Module 8 Lesson 3 - 4

Human Activity and Genetic Diversity

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Read pages 695 - 697

As humans, with all our technologies, we have had significant effects on other populations in our ecosystem. Many of our practices are controversial. Think about the following scenarios resulting from intended and unintended consequences of science and technology.

Overusing Antibiotics

Not many people think of bacteria or viruses as natural populations, but certainly they qualify. Antibiotics used to destroy bacteria can give a selective advantage to those bacteria that have alleles for antibiotic resistance. Many common 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?

Transgenic Organisms

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, such as inserting desirable genes from one species into another species to produce 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, can a hungry planet be fed without the use of these biotechnologies?

Cloning

Cloning has been used in an attempt to save endangered species from extinction, thus preserving gene pools. Similarly, animals with inserted genes (such as 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?

Invasive Non-native Species

The introduction of exotic species often results in unintended consequences to gene pools.

Wild pigs (often called wild boars) recently have been proclaimed 'pests' in central Alberta. These pigs were brought from Europe to satisfy a growing market for their 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 being a menace to people. They have few predators because of their size (and tusks), and they breed in the wild at an alarming rate.

Gene Banks

Gene banks preserve 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. (Today, only the varieties used to make French fries are profitable commercially.) Why should these gene sequences be stored? What possible use could they be in the future?

Self-Check

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1. In the 1800s, the population of whooping cranes was approximately in 1400 in northern Alberta. In the 1940s, the population dropped to about 15 whooping cranes. Due to conservation efforts, currently more than 300 whooping cranes exist worldwide. For more information, read page 696 in your textbook.
   
   
   1. The current whooping cranes are the descendants of the 15 whooping cranes that survived in the 1940s. How genetically diverse is the current population of whooping cranes?
   
   
   2. Adult whooping cranes mate for life. Does this help or hinder captive breeding programs?
   
   
   3. DNA sequencing can help determine the genetic diversity within the whooping crane population. How could this information help assess the vulnerability of the population to environmental changes?


2. Is it desirable to farmers that livestock populations remain in Hardy Weinberg equilibrium?
   
   
3. Are small, genetically similar populations of livestock subject to the negative effects of inbreeding and genetic drift? Explain.
   
   
4. List four 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. For more information, read page 695 in the textbook, Human Activities and Genetic Diversity.
   
   

   Human Activity	Effect on Genetic Diversity	Intended or Unintended Effect