Lecture 14d- Population Density and Models

Flashcards covering concepts of population density, spatial population models, mark-recapture formulas, and temporal variations in population size.

How is population density defined?

The number of individuals per unit area.

What are the recorded population densities for diatoms and soil arthropods?

Diatoms have a density of $5,000,000\,\text{m}^{-3}$, and soil arthropods have a density of $500,000\,\text{m}^{-2}$.

What are the population densities given for field mice and trees?

Field mice have a density of $200\,\text{ha}^{-1}$, and trees have a density of $100\,\text{ha}^{-1}$.

What are the human population densities listed for India, the USA, and Canada?

India has $371\,\text{km}^{-2}$, the USA has $34\,\text{km}^{-2}$, and Canada has $2\,\text{km}^{-2}$.

What general relationship between body mass and population density in herbivorous mammals is depicted in this graph?

There is a negative relationship; as log(body mass) increases, log(density per $\text{km}^2$) decreases.

Which songbird species is referenced when examining individuals per census route across its geographic range?

Spiza americana.

According to this model, how does dispersal influence the boundary of a population's distribution across environmental conditions?

Individuals disperse from areas of population increase (positive growth rate) to areas of population decrease (negative growth rate), which extends the limit of population distribution into poorer environmental conditions compared to the limit in the absence of dispersal.

Identify the three spatial population models shown in this diagram.

(a) Metapopulation model, (b) Source-sink model, and (c) Landscape model.

What types of patches are distinguished in the source-sink population model?

Source patches (high-quality) and sink patches (low-quality).

In the landscape model of populations, what governs the movement of individuals between patches?

Movement depends on the surrounding landscape matrix and habitats.

How is population size estimated for sessile organisms?

By counting the number of individuals per unit area and multiplying that value by the total area.

In the mark-recapture method, what ratio of marked individuals is expected in a subsequent sample assuming complete mixing?

A ratio equal to $M$ to $N$ (the ratio of marked individuals released to the total population size).

What is the formula to calculate the estimated population size ($N$) using the mark-recapture method with second sample size $n$, marked individuals released $M$, and recaptured marked individuals $x$?

$$N = \frac{n \times M}{x}$$

What insect species in Illinois varied temporally and spatially in density from a few to $1,000\,\text{per m}^2$ between the 1840s and 1930s?

The chinch bug.