Module 8

Module 8—Populations, Individuals, and Gene Pools

 

Module Summary

 

In this module you were asked the following inquiry questions:

• How does the biology of populations differ from the biology of individual organisms?
  
  
• How can an individual’s contributions to the gene pool of a population, and the interactions within a population and between populations, result in changes in communities?

The focus of this module was populations rather than individuals. You have learned that each individual that is part of a population experiences the same struggle for survival as its neighbours. Coded in its DNA, each individual brings its physical, chemical, and behavioural characteristics to the population into which it is born or migrates. Limiting factors act on this genetic raw material, selecting some individuals and rejecting others, thereby shaping the genetic composition of the population.

 

The more variation or biodiversity in a species, population, and community, the better the species' chances are to adapt to changes and disruptions in the environment. You have also come to understand that, in order to prevent extinction of any species, the immediate challenge for the human population of the world is to protect biodiversity and prevent disruption of habitat, climate, and other environmental limiting factors of natural populations.

In this module you explored concepts and developed skills related to populations and communities:

• The genes of all the individuals in a population together form a gene pool. Using Hardy and Weinberg’s work, you discovered the conditions that keep the frequency of alleles in the gene pool at equilibrium. By reversing the conditions for Hardy-Weinberg Equilibrium, you learned the mechanisms that are responsible for change or microevolution in a population’s gene pool. Those mechanisms are genetic drift, change in mutation rate, natural selection, gene flow, and mate selection. The only populations not evolving are those that humans have controlled. You learned how to use the Hardy-Weinberg Equation to calculate allele and genotype frequencies to determine if a population is evolving.
  
  
• You learned that variation in the gene pool is desirable because it prevents extinction in the face of environmental change and allows organisms to adapt to new conditions. You learned that many human activities have acted to reduce the amount of variation in wild and domestic populations, thereby putting the populations at risk.
  
  
• You learned that all members of a population are always interacting with each other and members of other populations in either predator-prey or symbiotic relationships (commensalism, parasitism, and mutualism). All organisms have either structural, chemical, or behavioural defences that allow them to compete interspecifically or intraspecifically, hopefully staying alive long enough to pass on their genes to the next generation. Staying alive means competing intraspecifically and interspecifically for scarce resources in one’s habitat. You learned that human activities often destroy habitat—limiting food, water, and territory and increasing competition for survival between wild organisms, reducing population numbers, and threatening extinction.
  
  
• You learned that the landscape undergoes a progressive change or aging called succession that begins with pioneer species and ends with a climax species unique to that biome. You learned what natural and artificial factors can result in a new primary or secondary succession and why, in some cases, it is a good thing.
  
  
• In terms of reproduction, you learned of two major kinds of growth patterns seen in living things: exponential growth, as shown in a J growth curve, and logistic growth, as shown in an S growth curve. In logistic growth, density-dependent limiting factors such as food, predators, and disease, flatten the growth curve to reach a population size known as carrying capacity (K) that can be supported by the environment. Carrying capacity will fall if habitat destruction occurs. In exponential growth, growth rates are at a maximal rate known as biotic potential (r). Population growth is exponential until the population crashes—often the result of density-independent factors, such as climate.
  
  
• You learned of two reproductive strategies for maximizing the number of offspring that will survive. Organisms that are r-selected will produce many young but with no investment in nurturing or teaching, so most offspring die. Organisms that are K-selected produce very few offspring, but nurture and teach them for a long time, increasing their chances of survival.
  
  
• You learned how organisms in a population are counted, and several ways of expressing that growth mathematically so that it has meaning to those whom are interested. Different patterns of distribution were studied showing that organisms live in different groupings.
  
  
• Finally, you looked at our own species as a population that is growing rapidly and is having a major effect on the species around you due to humankind's unique ability to alter environments to suit its needs. As human habitat increases, the habitat of other species decreases. You looked at several biotechnologies and how they have affected populations in both good and bad ways, emphasizing that human activities done with good intentions often have far-reaching, unintended consequences.

To review and summarize the concepts of Module 8, you may wish to complete a concept organizer. You may have saved a copy of this document when you encountered it at the beginning of Module 8. If you didn’t, you may download the Module 8 Concept Organizer now. The concept organizer provides an outline of the lessons and the focusing questions for each lesson you studied in Module 8. Fill in the concept organizer with the ideas that you have mastered in each lesson, and show how these ideas helped you answer the focusing questions. You can use keywords, point form, or any amount of detail that meets your needs. You may choose to work from the file on your computer, print the document and work from the paper copy, or copy the outline onto a large sheet of poster paper. This is a great tool to review and use for study purposes.

 

For an excellent review guide to Unit D: Module 8, conduct an Internet search for “Gene School Population Genetics.”  The website you will find offers helpful explanations and clear graphics to guide you and prepare you for your module and unit assessments. You have also been encouraged to complete the review questions at the end of the unit chapters on pages 700 to 701 and 740 to 741 in the textbook. You will find additional support at the textbook’s online website, www.albertabiology.ca. You can use the unit pre-quizzes, web links, chapter highlights, study tips, research tools, and other opportunities to review.

 

Module Assessment

 

For your Module 8 Assessment you will have a choice of two options. Option 1 consists of multiple-choice and numeric-response questions based on your studies of population dynamics and communities. This assessment is worth 40 marks. Option 2 is based on a population study and is a written response to a series of bullets for your essay. This assessment is worth 30 marks. After you finish the Module 8 Assessment, you will do the final Unit D Assessment.

 

Before you begin the Unit Assessment, you are reminded to do the Unit Review questions on pages 744 to 747 of your textbook. Your teacher may suggest particular questions for your review and will provide you with solutions to the questions.

 

Option 1 (40 marks)

 

This option for Module 8 Assessment consists of two parts:

Part A: multiple-choice and numerical-response questions based on your studies of Population Dynamics and Communities (26 marks)

 

Part B: written-response (14 marks)

 

If you want to complete Option 1, download the Module 8 Assessment now.

 

 

Option 2—Coyote Management Report (30 marks)

 

This assessment is worth 30 marks. Before beginning your work, study the rubric for assessment, which appears at the end of this section, carefully.

 

The assessment requires you to assume the role of a wildlife biologist who is preparing a report for the Alberta Department of Fish and Wildlife regarding the changes in the coyote population in a particular 1000-km2 area from 1990 to 2000. In addition to the population counts available in the chart below, you have the following data: increased sightings of coyotes, more livestock kills, more coyote-human interactions, and more attacks on pets. You will create a report with the following sections: data analysis, interpretations, conclusions. To do this you will need to use the concepts and vocabulary you’ve learned in Module 8.

• Data analysis should involve the formulas you have learned to quantify growth of populations: ∆N, growth rate, and per capita growth rate. You should also create a population growth graph to determine trends and identify and explain the reproductive growth pattern.
  
  
• Interpretations of analyzed data should indicate that you have understood what the analyzed data means. What do the calculated values and graphs tell you about the coyote population currently? What kind of reproductive strategy is in play and what factors might be influencing it currently? You need to consider both the qualitative and quantitative data, and use them to come up with possible explanations of the observed changes.
  
  
• Your conclusions should be presented in the form of a report to the wildlife manager responsible for the region. From the analysis of your findings you should be able to make clear recommendations to the wildlife manager regarding the management of this population in terms of hunting, habitat, and protection of livestock and the public. You must show evidence of using a risk/benefit model to determine what the best solutions might be. Your supervisor will need to look at the advantages and disadvantages of your recommendation and what evidence you have to support them. Be sure to date and sign your report.
  
  
• The report should include all data, calculations, graphs, mathematical analyses, interpretations of data, conclusions and recommendations.

Data Set for analysis

 

Coyote populations over a 150-year period in a 100-km2 parcel of land.

 

Year	Population Size (N)
1850	402
1860	50
1870	90
1880	150
1890	300
1900	700
1910	1000
1920	1100
1930	1120
1940	1000
1950	720
1960	700
1970	710
1980	720
1990	710
2000	1000

 

Your work will be assessed using the following rubric. (The mark will be taken out of 15 then multiplied by two for a mark out of 30.)

 

Data Analysis (5 marks)

 

Has the student

• made use of the formulas to calculate trends: DN, gr, cgr
• made calculations correctly
• created graphs to identify trends
• graphed the data correctly
• taken into account the qualitative data in the analysis
• other reasonable criteria

Interpretations (5 marks)

 

Has the student

• made a statement that indicates the meaning in the changes in population size, growth rate, and per capita growth rate
• made a statement(s) indicating what the trends indicated in the graph mean
• made a statement regarding the reproductive strategy used by the coyote
• indicated what limiting factors might be in play to explain the current changes in population size
• interpretated the qualitative as well as the quantitative information
• show creative or innovative interpretation of the data
• used the vocabulary and concepts from the module to discuss her or his interpretations
• any other reasonable criteria

Conclusions (5 marks)

 

Has the student

• formed conclusions
• evaluated different explanations to form conclusions
• made recommendations that can be supported by the data and interpretations
• shown advantages and disadvantages in deciding on recommendations
• shown evidence of using a risk/benefit model to decide on appropriate recommendations
• shown an understanding of the concepts in the module in making his or her conclusions
• any other reasonable criteria

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