Thermal 2

Question 1

life as an ectotherm: thermal limits for survival

Answer 1

• critical thermal (CT) min/max and incipient (I) lower/upper lethal temps (LT) represent limits for thermal tolerance
• a polar fish’s limits would be close to 0, a temperate would have a larger range of upper/lower limits, while a tropical fish would have limits much high and narrower (similar to polar fish on opposite end)

Question 2

range of temperature tolerances for an animal depend on…

Answer 2

the rapid/ACUTE changes in Ta

Question 3

eurytherm vs stenotherm ranges of temp tolerance

Answer 3

eurytherm=large range

stenotherm=small range

Question 4

because Mo2, growth, and fecundity are dependent on temp, they also measure…

Answer 4

animal performance

-thus temperature is considered a master factor for animals

Question 5

aerobic scope

Answer 5

=an animal’s ability to consume O2 beyond basic needs

–varies with temperature, along a FRY CURVE

Question 6

fry curves

Answer 6

• shows aerobic scope along temperature for various animals
• no aerobic scope=dead
• AS is a CAPACITY for consuming O2 at a certain temperature

Question 7

thermal acclimation

Answer 7

• physiological and biochemical acclimation allow ectotherms to tolerate new temp. ranges
• cold acclimation=lower ranger
• warm acclimation=higher range
• it takes several weeks at a new temperature to fully acclimate
• lethal temperatures change with acclimation

Question 8

fry temperature acclimation polygons

Answer 8

• polygon shaped because of upper/lower limits of acclimation temperature
• species with large thermal niche (eurytherms)=large area
• species with small thermal niche (stenotherms)=smaller area, still large acclimation range

Question 9

importance acclimation: cell membranes must remain functional and fluid, explain

Answer 9

• membranes must maintain internal cell environment stable and different from external
• membrane proteins are critical for cell homeostasis
• fluidity is reduced with greater temp.

Question 10

importance of acclimation: membrane composition and fluidity

Answer 10

• varies at different temperature
• fluidity depends on temperature and FATTY ACID SATURATION, and phospholipid class
• shorter FA chains are more fluid
• unsaturated FA are more fluid
• polar heads (phosphatidylcholine<phosphatidylethanolamine)
• fluidity increases with greater temperature

Question 11

physiological challenges of different thermal niches

Answer 11

• protein channels and pumps must remain fuctional
• membrane fluidity decreases with increased heat
• changes Vmax of enzymes
• must maintain affinity for substrates

Question 12

changes in Vmax of enzymes with temp change; solution for cold niches?

Answer 12

• -must express different isozymes with higher Vmax
• more enzymes per cell
• more cells per organ (aka hypertrophy)

Question 13

maintaining affinity for substrates (Km)

Answer 13

• substrate concentrations are constant across temperature
• need to keep Km constant across temperature
• -isozymes with lower Km can offset effects of warm temp on protein Km

Question 14

consequence of thermal acclimation on reaction rate

Answer 14

Q10 for reaction rates btw acclimation temperatures often <2.0

Question 15

why msut Tb for ectotherms follow Ta?

Answer 15

-ectotherms cannot directly change or control their internal body temperature, and instead alter their physiology to survive in the current Ta

Question 16

how do ectotherms adjust to new temps?

Answer 16

• acclimation through changes in membrane fatty acid chains length and saturation allow adaptable fluidity to keep cell structures together with changing temperatures
• create more enzymes per cell in cold environment and more cells per organ (hypertrophy) to keep up BMR
• maintain substrate affinity Km across temp changes