Lecture 22

Question 1

What is a life history?

Answer 1

pattern of survival and reproductive events for a species

Question 2

Why do life histories look so different between species?

Answer 2

life history patterns are an ‘optimization’ of tradeoffs between growth, survival, and reproduction

Question 3

What are some factors to consider when studying reproductive behaviour?

Answer 3

• how many offspring are produced per reproductive episode (fecundity)
• when reproduction begins (age at maturity)
• single vs multiple reproductive events (semelparity, iteroparity)

Question 4

Define fecundity

Answer 4

an organism’s reproductive capacity

• the higher its fecundity, the less energy it needs to invest per offspring

Question 5

Define parental investment

Answer 5

the energetic investment into each offspring (e.g. egg size, seed size, amount of parental care)

quantity vs quality tradeoff b/w number of offspring and a parent’s energetic investment in the individual offspring

Question 6

Example of how parental care is costly

Answer 6

• Researchers in Netherlands tested effects of parental caregiving in Eurasian kestrels over 5 years
• female parents with large broods had lower survival rates
• caring for more offspring negatively affected survival of the parents

Question 7

Pros & Cons of reproducing early?

Answer 7

• less risk of producing no offspring at all; HOWEVER, this may be at expense of their health + growth
• using all energy to reproduce so less energy used to grow - makes them more susceptible to predators

Question 8

Pros & Cons of reproducing late?

Answer 8

• organisms that produce later have better ‘fecundity’ (??) and are better able to care for their young
• run the risk of not surviving to reproductive age

Question 9

What is a semelparous species?

Answer 9

characterized by a single reproductive event before death

e.g. most invertebrates

Question 10

What is an iteroparous species?

Answer 10

characterized by multiple reproductive events throughout its lifetime

Question 11

Distinguish b/w K selected species and r-selected species

Answer 11

K-selected = density dependent

r-selected = density independent

Question 12

K selected species

Answer 12

• low rates of fecundity
• high levels of parental investment in the young
• low rates of morality of mature individuals
  LOGISTIC GROWTH

K – controlled more by carrying capacity + display more stable populations

Question 13

r selected species

Answer 13

• high rates of fecundity
• short gestation
• low levels of parental investment in young
• high rates of morality before individuals mature
  EXPONENTIAL GROWTH