Ecology Exam 3 homework review

For a population with a growth rate of 2 per 1,000/year, how would you express that growth rate as a percentage?

0.2%

Growth rates are often presented as percentages, which are calculated by multiplying the growth rate (per 1,000 individuals per year) by 100: growth rate/1,000 × 100 = growth rate (%)

1.2%

Assume there are 200 MendAliens living on an island in my back yard. If my island has an area of 20 hectares, what is the population density of MendAliens in terms of MendAliens per hectare?

10 MendAliens per hectare

Suppose you are studying a population with the following characteristics: Birth rate = 14 per 1,000/year Death rate = 6 per 1,000/year Immigration rate = 5 per 1,000/year Emigration rate = 1 per 1,000/year What is the growth rate for this population? 4 per 1,000/year 12 per 1,000/year 14 per 1,000/year 26 per 1,000/year

12 per 1,000/year

An ecologist spent a year studying the population dynamics of a species of duck on a lake. At the beginning of the year, there were 86 adults. Of these, 16 adults left the lake, 12 adults arrived on the lake from elsewhere, 76 chicks hatched from eggs, 24 chicks survived to become adults, and 8 adults died. How many individuals emigrated?

16

Suppose you are studying a population with the following characteristics: Birth rate = 11 per 1,000/year Death rate = 10 per 1,000/year Immigration rate = 4 per 1,000/year Emigration rate = 3 per 1,000/year What is the growth rate for this population? 0 per 1,000/year 2 per 1,000/year 14 per 1,000/year 28 per 1,000/year

2 per 1,000/year

You are doing a mark-recapture experiment to determine the population size of the MendAliens living on an island in my back yard. Initially, you catch and mark 130 MendAliens, which you then release. Next, you capture 90 MendAliens, of which 20 are marked. What is your estimate of the population size of MendAliens living on the island in my back yard?

585

What characteristics of lionfish contribute to their ability to spread and become established in new areas?

A single lionfish female may produce up to 2 million eggs a year. The eggs float for up to a month, spreading the lionfish populations.

How did the fish biologists determine the diet of lionfish in the regions where the lionfish have invaded?

Biologists examined the contents of the stomachs of lionfish caught in the wild.

Simberloff mentions Mediterranean cheatgrass as one example of a non-native species that has affected millions of acres. If Davis were the scientist talking to reporters, how might he frame the issue?

Cheatgrass is causing regional declines of native plant communities.

Which of the following statements about population distributions and densities is true?

Dispersal plays a major role in range expansion for populations that have been introduced into a new region.

Which of the following is not true regarding the seagrass Cymodocea nodosa?

It can reproduce sexually but does not have separate male and female individuals.

Why do we classify lionfish populations near the eastern United States as an invasive species? What suggests that these new populations are not an expansion of the lionfish's natural range?

Lionfish are native to the tropical Pacific. There are no natural water routes of warm water between the Pacific and Atlantic oceans.

Which of the following statements about the movement of organisms is FALSE?

Many plants use active dispersal mechanisms, like wind, for dispersal.

Mark Davis argues that non-natives rarely threaten natives with extinction. Davis would further say that:

None of the thousands of native plant species in North America has ever gone totally extinct due to a non-native species.

In 1958 federal law restricted the movement of soil and plants from areas where fire ants were established. Why was this law unsuccessful in stopping the spread of fire ant colonies?

People were unaware of the federal law and, when they moved, transported plants bearing fire ant colonies; a single mated queen can be transported without being noticed; and many states thought to be free of fire ant colonies already had them.

The mark-recapture method would be best for sampling a population of

Sharks

A new non-native species has recently been discovered in your area of North America. What information about the species would suggest the need for immediate action?

The non-native species occurs in lakes.

Based upon what we are learning about the lionfish diet, what is most likely going to happen to Caribbean coral reefs invaded by lionfish?

There will be fewer algae eating fish. More algae will grow over and damage corals.

Which of the following is a reason microsatellites are ideal for population studies?

They are typically abundant in all species.

From 1930 to 1939 fire ants spread inland about 60 miles from their point of introduction in Mobile, Alabama. What was the cause of their spread over this distance?

a natural spread

Ignoring migration, the age structure diagram of a human population likely to maintain a relatively stable size will have what shape?

a rectangle tapering toward the top

Based upon what we are learning about invasive lionfish populations in the Caribbean and along the Atlantic coast of the United States, these lionfish populations __________.

cannot be eliminated by any means currently known

In this study, the probability of clonal identity (Fr )

decreased with increasing distance

The meadow of Cymodocea nodosa sampled by Dr. Alberto would best be described as

genetically diverse but spatially dominated by a few large clones

Ignoring migration, the age structure of a human population likely to decrease in size will have what shape?

inverted pyramid

Which of the following statements would the two authors agree on?

many non-native species are not harmful

Daniel Simberloff states that non-native species are responsible for which of the following?

modifying fire regimes

Many plants are __________, which means that they are organisms that have a parental genet connected to asexually produced ramets.

modular

Which of the following sampling techniques represents an index of abundance rather than an estimate of density?

number of bear droppings along a trail

Ignoring migration, the age structure of a human population likely to increase in size will have what shape?

pyramid

In a life table, the age-specific mortality rate is represented by __________.

qx

Demographic stochasticity refers to __________.

random year-to-year variations in a population's birth and death rates

A modified, underground stem that often functions in asexual reproduction is called a

rhizome

Techniques used, or are being considered for use, in controlling the spread of fire ants include _____.

setting baits that kill the queen when they are carried back to the nest, applying chemical powders that kill the colony, introducing a protist to infect the fire ant queen and her eggs, and introducing a fly that lays eggs in fire ants so that the eggs will hatch into larvae that eat their way into the ants' heads, which will then fall off

Environmental heterogeneity often causes a population to be divided into __________.

subpopulations

How might a species' range be extended?

through climate change

In populations of animals that defend an area for their own exclusive use or in plants that compete intensively for belowground resources such as water or nutrients, the spatial distribution of individuals is usually

uniform

The demographic age pyramid of a rapidly growing population is

wide at the base, narrow at the top.

For a population with a growth rate of −3 per 1,000/year, how would you express that growth rate as a percentage?

−0.3%

Suppose you are studying a population with the following characteristics: Birth rate = 10 per 1,000/year Death rate = 12 per 1,000/year Immigration rate = 2 per 1,000/year Emigration rate = 3 per 1,000/year What is the growth rate for this population? −3 per 1,000/year −1 per 1,000/year 17 per 1,000/year 27 per 1,000/year

−3 per 1,000/year