Grade 11 Life Sciences: Population Ecology and Dynamics

Comprehensive vocabulary flashcards covering population ecology, limiting factors, estimation methods, species interactions, competition, ecological succession, and social organisation.

Ecology

The study of the interactions of organisms with their physical and biological environment and how these determine the distribution and makeup of populations within an ecosystem.

Biosphere

The global ecological system comprising all the ecosystems on Earth.

Population

A group of organisms of the same species that occupy a particular area at a specific time and can breed freely with one another.

Population ecology

The study of the fluctuations in population size and the physical and social factors that regulate these fluctuations.

Community

All the plants and animals of different species living and interacting in a defined area, including producers, consumers, and decomposers.

Community ecology

The study of the interactions between the populations that form a community.

Species

A group of closely related organisms that are similar to each other and can interbreed to produce viable, fertile offspring.

Habitat

The specific place or area where a plant or animal lives.

Ecosystem

A community of living organisms interacting with each other and with their non-living physical environment.

Biotic

The living organisms within an environment.

Abiotic

The non-living physical components of the environment.

Natality

The birth rate within a population.

Mortality

The death rate within a population.

Immigration

The movement of individuals into a population to stay permanently.

Emigration

The departure of individuals who leave a population and do not return.

Closed population

A population characterized by the complete absence of immigration or emigration.

Carrying capacity

The maximum population density that a specific environment can sustainably support.

Environmental resistance

The collection of limiting factors and increased demands that build up as population numbers rise, causing birth and immigration to decrease while death and emigration increase.

Density-independent factors

Natural physical factors (such as temperature, rainfall, and humidity) or catastrophic events (such as floods, fire, and earthquakes) that limit population growth regardless of population density.

Density-dependent factors

Factors that regulate growth primarily when a population is already crowded, including competition for resources, predation, and disease spread.

Stable population

A population whose numbers decrease when its size exceeds carrying capacity and increase when numbers fall below carrying capacity.

Unstable population

A population that far exceeds carrying capacity, causing habitat destruction that permanently lowers carrying capacity and leads to rapid population crash or extinction.

Census

A direct counting method of population estimation where every single individual is counted directly.

Quadrant method

An indirect population estimation method that involves counting individuals in small measured areas and applying the formula $N = \frac{\text{numbers in sample} \times \text{size of whole habitat}}{\text{size of quadrant}}$.

Mark and recapture

An indirect method used to estimate population size calculated by multiplying the total number of marked animals by the number of animals in a second sample, divided by the number of marked animals found in that second sample.

Predation

A biological interaction in which one organism, the predator, hunts, catches, kills, and eats another organism, the prey.

Intraspecific competition

The intense competition occurring between individuals of the same species for limited resources and mates.

Interspecific competition

Competition that occurs between individuals of different species that share very similar niches in a habitat.

Ecological niche

The functional role and position of a species within a community, including all environmental conditions necessary for it to survive and reproduce.

Specialisation

Structural and behavioural adaptations that enable individuals of closely related species with overlapping niches to co-exist.

Competitive exclusion

An outcome of niche overlap where one of two competing species is more successful, resulting in the survival of that species and the local disappearance or extinction of the other.

Competitive co-existence

A condition in which two competing species inhabit the same area despite overlapping niches by utilizing resources differently.

Resource partitioning

The evolutionary process where co-existing species evolve specialized traits to use resources at different times, in different places, or across different plant parts to reduce interspecific competition.

Ecological succession

The predictable pattern of gradual change over time in the composition of species within a community following an environmental disturbance.

Primary succession

Succession that initiates on barren sites where no plants or developed soil previously existed.

Secondary succession

Succession that begins in areas where an environmental disturbance has removed existing species but left the soil intact.

Pioneer species

Hardy, early successional plant species that establish rapidly on bare ground with little competition and alter the biotic and abiotic environment to prepare it for later colonists.

Climax community

The final, semi-stable stage representing the end point of ecological succession.

Social organisation

The structural arrangement of relationships and division of resources, protection, and labor among individuals living in groups or colonies.

Eusocial animals

Animals that display the most advanced and complex form of social organisation.