Deck 43: Population Ecology

Question 1

Population ecologists study the factors affecting the distribution and abundance of

A) organisms of a single species living in a defined geographic location.
B) organisms of more than one species living in a defined geographic location.
C) organisms of a single species living in geographically separate locations.
D) ecosystems to enable organisms to exist.
E) human infertility.

Answer 1

organisms of a single species living in a defined geographic location.

Question 2

Population ecology is concerned with the dynamics of

A) communities of organisms.
B) communities of organisms and their non-living surroundings.
C) groups of organisms of the same species.
D) ecosystems to enable organisms to exist.
E) biomes.

Answer 2

groups of organisms of the same species.

Question 3

A group of organisms of the same species living in a geographically distinct area is defined as a

A) realised distribution.
B) biome.
C) community.
D) habitation.
E) population.

Answer 3

population.

Question 4

An example of a biotic factor that may influence the abundance of a population of bivalve molluscs on a rocky shore is the

A) height of the bivalves on the shore relative to the low tide mark.
B) average velocity of waves striking the rocks on which the bivalves live.
C) salinity of the sea water in which the bivalves live.
D) number of people who regularly collect the bivalves for food.
E) temperature of the water.

Question 5

The potential distribution of a native tussock grass in central Victoria would best be determined by

A) carefully surveying the entire region and recording where it is growing.
B) excluding grazing animals from experimental plots where the grass is not currently growing and monitoring these plots to see if it begins to grow there.
C) transplanting the grass to locations where it is not currently growing and monitoring its survival and reproductive success in the new locations.
D) finding historical records of where it has grown in the past.
E) identifying how far the seed is able to disperse.

Question 6

Predictions about which areas of Australia may be colonised by a new species of marine pest would best be made by

A) estimating the species' potential distribution.
B) measuring the species' realised distribution.
C) studying records of where, in Australia, other pest species have been a serious problem.
D) determining the temperature range for its growth.
E) knowing that the species will only colonise an area around the point of its introduction and that the size of the area will be equal to the distance that a larva of the species can disperse from its parent.

Question 7

The rare ground parrot, Pezoporus wallicus, prefers patches of heath land. One group is found at Barren Grounds in NSW and they would form

A) a community.
B) a population.
C) a niche.
D) a group.
E) an allopatric species.

Question 8

In the environment of an organism, temperature is a factor that is

A) density dependent.
B) abiotic.
C) ecological.
D) biotic.
E) logistic.

Question 9

The distribution of a plant is likely to be influenced by

A) temperature.
B) other species present.
C) pollinator availability.
D) composition of the soil.
E) All of the answers are correct.

Question 10

Transplant experiments show that an endangered species of Banksia has the potential to grow in many areas of eastern Australia; however, it is only found in Western Australia. This is probably because of

A) the presence of a geographic barrier.
B) soil type.
C) habitat preference.
D) response to burning.
E) historical climate change.

Question 11

A closed population is characterised by

A) no immigration.
B) linear growth.
C) a density-dependent growth rate.
D) exponential growth.
E) a fluctuating population.

Question 12

The most appropriate method of estimating the abundance of large, highly mobile animals would be

A) quadrats.
B) transects.
C) sieving.
D) mark-recapture techniques.
E) studying population dynamics.

Question 13

A population showing density-independent dynamics can increase in the following ways:

A) birth, competition and predation.
B) birth and emigration.
C) birth and immigration.
D) birth, immigration and an increase in available resources.

Question 14

An ecologist decides that the aphids she is studying have density-independent population dynamics. This means that

A) birth and death rates per individual will not vary in response to the number of aphids in the population.
B) as the population grows in size the birth rates per individual must drop because resources will be in greater demand.
C) as the population grows in size the birth rates per individual must rise as there will be more reproductive individuals.
D) the population will fluctuate dependent on the climate.
E) it is impossible to tell how an increase in population size will affect birth and death rates.

Question 15

A closed population showing density-independent growth contained ten seasonally breeding females. If the geometric mean growth factor (R) for the population is two, then when the ecologist returns at the end of five years she would expect to count approximately

A) 320 females.
B) 20 females.
C) 5 females.
D) 320 individuals.

Question 16

A stochastic model of population growth uses

A) a mean figure for the population growth factor to give an estimate of population size at time t.
B) an exact figure for the population growth factor to predict the precise number of individuals that will be in a population at time t.
C) an exact figure for the population growth factor to give an estimate of population size at time t.
D) an exact figure for the population growth to give the precise number of individuals at time t.
E) a mean figure for the population growth factor to predict the precise number of individuals that will be in a population at time t.

Question 17

Male marsupial mice (Antechinus stuartii) die after mating in the spring. Death is therefore

A) logistic.
B) density-dependent.
C) density-independent.
D) stochastic.
E) density-vague.

Question 18

A population has an intrinsic growth rate R, which is less than zero (R < 0). Over time, you would expect the population to

A) grow exponentially.
B) grow linearly.
C) decline.
D) become extinct.
E) remain constant.

Question 19

In the early phases of a species colonising a new area

A) its rate of spread is proportional to its growth rate.
B) the population usually grows linearly.
C) the population usually decreases exponentially.
D) the population usually grows exponentially.
E) its rate of spread is inversely proportional to its growth rate

Question 20

Hermit crabs live in the shells of dead marine snails. When the supply of empty shells available to a hermit crab population was experimentally increased, the growth rate of the hermit crab population increased. This could be seen as evidence of

A) negative density-dependent population growth in the hermit crab population.
B) positive density-dependent population growth in the hermit crab population.
C) density-independent population growth in the hermit crab population.
D) density-vague population growth in the hermit crab population.
E) an imminent decline in the hermit crab population.

Question 21

Density-dependent population growth is likely to be a constant factor for populations of

A) any organism that is living at low density
B) the types of insects that show large fluctuations in population size and sometimes appear in plague proportions.
C) birds and other large vertebrate predators.
D) any organism that can experience exponential increases to high densities.
E) all organisms.

Question 22

Space would most likely be the limiting resource for organisms from which of the following groups?

A) Sessile, long-lived marine sponges that feed on food suspended in the water column.
B) Vertebrate carnivores such as lions that hunt over long distances in search of food.
C) Very large planktivores such as blue whales.
D) Sharks which must cover large areas looking for food.
E) All of the answers are correct.

Question 23

A small quantity of bacteria is placed in a jar containing an abundant food supply. Initially you would expect growth to be

A) density dependent.
B) linear.
C) exponential.
D) spasmodic.
E) slow.

Question 24

The carrying capacity (K) of a population is

A) the theoretical maximum number of individuals the environment could support.
B) the equilibrium population number reached when numbers of births and deaths are equal.
C) the initial increase in growth in a density-dependent population.
D) determined by the initial number of organisms.
E) independent of environmental conditions.

Question 25

Fecundity is best defined as

A) an organism's probability of reproducing.
B) an organism's probability of surviving.
C) the number of individuals in a population able to reproduce.
D) the number of individuals recruiting.
E) the settlement rate of sessile organisms.

Question 26

Which of the following relationships is described by the -3/2 self-thinning rule?

A) Plant weight is linearly related to plant density.
B) Plant weight is independent of growth rate.
C) Plant weight is inversely proportional to the growth rate of plants.
D) Plant weight is inversely proportional to the density of plants.
E) The number of individuals in a population able to reproduce.

Question 27

For an algal species living on an exposed rocky reef, a severe storm represents

A) a disturbance.
B) a stochastic event.
C) an opportunity for new recruits.
D) an opportunity for dispersal.
E) All of the answers are correct.

Question 28

The Department of Fisheries wishes to know how many blue fin tuna can be caught without endangering the population. Fisheries biologists would attempt to estimate

A) maximum sustainable yield.
B) equilibrium potential.
C) exponential growth range.
D) growth rate.
E) survivorship.

Question 29

Stochastic models

A) are not very useful tools for natural resource management because, in this important field, precise predictions must be used.
B) are important natural resource management tools because these models take account of the natural variation that occurs in the environment.
C) have not been used since modern computers became readily available to ecologists.
D) are important natural resource management tools because they give very precise predictions.
E) are essential for the management of exploited populations.

Question 30

Which of the following statements about conservation biology is true?

A) Understanding the maximum sustainable yield is essential to avoid extinction of animals.
B) Species cannot become extinct by chance alone.
C) Minimum viable population sizes are based on a probability of extinction of 1 percent.
D) There is no population size that can guarantee the persistence of a species.
E) An absolute minimum viable population size can be calculated for any species.

Question 31

Successful reproduction of flowering plants may depend on

A) the availability of a specific animal pollinator, an abiotic factor.
B) the temperature and climate, a biotic factor.
C) the realised distribution of the plant.
D) the availability of water, a direct environmental factor.
E) All of the answers are correct.

Question 32

Potential distribution may be determined by

A) the abiotic properties of where it grows.
B) the biotic properties of the surrounding land.
C) the number of pests in the area of growth.
D) the geographic range where individuals survive.
E) All of the answers are correct.

Question 33

The fundamental niche of an animal is

A) the temperature where the animal is living.
B) the total range of environmental conditions under which the animal may live and reproduce.
C) the habitat in which the animal lives the longest.
D) the habitat in which the animal chooses to live.
E) the area where the rate of reproduction is fastest.

Question 34

Population ecologists distinguish between two types of population, open and closed. In a closed population with density-independent birth and death rates there will be

A) an exponential increase in size.
B) a linear increase in size.
C) a decrease in size.
D) remain the same size.
E) All of the answers are possible.

Question 35

Population dynamics are determined by looking at population growth over discrete time intervals. However in the continuous-time model of population growth,

A) the population grows exponentially.
B) the intrinsic rate of increase determines the fate of the population.
C) the population remains constant.
D) the population increases linearly.
E) the population declines towards zero.

Question 36

Density-vague population dynamics describes

A) a population in which size fluctuates enormously.
B) a population in equilibrium due to an increase in population size causing a decrease in growth rate.
C) a population where size is influenced by environmental factors.
D) the dynamics of a population limited by resources and space.
E) the dynamics of a species whose population appears to be independent of population size.

Question 37

When a population experiences density-dependant growth, a decrease in population size results in a

A) decrease in growth rate.
B) equilibrium state.
C) steady death rate.
D) growth rate of one.
E) increase in growth rate.

Question 38

A population ecologist is studying a newly discovered population of small marsupials. After several months of careful observation and data collection, she determines that the population is increasing at an exponential rate. What could explain this observation?

A) The population is currently experiencing an evolutionary bottleneck.
B) There is limited food resources available.
C) The population has been in the habitat for a significant length of time.
D) It is a closed population.
E) The population is small.

Question 39

A fishery that harvests wild, migrating salmon has a carefully calculated MSY and annually takes a catch that is below this limit. The fishery maintains a consistent catch for many years and monitors conditions in the catch area which they use to adjust their MSY accordingly. However, despite no changes in the catch area, there is a sudden and sharp decline in fish stocks. What could explain this observation?

A) There is a decline in available food stocks.
B) A prolonged, extreme weather event in the high latitude rivers where the salmon spawn caused a sharp drop in recruitment.
C) The MSY was incorrectly calculated in the first instance.
D) The population has reached its carrying capacity.
E) The maturation rate of the population has slowed

Question 40

A large population of Eucalyptus delegatensis is separated into separate, smaller populations due to topographical restrictions. Collectively, these populations are a

A) exopopulation.
B) fragmented population.
C) geopopulation.
D) propopulation.
E) metapopulation.

Question 41

How does the realised distribution of a plant population correlate with its potential distribution?

A) They are usually the same.
B) They are always the same.
C) They are usually different.
D) They are always different.
E) The level of correlation is dependent on the level of population dynamism.

Question 42

When studying populations that breed continuously, what sort of equation is best suited to modelling their rate of change?

A) Binomial
B) Exponential
C) Quadratic
D) Differential
E) Linear

Question 43

Which of the following is an example of a biotic limitation on a population's growth?

A) Disease
B) Nesting sites
C) Food
D) Drought
E) All of the options listed are incorrect.

Question 44

A national park houses a rare population of Helmeted Honeyeaters (Lichenostomus melanops cassidix). The park rangers need to understand the dynamics of the population in order to effectively develop conservation policies. Specifically, the rangers need to describe the effect of age on the survival of the population, as earlier studies have revealed that many of the fertile individuals are well into adulthood. What is a useful tool that could be employed to describe this?

A) Develop a fecundity chart
B) Construct a life table
C) Catch the oldest individuals and measure their longevity in response to various environmental pressures
D) Measure the fecundity of young females
E) Analyse the population dynamics by employing a self-thinning rule equation

Question 45

A scientist has assessed the minimum viable population of the Helmeted Honeyeater (Lichenostomus melanops cassidix) in the national park. However, two years after the completion of this work, analysis reveals that the population is fragmented within the national park and breeding is only occurring within very small sub-populations. This impact on a species's likelihood of extinction is known as

A) a molecular meta-bottleneck.
B) nucleic plasticity.
C) genetic stochasticity.
D) transcriptional decoupling.
E) demographic contingent.