LIFE 320: Midterm 2

What do the two views of succession, Gleasonian and Clementsian, define?

What is the intermediate disturbance hypothesis and an example?

What are the various seral stages? Provide examples of each.

What is a Type I survivorship curve?

A population that experiences low mortality early in life and high mortality later in life, seen in humans, bears, elephants, and whales.

What is a Type II survivorship curve?

A population that experiences constant mortality throughout its lifespan, seen in squirrels and corals.

What is a Type III survivorship curve?

A population with high mortality early in life and high survival later in life, seen in weeds.

What species are cosmopolitan in range?

Species with large geographic ranges that can span several continents, which include orcas and mosquitoes.

What is the net reproductive rate?

The total number of female offspring that we expect an average female to produce over the course of her life.

What does a life table contain?

Class-specific survival and fecundity data, typically based on the number of female offspring per female.

Explain the mark-recapture survey.

Researchers capture and mark a subset of a population from an area, return it to the area, and capture a second sample of the population after time has passed.

What are habitat corridors?

Strips of favorable habitat are located between two large patches of habitat that facilitate dispersal.

What is negative density dependence?

When the rate of population growth decreases as population density increases, often caused by limited resources.

What is positive density dependence?

When the rate of population growth increases as population density increases, which typically occurs when population densities are low.

What is density dependence?

What is the logistic growth model?

A growth model that describes the slowing growth of populations at higher densities, which has an S-shaped curve.

What is sexual dimorphism?

A difference in the phenotype between males and females of the same species.

Explain some of the mating patterns. These include monogamy, polygyny, polyamory, and more.

What is inbreeding, and what is a species that commonly does it?

The mating of individuals that are closely related, which cheetahs commonly do.

What is inbreeding depression?

A family of responses that happen after inbreeding, including reduced fitness, genetic variability, and changes in mean trait characteristics.

What is genetic drift?

Sampling errors alter allele frequencies, which occurs when populations are small. It changes genotypes and allele frequencies.

What is the founder effect?

What is demographic stochasticity?

Variation in birth rates and death rates due to random differences among individuals.

What is environmental stochasticity?

Variation in birth rates and death rates due to random changes in the environmental conditions.

What is a source population?

A population in a high-quality patch that produces a large number of individuals that disperse to other patches.

What is a sink population?

A population in a low-quality patch that produces few individuals and relies on dispersers to keep the sink population from going extinct.

What is a metapopulation?

What is apparent competition?

When two species have a negative effect on each other through a shared enemy, including a predator, parasite, or herbivore.

What is exploitative competition?

Competition in which individuals consume and drive down the abundance of a resource to the point that other individuals cannot make use of it. It is considered indirect, occurring through a shared resource.

What is allelopathy?

A type of interference competition that occurs when organisms use chemicals to harm their competitors. It is an effective strategy for invasive plants.

What is habitat fragmentation?

The process of breaking up large habitats into a number of smaller habitats, which often occurs as a result of human activities.

Explain the basics of the carbon cycle.

Explain the basics of the nitrogen cycle.

Explain the basics of the phosphorus cycle.

What is alpha diversity?

The local diversity is the number of species in a relatively small area of a homogenous habitat, such as a stream.

What is beta diversity?

The number of species that differ in occurrence between two habitats. If stream A has five species not found in stream B, and stream B has three species not found in stream A, then beta diversity is eight.

What is gamma diversity?

The regional diversity is the number of species in all of the habitats that comprise a large geographic area.

What is species sorting?

The process of sorting species in the regional pool among localities according to their adaptations and interactions.

What is mutualism?

What is commensalism?

What is parasitism?

What is a compass sense?

Using the Sun, moon, or stars to maintain orientation.

What is the biogeographic filter?

What is the local filter?

What is vertical migration, and what species do it?

What is a biological control?

What is eusociality?

Several adults with overlapping generations of parents and offspring live together in a group and cooperate in nest building and brood care. This results in reproductive dominance by one or a few individuals and the presence of sterile individuals.

What is a census?

Counting every individual in a population, which is not feasible for most species.

What is a survey?

Counting a subset of a population.

What is a spatial structure?

The pattern of density and spacing of individuals in a population.

What is a geographic range?

A measure of the total area covered by a population. For example, temperature and drought define the range of the sugar maple.

What are endemic species?

Species that live in a single, often isolated, location, including koalas or giant tortoises.

What is population density?

The number of individuals per unit area in volume, which is calculated by dividing abundance by area.

What is dispersion?

The spacing of individuals with respect to one another.

What is clustered dispersion?

Individuals are dispersed in discrete groups, often clustering around resources in social groups.

What is evenly spaced dispersion?

Each individual maintains a uniform distance between itself and its neighbors, often in defended territories or croplands.

What is random dispersion?

The position of each individual is independent of that of other individuals, which is not common.

What is population dispersal?

The movement of individuals from one area to another, distinct from migration, which is a movement back and forth between habitats. It helps species avoid areas of high competition or predation risk.

What is a line-transect survey?

A survey that counts the number of individuals observed as one moves along a line, which can be converted into area estimates of a population. The Christmas Bird Count is a good example.

What makes doing either a census or a survey difficult?

Many animals are sensitive to the presence of researchers and will leave the area when surveyed, and other species are camouflaged and may be difficult to find.

How is population size estimated in the mark-recapture survey?

Researchers estimate that the number of marked recaptured individuals divided by the total number of individuals captured in the second sample is equal to the number of initially captured individuals divided by the population size.

What are the variables in the Lincoln-Peterson Index, N = MS/R?

N is the estimated population size.

M is the number of marked animals released.

S is the size of the second sample.

R is the number of marked animals recaptured.

What is a lifetime dispersal distance?

The average distance an individual moves from where it was born to where it reproduces, which provides an estimate for how fast a population can increase its range.

What is demography?

The study of populations.

What is the intrinsic growth rate?

The highest possible per capita growth rate, the new individuals minus the individuals that have died, for a population.

What is the exponential growth model?

A model of population growth in which the population increases continuously at an exponential rate, with a J-shaped curve.

N_t = N₀e^rt

What is the geometric growth model?

A model of population growth that compares population sizes at regular time intervals, expressed as a ratio of population size in one year to population size in the preceding year.

What are density-independent limitations?

Factors that limit population size regardless of the population density, often climatic events including tornadoes, floods, extreme temperatures, and droughts.

What are density-dependent limitations?

Factors that affect population size in relation to the population density.

What is the inflection point?

The point on a sigmoidal growth curve where the population has its highest growth rate.

When does the rate of increase stop growing in the logistic growth model?

When the population reaches half its carrying capacity.

What do different age structure diagrams imply?

Broad bases indicate a growing population, narrow bases indicate a declining population, and straight sides indicate a stable population.

What is fecundity?

What is parity?

What is a cohort life table?

A life table that follows a group of individuals born at the same time from birth to the death of the last individual.

What is a static life table?

A life table that quantifies the survival and fecundity of all individuals in a population during a single time interval.

What is an overshoot?

When a population grows beyond its carrying capacity. This often occurs when the carrying capacity of a habitat decreases from one year to the next.

What is a die-off?

A substantial decline in density after an overshoot that typically goes well below the carrying capacity.

What are population cycles?

The regular oscillation of a population over a longer period of time.

What is delayed density dependence?

When density dependence occurs based on a population density at some time in the past. As the time delay increases, density dependence is delayed, and the population is more prone to either overshoot or undershoot.

When r_T is less than what value, the population approaches the carrying capacity without oscillations?

0.37

What values does r_T have to be between for a population to exhibit damped oscillations?

0.37 and 1.57.

What is a damped oscillation?

A pattern of population growth where the population initially oscillates, but the magnitude of the oscillations declines over time.

What values does r_T have to be above for a population to exhibit a stable limit cycle?

1.57

What is a stable limit cycle?

A pattern of population growth where the population continues to exhibit large oscillations over time.

Are smaller or larger populations more prone to extinction?

Data suggest that small populations are more likely to go extinct, but growth models suggest that small populations should have more rapid growth and be resistant to extinction. This can be resolved by incorporating random variation of growth rates into growth models.

What is a deterministic model?

A model that is designed to predict a result without accounting for random variation in population growth rate.

What is a stochastic model?

A model that incorporates random variation in population growth rate. It assumes that variation in birth and death rates is due to random chance.

What does the basic metapopulation model assume about habitat fragmentation?

That all habitat patches are equal in quality and the matrix between patches is inhospitable.

What are subpopulations?

A large population broken up into smaller groups that live in isolated patches.

What is the basic metapopulation model?

A model that describes a scenario in which there are patches of suitable habitat embedded in a matrix of unsuitable habitat. All suitable patches are assumed to be of equal quality.

What is the landscape metapopulation model?

The most realistic and complex spatial structure of the basic metapopulation model. It considers both differences in patch quality and matrix quality.

When does the rescue effect occur?

When dispersers supplement a declining subpopulation and thereby prevent it from going extinct. Less isolated patches are more likely to be rescued.

What is the inbreeding coefficient?

F, which is the probability that two alleles within an individual are identical by descent. Spans from a value of zero, or no relatedness, to one, fully related. As F increases, fitness often decreases.

What are deleterious alleles?

They cannot be acted upon by natural selection unless they affect phenotypes.

What are effective populations?

What is asexual reproduction?

A reproduction mechanism in which offspring inherit DNA from one parent.