Behavioral Genetics and Animal Science - Genetics and the Behavior of Domestic Animals - page 5

tame foxes had higher levels of the neurotransmitter serotonin ( Popova
et al., 1975 ). Serotonin is known to inhibit certain kinds of aggression
( Belyaev, 1979 ). Serotonin levels are increased in the brains of people who
take Prozac (fluoxetine).
The fox experiments started by Dmitry Belyaev and Lyudmila Trut in the
late 1950s are still ongoing. Using molecular genetic techniques, Kukekova
et al. (Chapter 10) are working to understand basic biological principles that
guide social behavior. They suggest that domesticated behavior in dogs and
foxes may have a similar genetic basis.
Basic Genetic Mechanisms
Since the first edition, there has been a huge increase of research on genetic
mechanisms. By the time this topic is published, some of the material on
genetic mechanisms may be obsolete. However, behavior studies reviewed
in this topic will remain useful to scientists working to discover new genetic
mechanisms. The classical genetic concepts of recessive and dominant traits
discovered by Gregor Mendel explain only a small fraction of the genetic
factors affecting inheritance. It is beyond the scope of this topic to provide
an in-depth review of genetic mechanisms, instead we describe key princi-
ples that will make it easier for the non-geneticist to read and understand
the latest papers. Life is complicated. Increasingly complex non-Mendelian
genetic mechanisms are being discovered, and they are best viewed as
networks of information ( Hayden, 2012 ). Below is an outline of some basic
genetic mechanisms that produce changes in the appearance and behavior of
animals.
SNPs (Single Nucleotide Polymorphisms)
An SNP is a single code change in a single base pair of DNA. Guryev et al.
(2004) states that SNPs are a major factor in genetic variation. In some
Mendelian diseases single SNPs or multiple SNPs are involved in disease
inheritance ( Kong, et al., 2009; Shastry, 2002 ).
Repeats
Repeats are also called tandem repeats, single sequence repeats (SSRs), or
genetic stutters. Repeats are sequences of DNA code repeated more than once,
and the number of repeats can vary within a gene. The number of repeats can
determine many traits ranging from the length of a dog's nose to variations in
brain development ( Fondon and Garner, 2004; Fondon et al., 2008 ).
CNVs (Copy Number Variations)
CNVs are rearrangements of genetic code. It is likely CNVs contribute greatly
to genetic variation by modifying genetic expression ( Chaignat et al., 2011;