SCN3230-ABED_1: Module 8 Introduction

Introduction

In this module, focus shifts from the genetics of the individual to that of entire populations of organisms. All populations show greater or lesser degrees of variation: some members are taller, some shorter; some lighter, some darker. You are familiar with mutation as the source of this variation, but in this module you will begin to see why variation is essential for the survival of species.

This module has four lessons dealing with population changes. You will learn to use formulas for population size, density, growth rate, and per capita growth rate. These can be used to help make informed decisions as wildlife managers, developers, politicians, academics, and concerned citizens. You will see how comparing collected data with the normal patterns of growth observed in various species assists decision-making.

You will learn that various species have evolved two distinct strategies of growth to maximize their reproductive potential and survivability (r- and K-selection). A given set of species characteristics indicates each strategy. You will learn that the course of a given population can be predicted by matching it with those characteristics.

You will learn of debate and controversy about how human growth differs from the growth patterns of other species. You will consider how well human populations can be characterized by the same parameters as other species can be. You will study how human populations tend to differ from others due to our tendency to change our own environments using technology.

In the second half of the module, you will analyze complex ecosystems to identify the relationships among community members. You will see that each organism belongs to a given trophic level and has a role within the community. You will consider both interspecific and intraspecific competition for scarce resources. You will learn that individual organisms with alleles that allow them to compete better than others can live to reproduce, thereby improving the population gene pool within that environment.

You will learn about predator-prey or producer-consumer interactions in a community's food chain. You will learn how predators act as selecting agents, removing those with less successful alleles and leaving those who are more genetically fit. You will come to understand that predators and prey cycle together through time as the populations of one control the numbers of the other. You will see that prey species and producers have evolved many chemical, structural, and behavioural defences that protect them from consumption.

You will look at how an organism filling its niche in the food chain may have positive or negative effects on those with whom it lives. You will study mutualistic, commensal, and parasitic relationships among organisms.

You will study the changes that occur in communities as a geographical area ages. You will learn about succession and see how pioneer species invade a barren habitat and change the environment to the extent that the pioneer species can no longer survive there. Although having prepared the environment, the pioneer species will be replaced by a more suitable species. As producer species change through succession, the consumer species who rely on them change as well. Does the changing cast of characters in successions indicate a problem?

Suggested Timeline

This module has eight lessons. Please use the following suggested timeline to help keep on track. Keep in mind that the number of hours required on each lesson varies among individuals. Some students may find they need significantly more time to study the course material, while others who have completed this course before might require less time. Use the following table as a guide to set your own personal timeline to complete this course.

Lesson	Topic	Suggested Number of Hours to Spend on the Lesson (Studying, Reading, Labs, Self-Checks and Assignments)	Equivalent Number of Classes in School
1	The Gene Pool	2 hours	1 class
2	Hardy-Weinberg Calculations	8 hours	3 classes
3	Causes of Change in the Gene Pool	2 hours	1 class
4	Measuring Population Growth	5 hours	2 classes
5	Growth Patterns	2 hours	1 class
6	r and K Selected Life Strategies	2 hours	1 class
7	Species Interactions and Symbiotic Relationships	2 hours	1 class
8	Populations and Communities Changing over Time	2 hours	1 class

If you plan to spend about 2 hours per day on this course, you might complete this module in about 2.5 weeks.

Assignments

There are four assignments in this module. Assignment 8A, 8B, and 8C are computer graded and you will receive immediate feedback. Assignment 8D contains written response type questions and will not be computer graded.

Assignment	Topic	Number of Questions	Total Marks
Assignment 8A	Lessons 1 ~ 3	36 Questions	41 Marks
Assignment 8B	Lessons 4 ~ 5	38 Questions	41 Marks
Assignment 8C	Lessons 6 ~ 8	40 Questions	42.5 Marks
Assignment 8D (Written)	Lessons 1 ~ 8	20 Questions	49 Marks