biology 4.1

A scientist counted 200 individual deer in an area of 10 square kilometers. What is the population density?

20 deer per square kilometer

Is there evidence to suggest that the wolf population crashed? Is there to evidence to suggest that the moose population crashed? What might have caused these crashes?

A dramatic drop in the wolf population began around 1978. The population continued to crash even as the moose population rebounded, and plenty of prey was available. The moose population began to dramatically drop around 1994. With few predators, the moose population likely exceeded the environment's carrying capacity.

Ten years later, scientists return to the same area and find that the population density has declined to 5 deer per square kilometer. What might a decrease in the density of a deer population tell scientists about the habitat in the area?

Consider what may have changed in the ecosystem, such as predator/prey relationships or environmental factors, and how that may have affected the resource availability in the area.

What might cause exponential growth to occur only for a short period when a new species is introduced to a resource-filled environment?

Eventually, the growing population will consume all available resources, and the species may experience a population crash.

Describe three advantages an individual organism might have by living in a population with a clumped dispersal pattern.

Individuals do not have to move very much to find mates, organisms have better protection from predators, and there is more access to food resources.

What might happen when the carrying capacity for a population suddenly drops?

Population sizes decrease until the remaining resources can support them.

A herd of zebras has 9 males and 62 females. During a one-year period, 22 foals that are born survive and 25 adults die. Six females join the herd. Three males and 11 females leave the herd. Has the ecosystem reached carrying capacity for the herd? How do you know?

The ecosystem has reached its carrying capacity because the growth rate is negative.

A songbird has an equal chance of surviving at all stages of its life. According to the graph, which type of survivorship does the songbird exhibit?

Type II

A female salamander lays hundreds of eggs at a time. However, after hatching, few of the larvae survive to adulthood. According to the graph, which type of survivorship does the salamander exhibit?

Type III

A population of warblers experiences a period of exponential growth. Which of these factors would be a density-dependent limiting factor that could decrease the carrying capacity of the ecosystem for the warbler population?

a competing species moves into the forest

A population of deer is displaced by a massive flood in their habitat following a severe rainstorm. The flood is an example of

a density-independent limiting factor.

Predict the conditions that may occur when a population is in exponential growth.

birth rate is greater than death rate, birth rate is greater than death rate

A population of antelope has a negative population growth rate. Which of these conditions must also be true for the population growth rate to be negative?

births + immigrations < deaths + emigrations

fish is an example of what population disperation?

clumped

exponential growth

dramatic increase in population over a short period of time

density-independent factor

environmental resistance that affects a population regardless of population density (weather, natural disaters, human actvity)

density-dependent factor

environmental resistance that affects a population that has become overly crowded (competiton, predation, parasitism and disease)

survivorship curve

graph showing the surviving members of each age group of a population over time

Which of these abiotic factors would contribute to a clumped dispersion pattern in an ecosystem?

limited water, limited rainfall, moderate temperatures

Type III species produce__________offspring and provide ____________parental care. Examples of Type III species include fish and insects. By contrast, Type I species produce__________offspring and provide_________parental care.

more, less, fewer, more

carrying capacity

number of individuals that the resources of an environment can normally and persistently support

logistic growth

population growth that is characterized by a period of slow growth, followed by a period of exponential growth, followed by another period of almost no growth

what is R=(b+i) - (d+e)

r=population growth, b=born, i= immigation, d=death, e=emmigation

sloth is an example of what poplation disperation?

random

A population of rodents is introduced on a remote island due to a shipwreck. Eventually, the population reaches the island's carrying capacity. At this point, the birth and death rates are

relatively equal.

ducks are examples of what population disperation?

uniform