Chapter 3 - Genetics and Behavior

Question 1

Genotype

Answer 1

The genetic makeup of an individual

Question 2

Phenotype

Answer 2

he observable traits of an
individual that result from the interaction of its
genotype with the environment

Question 3

Nest cleaning behavior in honeybees

Answer 3

American foulbrood is a bacterial disease that
kills the larvae of honeybees.
* Contamination of the hive can be reduced by
removing dead larvae. This involves two distinct
behaviors: a) uncapping, wherein caps are
removed from comb cells with dead larvae, and
b) removal, wherein
dead larvae are
removed.
Each of these behaviors is controlled by an
independent recessive allele:
– u for uncapping
– r for removal behavior
* uurr = complete behavior
* uuRr or uuRR = will uncap, but do not remove
larvae
* Uurr or UUrr = do not uncap, but will remove
larvae that are already uncapped
* UuRr or UURR = do not perform either
behavior

Question 4

2 major ways genes can affect behavior

Answer 4

1. The expression of genes can affect the
   development of the nervous system and
   endocrine system.
2. The environment (including social
   interactions) can trigger changes in the
   expression of certain genes, which can, in
   turn, lead to alterations in behavior

Question 5

how do regulatory genes affect behavior

Answer 5

produce proteins called
transcription factors, which can increase or
decrease gene expression
EX: Courtship and Mating in Fruit Flies

Question 6

Four goals of behavioral genetics

Answer 6

– Identify genes that underlie a behavior.
– Learn the functions of those genes.
– Understand interactions amongst genes.
– Understand interactions between genes and
the environment.

Question 7

Heritability

Answer 7

a statistical measure that indicates
how strongly a trait (in this case a behavior) is
influenced by genes.
* It is defined as the ratio of the variation caused
by genetic differences to the total amount of
variability in that trait within a population

Question 8

Methods of Behavioral Genetics

Answer 8

1. Inbreeding
2. Artificial Selection
3. Hybridization
4. Alterations in Gene Activity

Question 9

Inbreeding

Answer 9

The use of inbred lines,
which are homozygous for nearly all of
their genes, can be useful
– To show the effects of genes, the behavior of
two different strains can be compared in the
same environment.
– To show the effects of the environment, the
same inbred strain can be studied in different
environments.
EX: Effects of Genes on antipredator responses in Paradise Fish

Question 10

Example - Effects of
Environment on Behavior of
Voles

Answer 10

Prairie voles exhibit more
parental care than meadow
voles. (Females spend more
time in the nest and nurse more
often. Males also show more
parental care.)
Cross-Fostering Experiment
* Meadow voles that were raised by prairie voles
gave more care to their own offspring than those
that had been placed in other meadow vole
nests.
* Therefore, the experience a vole has with its
own parents can influence how it treats its own
offspring.
* Other behaviors (food caching, tunnel building,
overall activity) were unaffected by cross-
fostering.

Question 11

Artificial Selection

Answer 11

If the frequency of a trait in
a population can be altered by choosing
appropriate breeders, then that trait must have a
genetic basis.

Question 12

Hybridization

Answer 12

If a behavior is exhibited
in two distinct forms, then it is more likely
that the relationship between genes and
behavior is more simple.
– Example: Foraging Strategies in Fruit Flies

Question 13

Alterations in Gene Activity

Answer 13

One way to
confirm whether a gene affects a behavior is
to alter the expression of that gene.
- This can involve increasing gene activity by
adding copies of the gene (knocking in)
or decreasing gene activity by disabling
the gene (knocking out).

Question 14

quantitative trait
locus (QTL).

Answer 14

A region of DNA associated with a particular
quantitative trait

Question 15

Dominance Relationships in
Cichlid Fish

Answer 15

Astatotilapia burtoni
* Dominant males are
brightly colored,
aggressively defend
territories, and have
greater reproductive
success.
* Subordinate males are
nonterritorial, have
camouflage coloration,
and are less likely to be
chosen as mates.

Question 16

Nerve cells may respond to stimuli by generating
electrical signals.

Answer 16

Those stimuli may also initiate a broader
response by activating early genes. These
genes may become active within minutes or
hours after stimulation, and they code for
proteins that regulate the activity of other genes.
In turn those genes may produce proteins that
might affect hormone production, hormone
receptors, the growth of nerve cells, etc.
If a nonterritorial male wins aggressive
encounters, expression of the GnRH gene is
increased, as are the number of GnRH receptors
in the pituitary gland.
* Increased GnRH levels are correlated with an
increase in social rank and the acquisition of a
territory.
* GnRH triggers the release of sex hormones
(androgens) that cause the development of the
testes and the production of sperm. This also
leads to changes in coloration.
Once dominance is obtained, growth rates slow
significantly.
* Social stimuli associated with dominance
increase the expression of a gene that codes for
somatostatin, which inhibits growth hormone.
* Opportunities to increase social status may
occur rapidly. The immediate early gene erg-1
orchestrates a subordinate male’s response to
these opportunities. He will almost immediately
change color and begin to exhibit aggressive
behavior.