03. Population Ecology and Human Demographics Free Online FlashCards

What is a population?

A population is a group of individuals of the same species living in a particular area and interacting with one another.

What equation describes population change?

ΔN = (B + I) − (D + E), where B is births, I immigration, D deaths, and E emigration.

What does the intrinsic rate of increase, r, indicate?

r is the per capita birth rate minus the per capita death rate. If r > 0 the population increases; if r < 0 it decreases; if r = 0 it is approximately stable when migration is negligible.

What characterizes exponential population growth?

Exponential growth occurs when resources are abundant and environmental resistance is minimal. It produces a J-shaped curve and follows dN/dt = rN.

How does logistic growth differ from exponential growth?

Logistic growth produces an S-shaped curve: growth starts rapidly, slows as resources become scarce, and levels off near carrying capacity K.

How does the rule of 70 estimate doubling time?

Doubling time ≈ 70 ÷ annual percentage growth rate. At 2% annual growth, a population doubles in approximately 35 years.

What does a Type I survivorship curve show?

Type I survivorship shows high survival through early and middle life followed by a steep decline in old age. Humans and many large mammals commonly show this pattern.

What does a Type III survivorship curve show?

Type III survivorship shows very high mortality among young individuals, followed by higher survival for those reaching adulthood. Many fish, insects, plants, and marine invertebrates show it.

Why is infectious disease density-dependent?

Infectious disease is density-dependent because transmission generally increases as population density rises and infected individuals contact more susceptible individuals.

What is carrying capacity?

Carrying capacity K is the largest population an environment can sustain for a particular period with available resources and technology.

What causes population momentum?

Population momentum is continued population growth after fertility declines because a large proportion of the population is still young.

What does the IPAT relationship express?

I = P × A × T, where I is environmental impact, P population, A affluence or consumption per person, and T technology or impact per unit of consumption.