Population Growth and Regulation Flashcards

Which equation correctly represents the net reproductive rate (R0) in a population?

Answer: R0 = Σ(lx × mx)

R0 is calculated by summing the products of age-specific survivorship (lx) and fecundity (mx) across all age classes.

A population grows from 500 to 550 individuals in one year. What is the per capita growth rate (r) approximately?

Answer: 0.095

r ≈ ln(550/500) = ln(1.1) ≈ 0.095 per year using the continuous growth formula.

What does a survivorship curve Type II indicate about a population?

Answer: Constant mortality rate at all ages

Type II survivorship curves are linear on a log scale, indicating a constant probability of dying at any age regardless of age class.

Scramble competition occurs when limited resources are divided among all competitors such that:

Answer: Everyone gets an insufficient share and many die

In scramble competition, resources are shared equally but often below the threshold needed for survival, leading to widespread mortality.

Which demographic concept describes the time it takes a population to double in size under exponential growth?

Answer: Doubling time (td = ln2 / r)

Doubling time is calculated as ln(2) divided by the intrinsic rate of increase (r), approximately 0.693/r.

Allee effects are most likely to threaten population persistence when:

Answer: Population density falls below a critical minimum threshold

Allee effects cause reduced fitness at low densities due to factors like mate finding failure, making small populations vulnerable to extinction.

In a stage-structured population model, a transition matrix element of 0.7 in row 2, column 1 represents:

Answer: 70% probability of individuals moving from stage 1 to stage 2

In a Leslie or Lefkovitch matrix, off-diagonal elements below the diagonal represent the probability of transitioning from one stage to the next.