Lecture 11: Body Size and Scaling

Question 1

Animal size examples:

Answer 1

VARY HUGELY

• Rotifers: 0.01micrograms (1x10^-8g)
• Pygmy Shrew: 1g
• Elephant 5000kg
• Blue Whale: 10,000kg

Question 2

what similar physiological functions do all animals share?

Answer 2

• metabolism
• homeostasis
• reproduction
• growth

Question 3

physics influences physiology: two exmaples

Answer 3

• gravity

- surface area to volume ratio

Question 4

Gravities affect on physiology

Answer 4

• circulation

- movement and locomotion

Question 5

Surface area to volume ratio affect on physiology:

Answer 5

• respiration
• digestion
• water balance
• thermoregulation

Question 6

which has greater SA:V ratio small or big animals

Answer 6

SMALL

Question 7

Isometric Scaling:

Answer 7

• growing in proportion -
• size of trait increases in proportion body size
  i. e. frog

Question 8

Allometry:

Answer 8

• the study of differential growth; biological scaling.

- How physiological processes scale with body size and with each other

Question 9

how can allometry be measured:

Answer 9

• during growth of single organisms (ONTOGENETIC ALLOMETRY)
• Between different organisms within a species (STATIC ALLOMETRY)
• between organisms in different species (EVOLUTIONARY ALLOMETRY)

Question 10

how can allometry be described on a graph

Answer 10

body size on X axis and other trait on Y

Question 11

Static allometry:

Answer 11

allometry also examines shape variation among individuals of a given age (and sex)

Question 12

describing allometric relationships: y =

Answer 12

aX^b (a power function) 
• Y = body part being measured in relationship to the size of the organism (or any set of two traits)
• X = measure of size used for basis of comparison
• usually a measure of whole body size
 • a = initial growth index
• size of Y when X = 1 
• b = scaling exponent
• proportional change in Y per unit X

Question 13

Describing Allometric Relationships: if B is +

Answer 13

• physiological variable increases with increased body mass

- -> organ has higher growth rate than the whole body

Question 14

Describing Allometric Relationships: if B is -

Answer 14

physiological variable decreases with increasing body mass

–> organ has smaller growth rate than the whole body

Question 15

Describing Allometric Relationships: if B is 0 :

Answer 15

physiological variable is unaffected by scale

-organ growth rate not release to whole body

Question 16

Describing Allometric Relationships: if B is 1 =

Answer 16

• physiological variable scales at the same rate as body mass
• organ growth rate the same as whole body

Question 17

simple: b >1

Answer 17

Positive allometry

Question 18

Simple b =1

Answer 18

isometric growth

Question 19

simple b < 1

Answer 19

negative allomtrey

Question 20

when looking at scaling relationships x + y must be

Answer 20

the same TYPES of units

Question 21

allometric equations: why do they use log-log scale

Answer 21

linearises a power function, making it easier to interpret

Question 22

isometry is the null:

Answer 22

• isometry preserves proportional relationships between traits
• “Square-cube law”
• Isometric doubling of length will increase surface area fourfold and volume (thus mass) eightfold.
• Means that allometric relationships indicate physiological compensation

Question 23

similarly sized endotherms will always have ____ BMRs than their exotherm counterparts

Answer 23

BMR - metabolic rate?

HIGHER

Question 24

BMR for marine mammals is __ that of similarly sized terrestrial mammals

Answer 24

2 times

Question 25

Increasing body size results in a ——– in mass specific MR

Answer 25

DECREASE