Ecology Exam 2: Population Dynamics, Competition, Predation, Parasitism, and Mutualism

A set of 100 comprehensive vocabulary flashcards covering life tables, population demography, metapopulations, competition models, predator-prey dynamics, parasitism, and mutualism based on the Exam 2 lecture notes.

Age structure

The proportion of individuals in different age groups within a population.

Survivorship curve

A graphical representation showing the proportion of individuals surviving to each age interval within a population.

Type I survivorship curve

A survivorship curve characterized by low mortality during early and middle life followed by rapid mortality in older individuals (late mortality).

Type II survivorship curve

A survivorship curve characterized by a roughly constant mortality rate throughout the lifespan of the organism.

Type III survivorship curve

A survivorship curve characterized by high initial mortality among offspring followed by relatively high survivorship among older individuals.

Cohort life table

A life table that tracks a single cohort of individuals from birth until all have died, directly recording their survival and reproduction.

Static life table

A life table that records survival patterns by observing individuals of various ages at a single snapshot in time or by using ages at death (e.g., from skulls, horns, or teeth).

Doubling time

The amount of time required for a population to double in size, calculated as $t = \frac{\ln(2)}{r}$.

Carrying capacity ($K$)

The maximum population size of a species that a given environment can sustainably support using its available resources.

Time lag

A delay in time between changes in population density and their resulting effects on population growth, survival, or reproduction.

Density-independent regulation

Population regulation by factors whose effects on population growth do not depend on the density of the population.

Density-dependent regulation

Population regulation influenced by population density, where per capita growth rate changes due to factors like competition for food or space.

Net reproductive rate ($R_0$)

The average number of female offspring produced by an individual female over her entire lifetime, calculated as $R_0 = \sum l_x m_x$.

Average generation time ($T$)

The average age of mothers at the birth of their offspring, calculated as $T = \frac{\sum x l_x m_x}{R_0}$.

Instantaneous per capita population growth rate ($r$)

The instantaneous rate of population change per individual, calculated as $r = \frac{\ln(R_0)}{T}$.

Finite population growth rate ($\lambda$)

The proportional change in population size over a discrete time interval, defined as $\lambda = \frac{N_{t+1}}{N_t}$.

Demographic transition

A shift in a population from high birth and death rates to lower birth and death rates.

Demographic stochasticity

Random, chance fluctuations in individual birth, death, and reproductive events that cause population size to vary.

Delayed density dependence

A phenomenon where population growth responds to population density after a time lag, often inducing oscillations around carrying capacity.

Source population

A local population in a high-quality habitat where reproduction exceeds mortality, producing excess individuals that disperse elsewhere.

Sink population

A local population occupying poor-quality habitat where mortality exceeds reproduction, unable to sustain itself without continuous immigration.

Rescue effect

The prevention of a sink population from going extinct via incoming migration from a source population.

Cattle egrets population growth

An ecological example of an invasive species that exhibited exponential population growth upon colonization.

Tasmanian sheep population growth

An ecological example of an introduced species that exhibited logistic population growth as it approached carrying capacity.

Allee effect

A decrease in per capita reproduction or survival at very low population densities, often caused by difficulty finding mates.

Environmental stochasticity

Unpredictable, random environmental fluctuations and events (such as droughts or storms) that increase the probability of extinction.

Habitat fragmentation

The division of continuous large habitats into smaller, isolated fragments, which reduces gene flow and increases genetic drift and inbreeding.

Metapopulation

A set of spatially separated local populations of the same species that interact and are connected via migration and dispersal.

Patch extinction rate ($e$)

The rate at which local populations in occupied habitat patches go extinct in a metapopulation.

Patch colonization rate ($c$)

The rate at which currently unoccupied habitat patches are successfully colonized by dispersing individuals.

Metapopulation occupancy model

A simple equilibrium model describing the proportion of occupied patches as $P = 1 - \frac{e}{c}$.

Metapopulation assumptions

Assumptions of the simple model including an infinite number of identical habitat patches, equal patch chances of colonization/extinction, and colonization occurring faster than extinction.

Exponential growth model

A density-independent growth model occurring with unlimited resources and no carrying capacity, described by $\frac{dN}{dt} = rN$.

Logistic growth model

A density-dependent growth model where per capita growth slows as population approaches carrying capacity, described by $\frac{dN}{dt} = rN\left(1 - \frac{N}{K}\right)$.

Intraspecific competition

Competition for resources occurring between members of the same species.

Interspecific competition

Competition for shared limiting resources occurring between individuals of different species.

Exploitative competition

Indirect competition occurring when individuals reduce the availability of a shared limiting resource by consuming it.

Interference competition

Direct competition occurring when an individual directly prevents another from accessing or utilizing a resource.

Symmetric competition

Competition in which both competing species experience similar degrees of negative effects on fitness or growth.

Asymmetric competition

Competition where one species experiences a significantly greater negative effect than its competitor.

Niche breadth

The total range of environmental conditions and resources that a particular species utilizes.

Niche overlap

The extent to which two or more species share common resources or environmental conditions.

Fundamental niche

The full range of physical and environmental conditions under which a species could persist in the absence of biotic restrictions like competition.

Realized niche

The actual range of environmental conditions and resources a species occupies when biotic interactions such as competition are present.

Niche partitioning

The evolutionary or behavioral division of resources among species to reduce competition and facilitate coexistence.

Competitive exclusion

The complete displacement or elimination of one species by another when competing for the same limiting resources without niche differentiation.

Competitive release

The expansion in population size, geographic distribution, or resource use of a species following the removal of a competitor.

Character displacement

The evolutionary divergence of morphological, physiological, or behavioral traits where competing species live in sympatry.

Competitive hierarchy

A ranking of competing species along a linear dominance gradient from superior to inferior competitors.

Competitive network

A non-linear, multi-directional network of competitive interactions where no single species dominates unconditionally.

Competition coefficient ($\alpha$)

A constant converting the per capita competitive effect of species 2 into equivalent individuals of species 1, calculated as $\alpha = \frac{\text{resources used by species 2}}{\text{resources used by species 1}}$.

Competition coefficient ($\beta$)

A constant converting the per capita competitive effect of species 1 into equivalent individuals of species 2, calculated as $\beta = \frac{\text{resources used by species 1}}{\text{resources used by species 2}}$.

Zero growth isocline

A phase-plane trajectory representing all population size combinations of two species at which the population growth of one species equals zero.

Stable coexistence

A competitive outcome where both species persist indefinitely and return to a stable equilibrium point after small disturbances.

Unstable coexistence

A competitive equilibrium where small disturbances cause one species to displace and exclude the other.

Diffuse competition

Competition resulting from the combined, simultaneous impacts of multiple competing species rather than a single competitor.

Indirect effects

Ecological interactions where one species influences another species through intermediate effects on third-party species.

Competitive exclusion principle

The ecological principle stating that two species competing for identical limiting resources cannot coexist indefinitely under stable environmental conditions.

Multidimensional niche

A multidimensional hypervolume comprising various physical and biological factors (such as diet, humidity, and feeding location) required by a species.

MacArthur's warblers

A classic field study demonstrating niche partitioning, where five coexisting warbler species fed in different zones of the same spruce trees.

Sympatry

The geographic condition where populations or species occur in the same area, favoring trait divergence to minimize interspecific competition.

Allopatry

The geographic condition where populations or species occur in separate areas, often resulting in more similar resource use due to absent competition.

Carnivore

An organism that feeds primarily or exclusively on other animals.

Herbivore

An organism that feeds primarily or exclusively on living plant tissues.

Omnivore

An organism that regularly feeds on both plant and animal matter.

Aposematic coloration

Conspicuous, bright warning coloration warning potential predators that an organism is toxic, unpalatable, or dangerous.

Crypsis

Camouflage adaptations that allow an organism to blend into its background and avoid visual detection by predators or prey.

Mimicry

An evolutionary adaptation where one species physically or behaviorally resembles another organism to gain protection from predators.

Vigilance

The behavioral vigilance of actively watching the surroundings to detect predators before an attack occurs.

Predator satiation

A defensive strategy where prey produce offspring synchronously in such massive numbers that predators are overwhelmed and become satiated.

Stable limit cycle

A persistent, recurring predator-prey population oscillation that maintains continuous cyclic fluctuations over time.

Prey refuge

A spatial location, morphological threshold, or temporal window that prevents predators from consuming prey, stabilizing dynamics.

Habitat heterogeneity

Structural variation and complexity across a habitat that provides refuges and alters dispersal, helping stabilize predator-prey interactions.

Functional response

The change in the number of prey consumed per predator as a function of changing prey population density.

Numerical response

The change in predator abundance or population size resulting from changes in prey availability and density.

Search image

A learned perceptual recognition screen developed by a predator for an abundant prey type, increasing its hunting efficiency.

Top-down control

The regulation of population densities at lower trophic levels by consumers or predators at higher trophic levels.

Induced defense

A defensive chemical, morphological, or behavioral response activated or upregulated only after an organism detects a threat or attack.

Red Queen hypothesis

The evolutionary hypothesis stating that organisms must continuously adapt and evolve just to maintain their relative fitness against co-evolving species.

Type I functional response

A linear functional response where the number of prey eaten per predator increases proportionally with prey density until saturation.

Type II functional response

A saturating functional response where prey intake initially increases with prey density but gradually decelerates to a plateau due to handling time.

Type III functional response

A sigmoidal (S-shaped) functional response where prey consumption starts slowly at low prey densities, accelerates at intermediate densities, and then levels off.

Predator aggregative response

The behavioral movement and concentration of predators in patches with high prey density.

Predator interference

Negative interactions among foraging predators at high densities that reduce individual predatory efficiency.

Ectoparasite

A parasite that attaches to and lives on the external surface of its host organism.

Endoparasite

A parasite that lives inside the cells, tissues, or internal organs of its host organism.

Parasitoid

An organism (typically a wasp) whose developing larvae feed on or inside a host organism, ultimately killing the host.

SIR model

An epidemiological model categorizing host populations into Susceptible ($S$), Infected ($I$), and Recovered ($R$) individuals.

Disease transmission rate equation

The rate of change in infected individuals, given by $\frac{dI}{dt} = \beta S I - m I$, where an infection spreads when $\frac{dI}{dt} > 0$.

Mutualism

An interspecific interaction between two species in which both interacting partners obtain a net fitness benefit ($+$ / $+$).

Obligate mutualism

A mutualistic interaction essential for survival, where at least one partner cannot survive or reproduce without the other.

Facultative mutualism

A mutualistic interaction that provides fitness benefits to both species, but is not strictly necessary for either species' survival.

Mycorrhizae

A mutualistic symbiosis between plant roots and soil fungi, in which the plant receives nutrients/water and the fungus receives photosynthetic carbon.

Extrafloral nectary

A nectar-secreting structure located on vegetative plant tissue outside of flowers that attracts protective ants.

Beltian bodies

Specialized nutrient-rich protein and lipid structures produced on the leaflets of acacias to nourish symbiotic ants.

Zooxanthellae

Photosynthetic endosymbiotic algae that live within the tissues of reef-building corals, providing energy in exchange for nutrients and shelter.

Conditional mutualism

A mutualistic interaction that provides a net benefit under certain environmental conditions, but becomes neutral or costly under others.

Cheater

An organism that exploits a mutualistic interaction by extracting benefits without providing reciprocal rewards or services.

Evolutionary Stable Strategy (ESS)

A behavioral strategy that cannot be displaced or invaded by an alternative strategy when it is adopted by most members of a population.

Relative neighbor effect (RNE)

A quantitative metric measuring the degree to which neighboring plants help (facilitation, positive value) or harm (competition, negative value) target plant growth.