Grade Population Ecology Test

Studying how populations live and interact with eachother.

Population Demography

The statistical study of populations Allows predictions to be made about how a population will change.

All the individuals of a species that live together in an area

Size Density Dispersion

number of individuals in an area Growth rate - birth rate (natality) –> death rate (mortality) - How many individuals are born vs. how many die - birth rate (b) - death rate (d) = rate of natural increase (r)

measurement of population per unit area or unit volume. - population density = # of individuals / unit of space

Uniformly dispersed, clumped (Flock of bird, school of fish), random (plants)

1) Immigration: movement of individuals into a population. 2) emmigration: movement of individuals out of a population. 3) Density-dependent facors: biotic factors in the environment that have an increasing affect as a population size increases (disease, competition, parasites) 4) density-independent factors: abiotic factors in the environment that effect the populations regardless of their density (temperature, weather)

An idea in evolutionary biology. Explains how similar species become different when they live in the same area. The differences (in traits or behaviors) help reduce competition between them. This happens because both species compete for the same resources, so they evolve in different ways to survive better.

Effects get stronger as the population gets more crowded. Example: disease, competition, food shortage. A density-dependent factor influences individuals in a population to a degree that varies in response to how crowded or dense the population is.

Weak, indirect competition between many different species. Each effect is small, but they add up in the ecosystem.

Affects individuals no matter how crowded the population is. Example: weather or natural disasters. Influences individuals in a population in a manner that does not vary with the extent of crowding present in the population.

A measurable trait that describes a population. Examples: growth rate, age structure, birth rate, reproduction rate.

How much energy is passed from one trophic level to the next. Measured by how much is stored in the next level’s biomass.

When similar species don’t compete or mate because they use different resources, live in different habitats, or are active at different times. This keeps them separate even if they live in the same area.

The number of individuals in a population that actually pass on genes to the next generation. Usually smaller than the total population size.

A once-domesticated animal that now lives in the wild.

How well an organism is suited to its environment. Genetic fitness = how much an organism contributes to the next generation. Higher fitness means more offspring → traits become more common.

Food chain: The path energy takes from the sun → producers → herbivores → carnivores. Food web: A group of connected food chains showing how energy flows through an ecosystem.

Shows how organisms in a community get energy and nutrients. Includes different roles: - Producers: Make energy (e.g., plants). - Herbivores: Eat producers. - Carnivores: Eat herbivores. Many food chains linked together.

refers to the proportion of a particular allele of a gene in the gene pool of a population.

The total energy made by plants from sunlight before they use any for themselves. 🟢 Think of it as: All the energy plants produce.

This means variety or difference in an environment or population. 🟢 Example 1: A natural area with many different types of habitats. 🟢 Example 2: A population with lots of genetic differences. 👉 Think of heterogeneity as “many different kinds or types.”