Genetics: Quantitative Inheritance

1. QUANTITATIVE
INHERITANCE
Reporter:
JAYLOU S. QUILLAMAR
Week 10

3. A. Inheritance of quantitative characters
1.multiple genes
• Multiple genes are
involved, polygenic
traits do not follow
the patterns of
Mendelian
inheritance.
• Many polygenic
traits are also
influenced by the
environment and are
called multifactorial.

4. 2. Number of genes in polygene system
• It is a condition in which two
or more genes influence a
single trait in an additive
manner. (Eg: human skin
colour and height which vary
in population in gradation.)
• Polygenic trait refers to a trait
that is controlled by multiple
non-allelic genes. These genes
are called polygenes. They are a
group of genes that, when
turned on, are expressed as a
unit.

5. 2. Number of genes in polygene system
• Polygenic inheritance refers
to the inheritance of a trait
governed by more than one
genes. Generally, three or
more genes govern the
inheritance of polygenic
traits.

6. 3. Regression to the mean
• regression to the mean (RTM), a widespread
statistical phenomenon that occurs when a
nonrandom sample is selected from a population
and the two variables of interest measured are
imperfectly correlated.

7. • Regression to the mean
(RTM) is a statistical
phenomenon that can
make natural variation
in repeated data look
like real change.
• It happens when
unusually large or small
measurements tend to
be followed by
measurements that are
closer to the mean

8. 4. Effect of dominance and
gene interaction
• Gene interaction is
interaction between genes
at different loci.
Dominance is interaction
between alleles at a single
locus.
• The dominance effect is a
kind of non-additive effect
due to the interaction
between alleles at the
same locus