GENETIC DRIFT - Founder and Bottleneck Effect

Achievement Standard 2.5
AS.91157
Demonstrate understanding of genetic variation and change
External 4 Credits
 
Demonstrate understanding involves defining, using annotated diagrams or models to describe, and describing characteristics of, or providing an account of, genetic variation and change and also involves providing reasons as to how or why genetic variation and change occurs.Comprehensive understanding involves linking biological ideas about genetic variation and change.  The discussion of ideas may involve justifying, relating, evaluating, comparing and contrasting, or analysing.
 
Genetic variation and change involves the following concepts:
  1. sources of variation within a gene pool and factors that cause changes to the allele frequency in a gene pool.
 
  1. Biological ideas and processes relating to sources of variation within a gene pool are selected from:
  • mutation as a source of new alleles
  • independent assortment, segregation and crossing over during meiosis
  • monohybrid inheritance to show the effect of co-dominance, incomplete dominance, lethal alleles, and multiple alleles
  • dihybrid inheritance with complete dominance
  • the effect of crossing over and linked genes on dihybrid inheritance.
 
2. Biological ideas and processes relating to factors affecting allele frequencies in a gene pool are selected from:
  • natural selection
  • migration
  • genetic drift.
CLASS 11 Students: The objective of this page is to help you understand Genetic Drift, Founder Effect and Bottlenecks.​The next section will focus on New Zealand Species - Founder Effect, Bottlenecks and Conservation.
  1. Take notes,
  2. Complete worksheets and activities
  3. make flashcards and
  4. complete sections in your workbooks. 

Useful Websites

https://www.passbiology.co.nz/biology-level-2/genetic-variation-and-change

https://ncgsk.weebly.com/genetic-variation.html
​
http://www.nobraintoosmall.co.nz/html/senior_biology/NCEA2_biology.html

Genetic Drift Intro

Genetic drift, also called genetic sampling error,
  • a change in the gene pool of a small population that takes place strictly by chance.
  • Genetic drift can result in genetic traits being lost from a population or becoming widespread in a population without respect to the survival or reproductive value of the alleles involved.
  • A random statistical effect, genetic drift can occur only in small, isolated populations in which the gene pool is small enough that chance events can change its makeup substantially.
 

geneticdrift-notes.pdf
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worksheet_-_genetic_drift.pdf
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Unit Planner & Guidelines

genetic_variation_and_change.pdf
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guideline_1_.pdf
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guideline_2.pdf
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FounderEffect  and Bottlenecks

Founder Effect - A founder population refers to a small group of individuals that colonises a new isolated area such as an island.
  • The range and frequency of alleles present in this small group is unlikely to be representative of that of the original population
  • Some alleles may not be present in this group, others will be less frequent or more frequent than in the original population
Bottleneck - populations may be suddenly reduced in numbers to a small size. This typically occurs as a result of the following:
  • A catastrophic environmental event (e.g. flood, fire, landslide, drought)- indiscriminately removes individuals regardless of their genetic makeup.
  • Human action (such as rapid habitat destruction or introduction of predators or competitors) removes individuals

FOR STUDENTS: FIND EXAMPLES of Founder effect and Bottleneck effects
difference founder /bottleneck_effect.pdf
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geneticdrift.worksheet.variety.pdf
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Genetic Drift_founder_effect.pptx
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impt_2_evol_.ppt
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genetic_drift_m_m_activity.pdf
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impt_2_evol_.ppt
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