Module 8 Population Genetics

4.8.4 page 2

Explore

As humans, with all our technologies, we have had a significant impact on other populations in our ecosystem. Many of man’s practices are controversial. For example:

• Not many people would think of bacteria or viruses as natural populations, but they certainly qualify. Antibiotics used to destroy bacteria can give a selective advantage to those bacteria that have alleles for antibiotic resistance. Many commonly used antibiotics are no longer effective because of this rapid evolution in many bacterial species. What does this mean for our ability to control disease in the future?
• Biotechnology, the use of organisms to benefit humanity, can be as simple and low-tech as selective-breeding programs to produce bigger crop yields or to produce livestock with more meat and better handling characteristics. Newer biotechnologies go beyond basic agriculture, inserting desirable genes from one species into another, producing transgenic organisms that are more profitable. Ethical questions arise when we ask whether transgenic organisms are new species and whether genetic engineers are altering the course of evolution. If so, is it justifiable?
• The unintended effects of introducing genes into organisms include effects on non-target genes and ‘jumping’ of genes from one species to another.  Is there adequate regulation and research to safeguard the gene pools of these species? On the other hand, is it possible to feed a hungry planet without the use of these biotechnologies?
• Cloning has been used in an attempt to save endangered species from extinction, thus preserving gene pools. Similarly, animals with inserted genes (e.g. for interferon, an anti-cancer drug) are being cloned and used as pharmaceutical factories. The cloned animals produce milk from which these expensive drugs are extracted. Are these reasonable uses of science and technology that justify manipulating gene pools?
• The introduction of exotic species often results in unintended consequences to gene pools. For example:
  
  
  • Wild boars have recently been proclaimed ‘pests’ in central Alberta. The Boars were brought from Europe to satisfy a growing market for boar meat. The animals are being raised as domestic livestock. However, traditional fencing is no match for wild boars and they have escaped from boar farms in large numbers, digging up cropland in search of roots and menacing people. They have few predators because of their size (and tusks!), and they breed in the wild at an alarming rate.
• Gene banks preserve the DNA sequences of genes from organisms that are endangered or extinct. 

Read

To further understand the impact of human activity, read p. 695-6 in your text.

 

Self-Check

SC 1. Maintaining Genetic diversity in Whooping Cranes p. 696.  Complete questions 1- 3.

 

 

Try This

Livestock Genetics

TR 1. Is it desirable to farmers that livestock populations remain in Hardy Weinberg Equilibrium?

 

TR 2. Are small, genetically similar populations of livestock subject to the negative effects of inbreeding and genetic drift? Why or why not?

 

 

Self-Check

 

Gene banks store the DNA sequences of genes from organisms that are endangered or extinct. Of the hundreds of varieties of rice that used to be grown, only a very few are grown now. The same can be said of potatoes (only the varieties used to make French fries are profitable now). Why store these gene sequences? What possible use could they be in the future?

 

Read p 695: Human activities and genetic diversity in order to answer the following:

 

SC 2. List 4 human activities that have had consequences for gene pools of natural populations. State how each has affected genetic diversity in a target population. State whether the effect was intended or unintended.

Human Activity	Effect on Genetic Diversity	Intended or Unintended Effect