Reptile Reproduction (Lecture 7) Flashcards
reptiles as ectotherms
- derive thermal energy from external force to regulate body temp
- pro:great deal of flexibility of energy use through metabolism
- good at regulating thermal regulation
- move in cooler or warmer area to regulate body temp
reptiles have lower metabolic rate
- dont go through insufficient metabolic
- can survive even during droughts
life history
- how energy is utilize for growth, maintenance, and reproduction
- incredibly variable for animals
ex. sea turtle, dragon
sea turtle
- live 70-80 yrs.
- breed multiple times in life
- spends a lot of time in growth for sexual maturity(largest proportional cost)
Green sea turtle
- female lay 4-6 clutches every 3 to 6 yr.
- larger than
- lay in clucthes of 100 to 140, 4 to 6 times in the breeding season
- 2 months for baby eggs to develop
- high mortality risk of baby turtles
- large clutches to compensate for mortality risk
- send offspring through rapid dispersal phase to get food and be away from predator
- offspring swim flat chap for two days
- get picked up by currents and stay there for 10 yrs.(go from Great Barrier re
- settle back down on reef
- fall out 2k km of coastline in QUeensland
- start to chew on sea grass and algae for 30 yrs. until reaching sexual maturity at 40 yrs.
Green sea turtle
- female lay 4-6 clutches every 3 to 6 yr.
- larger than
- lay in clucthes of 100 to 140, 4 to 6 times in the breeding season
- 2 months for baby eggs to develop
- high mortality risk of baby turtles
- large clutches to compensate for mortality risk
life history differ between species and sexes
- female much more costly
- 5-6 yrs of energy
- move from feeding ground to courtship (400 km)
- extremely slow long life history
factors influencing evolution of reproductive life histories in reptiles
- temp has prolific effect
- diet (ecology)
- some are herbivorous but most are predators
- phylogeny(animals come from different group)
- limit of design
- dictate the amount of eggs laid
- limit of design
- not endlessly plastic or variable
reproduction quite essential
- very complex
- different depending on the sex
- female determine reproductive success by the number of eggs she is carrying
- males compete and fight with other males
- wound each other to prevent optimizing a female
variation of reptiles
10,000 species breeding difference -tortoise 45 yrs -dragons 9 months -only breed 2 egg -others 600
within specie variation
- animals trying to maximize fitness to optimize investment
- decisions based on environment
- sceloporus undulatus
- vary in size across the U.S.
- use energy to display life history
constraints on reproduction by environment
temp
=vast variation in temp across the yr.
-reptiles in Tasmania
temp
thermal timing and opportunity
hot and cold environment place very different constraints on offsprings
-prolific effect on sex determination
incubation determines sex
reproductive cycle
- temp alter reproductive timing
- have to turn on reproductive tract
- reproduce through a series of event
- mature switch reproductive tract
- takes month
- undergo courtship and mating (usually quick
- dictate timing and how long who have to go through the reproductive cycle
different thermal constraints-nt
northern territory
- midwinter and mid-spring reproductive switch
- incubate in spring
- hatch in late spring
different thermal constraints-sp
southern population
short
mid-november to late december
get ready for phase switch for winter in the fall
most reptiles inactive in the winter
emerge in late spring
end of summer is the best time for hatching
temp
rate determing factor on reproduction
rate of offspring have major effect on phenotype
egg layers(oviparious)
-common for reptiles
viviparious
- live birth
- some reptiles can hold egg within utero
- can be simple(eggs)
- complex(placenta)
- has evolved over 100x in reptiles
- strong association with viviparity and temp
- evolved in response to cold climate
viviparity in cold temp benefits
female able to regulate her and the eggs temp
female holding on to offspring due to advantange to offspring
-warmer temp incubation to maximize offspring performance permanently
ex.
hot nest; fast running lizard
temp restraint on sex determinations
-some reptiles have thrown away sex chromosome
non-genetic sex determination
- sex allocated to temp during incubation
- all crocodiles use it, some lizards and turtles do it, but no snakes
colder temp produce all male
warmer temp produce all female
reptile evolve temp restraint determinants
better match sex with performance optimum for incubation environments
