2/10/2010
College of Agriculture Sciences and Natural Resources
Kevin Hamed
University of Tennessee
To familiarize students with salamander
courtship and mating strategies
Reading Assignments:
1) See Website
1. Migration
2. External / Internal Fertilization
3. Courtship
A. Plethodon
B. Desmognathus
C. Ambystomatid
D. Salamandridae
4. Sperm Competition
5. Egg Deposition
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2/10/2010
• Darwin
• Environmental Conditions
• Male & Female
• Transfer of Gametes
• Successful fertilization
• Often Ambystomatids
• Rainy nights
• Often 30 min after sunset (A. maculatum)
• Males typically migrate first
• 164 meters – 95% adults (Semlitsch
(S lit h 1998)
• Plethodontids?
Conservation Implications?
• Cryptobranchidae
• Sireniade
• Hynobiidae
Similar?
• Cloacal
Cl
l Swelling
S lli in
i males
l
• August - November
• Large flat rocks
• Male trap females in nest
• Mean fecundity = 450 eggs
• Polyspermy
• Male guards nest and often consumes eggs
Hellbender photos by Jeff Huphries
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2/10/2010
• Copulatory organ?
• Spermatophore
Organ
• Spermatotheca
Plethodon glutinosus
Ambystoma opacum
Arnold et al. 1993
4.5
Spermatop
phoreHeight (cm)
4
3.5
3
2.5
2
1.5
4
6
8
10
12
14
16
18
20
22
Maximum TL (cm)
(Organ and Lowenthal 1963)
• Males make females receptive
• Pheromones
Mental Glands – Clusters of exocrine glands (glycoprotein)
•Transfer to the female
Genial Glands – Newts
Cloacal Gland(s)
(Steve Arnold)
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2/10/2010
• Unicuspid teeth
• Small mental glands = larger teeth
• Male places
his snout along
the female’s
back and side
• “foot
“f t d
dance”
”
(Organ 1958)
• Male moves
head toward
female’s head
• Male presses
his mental gland
over female’s
nasolabial
grooves
(Organ 1958)
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2/10/2010
• Male circles under the female’s chin and begins to undulate his tail
(Organ 1958)
• Tail Undulation
(Organ 1958)
• 1.2 cycles per second
• Additional head slap
(Organ 1958)
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2/10/2010
• Spermatophore deposition – typically 1 per courtship attempt
• Successful insemination as low as 25%
• Not only nocturnal – 10:30 AM
• Mean time for spermatophore deposition = 56 min.
(Organ 1958)
Desmognathus ochrophaeus complex
• Male follows female
• Snout of male makes contact with
the body or tail of female
• Front limbs moved in a circular motion
• Male rubs females head
Photo by Steve Tilley
• Male places his head on the female’s dorsum
• Snap
Snap Behavior
• Tail undulation
• Slide
• Tail-straddling walk
Video
(Mead & Verrell 2002)
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2/10/2010
Can courtship be used for evolutionary relationships?
(Tilley)
(Mead & Verrell 2002)
• Desmognathus wrighti
• D. imitator
(Mead & Verrell 2002)
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2/10/2010
2. Male’s snout contacts
female repeatedly
2. Male’s snout
contacts female
repeatedly
2. Male’s head is
placed under the
female’s chin
3. Male repeatedly
circles the female
4. Male moves away
from the female
keeping his cloacae in
contact with the surface
5. Spermatophore is
deposited
6. Female searches for
spermatophore (moving
side to side)
7. Pick-up (15-20 by the
end of courtship)
p)
• Mean time for
spermatophore deposition
= 1.4 min.
(A. maculatum)
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2/10/2010
Mean number of spermatophores deposited by a single male
during a single courtship evening
• A. maculatum
40.4
• A. tigrinum
20.6
• A. dumerili
13.0
• A. laterale
23.6
• A. jeffersonianum
12.4
(Arnold 1977)
Ambystomatidae – Spermatophore covering
(Arnold 1980)
(Arnold 1980)
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2/10/2010
• Male grabs female with rear limbs
• Rubs female’s south with genial
glands
• Use tail to fan cloacal secretions
toward female (>1 hour)
• Violent body contortions
• Dismounts and moves in front of female
• Female presses her head onto males tail
• Deposit multiple spermatophores
(Arnold 1980)
♂
Sexual dimorphism
♀
(Arnold 1980)
T. marmoratus
T. carnifex
T. vittatus
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2/10/2010
•
Gelatinous base
•
Male faces away from female
•
Female orients toward male’s glands
•
Male responds to contact with
his cloacae
D. ochrophaeus
D. wrighti
D. fuscus
Paternity?
Inseminated as much as 15 times during one season
7% of all individual
clutches are products
of more than one male
Steve Tilley
(Houck et al. 1985)
• Aquatic vs. Terrestrial
(A. maculatum)
(D. quadramaculatus)
(P. cinereus)
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2/10/2010
Mean number of eggs
D. wrighti
6
D. orestes
15
D. quadramaculatus
P. glutinosus
A. opacum
~120
A. maculatum 400
32
A. tigrinum
700
Paedomorphs 5670
5-20
“K-selected”
?
“r-selected”
• Salamander eggs develop much slower than anurans
WHY?
Warmer temperatures
Faster development
Larger eggs
Slower development
More advanced
Terrestrial
Slower development
Larger
More advanced
Why?
Photo by Steve Tilley
• Why guard nests?
• Typically Plethodontidae
Desiccation
Antimicrobial
Predation
12