Chapter 51: Population Ecology
Which of the following assumptions have to be made regarding a mark-recapture estimate of population size? Marked and unmarked individuals have the same probability of being trapped. The marked individuals have thoroughly mixed with the population after being marked. No individuals have entered or left the population by immigration or emigration.
1, 2, and 3
In July 2008, the United States had a population of approximately 302 million people. How many Americans were there in July 2009, if the estimated 2008 growth rate was 0.88 percent?
304.7 million
In 2008, the population of New Zealand was approximately 4,275,000 people. If the birth rate was 14 births for every 1,000 people, approximately how many births occurred in New Zealand in 2008?
60,000
You wish to estimate the size of a population of rabbits living in a large urban park. What is the best method to use?
A capture set of rabbits, mark and release them, then capture a second set of rabbits.
Colonization of a new habitat
A few individuals start a new population in a new habitat with plentiful resources
Cohort
A group of individuals born at the same time
Age Class
A group of individuals of a specific age
Population
A group of individuals that belong to the same species and live in the same area
Recovery after disaster
A population has been devastated by a storm, flood, deforestation, or some other type of catastrophe and then begins to recover, starting with a few surviving individuals.
Metapopulation
A population of populations connected by dispersal.
Which population would be most likely to experience exponential growth?
A young population with few individuals
Two types of factors to determine range:
Abiotic factors: temperature, rainfall, the presence of geographical structures like mountains and oceans, and large-scale ongoing historical processes such as continental drift Biotic factors: past and current interactions with other species that provide habitat, food, or competition.
Which of the following would be an example of a population?
All the fleas living on your dog
What factors were shown experimentally to cause the lynx-hare cycles?
An interaction of top-down and bottom up interactions.
The number of individuals present in a population depends on four processes?
Birth, death, immigration, and emmigration.
Which of the following leads to growth of a population?
Births
Populations grow as a result of ?
Births and immigration
What is the difference between logistic and exponential growth model predictions when population numbers become high?
Both models are the same at low population densities, but when densities are high, growth is reduced or stopped in the logistic model, whereas growth continues in the exponential model regardless of population.
A(n) __________ distribution pattern occurs when resources are patchy.
Clumped
The dense school of fish in the opening slide might be best described as which type of distribution?
Clumped distribution
Which of the following is a factor that is used to calculate population growth?
Death Rate
Populations decline as a result of?
Deaths and emmigration
Life History
Describes how an individual allocates resources to growth, reproduction, and activities or structures that are related to survival.
Geographic Distribution
Distribution and abundance are two fundamental concepts in Ecology.
Uniform Distribution
Distribution where populations are spaced evenly
In the presence of strong density dependent factors within a population, growth will exhibit exponential growth?
False
Unhuman population growth projection estimates hinge on?
Fertility rate
Low Fecundity & High Survivorship
Few offspring, large offspring, late maturity, large body size, high disease resistance, high predator resistance, and long-life span
Survivorship Curve
Graph showing the number of survivors in different age groups for a particular species.
Logistic Growth
Growth pattern in which a population's growth rate slows or stops following a period of exponential growth
Age Structure
How many individuals of each age alive.
Type I
Humans and many other mammals have what biologists call a Type I survivorship curve. In this pattern, survivorship throughout a life is high and then drops dramatically in old age, indicating that most individuals approach the species' maximum life span.
White-tailed deer were quite rare across the northeastern United States approximately 100 years ago, but now their populations are generally considered to be too high. What do you predict has caused this?
Hunting females was prevented, and the intrinsic fecundity rate is actually quite high.
Why does the 2009 U.S. population continue to grow even though the United States has essentially established a zero population growth?
Immigration
Experiments performed on the bridled goby in coral reefs and on song sparrows on Mandarte Island support the hypothesis that density-dependent effects can cause logistic population growth. What conclusions can be drawn from logistic growth models?
Individuals survive better and clutch size increases when the population density is low.
During the Zootoca vivipara study, researchers monitored individuals on a daily basis to document the number of young produced by each female in the wild. What would be the best way to obtain the same type of data but not have to visit the site every day?
Install cameras on site to monitor lizard activity
What best explains snow-shoe hare-lynx population?
Interaction of food availability and predication intensity
What is the trade-off between like expectancy and fecundity?
Investing more resources in reproduction means there are fewer resources available for survival.
Carrying Capacity
Is defined as the maximum number of individuals in a population that can be supported in a particular habitat over a sustained period of time.
Metapopulations
Is made up of small, isolated, populations.
Population Ecology
Is the study of how and why the number of individuals in a population changes over time and space.
In some European countries, the population is declining. In these countries the net reproductive rate R0 is ?
Less than 1
A(n) __________ summarizes the probability that an individual will survive and reproduce in any given time interval over the course of its lifetime.
Life table
The carrying capacity cam be observed in which type of population growth?
Logistic growth
Top-down Hypothesis
Lynx populations reach high density in response to increases in hare density. At high density, lynx eat so many hares that the prey population crashes
Type III
Many insects and plants have this type of curve. A pattern defined by extremely high death rates for larvae or seedlings (which are produced in relatively large numbers) but high survival rates for individuals that make it past this risky age.
High Fecundity & Low Survivorship
Many offspring, small offspring, early maturity, small body size, low disease resistance, low predator resistance, and short-life span
N=(Mn)/m
Mark-recapture method N=total population size M=# of marked originally in capture m=# recaptured/ previously marked n=# captured
Intrinsic Rate of Increase, rmax
Meaning birth rates per individual are as high as possible and death rates per individual are as low as possible-then r reaches a maximal value.
Although humans are widely dispersed across the globe, until relatively recently most people rarely ventured more than a short distance from their home region. Because all humans are members of the same species, we form a ?
Metapopulation
Why can metapopulations remain stable over time even if some subpopulations go extinct?
Migration from other subpopulations can repopulate habitat fragments
You originally capture 15 pill bugs and mark them. The next day you capture 10, and 2 of them were previously marked. How big is the pill big population?
N=75 N= 15 x 10/2
Evolution is
Not goal directed
Immigration
Occurs when individuals enter a population by moving from another population.
Emmigration
Occurs when individuals leave a population to join another population.
Exponential Population Growth
Occurs when r does not change over time but the instantaneous growth dN/dt increases as population size N increases due to the product r x N.
Which of the following descriptions is an inference that can be made from these age pyramid models?
Older men are more common in developed countries
Range
Or geographic distribution, of different species.
Evolutionary change occurs in
Populations not organisms
Survivorship
Proportion that survive to a particular age
What type of spatial distribution pattern would be caused by variation in the dispersal of seeds, gametes, or larvae by wind or currents?
Random Distribution
Density Independent
Referring to any characteristic that is not affected by population density.
Density Dependent
Referring to any characteristic that varies according to an increase in population density.
Which species are most likely to be endangered by human activities?
Species with high juvenile mortality, low adult mortality, and low fecundity
Life Table
Summarizes the probability that an individual will survive and reproduce in any given time interval over the course of its lifetime.
Age-Specific Fecundity
The average number of female offspring produced by a female in each age class.
Generation Time
The average time between a mother's first offspring and her daughter's offspring.
Per Capita of Increase
The difference between the birth rate and death rate per individual and is symbolized as r.
What are the implications of the fact that hare populations increase most when food availability is high and predators (lynx) are excluded?
The hare population is controlled by both food supply and the lynx population
Fitness Trade-Offs
The inescapable compromise between two traits that cannot be optimized simutaneously
Population Density
The number of individuals per unit area.
Which of the following statements about exponential growth is true?
The per capita rate of increase, r, is an estimate of the number of births minus the number of deaths
What happens when the population growth when (K-N)/K is zero?
The population does not grow
If we were studying just one of the patches in the diagram and emigration was an issue?
The population would be declining
Demography
The study of factors that determine the size and structure of populations through time.
Population Dynamics
The study of how complex interactions between biotic and abiotic factors influence variations in population size.
Why can't organisms have both high survivorship and high fecundity?
There is limited resources and therefore there has to be a trade-off between the two.
Immigration increases the population size of the population that is being studied?
True
Several sub-populations existing in discrete patches that make up an overall population for an area could be described as a metapopulation?
True
Draw the curve using the number of survivors for the life table of zootoca vivipara. What type of survivorship curve did you find?
Type II
Type II
Type II survivorship curves occur in species where individuals have about the same probability of dying in each year of life. Blackbirds and other songbirds have this type of curve. They generally experience parental care early in life, preventing high rates of early mortality, but are vulnerable to predation or adverse weather events at any age.
Imagine some terrible disease that strikes and kills great numbers of children but has limited effects on adults. If such a disease were to afflict human populations, what type of survivorship curve would you expect to see four our species?
Type III
A carp has a large number of offspring, but predators eat many of them during the first year of life. Once they survive to maturity, they have few predators. What type of survivorship curve does a carp have and why?
Type III, because carp have a low survivorship initially but a high survivorship once they have matured.
Population Thinking
Variation among individuals in a population is not irrelevant; rather, understanding this variation is key to understanding how populations function and change through time in their abiotic and biotic environments.
Under what conditions might r, the per capita rate of increase, approach r max, the intrinsic rate of increase?
When resources are abundant
Bottom-up Hypothesis
When their populations reach high density, hares use up all their food and starve; in response, lynx also starve
Net Reproductive Rate
Which indicates whether the population is increasing or decreasing (as long as immigration and emigration are insignificant).
Zootoca vivipara lizards maintain feeding and mating territories within their range. Based on these facts, what would you conclude?
Zootoca vivipara are likely uniformly distributed within their range.
A population is a
a group of individuals of a single species that live and interact in one area
What are population dynamics?
changes in populations through time and space
Exponential Growth Equation
dN/dt = rN
Logistic Growth Equation
dN/dt=rN(K-N/K)
In species like sea turtles with high juvenile mortality, low adult mortality, and low fecundity, conservations can most effectively help them by?
focusing on keeping adults alive
The type III survivorship curve has
high initial death rates but later high survivorship (e.g., many insects)
Populations grow due to births and
immigration
Clumped Distribution
individuals are found in groups or patches within the habitat
What is rmax in a species like the giant panda?
it is low
Hanski's study of fritillaries showed that
metapopulations are dynamic over time
Random Distribution
organisms arranged in no particular pattern
Evolution does not
perfect organisms
Which of the following is a constant for a given species?
rmax, the intrinsic rate of increase