Receptor for Vasopressin
● Monogamous: has higher expression in the ventral pallidum (VP)
○ Prairie
● Non-monogamous: higher expression in the lateral septum (LS)
○ Meadow
● Vasopressin receptor is associated with monogamy for Male Wolves
○ Correlation affect
Study: manipulating the expression of a single gene
● In Male meta volve infused a virus
● The virus expressed more vase express little levels of Vasopressin
● Increase V1aR expression in adult males
● Non-monogamous evolve (meadow vole)
● Showed partner preference = manipulation has influenced
● Impacts the behavior of the animal from one gene in one part of the brain
● The virus that changed one gene altered their behavior = go back to origins mate
Evolution & Natural Selection
Evolution: a change in the frequency in a gene or a trait
● Occurs if 3 conditions are met
1. Variation: members of a species differ in some of their characteristics
2. Heredity: parents are able to pass on some of their distinctive characteristics to their
offspring
3. The difference in reproductive success: some individuals have more surviving offspring
than others in the population due to distinctive characteristics
Natural Selection: acts on individuals rather than groups
● Not primarily on species, groups , or populations
● Individual selection vs. group selection
Hanuman Langur Monkeys: Males fight to monopolize reproduction with females in the group
● Dominate male of the group is replaced the new male will spend much of the time trying
to kill infants of group
● Females often join forces to fight back and defend their infants
Hypothesis for Male Infanticide?
1. Social Pathology Hypothesis: infanticide is an abnormal, pathological response to
overcrowding in areas where they are fed by humans. Non-evolutionary
a. Infanticide regularly occurs in troops living … = does NOT support
2. Population regulation hypothesis: infant prevents the group from becoming too big
a. NOT support hypothesis
, 3. Quicker reproduction hypothesis: infanticide should occur soon after take over, killer
male should not kill any of his own young, dependent on group size or density
Lecture 3: Jan 15 Proximate and Ultimate Causes Pt.2
Proximate Mechanisms: Dialects & Development (2 simple alternative hypotheses)
1. Song dialect is the product of heredity, with birds from different regions differing in
genetics
2. Song dialects are the product of environmental variables )exp. Who they grow up
around)
Peter Marlen Experiment
1. Isolation Experiment:
a. collected eggs from the nest
b. Marler raised male WCSP in soundproof chambers in the lab (individuals vs.
group) = had experimental control
c. Males produced stage songs that barely resembled normal WCSP songs (isolate
songs) at 150 days of age
d. Manipulated the environment and not genetics all look different
e. Isolate or as a group, they sang similar songs = early development
f. Strength: there are no external factors affecting the birds, experimental/ control
g. Limitation: not in a natural environment, they are in the lab = does create a
difference (animals from the wild vs. animals that grew up in the lab)
2. Conspecific tape Tutoring Experiment
a. Brought eggs (same as above) but tutored young chicks that were 10-50 days
with tapes of WCSP song, then 150 days of age, they sang a good copy of the
taped song regardless of dialect on tape
b. Only 8 minutes per day for 2-3 weeks
c. Tutoring with tapes did not work with older male chicks (past 50 days old)
3. Heterospecific tape tutoring experiment
a. Marler tutored young male WCSP with tapes of song sparrow songs
b. Produced strange songs - similar to isolates that heard no song
c. When tutored with tapes of both WCSP and song sparrows, the males learned
the song
, Summary based on Lab Studies:
● Subsong = like when humans babble
● Nural template is open between 10- 50 but they are not actually producing any songs
● Similar to how humans learn the language
● Song dialects are the result of early experience
● MALE Wcsp cannot learn songs of other species
● Innate preference to learn a specific song
● Male must be exposed to WCSP song during a critical period for learning (10-50 days of
age)
● Must be able to hear himself practice during subsong phase
● Testosterone helps remain the ‘full song’ consistent throughout adulthood
4. Experiments on Social Influence
a. WCSP males could interact visually and vocally with love Strawberry Finches
learned finch song, even though they could hear (but not see) WCSP
b. Some adult WCSP male will change song slightly to match WCSP neighbors
Proximate Mechanisms: Immediate Causes (an understanding function of different brain areas
of behaviours)
● Brain is interconnected
● Songbirds have a circuit of brain nuclei that controls
the learning and production of the song
● Motor control:
○ Hvc = song output is a pattern, which projects
RA, which projects nXllts that control muscles of syrinx
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