Week 3. Natural Selection and Behavioral Genetics
Before going any further..... What do we mean by "Nature" and
how has this been shaped through evolution. In order to study behavior
as a phenotype we must understand how evolution shapes phenotypes through
Sinervo chapter 2,3,4
Like natural selection, artificial slection alters gene frequencies in a population.
Repeated examples of animal domestication results in similar phenotypes. The
geneitc architecture of domestication is currently under investigation.
Trut (1999) Early Canid Domestication:
The Farm-Fox Experiment American Scientist 87:159-169.
For a brief and entertaining historical account of Darwin's "Origin of Species" try reading
Keynes, RD (1996) Steps
on the Path to the Origin of Species. J. Theor. Biol. 187, 461-71
for fun: when and where were our pets domesticated?
Leonard et al (2002)
Ancient DNA Evidence for Old
World Origin of New World
Driscoll et al (2007)
The Near Eastern Origin of
Cat DomesticationpossiblyScience 317:519-523
When we search for the proximate factors for behavioral causes, we naturally
start with genes. Our understanding of how genes influence behavior has
been advanced both by studies of wild populations and model organisms
in the lab. While early studies identified single genes of large
effect we now know that the genomic architecture of many behaviors is
While much of our understanding of behavioral genetics derives from Drosophila mutants and white lab mice, the examples natural behavioral
phenotypes affected by naturally occurring allelic variation are by far
the most exciting. This excitiement comes at a cost and one must weigh
the relative benefits and choose experimental systems wisely.
Sinvero chapter 2
Sokolowski (2001) Drosophila:
Behavior meets Genetics. Nature Genetics 2:877-892.
Nair & Young (2005) Vasopressin
and Pair-Bond Formation: Genes to Brain to Behavior. Physiology 21:146-152.
To find human genes known to strongly influence behavior check out the NIH website Online Mendelian Inheritance of Man and look up behavior.
Fink, S., Excoffiel,
L., Heckel, G. (2006) Mammalian monogamy is not controlled by a single
gene PNAS 103:10956-10960.
Young, L.J., & Hammock
E.A.D. (2007) On switches and knobs, microsatellites and monogamy TIG 23:209-212.
--Strains of mice that show characteristic patterns of behavior are critical
research in neurobehavioral genetics. Crabbe (from OHSU) and colleagues
performed replicated behavioral tests in several labs across the country
to validate these assumptions (Wahlsten_2003).
--It is widely acknowledged that the nature of the
maternal care a child receives can have long-term reper-
cussions, and that children raised in deprived environments can have severe
cognitive and behavioural
difficulties that last into adulthood. The mechanisms
underlying these effects are one of the most exciting areas of research
right now (in my opinion). The rat model of maternal behavior offers us
our first understanding of the possible mechanisms that underlie this effect
(Meaney and Szyf, 2005).
Surprisingly, it is the protien structure of the chromosome, the chromatin,
that codes this affect. In a parallel study, researchers have identified
a specific allele of a neuotransmitter receptor that may affect a similar
plasticity of behavioral phenotype (Hariri
et al., 2002) that might even
extend to humans (Champoux
et al., 2004)