This document discusses quantitative inheritance, which involves traits controlled by multiple genes rather than single genes. It notes that quantitative traits are polygenic, meaning they are influenced by multiple genes interacting in an additive manner. Typically three or more genes contribute to polygenic traits. The document also explains regression to the mean, in which unusually large or small trait measurements tend to revert back toward the population average. Finally, it mentions dominance and gene interaction as non-additive effects that influence polygenic traits.

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