Genetics: In the
Veterinary World
By:
Shawn McCorkle
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What is genetics?
The study of how traits are passed
from generation to generation
OUTLINE
The Basics
 Dog Breeding
 Genetic Diversity in Wildlife

Review Terms



DNA- genetic material
that contains the
instructions for the
development of nearly all
living organisms
Chromosome-Contains
strands of DNA
Gene- Piece of DNA, the
unit of heredity
Review terms cont.
Homologous chromosomes-pairs of
chromosomes that have similar genetic
information.
O Allele-one alternative
form of a gene
 Dominant Alleles
 Recessive Alleles
 Homozygous = same allele
 Heterozygous = different alleles
O
Dominant
Alleles
Recessive
Allele
Recessive
Allele
Is this parent
Homozygous
or
Heterozygous?
B
b
B
B B
B b
B
B B
B b
What about this parent?
How do the
offspring
change?
So, How Do Genes Express Themselves?
Remember, A gene is a piece of DNA
DNA
STRAND
G
C
A
PROTEIN
3. Proteins carry out
functions in the body
Review Questions
What’s an allele?
 What does homozygous and heterozygous
mean?
 What is made when a gene expresses
itself?
 How many chromosomes do human cells
have?

Genetics and Dog Breeding

Pure Breed Dog - A recognized strain
established by breeding individuals over many
generations

In-Breeding- breeding between close relatives
Inbreeding
Recessive disease-carrying allele
http://en.wikipedia.org/wiki/Inbreeding_depression
Examples of Genetic Disorders
Magnified by In-Breeding in
Dogs
Hip dysplasia
 Deafness
 Heart Disease

Hip Dysplasia
Deafness
Heart Disease
Review Questions
What’s the ultimate negative effect of inbreeding?
 What are some examples of disorders as
a result of in-breeding?
 What type of dogs are more prone to
developing hip dysplasia?

Wildlife Genetics
Genetic Diversity
The total number of genetic
characteristic within a species
Refers to a population
Genetic Diversity
• Every individual has a unique set of genes
• This genetic diversity within a population is
what allows for organisms to adapt to various
environmental changes
The Cheetah
The Cheetah:
Small populations and lack of genetic diversity
• Past threats: Climate Change
– Population decline
and subsequent loss
of genetic diversity
• Current threats: Human induced
– Habitat destruction
– Hunting (poaching)
– Currently 12,00015,000
The Cheetah:
Small populations and lack of genetic diversity
• Are there now enough cheetahs to sustain a
population?
• So, how bad is the cheetah’s genetic diversity?
-Cheetahs share 99% of the same
genes. A normal species shares only 80%
Genetics in Real Life
Cloning
 Gene Therapy
 Stem Cell Research
 Human Genome Project
 Disorders caused by mutations:

Downs Syndrome
 Huntingtons
 Turner Syndrome
 Klinefelter’s Syndrome

THE END
THANK YOU!!!
Puppy Mills vs Animal Shelters
Large scale breeding facilities
that operate in bad
conditions
Can result in:
 Hereditary defects in
puppies
A facility that houses
homeless, lost or
abandoned animals
Promotes:
 “Muts,” which ultimately
leads to a more genetically
diverse population
Wildlife Population
What is the #1 problem facing wildlife
populations?
HABITAT LOSS/FRAGMENTATION
-Caused mostly by humans
Habitat Fragmentation
• Definition
– Discontinuities created in organism’s natural
habitat.
• Can occur naturally or by human influence
– Natural Habitat Fragmentation
• Typically occurs very slowly and does NOT lead to loss
in overall genetic diversity
– Man-made Habitat Fragmentation
• Typically occurs very rapidly and leads to some
degree of loss in genetic diversity
Man-Made Fragmentation:
England
Non-disturbed habitat is
shown in black.
Since the year 400, the
habitat has declined
until very little
undisturbed habitat
remains (1960)
GENE EXPRESSION
BODY
GENE
PROTEIN
GENETIC MUTATIONS
BODY
GENE
PROTEIN
Natural Selection vs. Artificial
Selection


Natural Selection
(“Survival of the Fittest”)
-Those who were able to
successfully compete for
food and shelter were
able to reproduce and
pass on their genes,
while others died
Artificial Selection (i.e.
Dog breeding)
-Breeding an animal to
enhance certain
characteristics
Charles Darwin
Homozygous
Dominant
Heterozygous
Homozygous
Recessive
Heterozygous
When DNA is mutated, A different Protein is
made, and a different function is carried out
G
C
A
DNA
STRAND
PROTEIN
NORMAL:
MUTATION:
G
C
C
Different Types of Mutations
Type of Mutation
Substitution
Deletion
Insertion
Inversion
Duplication
Original Sequence Mutated Sequence
ATCGTTAGGC
ATCCTTAGGC
ATCGTTAGGC
ATCGGGC
ATCGTTAGGC
ATCGTCCATAGGC
ATCGTTAGGC
ATTTGCAGGC
ATCGTTAGGC
ATCGTTCGTTAGGC
Deletion Mutation
SCRAMBLED CODE
• Original code: “The cat sat on the mat”
• Mutations that have little effect on the meaning:
“The cat on the mat” (DELETION)
“The kat sat on the mat” (SUBSTITUTION)
• Mutations that change the meaning
“The hat sat on the mat” (SUBSTITUTION)
“The cat the mat” (DELETION)
• Mutations that make the message nonsensical
“The cat eht no tas mat” (INVERSION)
Brooks, Martin. “Get A Grip on Genetics.” East Sussex, England, 1999. Pg 27
Cataracts
In-Breeding
In breeding over a period of time can lead
a higher frequency of weaker recessive
alleles
 Inbreeding Depression- a less healthy
and therefore less resilient population

Real Life Example
ABCB1-1∆ (multidrug sensitivity)
A deletion mutation
 Causes dogs to suffer bad reactions to
some dewormers
 Side effects can develop after a single
dose
 Primarily affects herding breeds of dogs
 The allele is said to have originated with
one British sheepdog in the mid-1800s

The Cheetah:
Small populations and lack of genetic diversity
• 10,000 years ago Climate Change caused the
majority of the population to die off
• Population
– 1900 – 100,000
– 1980 – 2,500
– Today – 12,000-15,000
King Cheetah
• First reported in 1927
• Example of recessive trait
that arose from a
mutation
Natural
• Occur over very long
periods of time – up to
millions of years
• Allows for organisms to
adapt to environmental
changes
• Usually leads to stable,
healthy populations
• Main contributor to the
appearance of new species
• Little loss in genetic
diversity
Anthropogenic
• Habitat is destroyed over a
short period of time
• Does not allow for
organisms to adapt and can
lead to species extinction
• Forest destruction provides
better habitat for disease
carriers like mosquitoes and
ticks
• Leaves poor genetic stock
and little opportunity for
gene dilution
• More likely to cause
significant loss of genetic
diversity
Mixed Breeds vs. Pure Breeds