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Kevin HamedUniversity of Tennessee

College of Agriculture Sciences and Natural Resources

To familiarize students with salamander courtship and mating strategies

Reading Assignments:

1) See Website

1. Migration

2. External / Internal Fertilization

3. CourtshipA. PlethodonB. DesmognathusC. AmbystomatidD. Salamandridae

4. Sperm Competition

5. Egg Deposition

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• Darwin

• Environmental Conditions

•Male & Female

Environmental Conditions

• Transfer of Gametes

• Successful fertilization

• Rainy nights• Often 30 min after sunset (A. maculatum)

•Males typically migrate first

• 164 meters 95% adults (S lit h 1998)

• Often Ambystomatids

• 164 meters – 95% adults (Semlitsch 1998)

Conservation Implications?• Plethodontids?

Cl l S lli i l

• Cryptobranchidae• Sireniade• Hynobiidae

Similar?

• Cloacal Swelling in males

Hellbender photos by Jeff Huphries

•August - November• Large flat rocks•Male trap females in nest

•Male guards nest and often consumes eggs

•Mean fecundity = 450 eggs• Polyspermy

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Organ

• Copulatory organ?

• Spermatophore

• Spermatotheca

Arnold et al. 1993

Plethodon glutinosus

Ambystoma opacum

3

3.5

4

4.5

phoreHeight (cm

)

1.5

2

2.5

4 6 8 10 12 14 16 18 20 22

Spermatop

Maximum TL (cm)(Organ and Lowenthal 1963)

•Males make females receptive• Pheromones

Mental Glands – Clusters of exocrine glands (glycoprotein)

•Transfer to the female

(Steve Arnold)

Genial Glands – Newts

Cloacal Gland(s)

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• Unicuspid teeth• Small mental glands = larger teeth

•Male places his snout along the female’s back and side

“f t d ”• “foot dance”

(Organ 1958)

•Male moves head toward female’s head

•Male pressesMale presses his mental gland over female’s nasolabial grooves

(Organ 1958)

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•Male circles under the female’s chin and begins to undulate his tail

(Organ 1958)

• Tail Undulation

(Organ 1958)

• 1.2 cycles per second

(Organ 1958)•Additional head slap

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• Spermatophore deposition – typically 1 per courtship attempt

(Organ 1958)

• Successful insemination as low as 25%

• Not only nocturnal – 10:30 AM

•Mean time for spermatophore deposition = 56 min.

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

Photo by Steve Tilley

•Male rubs females head•Male places his head on the female’s dorsum• Snap

Snap Behavior

• Tail undulation• Slide• Tail-straddling walk

(Mead & Verrell 2002)

Video

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Can courtship be used for evolutionary relationships?

(Tilley)

(Mead & Verrell 2002)

• Desmognathus wrighti• D. imitator

(Mead & Verrell 2002)

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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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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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•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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• Gelatinous base

• Male faces away from female

• Female orients toward male’s glands

• Male responds to contact with his cloacae

D. ochrophaeusD. wrightiD. fuscus

Inseminated as much as 15 times during one season

7% of all individual

Paternity?

clutches are products of more than one male Steve Tilley

(Houck et al. 1985)

•Aquatic vs. Terrestrial

(D. quadramaculatus)

(A. maculatum)

(P. cinereus)

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Mean number of eggs

D. wrighti 6D. orestes 15D. quadramaculatus 32

A. maculatum 400

A. opacum ~120

A. tigrinum 700Paedomorphs 5670Paedomorphs 5670

P. glutinosus 5-20

?“K-selected”

“r-selected”

• Salamander eggs develop much slower than anuransWHY?

Warmer temperatures Faster development

Larger eggs Slower developmentLarger eggs Slower developmentMore advanced

Terrestrial Slower developmentLargerMore advanced

Why?

Photo by Steve Tilley

•Why guard nests?

AntimicrobialDesiccation

• Typically Plethodontidae

Predation