BIOS 230: Population Ecology, Life History, and Species Interactions

Comprehensive vocabulary flashcards covering population ecology, demography, models of growth and regulation, life history strategies, interspecific interactions, predation, and parasitism from BIOS 230 Modules 21 through 28.

Ecology

The scientific study of the distribution and abundance of organisms and the biotic and abiotic interactions that determine that distribution and abundance.

Ecological Hierarchy

The nested organizational levels of ecological systems, ordered from smallest to largest: Individual, Population, Community, Ecosystem, Landscape, Biome, and Biosphere.

Geographic Range

The broadest spatial description of a species' distribution, encompassing the entire area that contains all individuals of that species.

Population Dispersion

The spatial pattern or evenness of individuals within a population's area, classified into random, uniform, or aggregated (clumped) patterns.

Uniform Dispersion

A spatial distribution pattern in which individuals are evenly spaced from one another, resulting from negative interactions such as territoriality or direct competition for limited resources like moisture.

Aggregated (Clumped) Dispersion

The most common spatial dispersion pattern, in which individuals cluster in patches due to localized resource availability or social grouping behavior for predator defense.

Quadrat Sampling

A sampling method used for plants and sessile animals where individuals are counted in standardized subsample plots, allowing total abundance to be estimated as average quadrat density multiplied by total surveyed area.

Mark-Recapture Method

A sampling technique for estimating mobile animal population size ($N$) based on the proportion equation $\frac{M}{N} = \frac{R}{C}$, yielding $N = \frac{MC}{R}$, where $M$ is initial marked individuals, $C$ is total recaptured individuals, and $R$ is marked recaptured individuals.

Demography

The study of statistical properties of populations, including age structure, life tables, mortality rates, and population growth trajectories.

Population Pyramid

An age-sex diagram depicting the proportion of individuals in prereproductive, reproductive, and postreproductive age classes at a specific point in time.

Expanding Population Pyramid

A triangular age structure diagram featuring a wide base due to high birth rates, characteristic of a rapidly growing population.

Contracting Population Pyramid

An age structure diagram characterized by a narrow base resulting from low birth rates, indicating an aging and declining population size.

Stationary Population Pyramid

An age structure diagram with roughly equal proportions across age classes where birth and death rates balance, indicating zero population growth ($r = 0$).

Closed Population

A population in which immigration and emigration do not occur, meaning changes in population size are determined entirely by birth rate ($b$) and death rate ($d$).

Cohort Life Table

A demographic tool that monitors a dynamic cohort—a group of individuals born during the same time interval—from birth until the death of the last individual.

Age-Specific Mortality ($d_x$)

The number of individuals from a cohort that die during a specific age interval ($x$), calculated as $d_x = n_x - n_{x+1}$.

Age-Specific Mortality Rate ($q_x$)

The proportion of individuals alive at the start of an age interval that die during that interval, calculated as $q_x = \frac{d_x}{n_x}$.

Survivorship Curves

Graphical plots of survivorship ($l_x$, plotted on a logarithmic scale) against age ($x$), categorized into Type I, Type II, and Type III curves.

Type I Survivorship Curve

A convex survivorship curve where survival rate remains high throughout most of the lifespan and heavy mortality occurs primarily in old age, typical of humans, large mammals, and $K$-strategists with high parental care.

Type II Survivorship Curve

A linear survivorship curve reflecting a constant mortality rate that does not vary significantly with age, observed in adult birds, rodents, reptiles, and perennial plants.

Type III Survivorship Curve

A concave survivorship curve characterized by extremely high mortality rates among juveniles and early age classes, typical of fish, many marine invertebrates, plants, and $r$-strategists.

Intrinsic Rate of Increase ($r_{\text{max}}$)

The maximum theoretical per capita growth rate of a population when resources are unlimited and environmental resistance is absent.

Exponential Population Growth Model

A mathematical model of unlimited population growth where the rate of change is directly proportional to population size, described differentially as $\frac{dN}{dt} = rN$ and integrated as $N(t) = N(0)e^{rt}$.

Carrying Capacity ($K$)

The maximum sustainable population size that an environment can support under prevailing conditions, reached when per capita birth rate equals per capita death rate ($b = d$).

Logistic Population Growth Model

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

Inflection Point

The point on a sigmoidal logistic growth curve ($N = \frac{K}{2}$) where the absolute population growth rate ($\frac{dN}{dt}$) reaches its maximum value before decelerating toward zero.

Density-Dependent Factors

Biotic regulatory mechanisms (such as intraspecific competition, dispersal, and disease) whose per capita impact on mortality or fecundity intensifies as population density increases, keeping the population near carrying capacity.

Density-Independent Factors

Abiotic environmental factors (such as freezing temperatures, droughts, floods, and natural disasters) that influence birth and death rates regardless of population density, causing population fluctuations without regulating around carrying capacity.

Self-Thinning

A progressive density-dependent process in crowded plant and sessile animal populations in which progressive mortality reduces population density while the average biomass of surviving individuals increases.

Exploitation Competition

Indirect competition (also called scramble competition) where individuals consume a shared, limited resource, reducing its availability and depressing growth, survival, or fecundity equally across the population.

Interference Competition

Direct competition (also called contest competition) where certain individuals actively prevent or restrict others from accessing shared resources through aggression, territoriality, or chemical interference.

Home Range

The total geographic area an animal traverses and utilizes throughout its normal yearly activities to forage, mate, and care for young.

Territory

A specific core portion of an animal's home range that is actively defended against conspecifics using song, visual displays, scents, or physical combat to secure exclusive resource access.

Semelparity

A life history reproductive strategy in which an individual expends all available energy in a single, massive, suicidal reproductive event before dying (known as monocarpy in plants).

Iteroparity

A life history reproductive strategy in which an organism allocates resources to repeated reproductive episodes across multiple breeding seasons throughout its lifetime (known as polycarpy in plants).

Altricial

A developmental pattern in which offspring hatch or are born blind, naked, immobile, and helpless, requiring extensive parental care and energetic investment.

Precocial

A developmental pattern in which offspring emerge from the egg or womb in an advanced state, capable of locomotion and independent foraging shortly after birth.

r-Selected Species (r-Strategist)

Organisms adapted to unstable, unpredictable environments characterized by high reproductive rates, small body size, early sexual maturity, short lifespans, minimal parental care, and density-independent mortality.

K-Selected Species (K-Strategist)

Organisms adapted to stable, crowded environments characterized by low reproductive rates, large body size, delayed reproduction, long lifespans, extensive parental investment, and density-dependent population regulation near carrying capacity.

C-S-R Triangle Theory

J.P. Grime's plant life-history classification model categorizing plant strategies into Competitive ($C$), Stress-tolerant ($S$), and Ruderal ($R$) based on environmental gradients of stress and disturbance.

Ruderal (R) Species

Plant species adapted to high-disturbance, low-stress environments that allocate resources primarily to rapid vegetative growth, early reproduction, and prolific seed dispersal.

Competitive (C) Species

Plant species adapted to low-disturbance, low-stress environments with abundant resources that allocate resources primarily to vegetative growth to outcompete neighbors for light, water, and nutrients.

Stress-Tolerant (S) Species

Plant species adapted to high-stress, low-disturbance habitats that allocate resources primarily to physiological maintenance and persistence rather than rapid growth or high reproductive output.

Reproductive Effort

The total proportion of an organism's time and energy budget allocated to reproduction rather than growth, maintenance, foraging, or defense.

Commensalism

An interspecific interaction designated as $(+, 0)$ in which one species benefits while the other species is completely unaffected.

Amensalism

An interspecific interaction designated as $(-, 0)$ in which one species is harmed or suppressed while the other species remains entirely unaffected.

Competitive Exclusion Principle

The ecological principle asserting that complete competitors living in the same habitat with identical ecological requirements cannot stably coexist; one species will inevitably drive the other to local extinction.

Competition Coefficient ($\alpha$ and $\beta$)

Per capita constants in the Lotka-Volterra competition model expressing the inhibitory competitive effect of one species relative to another ($\alpha$ measures the per capita effect of species 2 on species 1; $\beta$ measures the per capita effect of species 1 on species 2).

Zero-Growth Isocline

A linear boundary plotted on a phase plane representing combinations of population sizes of two competing species where the net population growth of one species equals zero ($\frac{dN}{dt} = 0$).

True Predator

A predator that kills its prey immediately upon capture and consumes multiple individual prey organisms throughout its lifetime (e.g., carnivores, seed-eating rodents).

Parasitoid

An organism (typically a wasp or fly) that deposits eggs on or in a living host; its larvae feed on host tissues and slowly kill the host from the inside out.

Planktivore

An aquatic predator that actively searches for and consumes zooplankton or phytoplankton, distinguished from passive filter feeders.

Functional Response

The relationship describing how the rate of prey consumption per individual predator changes as prey population density increases.

Type I Functional Response

A linear functional response in which the number of prey consumed increases in direct proportion to prey density, meaning the percentage of prey consumed remains constant, typical of passive filter feeders.

Type II Functional Response

A decelerating functional response where consumption rate initially increases but levels off to a plateau at high prey densities due to satiation or handling time constraints, causing the proportion of prey consumed to decline.

Type III Functional Response

A sigmoidal (S-shaped) functional response where consumption is depressed at low prey densities due to prey refuges, lack of search image, or prey switching, accelerates at intermediate densities, and levels off at satiation.

Search Image

A learned perceptual filter developed by a predator that improves its ability to detect and capture a specific cryptic prey type as that prey becomes more abundant.

Prey Switching

The behavior wherein a generalist predator shifts its primary feeding focus away from a scarce preferred prey to an alternate, more abundant prey species.

Numerical Response

An increase in predator population density in response to rising prey density, driven by increased predator reproduction or immigration.

Aggregative Response

A rapid behavioral numerical response in which predators quickly move into and concentrate within localized areas of high prey density.

Red Queen Hypothesis

The evolutionary principle proposing that interacting species (such as predators and prey or hosts and parasites) must continually coevolve adaptations simply to maintain their relative fitness and persist.

Warning Coloration (Aposematism)

Conspicuous bright color patterns utilized by toxic, venomous, or unpalatable organisms to advertise their danger or distastefulness to potential predators.

Cryptic Coloration

Morphological adaptations, such as camouflage and background matching, that allow an organism to avoid visual detection by blending into its environment.

Batesian Mimicry

A mimicry system where an edible, harmless mimic species evolves to resemble an unpalatable or venomous model species to deceive shared predators.

Müllerian Mimicry

A mimicry system where two or more distinct unpalatable or dangerous species evolve convergent warning coloration patterns, mutually reinforcing predator avoidance learning.

Selfish Herd Hypothesis

The concept that animals aggregate into groups because individuals actively position themselves to minimize their personal risk of predation, driven by self-interest rather than cooperative altruism.

Parasitism

An interspecific interaction $(+, -)$ where one organism (the parasite) lives on or inside another living organism (the host), obtaining nutrients while reducing host fitness without killing it immediately.

Ectoparasite

A parasite that lives externally on the skin, scales, feathers, or hair of its host organism (e.g., ticks, lice).

Endoparasite

A parasite that lives internally within the tissues, organs, bloodstream, or gut of its host organism (e.g., tapeworms, roundworms).

Hemiparasitic Plant

A parasitic plant that possesses chlorophyll and photosynthesizes but draws water, minerals, and nutrients from the tissues of a host plant (e.g., European mistletoe, Indian paintbrush).

Holoparasitic Plant

A non-photosynthetic parasitic plant lacking chlorophyll that is entirely dependent upon a host plant for carbon, water, and all nutritional requirements (e.g., Rafflesia, dodder).

Microparasite

A small parasite characterized by short generation times, microscopic size, and rapid intracellular or direct transmission between hosts (e.g., viruses, bacteria, protozoans).

Macroparasite

A relatively large parasite characterized by a long generation time, multicellular structure, and a complex life cycle often involving intermediate hosts (e.g., flatworms, nematodes, parasitic arthropods, fungi).

Definitive Host

The specific host organism in which a parasite reaches sexual maturity and undergoes sexual reproduction.

Intermediate Host

A host organism that shelters the larval, asexual, or developmental stages of a parasite, frequently acting as a vector required to complete the transmission cycle to the definitive host.