

Question 12

Body temperature

Answer 12

At below 0 water freezes, crystals form inside the cells and rapture membranes. But above 40 degrees enzymes denature. There is a much narrower range for the optimal rate of chemical reactions in humans. It depends on a balance between heat generated internally and heat exchanged with the environment.

Question 13

Ectothermic

Answer 13

Body temp dependent on external heat resources. Have a poor metabolism and suck at generating their own heat. But they can thermoconform and thermoregulate.

Question 14

Endothermic

Answer 14

Body temp dependent on internally generated metabolic heat.

Question 15

Homeotherms vs poikilotherms

Answer 15

Homeotherms are birds and mammals, poikilotherms are more like fish.

Question 16

Heat exchange

Answer 16

By evaporation, radiation (emission of electromagnetic radiation), conduction (direct contact), convection (moving air or water radiates heat).

Question 17

Metabolism, Catabolism, Anabolism

Answer 17

Metabolism- the totality of an organisms chemical reactions, consisting of catabolic and anabolic pathways, which manage the material and energy resources of the organism. Metabolic rate is the measure of the total energy metabolised by an animal in a unit time.

Catabolism is the breakdown of macromolecules to produce energy.

Anabolism is the concurrent synthesis of large macromolecules.

Question 18

Thermoregulation in endotherms

Answer 18

Metabolism generates internal heat, allowing them to maintain an internal temperature. Up until the low and highest critical temperatures.
-Once they are out of the thermoneutral zone their energy costs increase.
-They either enter the zone of metabolic regulation or of active heat dissipation.

Heating by insulation (like blubber), vasoconstriction and vasodilation, Countercurrent heat exchange (have warm arteries close to venous blood, making it less cold when returning to the heart, shivering (takes ATP but often worth it), non-shivering thermogenesis (often in mammals, brown adipose tissue, hormonally coordinated, skips a few steps to save energy and generate a lot of heat).

Cooling by bathing or sweating, could bathe or migrate if extreme.

Question 19

Thermoregulation in ectotherms

Answer 19

-Low metabolic rates so the heat they generate is small and doesn’t affect the body temperature too much. Some can only generate heat locally (regional endotherms).

-Tuna generate heat by anaerobic and aerobic swimming motions. Blood is delivered to red muscle by subcutaneous arteries and returned by vessels, creating Countercurrent heat exchange and a strong temp gradient across the whole body keeping the heat at the chore. Bigger tuna are better able to thermoregulate compared to smaller ones (heat retention). Stevens et al. 1974, Wilmer et al.

Question 20

Non-shivering calcium related thermogenesis

Answer 20

-Found in swordfish, they are very good at it. Specialised heater cells through shifting ions. Calcium is shunted through the membrane and comes back through the protein calcium ATPase (which means ATP is split), ATP becomes ADP and then it is used to generate ATP again and then heat. These are metabolic reactions.

Question 21

Thermoregulation in fish (ectotherms)

Answer 21

Maintain body temperatures close to their surroundings.
Exploit differences in water temperature (behavioural thermoregulation).
They show adaptations in colder waters (supercooling, antifreeze proteins, high plasma NaCl concentrations).

Question 22

Thermoregulation in invertebrates (ectotherms)

Answer 22

At low temperatures, their body temps don’t differ much from the environment.
Position themselves in clusters/clumps, or burrow.
Evaporative cooling.

Question 23

Pacific salmon example

Answer 23

Used directional cues in shallow water during migration, cold-water fish have to deal with warm water while gathering directional information. As the surface temperature gets warmer, they go deeper, this means they rely on cues at the surface to migrate.

Question 24

Temperature and activation energy

Answer 24

-A small fraction of collisions has enough energy to react
-The proportion of collisions that have enough activation energy to react increases with temperature
-However this declines if the denaturation temperature is reached.

Question 25

Km- Michaelis-Menten constant

Answer 25

Measure of the ability/affinity of the enzyme to bind its substrate. One you get past a certain temperature the Km will increase the lower the constant, the better the affinity to bind to substrates.

Question 26

Kcat- Catalytic rate constant

Answer 26

Moles of substrate converted to product per moles of enzymes per second. Substrate turnover.

Question 27

Temperature on reaction rates: Q10

Answer 27

-For a reaction in which the rate doubles every ten degrees, Q10 = 2 -Q10 standardises a rate for every ten degrees, so you can compare across experiments -If you plug 4 into R2 and 2 into R1, you get 10/30-20 = Q10 = 2 -The higher Q10, the more sensitive it is, if it is 1 it means it's thermally insensitive. But they tend to double or triple with every ten degrees increase in temperature.

Question 28

Animals maintain biochemical reactions over a range of temperatures (hours-days) by

Answer 28

-Alterations on enzyme effective concentration -Alteration on the concentration of the substrate -Increased energy supply of the reaction being catalysed -Alteration in intracellular environments (altering the ion regulations, pH)

Question 29

Green Sunfish (Sidell 1977)

Answer 29

-They warmed up the fish to 25 degrees, and measured the cytochrome C enzyme at different time points. -If they increased the temperature the enzyme concentration increases initially but then came back down. Showing the initial cost. -Whereas when the temperature was put to 5 degrees, they increased the enzyme concentration over time. -They use the enzyme to buffer against thermal changes around them. -In the cold the rates of production (synthesis) decreases, but there is higher degradation so there is an overall net increase, and in the warm it’s the opposite. -This is all to offset thermal changes in their environments.

Question 30

Animals maintain biochemical reactions over a range of temperatures (days to months) by

Answer 30

-Switching the nature of muscle fibres for performance (isoform change). Example = the myosin in slow muscle fibres of common carp. -In the cold there are modest improvements in the contractile performance of slow muscle fibres at low temperatures. -In the warm, carp had almost only slow myosin light chains, and in the cold they have almost only fast myosin light chains. -The mechanism involves the expression of myosin light chain isoforms, normally associate with faster-contracting fibre types.

Question 31

Animals maintain biochemical reactions over a range of temperatures (months-years) by

Answer 31

-Building of the cofactor NADH is lss perturbed bur sing temperature in the case of the enzyme. -A single amino acid difference distinguished two forms’ ability to adapt to temperature.

Question 32

Enzymatic adaptation

Answer 32

Enzymes from species with low body temperatures have higher Kcat values (measure of substrate turnover rate), than the homologous for warm bodied species. - Cold- and warm-adapted enzymes have similar Km values (measure of affinity), when determined at their relevant working temperatures. Enzymes show temperature compensation through evolutionary adaptation.

Question 33

How animals maintain membrane stability over a range of temperatures

Answer 33

-Short-term changes = in a range of animals the fatty acid composition of the membrane lipids vary with ambient temperature. Short and unsaturated fatty acids are more fluid than longer, or saturated fatty acids. Membrane composition depends upon diet. -Homoviscous adaptation = of membrane structures in membranes from brain tissues of differently thermally adapted vertebrates. Adjusting membrane viscosity. - membranes have similar fluidity for all species at the temperature at which they normally live. - cold-adapted species don’t fully compensate at sub-zero temperatures, they have less fluid membranes.

Question 34

Antifreeze proteins in Antarctic notothenoid fish

Answer 34

AFP’s (antifreeze protein) attach to the ice crystal lattices which prevents new water molecules from adding, however they will accumulate these throughout their lives since it’s not sure that it will melt again in summer. The effect of this on the organisms fitness is not yet known.

Question 35

Cold hardiness in molluscs (Murphy1977)

Answer 35

Low temperature increases the concentration of blood calcium, increases in this is associated with an increased freezing tolerance. Calcium binds to cell membranes, reducing cell damage during freezing by either physical stabilisation of the membrane against mechanical disruption caused by cell shrinkage, or by preventing the denaturation of membrane compounds.

Question 36

How do organisms avoid denaturation at high temperatures?

Answer 36

-Stress response to maintain homeostasis. -Come in heat shock proteins which are molecular chaperones and assist protein folding under normal conditions, they act to refold proteins that are damaged during the heat stress (ATP-dependent) -Constitutive and inducible forms, classified by molecular weight of 70KDa.

Question 37

Short-term

Answer 37

Maintain enzyme function through: alteration on the concentration of the substrate. Increased energy supply for the reaction being catalysed. Alterations in intracellular environment (alteration of ionic regulation, thus pH). Isozyme change (mid-term). And maintain membrane fluidity through altering composition. Mechanisms of repair = heat shock response- acute but also influenced by environmental history.

Question 38

Long-term

Answer 38

Adaptations include changes in: membrane fluidity- Homeoviscous adaptation. Enzyme structure and function. Mechanisms of cold hardiness = freeze tolerance, e.g. ice nucleating proteins. Freeze avoidance, e.g. antifreeze proteins.

Question 39

Metabolism at a molecular level

Answer 39

Metabolism is a high energy electron donor going to a low energy electron receptor, giving energy for metabolism along the way, where energy can also be dissipated as heat.

Question 40

Metabolism

Answer 40

The measure of the total energy metabolised by an animal in a unit time. Determined indirectly by; energy value of food in minus waste, amount of heat produced, amount of metabolic water produced, amount of oxygen used up. -Oxygen consumption correlates closely with heat production, this can be used as a proxy for determining the whole metabolism.

Question 41

Standard metabolic rate (SMR)

Answer 41

The minimum cost of living, metabolism for a still lifestyle -The level required for a resting lifestyle with no activity, digestion or stress -Temperature dependent on ectotherms -It’s a good measure but not many animals do minimal activity -In endotherms in TNZ = basal metabolic rate (BMR)

Question 42

Routine/Resting metabolic rate (RMR)

Answer 42

-Level required for minimal activity -In vertebrates this includes cardiovascular circulation, immune systems, nervous system, nitrogen excretion.

Question 43

Maximum metabolic rate (MMR)

Answer 43

-Maximum possible level during exercising activity. -The other end of the scale, for animals that tend to never rest.

Question 44

Aerobic scope

Answer 44

Rest - active (basically the difference between SMR and MMR). -The extent to which MMR exceeds RMR -Max amount of oxygen available for aerobic activity, and therefore physiological performance. -Cost of existence represented by RMR is around 35% of daily energy expenditure. The cost of the organisms ecology (growth, reproduction, movement) is additional to existence. -Absolute AS = MMR – RMR

Question 45

How to measure metabolic rate in the field

Answer 45

-Diel and seasonal patterns in field metabolic rate, daily scale = crepuscular, seasonally = highly temperature dependent in the wild. -Rainbow trout in the field use <20% of the available scope for activity. -FMR allows estimation of daily energy expenditure.

Question 46

Mass + metabolism

Answer 46

-Metabolic rate increases with mass but not in direct proportion -Mass-specific metabolic rate = when you divide the oxygen consumption by the mass -Small animals have tissues that are more metabolically active and larger animals have a larger surface area so they may lose heat faster, meaning their metabolism has to make up for it.

Question 47

Key factors influencing metabolic rate

Answer 47

-Metabolic rate varies depending on what it’s doing and it’s environment -Varies with mass (complex, positive relationship), temperature, and other factors like environmental oxygen, food and genetic differences).

Question 48

Temperature affecting resting metabolic rate

Answer 48

Krogh’s normal curve 1914 -Looking at the metabolic rate of goldfish across a temperature range, measured by oxygen consumption -It’s an ectotherm so as you increase temperature, its body temperature increases, and the metabolism increases due to a faster rate of reaction at higher temperatures.

Question 49

Temperature and mass on SMR, MMR and AS on juvenile brown trout

Answer 49

-Measured after 5 weeks acclimatation to each of three consecutive test temperatures, simulating warming conditions that they experience throughout their first summer of growth -All traits increase with mass in a predictable manner -Temperature raised basic costs, but it can affect traits differently. Since variation can occur you have to be sure of which type of metabolism you will measure.

Question 50

Temperature sensitivity of metabolism: Q10

Answer 50

-For any two temperatures you can use Q10 (the temperature coefficient) -Temperature sensitivity of metabolism is very similar across a wide variety of organisms, highly conserved -But Q10 cant capture the full nature of the relationship between metabolism and temperature (Q10 can increase at both high and low temperatures)

Question 51

Has temperature sensitivity of metabolism changed over evolution?

Answer 51

-As the mechanisms of metabolism is common to all organisms, temperature sensitivity is, to an extent, similar across species. -It is highly conserved across the tree of life.

Question 52

Why does resting metabolism increase with temperature? Direct

Answer 52

RMR is driven higher in a deterministic manner by an increase in temperature (UTD-universal temperature dependence). Temperature governs metabolism through its effects on rates of biochemical reactions. Metabolic rate would therefore be driven by temperature.

Question 53

UTD suggests metabolism can be described in one equation

Answer 53

Q = metabolic rate, M = body mass, E = activation energy, T = absolute temperature, k = Boltzmann’s constant (average relative kinetic energy), b0 = normalisation constant independent of M and T. Essentially body mass x temperature dependency.

Question 54

Why does resting metabolism increase with temperature? Indirect

Answer 54

Temperature affects aspects of cellular physiology such that there is an increase in ATP demand (and so also oxygen consumption) at higher cell temperatures. -The influence is indirect, through a combination of energetic trade-offs and evolutionary temperature adaptation. -The RMR of one species at its normal environmental temperature represents an evolutionary optimisation for that species influenced by evolutionary trade-offs between cost and benefits and ecological lifestyle.

Question 55

Thermal tolerance

Answer 55

Animals have a window of temperature that they can exist in. The limits shift to the cold in winter, and to the warm in the summer. There is a greater tolerance width in temperate species. Seasonal temperature variation is low at equator and increases towards the temperate regions. Tolerance varies across taxa.

Question 56

Marine vs terrestrial limits

Answer 56

- Upper thermal limits vary little in terrestrial ectotherms, while lower thermal limits decrease with latitude. - In marine species, thermal breadth increases with latitude up to 60 degrees, and decreases near the poles.

Question 57

Thermal acclimation

Answer 57

Prolonged exposure to moderately altered temperatures can trigger lasting changes to thermal sensitivity. Animals can adjust their physiology over time. This also alters their performance, and it is ‘plausible’ that it may be beneficial to their fitness.

Question 58

Reversible plasticity

Answer 58

If you give adult species a longer term of heat change, they may adjust their physiology and then go back to how they were before when the temperature changes again.

Question 59

Developmental plasticity

Answer 59

In early life stages, growing up in different temperatures will allow a physiological change which then then cannot reverse.

Question 60

Partial vs complete compensation response

Answer 60

Partial- they somewhat change their physiology to the change in temperature which affects them in some ways. Complete- is when the metabolic rate fully returns to its normal state. There are also more types of compensation.

Question 61

Stenothermal vs eurythermal organisms

Answer 61

Very narrow temperature range, much lower thermal limits. These limits can shift with acclimation. For example, polar bears at the poles, more vulnerable to warming because of low limits and they have a limited acclimation capacity. The acclimation can take 2.4x longer to acclimate than temperate ones, which means they often cannot keep up. Some species show no acclimation capacity at all, so when the temperature exceeds their limit, they have nowhere to go. Eurythermal organisms- very wide temperature range, much higher thermal limits.

Question 62

Thermal performance curves

Answer 62

Measure of physiological performance across a temp range. -In ectotherms, performance varies with temperature exponentially. -Limits of performance curves are critical thermal limits (CTmin and CTmax) -Different organisms have different performance curves for given traits, which can be influenced by the environment and the evolutionary history. -Topt = temperature where performance is at its optimum, it doesn’t necessarily mean it’s best for fitness in the long term. Going at maximum for a long time isn’t normally good. -If there is a broader B breadth, it means they can maintain fitness over a wider range of temperatures. These differ between ectotherms and endotherms since endotherms have some independence from the environment.

Question 63

Acclimation of physiological performance

Answer 63

Possible responses to cold and warm temperature acclimation in marine species -Topt is displaced towards higher temperatures, -There is an increase in maximum performance -An increase in CTmax and wider breadth, but at the expense of reduced performance.

Question 64

What limits performance? OCLTT

Answer 64

-Suggests that there is a pattern of thermal performance due to oxygen -The initial increase in metabolic rate is due to an increase in oxygen demand which has to be solved by metabolism, since oxygen demand is exceeding supply. Occurring towards both warmer and colder temperatures.

Question 65

Problem with O2 supply in cold species

Answer 65

-Oxygen supply seems to only be a problem in cold species, not warm. In cold species, they can sometimes asphyxiate since they cannot get enough oxygen through blood or haemolymph. -Tropical species cardiorespiratory systems are adapted to function at high temperatures and therefore don’t experience a gradual decrease in aerobic performance at high temperatures. -Aerobic performance is maintained until denaturation temperature and the primary determinates of Tcryt are more generalised heat-induced loos of protein structure or membrane integrity leading to a very sharp decline in metabolic and physiological functions.

Question 66

Thermal safety margins (TSM’s)

Answer 66

Difference between a species’ maximum tolerance to heat and the temperatures it regularly experiences in its environment.

Question 67

Relationship between habitat temperature and acute thermal tolerance limits for congeneric porcelain crabs.

Answer 67

From Alaska to Chile on shore hights. For both tropical and temperate congeners, the most heat-tolerant species are in general most threatened by further increases in habitat temperature because current Maximal Habitat Temperatures (MHT’s) may reach or exceed the LT50 since they already live close to their thermal limits. -Higher thermal temperature results in higher thermal tolerance, but often also reduced TSM’s since populations already live close to their limits.

Question 68

Can thermal tolerance be modified through acclimation?

Answer 68

-The most heat-adapted congeners of porcelain crabs are disadvantages by possessing a relatively small ability to increase thermal tolerance during acclimation.

Question 69

High latitudes (arctic) are warming faster, but extinction rates indicate the greatest loss of biodiversity will be in the tropics.

Answer 69

-Since they are already closer to their thermal limits (thermal safety margins) -Less used to adapting to thermal change -They have climatic niches and limited acclimation capacity since they have evolved in thermo-stable environments, they are thermal specialists -There is a higher frequency of local extinctions in tropical regions, compared to temperate regions.

Question 70

Terrestrial ectotherms

Answer 70

Narrow TSM’s -Latitudinal trends in warming tolerance (CTmax−Thab) -Thermal safety margin (TSM = Topt−Thab)

Question 71

Marine ectotherms

Answer 71

Narrower TSM’s -The warmest extremes are at mid-latitudes on land and in the tropics in the ocean -Terrestrial systems will warm more, but tropical marine ecosystems will be more impacted because of lowers TSM’s and limited acclimation capacity. Many marine ecosystems are vulnerable to warming.

Question 72

Polar species

Answer 72

Many lack the capacity to acclimate to temperatures even 3 degrees above their environmental temperatures. For those showing acclimation potential, acclimation times are longer than required for temperate species (5-10 instead of 2-5 days). May show a trade-off between the ability to survival in extreme cold, instead of the acclimation potential. -Polar, marine ectotherms living at a constant near-freezing temperature may share the same high vulnerability to climate change as tropical species.