Population Ecology Vocabulary

Vocabulary practice flashcards generated from the Population Ecology lecture notes covering key terms, growth forms, environmental interactions, and human population growth pyramids.

Species

A group of organisms capable of interbreeding and producing fertile offspring.

Population

A group of individuals of the same species that occupies the same habitat at the same time and are able to interbreed.

Community

Groups of different species populations that interact with each other within a specific habitat.

Ecosystem

A biological community of interacting organisms and their physical environment.

Abiotic factors

Non-living factors in an ecosystem.

Biotic factors

Living factors of an ecosystem.

Environment

The sum of all biotic and abiotic factors in an ecosystem.

Habitat

The environment in which an organism completes its lifecycle, including growth, reproduction, and eventual death.

Niche

The specific area where an organism inhabits.

Natality

The percentage increase of a population because of the number of births in a given season or year.

Mortality

The death rate within a population, usually expressed as a percentage of the population.

Fertility

The number of births per year for all females who can produce offspring, typically between the ages of 15 to 45.

Immigration

The movement of new members into a population, either temporarily for breeding season or permanently.

Emigration

The movement of individuals leaving a population due to migrations at the end of a season or splitting into sub-populations across a large geographical area.

Migration

Movement from one place to another at certain times of the year or during a particular period of an organism's life cycle.

Environmental resistance

All factors that limit the biotic potential and numerical increase of a population, such as lack of water, food, or space.

Carrying capacity

The largest number of individuals in a biological species that an ecosystem can support over an indefinite time.

Stable population

A population with a zero growth rate, neither growing nor shrinking in size, fluctuating around the carrying capacity.

Unstable population

A population whose size exceeds the carrying capacity of an area.

Density dependent factors

Factors that have a direct correlation to the size of a population in an area, exerting a greater influence when the population is large.

Density independent factors

Factors that exert an influence on a population regardless of its size, often consisting of abnormal or random natural events.

Endemic

Organisms found only in a specific area and nowhere else in the world.

Indigenous

Organisms found naturally in a specific area or country.

Endangered

Organisms threatened with extinction or dying out forever.

Closed population

A population where only natality and mortality influence population size, with no emigration or immigration.

Direct counting

Techniques that attempt to measure exact population sizes without estimation, suitable for large or slow-moving organisms.

Census

An official count or survey of a population, used as a direct method to determine human population size.

Indirect counting

Techniques used to estimate population size where direct counting is difficult, ideal for smaller or fast-moving organisms.

Mark-recapture

An indirect technique used to estimate population size by capturing and marking a sample, releasing it, and later capturing a second sample to count marked organisms.

Quadrat

Square frames placed randomly on an area containing organisms, useful for estimating populations of small sedentary animals and small plants.

Petersen Index

The formula $N = \frac{M \times C}{R}$ used in mark-recapture estimation, where $N$ is total population size, $M$ is marked individuals in the first sample, $C$ is total individuals in the second sample, and $R$ is marked individuals in the second sample.

Geometric growth

Population growth characterized by a doubling after every reproductive event, exhibiting exponential growth and a J-shaped curve.

Logistic growth

Population growth that begins with a few individuals, accelerates as resources allow, and levels off as resources are consumed, resulting in an S-shaped graph.

Lag phase

The initial phase in a population growth curve where growth is slow because individuals are acclimatizing to their environment, finding mates, or sexually immature.

Exponential growth phase

The phase in a growth curve marked by rapid population increase due to acclimatized individuals, high birth rates, and abundant resources.

Decelerating growth phase

The phase in a growth curve where environmental resistance causes growth to slow as mortality increases relative to natality.

Equilibrium phase

The phase in a growth curve where carrying capacity is reached and limiting factors maintain population size at a stable value.

Death phase

The phase in a population curve where a population enters a crash phase because it cannot sustain itself due to resource depletion or environmental changes.

Predation

An interaction where a heterotrophic organism actively hunts, kills, and consumes another organism for energy.

Predator

A heterotrophic organism (usually an animal) that hunts, kills, and eats other organisms.

Predator-prey curve

A graph describing the population dynamics and cyclical relationship over time between interacting predator and prey species.

Competition

Social interaction between organisms fighting for dominance over the same limited resources, such as food or living space.

Interspecific competition

Competition for limited resources occurring between individuals of two or more different species.

Intraspecific competition

Competition for limited resources occurring between members of the same species.

Competitive exclusion principle

The principle stating that when two species compete for the exact same limited resources in an environment, one species will out-compete the other and cause its extinction or death.

Resource partitioning

The division or sharing of resources among different species by feeding at different heights, on different parts, or at different times to allow co-existence.

Symbiotic relationship

A close, long-term physical or biological association between individuals of two or more different species.

Mutualism

A symbiotic relationship between two different species in which both participating species benefit equally.

Commensalism

A symbiotic relationship in which one organism benefits while the other organism is neither harmed nor affected.

Parasitism

A symbiotic relationship in which one organism (the parasite) benefits while causing harm to its host.

Obligatory parasitism

A form of parasitism in which the parasite cannot complete its life cycle without exploiting the body of a suitable host.

Expanding population growth pyramid

An age-gender pyramid with a wide base indicating more youth than elderly, high natality and mortality rates, and low life expectancy, characteristic of developing countries.

Stable population growth pyramid

An age-gender pyramid where the pre-reproductive population is roughly equal to the reproductive population, natality rates are low, and life expectancy is high.

Declining population growth pyramid

An age-gender pyramid where pre-reproductive groups are smaller than reproductive groups, characterized by low natality and mortality rates and high life expectancy.