Evolution 2

Question 1

What are processes that affect population size?

Answer 1

Births, deaths, emigration and immigration.

Question 2

What are intrinsic factors that affect population size?

Answer 2

Factors such as the age of first reproduction - directly related to the individual and are built into the genetic basis of the individual.

Question 3

What are extrinsic factors that affect population size?

Answer 3

External factors such as predation and natural catastrophes.

Question 4

What are density dependent factors?

Answer 4

Factors that affect the size of the population in a way dependent on the size of the population such as the effects of food supply.

Question 5

What are density independent factors?

Answer 5

Factors that influence populations independently from population size such as the effects of weather and catastrophic events.

Question 6

What is the population change dependent on?

Answer 6

Births-deaths.

Question 7

What is more useful than calculating births and deaths over a certain time?

Answer 7

Per capita birth/death rate.

Question 8

What is r?

Answer 8

Intrinsic growth rate.

Question 9

What is the exponential population growth curve?

Answer 9

dN/dt = r (instant)N where dN is a small change in the number of individuals and dt is a small change in time.

Question 10

What do we know if we know r?

Answer 10

The population dynamics.

Question 11

What prevents populations from growing indefinitely?

Answer 11

Limited resources.

Question 12

When does growth start to decrease?

Answer 12

As the number of individuals approaches the carrying capacity of the environment.

Question 13

What other factors beside the carrying capacity are important?

Answer 13

Lagtime in the response to change in conditions.

Question 14

What is population growth linked to?

Answer 14

Life history traits.

Question 15

What are life history traits determined by?

Answer 15

Evolutionary constraints and natural selection.

Question 16

Example of animal that lives for a short time but produces lots of offspring?

Answer 16

Flies.

Question 17

Example of animal that lives for a long period of time but only produces a few offspring?

Answer 17

Albatrosses.

Question 18

What is life history?

Answer 18

The pattern of allocation to growth, development, reproduction, survival etc.

Question 19

What does semelparous mean?

Answer 19

Only one reproductive season.

Question 20

What does iteroparous mean?

Answer 20

Have many reproductive seasons.

Question 21

What are some life history traits?

Answer 21

Age and size at reproduction, number of reproductive seasons, life span, number and size of offspring.

Question 22

What are the predictions for the perfect life history?

Answer 22

Mature at birth, continuously produce high-quality offspring in large numbers and live forever.

Question 23

Why does the perfect life history not exist?

Answer 23

The amount of resources available to an organism is finite - this generates trade offs.

Question 24

What may a mutation result in in terms of life history strategies?

Answer 24

There may be an increase in the focus on reproduction rather than maintenance or growth.

Question 25

What is a common trade off?

Answer 25

Life span vs reproductive output.

Question 26

Why is life span different from senescence?

Answer 26

Life span is only determined by senescence if an organism lives in a protected environment.

Question 27

What is senescence?

Answer 27

The condition of process of deterioration with age.

Question 28

Even if an organism could live forever, why doesn't it?

Answer 28

Due to random chance, predators and parasites.

Question 29

What is life span a result of?

Answer 29

An organisms genetics and its environment.

Question 30

What is a result of the factors influencing lifespan?

Answer 30

The probability of reproducing reduces with age.

Question 31

Why do organisms not always reproduce really early?

Answer 31

Larger individuals produce more and/or larger offspring.

Question 32

What happens if reproduction occurs too early?

Answer 32

There is not sufficient resources and there is selection to reproduce later.

Question 33

What happens if reproduction occurs too late?

Answer 33

Death comes before reproduction and there is selection to reproduce earlier.

Question 34

What does natural selection favour?

Answer 34

Maximum total fitness - for organisms that reproduce multiple times, the number of progenies is important, and not just the size of the clutch.

Question 35

How does mortality rate differ between deer nursing and deer not nursing?

Answer 35

Mortality for deer that are not nursing is much less than for those that are nursing.

Question 36

What did experiments with male drosophila show about reproduction?

Answer 36

Males kept with inseminated females/no females lived longer than those kept with virgin females.

Question 37

Why can large numbers of large offspring not be produced?

Answer 37

There are limited resources.

Question 38

What does natural selection favour in terms of clutch size?

Answer 38

The clutch size that produces the most surviving offspring.

Question 39

What is experimental evidence for the ideal clutch size?

Answer 39

Experiment with a magpie - showed that the modal clutch size of 7 is optimum- maximises the size of the offspring.

Question 40

Why do extremes still exist between number and size of offspring?

Answer 40

Different environments may favour different strategies.

Question 41

What are r selected populations?

Answer 41

They reproduce rapidly and use resources wastefully. Their success relies on finding new resources elsewhere.

Question 42

What are K selected populations.

Answer 42

They breed slower and use resources more efficiently.

Question 43

What are the characteristics of R selected populations?

Answer 43

They have small organisms, short life time, large progenies, small offspring and high dispersal. There is low competition, high predation.

Question 44

What are the characteristics of K selected species?

Answer 44

They are larger individuals that are slow to mature and have few large offspring. There is high parental care and competitive environments. There is a high risk of mortaility in these environments.