Effects of Inbreeding & Inbreeding depression

1. Effects Of Inbreeding
&
Inbreeding depression
2K15-AV-167 BY SHIZRA
RASHID

2. EFFECTSOF
INBREEDING

3. Inbreeding
Expression
of deleterious
alleles
Prepotency

4. Prepotency
 "The ability of an individual to produce
progeny whose performance is especially
like its own"
 One of the consequence of inbreeding is
the greater prepotency in the
animals, means the performance of the
offspring is similar to their parents.
 And that is why the inbreeding is
performed.

5. Deleterious
Alleles
 "Are the damaging or defected genes
produced after certain spontaneous
mutation in the genotype."
 These alleles are often recessive and
a heterozygous individual carrying a
single recessive deleterious allele will not
be affected. But if it is
homozygous carrying both recessive
deleterious allele will be affected by any
particular defect.
 As inbreeding causes the increase in the
homozygosity it causes the expression of
deleterious genes.

6. For
Example
There are lot of genetic defects in
the animals, that are produced due
to the expression of these
deleterious alleles.
For example, Spider Leg condition
in Sheep, Dwarfism in cattle, or
Diaphragmatic Hernia in Dogs etc.
All these defects decreases the
overall performance of the animals.
And this decline in their
performance is known
as Inbreeding depression.

7. Inbreeding
Definition
“A decrease in the performance
of animals, as a result of
inbreeding"

8. Affected Traits
Inbreeding depression is most
noticeable in the traits like fertility
and survivability.
It is one of the adverse consequence
of inbreeding.
It occurs due to the increased
homozygosity in the offspring of
related animals.

9. Mechanism
 Inbreeding results in
more recessive traits manifesting
themselves, as the genomes of pair-mates
are more similar.
 Recessive traits can only occur in an
offspring if present in both parents'
genomes. The more genetically similar
the parents are, the more often recessive
traits appear in their offspring.

10. Cont..
 Consequently, the more closely related
the breeding pair is, the
more homozygous,
deleterious genes the offspring may have,
resulting in very unfit individuals.
 In general, the higher the genetic
variation or gene pool within a breeding
population, the less likely it is to suffer
from inbreeding depression.

11. EXAMPLE

12. Illustration
 In this example, a is the recessive
allele which has negative effects. In
order for the a phenotype to
become active, the gene must end
up as homozygous aa because in
the geneotype Aa, the A takes
dominance over the a and
the a does not have any effect.

13. Cont...
 Due to their reduced phenotypic
expression and their consequent
reduced selection, recessive genes
are, more often than not,
detrimental phenotypes by causing
the organism to be less fit to its
natural environment.

14. Howtoreduce
inbreeding
depression?
 Natural Selection:- cannot effectively
remove all deleterious recessive genes
from a population for several reasons.
First, deleterious genes arise constantly
through mutation within a population.
Second, in a population where inbreeding
occurs frequently, most offspring will
have some deleterious traits, so few will
be more fit for survival than the others.

15. Artificial
Selection
Introducing alleles from a different
population can reverse inbreeding
depression. Different populations
of the same species have different
deleterious traits, and therefore
their cross breeding will not result
in homozygosity at most loci in the
offspring.