Population ecology + Statistics

(Criterion A_Science)

Low standard deviation

Data is clustered closer to the mean; indicates higher reliability.

Species diversity

Measures both species richness and abundance.

Uniform dispersion

Individuals are evenly spaced.

Standard deviation (SD)

Measures how spread out data values are around the mean

Biotic factor

Living factors affecting ecosystems, e.g. competition and predation.

Limiting factor

Anything that causes population growth or decrease.

Population ecology

Study of populations in relation to their environment.

Dependent variable (DV)

Variable measured. changes in response to the IV.

Dispersion

How individuals in a population are arranged.

When to fail to reject (accept) the null hypothesis?

P-value above 0.05 or F-value below 2, high p-value and low F-value.

Null hypothesis (H₀)

States there is no relationship or effect.

Species abundance

Number of individuals of each species.

When to reject the null hypothesis?

p-value below 0.05 or F-value above 2, low p-value and high F-value.

Independent variable (IV)

Variable that is changed.

What does rejecting the null hypothesis mean?

A statistically significant difference exists, unlikely to be due to chance.

Population density

Number of individuals per unit area.

Clumped dispersion

Individuals stay together in patches.

Mark-Recapture formula

N = (M x C) ÷ R

Random dispersion

Each individual’s position is independent of the others.

What does failing to reject (accepting) the null hypothesis mean?

Not enough evidence of a significant difference.

High standard deviation

Data is more spread out, indicating lower reliability.

P-value

Measures how likely the results are due to chance, assuming the null hypothesis is true.

Density-independent limiting factor

Affects individuals regardless of population size, e.g weather or natural disasters.

Species richness

Number of difference species in a community.

Alternative hypothesis (Hₐ)

States there is a relationship or effect.

Density-dependent limiting factor

Effect depends on population density, e.g competition, predation, disease, parasitism.

F-value

Compares variation between groups and within groups.

Species evenness

How equally individuals are distributed among different species.

Distribution

Where a population is located.

Population

Organisms of the same species living in the same area.

Abiotic factor

Non-living factors affecting ecosystems, e.g temperature and rainfall.