Hormones and Reproduction in Other Vertebrates

1
Hormones and Reproduction in Other Vertebrates
Page 261-269
2
Copulation of Japanese quails
3

• Males - ZZ females - ZW
• Male - default
• Mating behavior is sexually dimorphic
• males strut around and crow
• Separation of mating from other reproductive
  behaviors

4

• Castration reduces whereas T restores male
  copulatory behavior
• Aromatase or E receptor blockers prevent T
  effects
• DHT restores crowing but not copulatory behavior
• Activation T is converted into E or DHT to
  affect copulatory and crow behaviors,
  respectively.

5

• T in adult females - no male-typical behavior
• T or E in male embryos - demasculinization
• T or E in female embryos - unaffected
• Anti-E in female embryos - masculinization
• E demasculinizes copulatory behavior of female
  quails in early development

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Copulation
Territorial fights
In song
Incubation
Feeding young
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A schematic diagram of the relationship between
the CNS and reproductive system of male birds
Receptors

• Retinal
• Pineal
• Tactile
• Auditory
• Chemical
• Other?

Central Processing
Internal information
Anterior hypothalamus others
GnRH
Effects on aggression
Anterior pituitary
- feedback
LH/FSH
T
T
Gonad
Secondary sex characteristics
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• Seasonal changes of reproductive organs
• Testes from 1-2 mg to 600 mg
• energy and cost saving
• respond precisely to the environmental cues
• T aggression reproductive behavior
• T may have both organization/activation or just
  one effects on behavior
• Temporal patterns of reproductive behavior and
  hormones

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Changes in LH and T during a breeding cycle of
free-living sparrowsM migrationE
establishing territoryP pair formationL
egg-layingI incubationN feeding nestlingsF
feeding fledglingsMt molt
Gambels sparrows
Pugets sparrows
Song sparrows
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Why is there no increase in T for the 2nd clutch
in multiple-brooding sparrows?

• feeding copulating
• mate-guard may not be intensive
• high T may inhibit parental behavior
• advantageous to ensure that the 1st brood reaches
  independence

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LH and T during renesting in male Gambels
sparrows
1 migration2 arriving3 egg-laying4 early
incubation5 later incubation6 feeding
nestlings7 renesting8 incubation9 feeding
nestlings10 feeding fledglings11 molting
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Challenge Hypothesis

• Androgens are elevated with aggressive behavior
  only when a male is challenged by another
  individual.
• T in spring is associated with elevated
  territorial aggression.

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Is increased T coincided with (1) obtaining
territory (2) interacting with other males?

• Territorial song sparrows were captured in
  spring, and held in captivity or released back
  into their territories (control).
• T levels were higher in the replacement males or
  neighboring males but not the control residents.

• Interaction, but not the ownership of a territory
  per se, is a major stimulus for increased T.

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The hypothetical evolution of the
parthenogenetic, all-female whiptail lizards.
gonochoristic
C. inornatus
C. gularis
F1 hybrid
C. inornatus
F1 hybrid
unisexual
C. uniparens
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Mating in C. inornatus
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Courtship behavior by males

• insures fertilization
• facilitates ovarian growth
• synchronizes reproductive physiology of both
  sexes
• females will not undergo normal ovarian
  development in the absence of sexually active
  males

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Courtship behavior exhibited by castrated male C.
inornatus treated with hormones
T
DHT
Prog
Blank
18
Alternations in behavioral roles, ovarian state
and circulating levels of sex-steroid hormones in
the C. uniparens.
19
Activation of pseudocopulatory behavior in
unisexual lizards (C. uniparens) that were
treated with progesterone (P), estradiol (E), or
a blank Silastic capsule (B)