Body Size

Question 1

Are there more small or large species?

Answer 1

Small

Question 2

Why can aquatic endotherms get bigger than terrestrial endotherms?

Answer 2

Water has specific heat capacity of 4.23 and so acquatic endotherms can get bigger without the risk of overheating

Acquatic endotherms have more boyancy

Question 3

What constrains bird mass?

Answer 3

Bi-pedal movement

Question 4

What is the equation for surface area?

Answer 4

Surface area = body mass ^2/3

Question 5

What is heat loss of an organism proportional to?

Answer 5

Surface area

Question 6

What factor does the use of 2/3 vs 3/4 depend on?

Answer 6

If measuring active or resting metabolic rate

Question 7

Why does body size matter?

Answer 7

Body size controls energy use

Energy use determins how many individuals can live in an area e.g. population density

Population density determines key ecological attributes e.g. extinction risk, competition rate and predation rate

Question 8

What is the metabolic theory of ecology?

Answer 8

Warmer individuals have higher metabolic rates

Warmer individuals are either due to being in a warmer climate or endothermy

Question 9

What does macroecological theory argue?

Answer 9

Metabolic rate is the primary constraint that determines all biological processes by determining rate and timing

Question 10

What is the metabolic theory of ecology on an individual level?

Answer 10

Small animals grow fast, breed early and die young

Due to having a higher metabolic rate which causes trade offs such as free radical production which accelerates senescence

Question 11

What is the metabolic theory of ecology in terms of diversity patterns?

Answer 11

More small species than large

More species in the tropics

As molecualr evolution scales with metabolic rate so faster molecular evolution = faster speciation

Question 12

What is the relationship between body mass and dispersal?

Answer 12

Inceased body mass = increased dispersal

Question 13

What is the relationship between body size and extinction risk? Why?

Answer 13

Larger the body size, the more vulnerbale they become to extinction

Due to hunting/persecution and how life histories correlate (e.g. larger animals have slower reproductive rates)

Question 14

What is Bergmann’s rule?

Answer 14

Tendency for a positive association between the body mass of a species in a monophyletic higher taxon and the latitude inhabited by those species

Question 15

What did Bergmann originally observe?

Answer 15

Body size increases at high latitudes in mammals

this was an INTRA-specific pattern

Question 16

What conclusions can be made from testing Bergmann’s rule?

Answer 16

There is a common pattern

Occurs intra nd inter-specifically

Driven by multiple processes - temperature and species turnover being major ones

Question 17

What was the hypothesis for Allen’s rule?

Answer 17

Shorter appendages conserve heat and longer appendages are more effective in dissipating heat