Ch13: Life History (r/K)

Question 1

Define life history

Answer 1

Survival and reproductive events throughout an organisms life cycle

Question 2

What are the 3 stages of life?

Answer 2

1) Juvenile: non-reproductive + major growth

2) Reproductive

3) Non-reproductive: rest or too old to breed

Question 3

Difference between semelparous and iteroparous?

Answer 3

Semelparous: organisms are only able to reproduce ONCE in their lives
- usually followed by death of the parent as they have invested all of their resources into reproducing and birth

Iteroparous: organisms are able (have the capacity to) reproduce multiple times throughout their life cycle (do NOT die immediately after)

Question 4

Difference between annual and perennials?

Answer 4

Annual: an organism fulfills its life cycle in a SINGLE year
- goes through all phases of life in this year

Perennials: an organisms life cycle is spread over several (>1) years
- have (generally) repeated breeding phases that are predictable; depend on seasons and resource availability

Question 5

Define fecundity

Answer 5

the number of offspring a species is capable of producing

Question 6

Define parental investment and describe how parental care affects survival rate

Answer 6

Investment: amount of energy the parent puts into each offspring (ie~ egg size, seed size, or parent care)

Care/energy invested: decreases survival rate of parents as it is energetically (and resource) costly that there may be negative effects

Question 7

Do plants give parent care? If not what do they give instead?

Answer 7

No, but they invest in seed size

Question 8

Quality vs quantity in terms of fecundity?

Answer 8

Quality: less offspring = rely on care of a parent to survive

Quantity: increases chance at least SOME survive (less parental investment)

Question 9

Difference between early and late reproductive strategies?

Answer 9

Early: invest energy into reproduction = generally small + short lifespans
- unable to protect themselves as well, but reduce the risk of dying before they are able to reproduce (reach reproduction phase)

Late: invest energy into growth
- generally large + longer life spans (able to protect themselves)
- increase risk of dying before being able to reproduce

Question 10

What is the trade-off of reproduction?

Answer 10

When an organism is reproducing they use their energy on reproduction and NOT on growth

So when they have lots of energy (or nitrogen for plants) they will reproduce

Question 11

r vs K selected species for:
a: Intrinsic rate of increase (rMAX)
b: suitable to population density
c: competitive ability
d: development
e: reproduction
f: body size
g: offspring

Answer 11

a: Intrinsic rate of increase (rMAX)
- r = High
- k = low

b: suitable to population density
- r = Low
- k = High

c: competitive ability
- r = Low
- k = High

d: development
- r = Fast
- k = Slow

e: reproduction
- r = Early in life (semelparous)
- k = Late in life (iteroparous)

f: body size
- r = Small
- k = Large

g: offspring
- r = Many
- k = Few

Question 12

How does population growth generally respond to favourable environments in r vs k selected species

Answer 12

r = generally respond rapidly to favourable environments

k = stable populations (lower levels of growth)

Question 13

Describe booms and busts for r-selected species. NOTE: these are usually seasonal

Answer 13

Booms: when conditions are optimal = due to life history strategy

Busts: resources decrease/disappear = major drop in population

Question 14

What do k-selected species experience rather than booms/busts, and what are these due to?

Answer 14

They experience fluctuations; these are due to biotic and abiotic factors