Behavioral Genetics and Animal Science - Genetics and the Behavior of Domestic Animals - page 6

Henrichson et al., 2009 ). CNVs are often spontaneous (de novo) mutations not
inherited form the parents. The many types of CNVs range from translocation
of pieces of genetic code, to deletions of genetic code, or to extra copies
of code. Twelve per cent of the human genome is in copy number variable
regions of the genome ( Redon et al., 2006 ). CNVs are very numerous in the
brain and the immune system.
Jumping Genes
Also called transposable elements (transposons), jumping genes are short
segments of genetic material that transport themselves throughout the genome
in a “cut and paste”, or a “copy and paste” manner. Mikkelson et al.(2007)
states that transposons are a “creative force” in the evolution of mammalian
gene regulation.” Jumping genes are more numerous in the brain than in liver
or heart cells ( Vogel, 2011 ).
Coding DNA
The very small percentage of the genome that specifically codes for proteins
used in development of the animal. Until recently, only coding DNA was
sequenced.
Non-Coding DNA, Also Called Regulatory DNA
In the 1980s, this was called junk DNA because it does not code for proteins.
Researchers have discovered that non-coding DNA has a regulatory function
and approximately 80% of the non-coding DNA is transcribed by RNA and has
biochemical functions ( ENCODE Project Consortium 2012 ). Non-coding DNA
is the “computer operating system” that directs the coding DNA. Non-coding
DNA may be the gene's “project managers” that orchestrate and direct the
sequence of building proteins ( Saey, 2011 ). Chakravarti and Kapoor (2012)
state that to understand the genes that code for proteins, the regulatory
non-coding DNA needs to be understood. Some portions of non-coding DNA
are highly conserved, and similar sequences occur in many different animals.
Other portions of non-coding genome may rapidly evolve ( Maher, 2012 ).
Coding regions of DNA that direct the development of basic patterning of the
body (hoxgenes) are highly conserved across many species from arthropods to
mammals ( Linn et al.,2008 ). Early pattern formation of the notochord and neu-
ral tube is also highly conserved ( Richardson, 2012 ). In both plants and animals,
the embryos of many species look similar during the mid-embryonic stage of
development. The mid-stage of development is “dominated by ancient genes”
( Quint et al., 2012 ). A basic principle is that similar traits in a species originate
from highly conserved genetic code. Traits that have recently changed origin-
ate from newer code. Research shows that changes in non-coding DNA are
drivers of evolutionary change. The human neocortex has a higher percent-
age of young genes expressed during fetal development compared to mice