BIOL112 - Ecology (Set 5)

Lecture 25 - Population Ecology

(Review) what are the three main trade-offs involved in life history traits?

Reproduction vs growth, reproduction vs survival, and size vs number of offspring (note that species optimise traits which leads to a few successful strategies, i.e. sets of related traits).

What is demography?

The study of factors affecting a population (especially in terms of numbers).

What is immigration?

The movement of individuals into a population.

What is emigration?

The movement of individuals out of a population.

What are the elements of demography (life history aspects of interest)?

Birth, immigration, death, emigration (BIDE).

What is population size (n) and how is it expressed?

The total number of individuals, expressed as a whole number.

What is population density and how is it expressed?

The number of individuals within a specific area or volume, expressed as a number per unit area.

What is the mark and recapture technique?

The capturing and tagging of individuals, which are then returned to the environment to repeat the effort, noting the proportion of individuals captured on the second effort that are marked.

What are the assumptions of the mark and recapture technique?

The population is closed, there is equal capture probability across efforts for both marked and unmarked individuals.

What is the formula for the mark and recapture method?

(Number marked on first catch x total number of second catch)/(number marked on second catch).

Why doesn’t exponential growth continue indefinitely?

Because resources aren’t unlimited.

What is carrying capacity (K)?

The population size at which growth stops; generally the number of individuals belonging to a particular species that the local environment can support.

Why is carrying capacity (K) usually reached?

When birth + immigration = death + emigration.