Lecture 15: Physiological Ecology Flashcards

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1
Q

Physiology

A

how organisms acquire energy

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2
Q

core concepts of physiological ecology

A
  • ranges of tolerance
  • organisms = complex chemical reactions
  • reactions occur at optimal temperature and osmotic conditions
  • many mechanisms for homeostasis have evolved to challenge hostile environments
  • maintenance of homeostasis requires energy and is limited by constraints and tradeoffs
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3
Q

biodiversity

A

diversity of morphologies and behaviours (even within a species)

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4
Q

Organisms in similar environments have similar…

A

physiologies because of convergent evolution

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5
Q

How are an organism’s tolerance levels tested?

A

Scientists look at critical temperatures—the point at which the animal loses some critical function (walking, flying, etc)

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6
Q

Thermal tolerance breadth

A

number of degrees between maximum and minimum temperature organism can tolerate

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7
Q

Why do animals from equatorial regions have lower thermal tolerance breadth?

A

Temperature is largely invariable near the equator (seasonality is not really a thing because solar radiation is fairly constant).

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8
Q

poikilotherms

A

coldblooded
- lack physiological means to regulate their body temp HOWEVER they often compensate with behavioural means (basking or burrowing) ex. snakes, mole rats, frogs

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9
Q

homeotherms

A

warm blooded

- have to keep body within certain range ex. birds, mammals

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10
Q

Modes of heat gain or loss

A
  • radiation
  • conduction (direct contact)
  • convection (heat transfer by moving fluid ex. air/water)
  • evaporation
  • redistribution - homeotherms tend to redistribute heat from core to appendages
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11
Q

Why does size matter for heat balance?

A

Heat can only be shed through surface area. Larger animals are better at retaining heat than smaller animals because as size increases, ratio of SA to volume decreases.

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12
Q

SA determines . . . . and volume provides . . . ?

A
  • equilibration rate (to environment)

- inertia

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13
Q

Bergmann’s rule

A

homeotherms tend to be larger at higher latitudes where it’s colder
ex. bears, woodrats, elephants (they’re huge but still smaller than wooly mammoths were)

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14
Q

Animal with maximum SA to volume ratio

A

Chrysopelen gliding snake (found in warm tropics)

- COMPLETELY flat, looks like a ribbon

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15
Q

Animal with minimum SA to volume ratio

A
American Pika (found high in mountains)
- basically a ball of fur with tiny ears
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16
Q

Allen’s rule

A

homeotherms tend to have smaller appendages at higher colder latitudes

17
Q

countercurrent circulation

A

veins return blood from appendages to core while arteries bring warm blood from core to appendages. If arteries and veins are close together it keeps warm blood near core as heat transfers from arteries to veins so that the blood returning to core is warmed. If the vessels are partitioned in a way that no heat transfer is possible, heat is brought to appendages and thus more heat is shed

18
Q

A case study: Weasels

A

Very long and thin thus high SA to volume ratio. Cannot curl up in spherical resting position (flat disk) because they are so long. Seems counterintuitive as they live in cooler climates but their typical prey is the pocket gopher. Body shape allows them to burrow into gopher tunnels for prey. TRADEOFF.