Biology Chapter 36
A group of individuals belonging to one species and living in the same geographic area.
Population
Type I survivorship curves are characteristic of what type of organisms.
Squid and human populations
If an ecosystem has a carrying capacity of 1,000 individuals for a given species, and 2,000 individuals of that species are present, we can predict that the population ______
size will decrease.
For a _____ distribution, as the population size changes, animals that are younger or less fit will be pushed to theoutside of the cluster.
clustered
In ______situations the animals are clumped together in little groups. Imagine things like bird nesting colonies. You may have a lot of birds in the population but they all nest in the same colony.
clustered
dN/dt = rN
continuous change equation,a differential equation that talks about an instantaneous change in numbers. exponential growth
A human population will achieve zero population growth if
couples have an average of about 2.25 children each (to account for some children who do not survive to reproduce).
What type of organisms display the Type III survivorship curve?
invertebrates, sea urchins or lobsters, things that are larvae when they're young, their larvae are part of the plankton that everything in the ocean eats so when you are young, a lot of you die. Once you become an adult sea urchin, your survivorship is much better.
Describing a dispersion pattern in which individuals are evenly distributed.
uniform
Populations that are uniformly distributed, have some size that the individual maintains and therefore the individuals would be distributed in a _____ packing manner based on the size of the territory.
uniform
The concept that in certain (K-selected) populations, life history is centered around producing relatively few offspring that have a good chance of survival.
K-selection
Density Dependent Factors influencing Population size
Predation. Mates (depending on mating structure - monogamy or harem) Space / Territory size Competition - Intraspecific competition is between individuals of the same species. Interspecific competition is between individuals of different species. If you are a deer and you live near cattle, or goats, you compete with the goats for food. Resources - food and water. Pollution - Remember yeast: they will utilize cellular respiration until they run out of oxygen. Once they start to run out of oxygen they switch to alcohol fermentation. Eventually it kills them because alcohol is a toxin so it is for them a waste that at some point will kill them. The same is true of all sorts of organisms. Wastes are often toxic or, as in the case of cholera, they allow the replication of things that are bad for the organisms. Disease
A population of fungi in a yard produces 10 mushrooms in year 1, 20 in year 2, and 40 in year 3. If this trend continues, by year 5 there will be ________ mushrooms.
160
At low population sizes, you don't have very many individuals, and so you don't have very many genes. What do we call that?
A founder effect.
Which of the following best illustrates a feature of K-selection? A mother elephant spends several years protecting her baby. A female frog produces more than a thousand eggs each year. Fireweed spreads quickly into a portion of a forest that has recently been burned. Young members of a population experience high predation
A mother elephant spends several years protecting her baby.
An ecologist hypothesizes that predation by a particular owl species is the major factor controlling the population of a particular rabbit species. If this is the case, which of the following population effects could be expected in this rabbit-owl pair? A fall in the rabbit population should cause an increase in the owl population. An increase in the incidence of disease in the rabbit population should not change the owl population. A fall in the owl population should cause a fall in the rabbit population. An increase in the owl population should cause a fall in the rabbit population.
An increase in the owl population should cause a fall in the rabbit population.
Describing a dispersion pattern in which individuals are aggregated in patches.
Clumped
Which of the following statements about human population growth is true? During a demographic transition, birth rates typically drop first due to the availability of reliable contraception. Demographic transition is a transition from high birth rates and high death rates to low birth rates and low death rates. Human population size on Earth today is at equilibrium. Human population size has increased faster and faster throughout human history.
Demographic transition is a transition from high birth rates and high death rates to low birth rates and low death rates.
______ and _____ end up being a fairly common consequence of the exponential population growth model.
Founder effects...extinctions
If a population has a birth rate of 40 individuals per 1,000 per year and a death rate of 30 individuals per 1,000 per year, how will the population change each year? (Assume that the population is below carrying capacity and that there is no immigration or emigration.)
It will increase by 1%.
Density Independent Factors
Random factors - If a tree falls in a forest and knocks over some small mammal, is that density dependent or independent? Probably independent. What about random factors like landslides - for people that may not be true. Why might that not be true for people? Because of the way we excavate and irrigate. Similarly, avalanches. Earthquakes, Volcanoes - Earthquakes and volcanoes don't occur in proportion to density. "acts of God."
At K, what is being maximized?
The ability to find a place in the population or their ability to find their niche
ΔN = rN
The equation for exponential growth
A small population of 1,000 mice lives on a 100-acre island in the middle of a large lake. One dry summer, the lake level drops dramatically. The island's size increases to 1,000 acres, and the island remains at this expanded size. The vegetation quickly spreads, and the mouse population grows. The population expands greatly, doubling in size each year for three straight years. However, the hawk populations expand too. From the fourth year until the present, the death rate of the mouse population has been equal to the birth rate. Which of the following statements about this population of mice is true? The current mouse population is much less than the carrying capacity. The new population is about 16,000 mice. The logistic curve for this population will be J-shaped. The population density of the mice went from 10 mice per acre before the lake level changed to 8 mice per acre at its new carrying capacity.
The population density of the mice went from 10 mice per acre before the lake level changed to 8 mice per acre at its new carrying capacity.
(Nt - Nt-1) = rN
This is a difference equation. exponential growth The change in numbers, ΔN, is equal to the number at time T- the number at time T minus 1 (one time period earlier).
______survivorship curve shows early , high mortality (low survivorship) but once you get to a certain age you live pretty well.
Type III
Biologists studying red-tailed hawks in eastern Kentucky discovered that the hawks mainly ate squirrels. We would expect that _____. a decrease in the food supply of squirrels in this region would result in a decline in the red-tailed hawk population a decline in the red-tailed hawk population would cause a decline in the squirrel population if people started killing red-tailed hawks, we would have fewer squirrels an increase in the food supply of squirrels in this region would result in a decline in the red-tailed hawk population
a decrease in the food supply of squirrels in this region would result in a decline in the red-tailed hawk population
(Nt - Nt-1) = rN[(K-N)/K ]
a difference equation for logistic growth
dN/dt = rN[(K-N)/K ]
a differential equation for logistic growth
What does (K) represent in the logistic growht equation?
arrying capacity. In other words, the carrying capacity is going to be the number of individuals that the environment can support sustainably
The relative number of individuals of each age in a population.
age structure
In a population, the number of individuals that an environment can sustain.
carrying capacity
The maximum number of individuals a habitat can support is called its _______.
carrying capacity.
A shift from zero population growth in which birth rates and death rates are high to zero population growth characterized instead by low birth and death rates.
demographic transition
A population-limiting factor whose intensity is linked to population density. For example, there may be a decline in birth rates or a rise in death rates in response to an increase in the number of individuals living in a designated area.
density dependent factor
The manner in which individuals in a population are spaced within their area. Three types of dispersion patterns are clumped (individuals are aggregated in patches), uniform (individuals are evenly distributed), and random (unpredictable distribution).
dispersion pattern
A method of using multiple constraints, including food, fuel, water, housing, and waste deposits, to estimate the human carrying capacity of the Earth.
ecological footprint
Type II survivorship curves are characteristic of what type of organisms.
elephants, Mortality for an elephant is uniform across the lifespan. Younger elephants can be killed by predators but older ones are pretty good
At the carrying capacity, births ____ deaths.
equal
During _____ growth, the population is selected so those individuals that can maximally reproduce are favored.
exponential
The ______ growth model does not have a limit in the equation. It goes up forever.
exponential
A mathematical description of idealized, unregulated population growth.
exponential growth model
Above carrying capacity, deaths are _____ than births.
greater
Below the carrying capacity, births will be ____ than deaths.
greater
An r-selected species typically offers considerable parental care to offspring. has an advantage in habitats that experience unpredictable disturbances. is large-bodied and long-lived. lives in stable climates.
has an advantage in habitats that experience unpredictable disturbances.
The series of events from birth through reproduction to death.
life history
A listing of survivals and deaths in a population in a particular time period and predictions of how long, on average, an individual of a given age will live.
life table
ΔN = rN[(K-N)/K ]
logistic growth equation
A mathematical description of idealized population growth that is restricted by limiting factors.
logistic growth model
The level of harvest that produces a consistent yield without forcing a population into decline.
maximum sustained yield
Which of the following increases human population growth? medical advances that decrease infant mortality delayed age at first reproduction the increased availability of birth control an increase in the death rate, perhaps due to war or epidemics
medical advances that decrease infant mortality
In the euqations what does (N) represent?
number of individuals
The average contribution of each individual in a population to population growth.
per capita rate of increase
Mortality is relatively low but then increases rapidly once organisms reach a certain age.
type I survivorship curve
The number of individuals of a species per unit area or volume.
population density
The study of how members of a population interact with their environment, focusing on factors that influence population density and growth.
population ecology
In a population in which r = 0, the continuation of population growth as girls in the prereproductive age group reach their reproductive years.
population momentum
The ______ can have an effect on distribution.
population size
In the euqations what does (r) represent?
r is the intrinsic rate of reproduction. If I can optimize this population to reproduce maximally, that is r. Given unlimited resources and absolutely the best environment possible, that rate of reproduction is r.
The concept that in certain (r-selected) populations, a high reproductive rate is the chief determinant of life history.
r-selection
Describing a dispersion pattern in which individuals are spaced in a patternless, unpredictable way.
random
A plot of the number of members of a cohort that are still alive at each age; one way to represent age-specific mortality.
survivorship curve
where mortality is uniform across the lifespan
type II survivorship curve
Which of the following represents an example of a population? the eastern gray squirrels that live in New York City's Central Park all of the mammals living in the region of Boulder, Colorado the gray squirrels and fox squirrels living in Springfield, Illinois the red foxes found east of the Mississippi River in the United States
the eastern gray squirrels that live in New York City's Central Park
Which of the following is the best example of an abiotic factor limiting population size? the amount of aquatic plants eaten by snails in a pond the frequency of rainfall needed for the germination of desert plant seeds the spread of deadly human flu virus from one person to another by touching and sneezing the number of dead standing trees available as nesting sites for downy woodpeckers
the frequency of rainfall needed for the germination of desert plant seeds
Which of the following would be a limiting factor for growth of a population of downy woodpeckers living in the Ozark Mountains of southwestern Missouri? lack of black rat snakes that feed on young woodpeckers living in this area the presence of West Nile virus in this region, which has been known to kill a wide variety of birds, including downy woodpeckers limiting insecticide use in the area to control mosquito populations (the food source of downy woodpeckers) introduction of individuals of the same species from other areas
the presence of West Nile virus in this region, which has been known to kill a wide variety of birds, including downy woodpeckers
You represent a timber company that specializes in Douglas fir trees. You manage 10,000 acres for the company. On this property are mostly mature Douglas firs 200 to 300 years old. However, productivity of Douglas fir trees peaks between 60 and 90 years of age. Past studies have indicated that Douglas fir trees follow the logistic growth model. Which of the following will likely decrease your timber harvest over the next 50 years? practicing sustainable resource management in the newly planted regions, thinning the forests at 20 to 40 years of age increasing the fertility of the soil waiting to harvest trees in their most mature stages of growth, when they are over 200 years old
waiting to harvest trees in their most mature stages of growth, when they are over 200 years old
