Life Histories

Question 1

Why are there variations in life histories?

Answer 1

due to physical or physiological constraints and trade-offs, among competing functions

Question 2

What are examples of ways life histories can vary?

Answer 2

growth, competitiveness, reproduction, tolerance of extremes, defense

Question 3

How was Lack’s Optimal Clutch Size Model determined?

Answer 3

optimal clutch size determined by trade-offs between number of eggs laid and egg size

Question 4

What is optimal clutch size?

Answer 4

highest number of offspring from intermediate clutch sizes

Question 5

Why would a bird lay less than “optimal” amount of eggs?

Answer 5

based upon fitness elements, as a way of hedging against possible future environmental change

Question 6

Is behavior learned?

Answer 6

not entirely, some aspects are hardwired and genetics

Question 7

What is type I survivorship?

Answer 7

parental care, large offspring size
- starts high number of survivors and stays steady until dropping near end of % of lifespan

Question 8

What is type II survivorship?

Answer 8

steady decline

Question 9

What is type III survivorship?

Answer 9

very few survive in beginning, but once get big/old enough live long time

Question 10

What is an example of type I survivorship?

Answer 10

humans

Question 11

What is an example of type II survivorship?

Answer 11

rodents, adult birds

Question 12

What is an example of type III survivorship?

Answer 12

sea turtles

Question 13

What is fecundity?

Answer 13

number of offspring/eggs produced per individual per year

Question 14

What would have the greatest positive effect on R?

Answer 14

increasing survivorship on hatchlings

Question 15

In a life history table what is lx?

Answer 15

survivorship to age (x)

Question 16

In a life history table what is mx?

Answer 16

average birth rate per individual at age (x)

Question 17

What is the net reproductive rate per generation in life history table?

Answer 17

sum of (lx)(mx)

Question 18

What is the generation time from a life history table?

Answer 18

sum of [(X)(lx)(mx)] / sum of (lx)(mx)

Question 19

What do r selected species do?

Answer 19

• maximize reproduction
• populations able to grow fast in non-competitive conditions

Question 20

What do K selected species do?

Answer 20

• maximize competitive ability
• maintain stable population near K

Question 21

What is resource allocation?

Answer 21

the amount of resources devoted to competing demographic functions

Question 22

What is the cost of reproduction?

Answer 22

reduction in growth or survivorship associated with reproduction

Question 23

What species make up Grimes “Triangle”?

Answer 23

• ruderal species
• competitive species
• stress tolerant species

Question 24

What are ruderal species?

Answer 24

• similar to r-selected, favor reproduction
• low stress, high disturbed environments

Question 25

What are competitive species?

Answer 25

• similar to K selected, favor growth
• stable, low stress environments

Question 26

What are stress tolerant species?

Answer 26

• grow and reproduce slowly, favor survivorship
• stable, stressful environments

Question 27

What does the Winemuller and Rose system apply to?

Answer 27

ocean species

Question 28

What are the species in the Winemuller and Rose system?

Answer 28

• opportunistic
• equilibrium
• periodic

Question 29

What are opportunistic species?

Answer 29

• similar to ruderal
• mature early, few offspring, can exploit very unpredictable conditions

Question 30

What are equilibrium species?

Answer 30

• mature late, few offspring, high juvenile survivorship, suited for predictably stable conditions

Question 31

What are periodic species?

Answer 31

• mature late, many offspring, low juvenile survivorship, suited for environments that periodically become favorable

Question 32

How can fitness in offspring be increased?

Answer 32

parental care

Question 33

What does the degree of parental fitness depend on?

Answer 33

fitness benefit gained

Question 34

What is the desertion threshold?

Answer 34

abandonment of offspring when benefits of continued care are low

Question 35

What is an example of demographic plasticity?

Answer 35

adjusting parental investment based on current conditions

Question 36

How do bluegills have an alternate reproductive strategy?

Answer 36

• “normal” males defend nest
• “sneaky” males mimic females

Question 37

What trade off do bluegills experience?

Answer 37

sneaky males are smaller, reproduce earlier, and produce more sperm