TOPIC 8: ANIMAL ADAPTATIONS

Question 1

What does an individuals fitness depend on?

Answer 1

Fitness depends on an individual’s ability to cope with environmental change

Question 2

What is done to maximize fitness?

Answer 2

To maximize fitness - an individual’s response to these changes must be shorter
than the period of chane

Question 3

List the 3 categories of individual responses

Answer 3

1. developmental (years)
2. Acclimatory (days – weeks)
3. Regulatory (seconds – minutes)

Question 4

Developmental (years)

Answer 4

Individual alters its development to produce a phenotype most suitable to
a persistent slow change in environmental conditions

Question 5

Give an example of a developmental response

Answer 5

e.g. Wing length in European freshwater Water Striders (Gerris spp.) – inhabiting temporary
ponds
Eggs hatch (spring)
Adult lifespan is short (reproduce & die during one summer)
2 morphs (discrete phenotypes)
Long winged - can fly
move if pond dries up
more energy into survival than reproduction
Short-winged - cannot fly
cannot move if pond dries up
more energy into reproduction than survival

Question 6

Acclimatory

Answer 6

(days – weeks)
* changes in response to seasonal variations
habituation of an organism’s physiological response to environmental conditions
* Tolerances are not fixed but are preconditioned by recent experience with
environmental conditions

Question 7

Give an example of a Acclimatory

Answer 7

e.g. thickening of fur for winter
fur and feathers create an insulative boundary later

Question 8

. Insect – “freeze avoidance strategy”

Answer 8

as temperatures start to decrease in fall
* convert glycogen reserves → alcohol
* alcohol – depress the freezing point of the body → freeze avoidance

Question 9

Freeze Tolerance

Answer 9

• • wood frog (Rana sylvatica)
• • similar to frost hardening in plants
• • expels fluid interior of cells and controls the ice nucleation process in
    intercellular space
• • can survive temps up to -50⁰C

Question 10

Dessication Tolerance

Answer 10

Tardigrades or “water bears”
- allow their tissues to dry up when there is no available water
-revitalized when water again becomes available
-not a permanent solution

Question 11

Regulatory

Answer 11

(seconds – minutes)
* Rapid changes in behaviour or rates of physiological processes

Question 12

Conformers

Answer 12

allow internal conditions to follow external changes

Question 13

Regulators

Answer 13

– maintain constant internal conditions

Question 14

• Homeostasis

Answer 14

= ability to maintain constant internal conditions in a varying
environment
* Always involves a negative feedback system

Question 15

Poikilothermy

Answer 15

– cannot maintain constant body temperature (body temp varies)
* Most amphibians, fish and insects
* Most aquatic organisms
* Only active in a narrow range of temperatures

Question 16

Homeothermy

Answer 16

Regulating) – maintain constant body temperature
most birds and mammals ~ 36 – 410C (temp. at which biochemical processes within cells are efficient)
* Highly active under varying temperatures

Question 17

List the ways in which organisms can regulate body temperature within a certain range

Answer 17

Ectotherms
Endotherms

Question 18

Ectotherms -

Answer 18

• regulate body temperature by gaining heat from external sources
  (Poikilotherm)
• Adv. - energy expenditure can be low
• Disadv. – growth, reproduction and survival is limited by temperature fluctuations
• Active only in a narrow range of temps

Question 19

• Endotherms -

Answer 19

regulate body temperature by the production of heat (metabolism)
(Homeotherm)

Adv. – growth, reproduction & survival is not as affected by temperature
fluctuations
* Constant performance of biochemical reactions at a range of
environmental temperatures
* Active at a wide range of temperatures

• Disadv. - energy expenditure must be high to maintain metabolic heat production

Question 20

What are the limitations of ectotherms?

Answer 20

• must behaviourally generate heat
• Ectotherms generate heat when active
• Every aspect of ecology and behaviour is influenced by the need to regulate body
  temperature

Question 21

What are the limitations of endotherms?

Answer 21

• Endotherm’s ability to maintain constant body temperature is limited under low
  temperatures
• Short-term – by physiological capacity to generate heat
• Long-term – by ability to gather food (or energy) to satisfy requirements for
  metabolic heat production
• animals usually starve to death before they die of direct causes of cold
  temperatures

Question 22

Allometric relationship

Answer 22

= a relative increase in a physical or physiological property of an organism in
relation to its body size

As body size ↑,
V ↑ faster than SA
As body size changes,
SA/V ratio changes
As SA/V ratio changes,
Heat loss to environment changes

• Body heat is produced through metabolic processes (endotherms)
• The larger the V, the greater the total amount of heat required to keep warm
  … but less heat is lost through the outer surface of the organism
  Heat gain must be greater than heat loss

Question 23

• Small Organisms:

Answer 23

• High SA/V
• Require less heat but hard to keep warm!

Question 24

• Large Organisms

Answer 24

• Low SA/V
• Require more heat but it is retained easier

Question 25

• Bergmann’s Rule

Answer 25

A broadly distributed group of species tend to be larger in size in
colder environments and smaller in warmer environment
* On a single species scale think of the white-tailed deer example
* On a multi-species scale this rule often breaks down