Module 8 Population Genetics

4.8.4 page 3

Lesson Summary

Technologies developed to meet human needs often have consequences for gene pools of natural populations – some intended, some not.

Intended:

• Use of antibiotics increase natural selection and frequency of resistant alleles in bacterial populations. 
• Widespread and effective medical/pharmaceutical/surgical technologies increase survivability of individuals with deleterious alleles.
• Transfer of advantageous genes into crops and livestock improve yields and profitability, but change gene pools and evolutionary paths.
• Cloning of endangered or possibly extinct organisms is done to preserve rare alleles. 
• Crops and livestock with advantageous qualities are cloned to create a uniform and economically profitable product, but this reduces diversity in the gene pool. 
• Creation of wild-life corridors increases gene flow and maintains diversity in populations.
• Creation of wildlife preserves can lead to genetic drift if either the Founder or the Bottleneck effect is in play. Wildlife preserves lead to inbreeding which can also result in genetic drift reducing diversity substantially.

 Unintended:

• Agriculture, dam construction, road building, urban sprawl, logging, and industrialization result in habitat destruction and fragmentation leading to rapid selection and reduced genetic diversity.
• Over-hunting can reduce diversity by removing ‘desirable’ alleles from the gene pool. (e.g. the biggest and strongest animals are valued more by hunters)
• Introducing genes into crops and livestock can have unintended effects on the expression of other genes, leading to reduced survivability and loss of diversity.
• Genes introduced into domestic species can ‘jump’ to wild species, changing the gene pool substantially. (e.g. gene for herbicide resistance jumping from corn to weed species)