Reproduction in reptiles

study of reptiles
define herpetology
– Testudines ‐ turtles
– Crocodilia ‐ alligators, crocodiles, gharials
– Sphenodonta ‐ tuatara
– Squamata ‐ lizards and snakes
What are the 4 extant orders of reptiles?
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What percentage of living reptiles does Squamata make up of?
How many species of reptiles are there?
What percentage of reptiles lay eggs?
– Soft shelled
– Hard shelled
– All permeable
What prevents egg desiccation?
What was a large evolutionary step in the reproduction of reptiles?
* Incubating eggs = can’t go get food to eat
* Can’t restrict prey properly when they have eggs producing in them
* Maternal costs 60% body weight
How is reproduction expensive to a reptile?
30 – 280 days
How long can egg incubation last?
Every 4 years
How often do reptiles reproduce?
shivers = friction which warms the eggs to approx 0.5oC above embryo temperature
How does a snake incubate its eggs?
nutrition, temperature and photoperiod cycles, Hormones, Presence of (multiple) males, Male combat, Male fertility, Colony size – sex ratios, Yolk formation, Ovulation, Gravid nutrition, Pre‐lay care of female, Nest location, safety and design, Egg deposition/parturition, Post‐lay care and survivability, Incubation methods and success, Managing the hatching process, Maternal care? Neonate survivability
What are some factors of reproduction other than physical?
to keep them warm
Why is the location of laying eggs critical?
urinate on eggs for moisture and humidity
How do some reptiles control the humidity of eggs?
60 -70 days
How long do pythons usually incubate their eggs for?
Male gonads – sperm, sperm travels to
hemipenes through vas deferens
Describe the male reproductive system in reptiles
– Female ovaries – oocytes
– Not born with set number
– produced as needed
– Oviducts through to cloaca
– Females will not produce ova unless they have the right stimuli
Describe the female reproductive system in reptiles
– Reproductive cues result in females producing yolk
– Proteins, phospholipids and fats and is produced outside of the ovaries.
– Predominantly formed in the liver and transported to the oocytes in the ovaries through the blood.
– During vitellogenesis, the oocytes grow enormously in size and are termed follicles
– Matured then released for fertilisation
Describe follicular development in female reptiles
reproductive cues resulting in females producing a yolk
define vitellogenesis
– pair of reproductive organs of snakes and lizards.
– Crocodilians and turtles have only one
– usually held inverted, within the body, and are everted for reproduction via erectile tissue like that in the human penis.
– Often the hemipenis bears spines or hooks, in order to anchor the male within the female
Describe the hemipenis
What are the types of reptile reproduction?
virgin birth, populations typically all female, populations of clones
What is parthogenesis?
No need to find a (suitable) mate
What are some advantages of parthogenesis?
Little genetic variability and susceptibility to disease or environmental change
No sexual selection process
What are disadvantages of parthogenesis?
Komodo dragons
Water dragons
What reptile species perform Spontaneous parthenogenesis?
Bynoes geckoes
Whiptail skinks
What species perform Species specific parthenogenesis?
many species known to ‘store’ sperm for several years.
What is sperm storage?
– Complex behaviours
– bellow (vocalize) to call in females.
– make loud noises by slapping
his head, tail and body hard against the water, this is a sign of dominance.
Describe how the male american alligator attracts a mate
– Courtship can last a couple of days before copulation
– They will rub each others heads, and sleep on each other during the courtship phase.
– Males will also blow bubbles under the water under the females body to stimulate her.
What are the mating habits of alligators?
Are alligator eggs temperature dependent?
will not hatch
What will occur with alligator eggs at 27oC and under?
will be all females
What will occur with alligator eggs between 28-31oC
some females and some males
What will occur with alligator eggs between 32-34oC?
will be all male
What will occur with alligator eggs between 35 -38oC?
will not hatch
What will occur with alligators eggs 39oC +?
Duration of incubation
Pigmentation – both colour and patternation
Size and growth rates
Rate of abnormalities
Behaviours (aggression, defensive behaviours, foraging ability
What does incubation temperatures affect?
Female alligators lay eggs in the nest and protect them until they hatch and for 2 years after
Describe the relationship between crocodile eggs and the mother
• Males will mount the females, and penetration occurs.
• Males will often bite the females neck to help stimulate estrogens in the females body and keeps the
female from running away
The male hemipenes evert’s and penetrate into the females cloacae
Penetration lasts only a few minutes
Describe lizard reproduction
Some females can restore sperm for many months for
future use, if no suitable partner can be located
Can lizards store sperm?
offspring size
What does clutch size match?
Out of 50-60 eggs how many offspring would be born?
50 – 280 days, babies double their size in the first year.
How long is incubation of lizards generally?
can range from months (same year) to 4 years of age
When do lizards mature sexually?
giving birth to live offspring
define viviparous
lay eggs
define oviparous
pythons and some elapids
What are some egg laying snakes?
climatic conditions
What influences whether a snake is viviparous or oviparous?
placing their tails in position so the males hemipenis and the females cloacae will line up.
How do snakes copulate?
Duration from follicle development to ovulation
Duration from ovulation to sloughing
Timing From sloughing to oviposition
What regulates snake reproduction?
the breeding ball consists of 2-12 males coiled around one female for as long as four weeks.
Describe male anaconda combat
This ensures that the strongest snake will win the wrestling match, and therefore pass on his strong genetics by breeding or mating
What is the purpose of a breeding ball?

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