Tuatara is unique because it is the last survivor of the order Sphenodontia, which are usually regarded as sister to squamates. Sphenodontids diverged from other reptiles about 230 MYA and were globally widespread until the late Cretaceous (65–80 MYA). They are now found only on the offshore islands of New Zealand and are represented by two species: Sphenodon guntheri, found only on North Brother Island, Cook Strait and Sphenodon punctatus which is present on islands in Cook Strait and off the northeastern coast of New Zealand's North Island. Tuatara's closest relatives are "extinct" group of reptiles, therefore scientists refer to tuatara as living fossils (http://www.sandiegozoo.org/animalbytes/t-tuatara.html)
Watch footage explaining the evolution of tuatara, which have hardly changed in 230 million years ago
http://www.teara.govt.nz/en/tuatara/1/2 (Daugherty and Keall, 2009)
The life of Tuatara
A tuatara has a large head on a sturdy body. Their skin is rough and covered with beady scales and it has a very thick tail.
(http://animals.jrank.org/pages/3645/Tuatara-Sphenodontidae-PHYSICAL-CHARACTERISTICS.html)
On the left is Male tautara and on the right is the female tautara
The male tuatara is bigger than the female tuatara and has more prominent crest of spines along its neck, back and tail.
Habitat and Feeding
Tuatara feeding on insect
- Tuatara live in burrows
- They are more active at night, but will come out during the day to lie in the sun.
- Both sexes are territorial, and males aggressively defend their territory by posturing, displaying, and fighting.
- Teeth are their main weapons, and a bite can cause serious injury. Therefore they are carnivorous, i.e eat invertebrates, lizards, frogs, small tuatara, and the chicks of seabirds with which they often share burrows.
Reproduction
Male and Female Tuatara mating
- Tuatara mate during the late summer. The male courts the female by approaching her with a proud walk.He mounts the female, positioning her with his hind legs and tail to align their reproductive openings for the transferring of sperm.
-The female usually lays 6–10 eggs the following spring, in a shallow nest in the ground.
-The eggs incubate for about a year, so hatchlings emerge when eggs are being laid the following season. The hatchlings take care of themselves ( no parental care).
-Male tuatara mate annually, while females mate only once every two to seven years, depending on how much food they find.
Here is the really interesting part!! The soil temperature determines the sex of their embryos. The warmer the soil around the eggs, the greater chance that they will hatch into males and the cooler the soil, the greater the chance that they will hatch into females- what a cool discovery**
Importance
- Tuatara are of great cultural significance to Maori ( indigenous Polynesian people of New Zealand), and they feature in some creation stories. Some tribes (like iwi) view tuatara as the kaitiaki (guardians) of knowledge.
- They are used in paintings and sculptures, record covers, stamps and coins.
(http://coins.nzpost.co.nz/2007/new-zealand-tuatara-silver-proof-coin)
[ Daugherty and Keall, 2009]
- Sequences from tuatara genome can be used to identify the evolutionary origin of parts of the human genome
(http://chickenoreggblog.wordpress.com/2010/06/16/tuatara-holds-clues-to-human-evolution/)
Recently, our climate is warming rapidly, basically it means all the tuatara that hatch will be male. These male tuatara that hatch will not be able to find mates and that means they won’t be able to have babies. What will happen to our tuatara?????
I really like the way you put many details in your original diagram. I suggest that you might want to put your original diagram in page of "What will happen to Tautara?" because the diagram seems more related to the context of that page. But I like that how each page is focused on the reproduction of Tautara and its relatedness to Tautara's survival to global warming.
ReplyDeleteI enjoyed reading your blog! It’s interesting and engaging, and I liked how you focused on temperature-dependent sex determination. I have a few questions about the diagram on this page. Is the y-axis the percentage of male hatchlings? And also what year or timeframe is “past temp” from? Why are there mixed hatchlings at maximum temperature-- shouldn't there be just males or mostly males?
ReplyDeleteI think it would be useful to add why sex determination may be temperature dependent. What fitness benefits does it provide? To me, it would seem detrimental because in extreme environments, there would be too few of one sex. Maybe it has something to do with how often each sex reproduces.
ReplyDeleteAlso, I like all of the pictures. Very visually appealing blog.