Population and Community Ecology Flashcards

These vocabulary flashcards cover key concepts from the lecture on Population and Community Ecology, including growth models, species interactions, and ecosystem successional factors affecting biodiversity and succession.

Population

All individuals of a species living in the same general area.

Demography

The statistical study of population dynamics using mathematical tools to investigate how populations respond to changes in their biotic and abiotic environments.

Population density

The number of individuals per unit area or volume; it is increased by births and immigration and decreased by deaths and emigration.

Population distribution

How individuals within a population are spaced within an area, which can be uniform, random, or clumped.

Uniform distribution

A dispersion pattern where individuals are evenly distributed, often influenced by social interactions such as territoriality like in penguins.

Random distribution

A dispersion pattern where the position of each individual is independent of others, such as plants with wind-dispersed seeds.

Clumped distribution

The most common dispersion pattern where individuals aggregate in patches, often seen in animals like elephants that travel in herds.

Survivorship curves

Graphs showing the number of survivors of each age for a given species or group.

Type 1 survivorship curve

A pattern characterized by low death rates among all but the old, typical of humans and mammals with few offspring and good parental care.

Type 2 survivorship curve

A pattern characterized by even death rates throughout the lifespan, common in rodents, birds, and reptiles.

Type 3 survivorship curve

A pattern characterized by high death rates for the young, followed by a decreasing death rate for survivors, typical of plants and fishes.

Life History

The series of events over an organism's lifetime, including age of first reproduction, frequency of reproduction, and number of offspring.

Fecundity

The potential reproductive capacity of an individual within a population, which is inversely related to the amount of parental care given.

Semelparity

A life history strategy where a species reproduces only once during its lifetime and then dies, such as the Chinook salmon or century plant.

Iteroparity

A life history strategy where species reproduce repeatedly during their lives, common in most mammals, birds, and reptiles.

Exponential Population Growth

Growth that occurs with unlimited natural resources, represented by the equation $\frac{dN}{dt} = rN$, producing a J-shaped curve.

Zero population growth

A condition where the per capita rate of change ($r$) is equal to zero, meaning the population’s size is unchanging.

Biotic potential ($rmax$)

The maximal growth rate for a species under ideal conditions.

Carrying capacity ($K$)

The maximum population size that a particular environment can support.

Logistic growth model

A model describing population growth that slows as resources become depleted and levels off at the carrying capacity, represented by $\frac{dN}{dt} = rmax \times N \times \frac{K - N}{K}$, producing an S-shaped curve.

Intraspecific competition

Competition for resources between members of the same species.

Density-independent factors

Abiotic factors like natural disasters and weather that affect all individuals in a population regardless of density.

Density-dependent factors

Factors like competition, disease, and predation where the death or birth rate changes as the population density changes.

K-selected species

Species adapted to stable, predictable environments that mature late, have greater longevity, and provide increased parental care to fewer offspring.

r-selected species

Species adapted to unpredictable or changing environments that mature early, have lower longevity, and produce many small offspring with decreased parental care.

Ecological Footprint

A comprehensive approach to estimating the land and water area required by a person, city, or nation to produce consumed resources and absorb generated waste.

Hectare ($ha$)

A unit of area equal to approximately $2+$ acres, used to measure how much land is needed to produce the goods used per person.

Community

Populations of different species inhabiting a specific area at the same time.

Species diversity

The number of different species occupying the same habitat and their relative abundance.

Aposematic coloration

Warning coloration used by species to signal foul taste, toxic chemicals, or the ability to sting or bite to predators.

Batesian mimicry

A defense mechanism where a harmless species imitates the warning coloration of a harmful one.

Müllerian mimicry

A defense mechanism where multiple species share the same warning coloration, and all of them possess actual defenses.

Competitive exclusion principle

The principle stating that two species cannot occupy the same ecological niche in a habitat if they are competing for all the same resources.

Commensalism

A symbiotic relationship where one species benefits while the other is neither helped nor harmed.

Mutualism

A symbiotic relationship where two species benefit from their interaction.

Parasitism

A symbiotic relationship where an organism lives on or in a host and derives nutrients from it, benefiting while the host is harmed.

Foundation species

Species considered the bedrock of a community that have the greatest influence on its overall structure, such as kelp or coral.

Species richness

The number of different species living in a habitat, biome, or particular area.

Keystone species

A species whose presence is key to maintaining biodiversity and upholding a community's ecological structure, such as the intertidal sea star Pisaster ochraceus.

Primary succession

The sequential appearance of species on newly exposed or newly formed land, such as after a volcanic eruption.

Secondary succession

Succession that occurs when part of an ecosystem is disturbed but remnants of the previous community, such as soil, remain.

Pioneer species

The first hearty species to establish themselves in a new area during succession, such as succulent plants on lava or annual plants after a fire.

Climax community

The final equilibrium state of a forest or ecosystem where species composition is no longer changing significantly.