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BVetMed3 POS - Integrated Applied Science > Population Genetics In Companion Animals > Flashcards

Population Genetics In Companion Animals Flashcards

(48 cards)

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1
Q

How many chromosomes do dogs have?

A

78

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2
Q

How many chromosomes do cats have?

A

38

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3
Q

How many chromosomes do rabbits have?

A

44

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4
Q

How does the number of genes relate to the number of chromosomes as chromosome number varies between species?

A

Roughly the same number of genes

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5
Q

What does the founder effect mean?

A

New colony started by a few members of original population

Not all genes from original population present for repopulation:

  • reduced genetic variation
  • non-random sample of genes from original population
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6
Q

What is a genetic bottleneck?

A

Occur when a populations size is reduced for at least one generation

Reduced genetic diversity

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7
Q

What are the types of simple/Mendelian inheritance?

A

Autosomal dominant
Autosomal recessive
X-linked dominant
X-linked recessive

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8
Q

What are the broad categories of inheritance?

A

Simple
Complex
Selection:natural or artificial

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9
Q

What is the difference between simple and complex inheritance?

A

Genes interact with each other

Can interact in different ways in each individual to create huge variations in phenotype

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10
Q

What is the definition of reproductive success?

A

Survival of the form that will leave the most copies of itself in successive generations

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11
Q

What are the ‘genetic forces’ acting on breeds/populations?

A

Selection (natural or artificial)

Loss of genetic diversity (inbreeding or genetic drift)

Immigration

Mutation

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12
Q

When does genetic drift occur?

A

In a SMALL population

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13
Q

What is genetic drift

A

Variation in the relative frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce

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14
Q

What can occur secondary to planned selection?

Give an example

A

Unplanned selection

Deafness with the extreme piebald gene in Dalmatians, english setters, collies, Aussies, white boxers and white bull terriers

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15
Q

When is molecular genotyping in dogs useful?

A

Simple inherited disorders - conditions caused by a mutation in just one gene

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16
Q

How are samples obtained for DNA testing in dogs?

A

Blood or mouth swabs

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17
Q

What is the goal of molecular genotyping in dogs?

A

Identify clear, carrier and affected dogs

Effectively reduce or eliminate undesirable disease genes

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18
Q

What animals should you breed together (based on clinical presentation and genotype)?

A

Clinically normal animals

for autosomal recessive, breed clear and carriers etc,

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19
Q

Why shouldn’t you just breed clear to clear?

A

Reduces genetic variation as cuts out half the population

— will result in more diseases

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20
Q

What animals could you breed with an affected dog?

Why?

Study These Flashcards
A

Clear dogs

Will get all carriers as offspring

21
Q

Give examples of some simple genetic conditions.

Study These Flashcards
A

PRA - progressive retinal atrophy
PLL - primary lens luxation
CLAD
copper toxicosis

22
Q

Give examples of diseases caused by complex genetics

Study These Flashcards
A

Hip dysplasia

Elbow dysplasia

Epilepsy

Bloat

23
Q

Which are more common, simple or complex genetic conditions?

24
Q

What can cause differences between genotype and phenotype?

Study These Flashcards
A 
in utero environment 
Neo natal environment 
Feed intake 
Diet 
Exercise
25
What is meant by the term heritability?
The proportion of the phenotypic variation made up of variation in the genes
26
What does a higher heritability indicate?
We can drive away from the condition by breeding
27
What is the EBV?
Estimated breeding value Tendency of an animal to pass on or develop a disease Used for complex disease
28
What is the difference between the true and estimated breeding value?
True - relevant genotype Estimated - relevant phenotype
29
What can EBVs be used for?
Select towards a positive trait - milk yield in cows Select away from a negative trait - hip dysplasia in dogs
30
When might an individual with bad hips still be used for breeding?
If previous generations have good hips, the implication is that good genes are still present
31
What is the difference between binary disease traits and EBVs? Why might this be beneficial
EBVs are continuous Allow discrimination between ‘healthier’ animals
32
What is the selection intensity?
The difference between the mean of selected individuals and the population mean
33
What does an increased selection intensity risk?
Decreased genetic diversity inadvertently be selecting for other diseases INCREASED RISK OF INBREEDING
34
Why does selection increase risk of inbreeding?
Relatives resemble eachother Selection will result in mating more closely related individuals
35
What is IBD?
Identical by descent Have exact same copy of a gene - same alleles REDUCED HETEROZYGOCITY
36
What is the COI?
Coefficient of Inbreeding Probability that two copies of a gene at a locus are IBD 0.5 x relationship between parents
37
How can inbreeding lead to specific inherited disease?
Reduced number of heterozygotes which ‘hide’ harmful recessive genes
38
What is inbreeding depression?
Reduction in beneficial traits as a result of inbreeding
39
What loci does inbreeding depression affect most?
Any locus where heterozygous performance is better than homozygote performance
40
What is hybrid vigour?
Superior average performance of crossbred progeny compared with the average of their purebreds parent species
41
How long does heterosis / hybrid vigour last for?
Deteriorates after first generation
42
What is the effective population size?
The number of breeding individuals in a random mating population that would have the same rate of inbreeding as seen in the real population
43
How can the effective population size be calculated?
1/ (2x the rate of inbreeding)
44
What is the ideal rate of inbreeding?
Less than 0.05%
45
What happens if the effective population size is less than 50?
Population fitness steadily declines and becomes UNVIABLE in the long term
46
How can you control the rate of inbreeding?
Minimise kinship (coancestry) of matings Increase number of animals used for breeding Equalise use of males and females Monitor genetic contributions Outcrossing
47
What is outcrossing?
Breeding animals in the same breed but with completely separate families
48
What is the ideal effective population size to conserve genetic diversity?
>500

BVetMed3 POS - Integrated Applied Science (2 decks)

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