Lecture 8 Flashcards
(21 cards)
What is conservation genetics?
Conservation genetics studies the genetic factors affecting the survival and reproduction of species, especially small populations.
Mnemonic: Picture a tree with roots labeled “Genetics” and branches labeled “Survival” and “Reproduction.”
What is the aim of conservation genetics?
To ensure the survival of small and endangered populations by maintaining genetic diversity and reducing inbreeding.
Example: The Javan black rhinoceros population (40-60 individuals in Java).
Mnemonic: A rhinoceros balancing on a tightrope labeled “Survival.”
What are the problems faced by small populations?
Genetic instability due to inbreeding.
Loss of genetic diversity.
Increased susceptibility to extinction.
Example: Remote human tribes and Siberian tigers.
Mnemonic: A small group of animals inside a shrinking circle.
What is inbreeding depression?
The reduction in reproductive fitness and survivability caused by inbreeding.
Example: Siberian tigers bred from only 8 founders, leading to genetic defects like blurred stripes.
Mnemonic: A tiger with blurred stripes under a magnifying glass labeled “Inbreeding.”
What happens to heterozygosity in selfing populations?
Selfing reduces heterozygosity and hybrid vigor over generations, increasing the frequency of harmful traits.
Mnemonic: A family tree with fewer branches labeled “Reduced Heterozygosity.”
What is hybrid vigor?
Hybrid vigor (heterosis) occurs when offspring from genetically diverse parents show improved survival and reproduction.
Mnemonic: A bright, healthy plant labeled “Hybrid Vigor” beside a wilting one labeled “Inbreeding.”
How does inbreeding affect the frequency of deleterious mutations?
Inbreeding increases the likelihood of harmful recessive alleles pairing, leading to higher frequencies of genetic disorders.
Example: Down syndrome in inbred white tigers.
Mnemonic: A DNA strand with red warning signs labeled “Mutations.”
What is the inbreeding coefficient (F)?
F
F measures the probability that two alleles are identical by descent.
Values range from 0 (no inbreeding) to 1 (complete inbreeding).
Mnemonic: A slider bar going from “0% Related” to “100% Inbred.”
What is effective population size (N e)?
The number of individuals in a population that contribute to the next generation.
Factors:
Sex ratio imbalance.
Age structure.
Mnemonic: A pie chart split unevenly for “Breeding Males” and “Breeding Females.”
What happens to F over generations?
F increases over generations in small populations, leading to higher inbreeding.
Example: In 15 generations, F in Javan rhinos increased from 0.1 to 0.25.
Mnemonic: A graph showing a rising red line labeled “Inbreeding Over Time.”
What are the three conservation scenarios?
Unmanaged populations: Random breeding.
Managed populations: Controlled breeding in zoos or parks.
Wild populations: Natural mate choice.
Example: Sorraia horses saved with 5 males and 7 females.
Mnemonic: Three circles labeled “Wild,” “Zoo,” and “Natural.”
What is a genetic bottleneck?
A sharp reduction in population size that decreases genetic diversity.
Example: Sorraia horses descended from only two females.
Mnemonic: A narrow funnel with only a few animals passing through.
How is genetic variation maintained in managed populations?
Use studbooks or electronic databases to plan matings and maximize outbreeding.
Mnemonic: A book labeled “Studbook” with diagrams of animal pairings.
How is genetic variation measured in populations?
Methods:
Pedigree analysis: Useful for captive populations.
Genetic testing: Uses microsatellites and minisatellites.
PCR: Amplifies small DNA samples.
Mnemonic: A DNA helix surrounded by tools like a microscope, test tubes, and a family tree.
What are microsatellites and minisatellites?
Microsatellites: 1-7 base repeats, scattered in the genome.
Minisatellites: 6-100 base repeats, often near chromosome ends.
Mnemonic: A ladder with short rungs for microsatellites and long rungs for minisatellites.
How does PCR help in conservation genetics?
PCR amplifies DNA from small samples (e.g., hair, blood, or feces) to analyze genetic diversity and identify individuals.
Mnemonic: A DNA strand glowing as it multiplies under a PCR machine.
What happened to the Javan black rhinoceros population?
40-60 individuals remain in Java.
Fewer than 8 remain in Vietnam.
Threats: Genetic instability and inbreeding.
How were Sorraia horses saved from extinction?
By 1937, only 5 males and 7 females remained.
Random interbreeding led to 160 animals by 2001, though highly inbred.
Mnemonic: A horse herd rebuilding from a single pair.
What challenges exist for conservation of domestic breeds?
Domestic animals (e.g., dairy cows, pet dogs) are often highly inbred, leading to traits like reduced reproductive fitness and inbreeding depression.
What is hybrid vigor, and how does inbreeding affect it?
Hybrid vigor (heterosis) is the improved fitness of genetically diverse offspring.
Inbreeding reduces hybrid vigor by increasing homozygosity and harmful recessive traits.
Example: Inbred Siberian tigers show blurred stripes and deformities.
Mnemonic: A healthy, bright tiger labeled “Diverse Genes” next to a blurred tiger labeled “Inbreeding.”
What are the advantages of using PCR?
Requires minimal DNA.
High sensitivity and specificity.
Can analyze degraded samples.
Example: Used to identify individual Javan rhinos from fecal samples.
Mnemonic: A magnifying glass zooming in on a tiny DNA strand.
