Study Guide
Lecture 19 – Population Ecology: Population Growth
Be familiar with idealized patterns (models) of population growth:
1) Exponential (or geometric)
2) Logistic (S-shaped)
Know the implicit assumptions of these models, and understand that these assumptions are often violated.
Know the conditions where you are likely to find one or the other, and understand why real populations in nature often do not obey these patterns of growth.
Be familiar with the basic equations for exponential, geometric, and logistic growth, and be able to use these equations in an exam question.
Be able to explain why we sometimes use the exponential form, and sometimes use the geometric form, of these equations, yet both show a similar growth pattern. In other words, understand the difference between discrete and continuous growth, and be able to provide examples of organisms exhibiting one or the other growth pattern.
Know how to combine survivorship and production (recruitment) data in a life table, and how to use this to calculate the net reproductive rate (e.g. R0). Be familiar with the alternate terms for net reproductive rate (e.g. R0 vs λ).
Know why we sometimes use r and other times use rmax or R0 to express population growth rate.
Understand how varying growth rate (r, rmax or R0) affects the pattern of population growth and the ultimate population size.
Be able to explain conditions (and provide examples from your text or lecture) where organisms exhibit exponential or geometric population growth.
Be able to define carrying capacity (K).
Be able to explain why and how growth can slow, particularly as it relates to the concept of carrying capacity (K). Also understand how the Demographic Transition model has been used to explain slowing of human population growth for certain regions of the world. Understand the different mechanisms that may be involved in these alternate views.
Know how the logistic population model is a modification of the exponential (or geometric) model. Be able to explain the modification, or to complete calculations of population growth using this equation.
Understand the concept of density dependence as it relates to r (rate of population increase), and how this effects population growth patterns. Be familiar with examples of density-dependent growth patterns from your text, lecture, or lab.
Why do populations sometimes oscillate? Be able to provide an explanation and example from your text or lecture.
Be able to provide and discuss examples from your text or lecture that fit (or fail to fit) these basic models of population growth.
Why is it hard to estimate carrying capacity (K) for human populations?
What happens to populations that overshoot their carrying capacity?