Chelonians in the news!

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Berkeley Boone
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Chelonians in the news!

Post by Berkeley Boone »

Have yall seen this yet? This is really cool!
I guess this may go best in the "News" subforum.

--Berkeley


First Reported Occurrence of Viviparity in Chelonians

[Ministry of Science and Technology Technical Report, Prof. Shangdang Nin, C-177.3: 27 pp. 1 April 2015]

True viviparity in reptiles is rare. Exchange of materials between embryonic and maternal bloodstreams is known in lizards of the family Xantusidae, the European skink, Chalcides ocellatus, the Australian skinks of the genera Tiliqua and Lygosoma, and the Australian snake Denisonia. Prior to the research abstracted here, no species of turtles were known to be ovoviviparious or viviparous.

After a number of independent and unexplained cases of young Platysternon being found in aquaria with adult captive females, the authors of this report investigated the reproductive habits of this freshwater turtle. In three cases they found young in containers where the adults had no nesting substrate and the aquaria were cleaned weekly. Two of the young were alive and one was found at full-term but was dead.

Several years of additional laboratory and field research (2007-2014) showed that the turtles indeed were producing live young and were all of the same subspecies Platysternon megacephalum tristernalis. All were from high elevation (above 2,000 m) mountain streams in north Western Guangxi province and adjacent areas in Guizhou province, China. (The species was previously unknown from Guizhou province.) In total, 18 young were produced from a series of 39 adult female big-headed turtles, all collected in the same remote mountain area. The captive adults, as well as individuals from other localities were maintained outdoors to best approximate regional climatic conditions.

Other subspecies of the monotypic Platysternon collected from random sites and those of P. m. tristernalis collected below 2,000 meters were all oviparious.

Wild caught females of all samples were able to produce viable eggs or live young for at least 4 years when maintained separately from males.

X-rays of gravid females indicate that embryos of high elevation P. m. tristernalis take 22 months to develop, and that the embryonic development stops, or at least cannot be detected, during the winter. Eggs of typical populations hatch in 65-75 days. The young of the viviparous females averaged 17.3% greater in mass than ones coming from eggs (n=22). It is suspected that at the high elevation zones where the live-bearing Platysternon occur, the embryonic development would be even more protracted.

“Birth” occurs at night and was observed only on two occasions. The young turtles are in transparent sacks. In one case, the young broke free of the sac as a result of its own movements, in the other the female was observed to slowly turn, and nip at one corner of the sac. The sac split and the young turtle climbed free. The female turtle paid no additional attention to the young turtle although on several occasions the young turtles were heard to vocalize.

The researchers showed that despite the large amount of yolk present in the ova of the high elevation turtles, the embryos receive additional nourishment directly from the female. The lower portion of the oviduct is modified into a brood pouch-like chamber. The pouch fluid is a source of calcium (and perhaps other vital nutrients) for the forming embryo. The calcium was dissolved from bone and shell tissue and accumulates in the pouch. The calcium is not only important for embryonic development but it neutralized lactic acid accumulating in the blood in both the unborn turtle and in hibernating females. The highly vascular brood pouch indicates that gases and nitrogen waste products are conducted out through the pouch's lining. The latter has yet to be confirmed.

It appears that viviparity is a strategy allowing reproduction in turtles living in high elevation habitats where growing seasons are short and do not allow for development of and hatching of eggs. The captive live-bearing big-headed turtles all produced young early in the growing season, giving them several months to grow before winter arrives. The turtles in the mountain regions of Guangxi and Guizhou provinces appear to represent a disjunct population.

daniel
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Re: Chelonians in the news!

Post by daniel »

This is sooo cool, thank you for sharing!

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TurtleTim
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Re: Chelonians in the news!

Post by TurtleTim »

Someone put a lot of thought into this April fools. :thumb:

daniel
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Re: Chelonians in the news!

Post by daniel »

Damn. :oops:

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Berkeley Boone
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Re: Chelonians in the news!

Post by Berkeley Boone »

TurtleTim wrote:Someone put a lot of thought into this April fools. :thumb:
Thanks man. I was pretty pleased with the name I created for the Professor: it is Mandarin for 'Fooled You'.

daniel wrote:Damn. :oops:
Sorry to get your hopes up!

--Berkeley

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Kelly Mc
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Re: Chelonians in the news!

Post by Kelly Mc »

..highly vascular brood pouch

Splendid. :beer:

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TurtleTim
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Re: Chelonians in the news!

Post by TurtleTim »

You definitely chose the right genus to make it sound somewhat plausible!

rtdunham
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Re: Chelonians in the news!

Post by rtdunham »

I heard it is all true and is being claimed to be a hoax in order to protect the animals in the wild. (hey, why not feed a hoax!?)

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VanAR
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Re: Chelonians in the news!

Post by VanAR »

Damn you had me going, even as a specialist in this field I was getting very excited! Discovery of a viviparous turtle would certainly be a nature paper.

FWIW, I DID question the veracity off the first paragraph due to it's inaccuracies:
True viviparity in reptiles is rare. Exchange of materials between embryonic and maternal bloodstreams is known in lizards of the family Xantusidae, the European skink, Chalcides ocellatus, the Australian skinks of the genera Tiliqua and Lygosoma, and the Australian snake Denisonia. Prior to the research abstracted here, no species of turtles were known to be ovoviviparious or viviparous.
Major placental transfer of nutrients hasn't been found in any of these taxa. Check out the skink genera Mabuya (or the South American skinks formerly known as Mabuya, as I heard it was changed recently), Trachylepis (levis, anyway), Eumecia, Pseudemoia, Niveoscincus (especially ocellatus), and the species Chalcides chalcides for the really exciting stuff. Most viviparous reptiles (all studied, anyway) transfer moderate amounts of calcium and sodium but very small amounts of organic nutrients (amino acids), but these taxa all rely heavily on a placenta for more than half, and sometimes nearly all, of their embryonic nutrition.

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Berkeley Boone
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Re: Chelonians in the news!

Post by Berkeley Boone »

Ha ha! Thanks yall, glad you enjoyed that.
VanAR wrote:Damn you had me going, even as a specialist in this field I was getting very excited! Discovery of a viviparous turtle would certainly be a nature paper.
That made my day, Van!
VanAR wrote:FWIW, I DID question the veracity off the first paragraph due to it's inaccuracies:
True viviparity in reptiles is rare. Exchange of materials between embryonic and maternal bloodstreams is known in lizards of the family Xantusidae, the European skink, Chalcides ocellatus, the Australian skinks of the genera Tiliqua and Lygosoma, and the Australian snake Denisonia. Prior to the research abstracted here, no species of turtles were known to be ovoviviparious or viviparous.
Major placental transfer of nutrients hasn't been found in any of these taxa. Check out the skink genera Mabuya (or the South American skinks formerly known as Mabuya, as I heard it was changed recently), Trachylepis (levis, anyway), Eumecia, Pseudemoia, Niveoscincus (especially ocellatus), and the species Chalcides chalcides for the really exciting stuff. Most viviparous reptiles (all studied, anyway) transfer moderate amounts of calcium and sodium but very small amounts of organic nutrients (amino acids), but these taxa all rely heavily on a placenta for more than half, and sometimes nearly all, of their embryonic nutrition.
Busted. To tell you the truth, I did not create that sentence. I don't even remember where I saw it, but I thought to myself 'man, that sounds good, I'll work that in'. So I copied and pasted it on in. Didn't check into it at all. Good info to know, and thanks for the clarification.

I'm glad you enjoyed the read.

--Berkeley

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