population growth Flashcards
(20 cards)
What are the four basic components of a population growth equation?
Birth rate, Death rate, emigration, immigration
What is the formula for population growth?
Population Growth = (Birth Rate + Immigration) - (Death Rate + Emigration)
What is meant by the term ‘closed population’?
A closed population is one in which immigration and emigration do not occur, so population change is determined only by births and deaths.
What is the expected population growth pattern when resources are not limiting and there are few consumers of the population?
Exponential growth
If the lambda in a Malthusian growth model is 1.5 for one growth interval, what is the population size after three growth intervals when the initial population size was 100?
Population size after three growth intervals is 100 * (1.5^3)
What does a lambda of < 1 indicate?
Population decline
What does r > 0 indicate?
Population growth
If the log of population number increases linearly with time, what sort of population dynamic does this indicate?
Exponential growth
In what ecological circumstance may we expect to see exponential growth, at least initially?
After introduction of a new species, When a species expands its range, After disturbance when a population recovers
What is the difference between an age-structured and a stage-structured model?
Age-structured: based on individual age; Stage-structured: based on developmental stage, which may not correspond directly to age
What kind of transition does not occur in an age-structured model but can occur in a stage-structured model?
Shrinking (moving from a higher to a lower stage), Staying in the same stage
What are the meanings of the parameters in a population matrix model?
p: probability of transition between stages (including survival); F: number of new individuals produced per individual in the reproductive stage
Define what a stable age (or stage) structure is in matrix models of population growth.
A stable stage structure is when the proportion of individuals in each stage remains constant across time.
Give examples of positive and negative density-dependent effects on population growth.
Negative: Crowding increases death rate and reduces birth rate; Positive: [specific examples needed]
What does the constant yield law say?
After a certain density, total biomass or yield no longer increases; Maximal yield depends on resource input (e.g., fertilizer)
What is self-thinning?
Progressive death of smaller, subordinate individuals in crowded populations, which reduces density and increases average individual size.
What is size inequality?
Situation where a few large individuals dominate in size and resource uptake, while most remain small or die.
What is asymmetric competition?
Asymmetric competition: larger individuals get disproportionately more resources; Occurs when light is the main limiting factor; Increases size differences over time
Which population would be expected to have greater size inequality, one that competes for light or one that competes for water?
Light — because light competition is asymmetric
Why are small populations more at risk from random disturbance events?
Because random events can wipe out all individuals more easily when the population is small — there is less buffering against loss.
