lecture 3

Question 1

What are some core ideas of ecology?

Answer 1

Ranges of tolerance limit distribution

Organisms are complex chemical reactions

Reactions occur at optimal temperatures and osmotic conditions, where fitness is maximized.

Machanism for homeostatis evolved to challenge hostile environment

Homeostasis is limited by constraints and tradeoffs

Question 2

What is homeostasis limited by?

Answer 2

Constraints and trade offs because it requires energy. (it evolves by natural selection)

Question 3

What is an important aspect of homeostasis?

Answer 3

Maintaining constant internal temperature in a variable external temperature.

Question 4

What is convergent evolution?

Answer 4

Similar environments lead to similar adaptations known as convergent evolution.

Question 5

What does an organisms physiology reflect?

Answer 5

Its climate and other conditions to which an organism has adapted.

Question 6

What is critical temperature limit?

Answer 6

It is the temperature at which an organism loses its critical motor functions like ability to walk or fly.

Question 7

What did ‘Jennifer Sunday’s’ study show?

Answer 7

THIS WAS FOR COLD-BLOODED It showed that organisms ( arthropods, amphibians, reptiles) in temperate regions tolerate cold temperatures better than organisms in tropical temperatures.

X axis: Absolute latitude

Y axis: tolerance limit.

Question 8

What were the observations from Jennifer Sunday’s graph?

Answer 8

1) Animals in (higher latitudes) temperate zones have lower temperature tolerance limits.

2) Animals in lower latitudes (towards equator) have slightly higher temperature tolerance limits.

3) Heat tolerance changes less with latitude than cold tolerance.

4) Temperate animals tolerate wider range of temperatures than tropical animals.

Question 9

What is ‘thermal tolerance breath’?

Answer 9

Maximum temperature animal can tolerate - minimum temperature an animal can tolerate (It increases from equator to the poles)

Question 10

Who are ‘poikilotherms’?

Answer 10

(cold-blooded) Lack of physiological means to deviate from external temperature. (Like snakes.. they use behavioral thermoregulation) and their body temperature fluctuates.

Question 11

Define homeotherms

Answer 11

Organisms that regulate internal body temperatures within a narrow range.

Question 12

Why do poikilotherms have lower energy requirements than homeotherms?

Answer 12

Because homeostasis requires a lot of energy.

Question 13

How do animals balance heat?

Answer 13

1) Radiation: Heat transfer by electromagnetism (like sitting by fire)

2) Conduction: transfer by direct contact with the substrate ( feet transferring energy to ground)

3) Convection: Heat transfer mediated by moving fluid (warming in a bath or cool when swimming)

4) Evaporation: Efficient cooling from wet surfaces (Sweating)

5) Redistribution: Circulatory system redistributes heat in the body parts. (From core to appendages)

Question 14

What does surface area determine?

Answer 14

The equilibration rate.

Question 15

What does volume determine?

Answer 15

The inertia

Question 16

How does SA/V ratio affect one’s heat balance?

Answer 16

More ratio means easier to lose heat (small spears) while larger size means harder to lose heat.

Question 17

How does SA/V determine where an animal is suited well?

Answer 17

Larger ratio: Better in cold environment

Smaller ratio: Bette in hot environment.

Question 18

What is bergmann’s rule?

Answer 18

Homeotherms tend to be larger in higher latitudes (ie where its colder)

Reason: larger animals have lower surface area / volume ration which means they lose less heat to the environment.

Question 19

What did the graphs show for bergmann’s rule for woodrats?

Answer 19

1) Bergmann’s rule can be applied to both same and different species.

2) X-axis has body weight y axis has temperature

3) Woodrats in higer temp has samller body size than wood rats in lower temp.

Question 20

Why aren’t all animals spherical?

Answer 20

Because of a trade off, inoder to have other functions like mobility to run from prey’s.

Question 21

Which animal has the maximum surface area?

Answer 21

Gliding snake (which lives in warm temp)
This shape helps because, it lives in warm temp, and has more SA, less volume, which means the ratio is higher, hence loses more heat)

Question 22

Which animal has a minimum surface area?

Answer 22

American pika: restricted to high elevation, hence live in very cold climate.

Question 23

What is ‘Allen’s rule’?

Answer 23

Homeotherms have smaller appendages at higher latitudes (at lower temperatures)

Reasoning: Have smaller appendages lowers the surface area tp volume ration, hence decreases heat loss.

ex: arctic fox has smaller ears. while red fox has bigger ear, and fennec ears have huge ears to shed heat.

Ex: Arctic hare and dessert hare.

Question 24

What type of heat conservation method is more important than size and shape?

Answer 24

Insulation. (Fur and Blubber)
A lot of resources go into keeping animals warm!

Animals in cold places have longer hair like the musk oxen

Animals also have blubber, like seal. 58% is blubber in seal (cross-sectional)

Question 25

How does circulatory system help animals to shed out heat in dessert animals?

Answer 25

The circulatory system sheds heat from the core to the appendages which have many vessels in them. Having larger surface area of the appendages, and vascularization helps to perform convective cooling.

Question 26

What is counter current circulation?

Answer 26

In counter-current circulation , the arteries and veins are appressed together in appendages to conserve heat.

In animals that need to shed heat, arteries and veins are distanced from each other.

Question 27

What gradient does counter current follow?

Answer 27

Heat flows from out going blood to incoming blood.

Question 28

What method do dogs use for cooling?

Answer 28

Evaporative cooling. (stick their tongue out)

Question 29

What are ways heat is saved?

Answer 29

1) Size
2) Shape
3) Insulation
4) Evaporative cooling
5) Behavioral thermoregulation

Question 30

Why are weasels the size and shape they are? How is the paradox solved?

Answer 30

Weasels mainly hunt pocket gofers, that live in burrows hence weasels are thin, long and have less fur while spending 50 - 100% of energy on heat helps them be a better predator. This is an example of a trade-off.

Question 31

What is the fitness gains and fitness costs for weasels?

Answer 31

Fitness gains: Being a good hunter

Fitness costs: An expensive metabolism

Question 32

What is a trade-off?

Answer 32

Being good at x implying being bad at y.

Question 33

What are two reasons why natural selection produces deeply imperfect organisms?

Answer 33

1) Trade offs
2) Constraints

Question 34

What are constraints?

Answer 34

The development is on the phenotypes, that is changes are made on existing programs and new models cannot be created.