Galapagos Tortoises

Olddog

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Temperature Dependent Sex Determination

Sex of many species of turtles and tortoises has been known by reptile stewarts to be determined by incubation temperatures for many years. This was felt to be particularly critical at embryonic stages 17-21affecting aromatse activity with sex being irreversibly determined by embryonic stage 22. In this paper, transcriptional changes were demonstrated as early as embroyonic stage 3 at Female Producing Temperatures (31 degrees C) and stage 5 at Male Producing Temperatures (26 degrees C) in Chrysemys picta (red slider) turtles. Much occured differentialy prior to embryonic stages 17-21. If applicable to other Temperature Dependent Sex Determination turtles and tortoises, this suggests aspects of sexual determination started occuring much earlier in incubation than most of us have previously appreciated.

Thermal Response of Epigenetic Genes Informs Turtle Sex Determination with and without Sex Chromosomes
Srihari Radhakrishnana, Robert Litermanb, Jennifer L. Neuwaldc, Nicole Valenzuelac 2018


http://www.public.iastate.edu/~nval...shnanEtAl2018_EpiGenesThermoTranscription.pdf

Abstract

Vertebrate sexual fate can be established by environmental cues (e.g., temperature-dependent sex determination, TSD) or by genetic content (genotypic sex determination, GSD). While methylation is implicated in TSD, the influence of broader epigenetic processes in sexual development remains obscure. Here, we investigated for the first time the embryonic gonadal expression of the genome-wide epigenetic machinery in turtles, including genes and noncoding RNAs (ncRNAs) involved in DNA/histone acetylation, methylation, ubiquitination, phosphorylation, and RNAi. This ma- chinery was active and differentially thermosensitive in TSD versus GSD (ZZ/ZW) turtles. Methylation and histone acety- lation genes responded the strongest. The results suggest these working hypotheses: (i) TSD might be mediated by epigenetically controlled hormonal pathways (via acetylation, methylation, and ncRNAs), or by (ii) hormonally controlled epigenetic processes, and (iii) key epigenetic events prior to the canonical thermosensitive period may explain differenc- es between TSD and GSD. Novel epigenetic candidate regulators other than methylation were identified, including previously unknown ncRNAs that could potentially mediate gonadogenesis. These findings illuminate the molecular ecology of reptilian sex determination and permitted hypothesis building to help guide future functional studies on the epigenetic transduction of external cues in TSD versus GSD systems.
 

Olddog

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Impact of LayIng Date and FIre Ants on Hatchlings of Chelonoidis porteri on Santa Cruz Island, Galápagos, Ecuador
Nina Wauters, Wouter Dekoninck, Zoltan T. Nagy, and Denis Fournier

Herpetological Conservation and Biology 13(2):479–487.
Submitted: 15 September 2015; Accepted: 14 July 2018; Published: 31 August 2018.
http://www.herpconbio.org/Volume_13/Issue_2/Wauters_etal_2018.pdf

Abstract.—Chelonoidis land tortoises are iconic species endemic to the Galápagos Islands of Ecuador. Their populations have been dramatically reduced by human activities in the last three centuries, including indirect effects such as the introduction of invasive species. We investigated the mortality of eggs and hatchlings in 48 nests of Chelonoidis porteri on Santa Cruz Island with regard to various mortality causes such as the occurrence of fireants and the date of laying. The average mortality rate was 0.56. Tropical Fire Ants (Solenopsis geminata) were present within 1 m of 75% of the C. porteri nests, and we encountered fire ants in 12.5% of excavated nests. We found no relationship between Tropical Fire Ant abundance and C. porteri egg and hatchling survivorship. We observed no signs of mold inside the nests. We determined that early deposition dates were associated with lower clutch survival and identified egg development as the critical life stage. Finally, we discuss the potential impacts of fire ants and climate change on tortoise survival and reproduction and stress the importance of taking these factors into account for the conservation of the endemic land tortoises of the Galápagos.
 

Olddog

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Giant Tortoises (Aldabras) and Internal Temperatures. Evaluation of Artificial Heat Sources


SEED DISPERSAL BY CHELONIANS: FROM INDIVIDUALS TO COMMUNITIES
WF LINERO, O LPetchey, D MHansen, N BUNBURY…2018

https://www.researchgate.net/profil...helonians-From-individuals-to-communities.pdf

This may be a slow free download from Researchgate. This is a portion of a disertation. The studies are primarily focused on Aldabra giant tortoises (Aldabrachelys gigantea) done on Aldabra Atoll with some studies done on animals at the Zurich zoo. In their study (Chapter 3) they concluded neither body size or seed size affected gut retention times of Aldabra giant tortoises. They fed the tortoises artificial seeds (plastic beads of different sizes and weights) in rice balls with tomato paste and counted passage time of each in scat sampled twice daily.

Perhaps more applicable to giant tortoise keepers are the temperature studies and application to artificial heating of tortoises. Among other things, they studied “tortoise body temperature fluctuations, including how their core and external body temperatures vary in relation to different environmental temperature ranges”. Temperature loggers were fed to the tortoises, internal temperature recorded every 15 minutes, and compared to external temperatures. Part of the study time other body surface temperatures were measured as well.

This technology and findings were utilized in Chapter 5: Evaluation of Artificial Heating Sources for the Thermoregulation of Aldabra Giant Tortoises (Aldabrachelys gigantea) in Zürich Zoo. They suggested “basking lamps can be insufficient to heat up the ground and provide appropriate heating for basking species in temperate climates (which can lead to rapid heat loss through conduction), and result in low Tbc as well as cloacal infections in tortoises (Samour et al. 1986).” They state “Chelonians lack suitable pain receptors and appear to be unable to respond to heat trauma, so it is important to carefully monitor ground heating areas to avoid injuries and fatalities (McArthur & Barrows 2008).“ Other heat sources and precautions are discussed.
 

Taco*mom

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Just happen to find this thread! Amazing, very informative and wonderful pictures and videos!! Absolutely love this.

Whats' current PM temperature there? Would you worry that overnight sleeping in water/mud will make these giants sick?
 

Olddog

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Just happen to find this thread! Amazing, very informative and wonderful pictures and videos!! Absolutely love this.

Whats' current PM temperature there? Would you worry that overnight sleeping in water/mud will make these giants sick?

Presently it is about 6 am, still dark and our temperature is 69 degrees F. The ground (and water ) is still warm and will not worry much about short minor dips in temp at present. This is warmer and less windy than the caldera rim on of volcano Alcedo at times. The three year olds have a heated night house. A few older animals choose to go in a shelter overnight year-round. It will probably be another month before transfer of some the tortoises back to their winter yards ( in which I am currently workin). They will quickly demolish the grasses near the heated buildings and much prefer to spread out over space. When they sleep outside in cooler nights, they typically will find a sheltered area to which they return each evening and where they get first sun in the am. Although some readily go into the heated buildings in the winter areas, moving them can be challenging, takes time, and frequently involves bribery. Big males prefer not to share a building with another male (at least when females are present). It takes many hours to get all the stragglers inside when it becomes cold. Ideally they are confined to small yards next to the heated structures when there are several days of cold but most of those confinement yards were destroyed by falling trees with Hurricane Irma.
 

Olddog

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Captive breeding / Headstarting Program works from a genetic / population genomics viewpoint:

Population genomics through time provides insights into the consequences of decline and rapid demographic recovery through head‐starting in a Galapagos giant tortoise
Jensen EL, Edwards DL, Garrick RC4, Miller JM, Gibbs JP, Cayot LJ, Tapia W, Caccone A, Russello MA.
First published: 23 July 2018
https://doi.org/10.1111/eva.12682

Abstract
Population genetic theory related to the consequences of rapid population decline is well-developed, but there are very few empirical studies where sampling was conducted before and after a known bottleneck event. Such knowledge is of particular importance for species restoration, given links between genetic diversity and the probability of long-term persistence. To directly evaluate the relationship between current genetic diversity and past demographic events, we collected genome-wide single nucleotide polymorphism data from prebottleneck historical (c.1906) and postbottleneck contemporary (c.2014) samples of Pinzón giant tortoises (Chelonoidis duncanensis; n = 25 and 149 individuals, respectively) endemic to a single island in the Galapagos. Pinzón giant tortoises had a historically large population size that was reduced to just 150-200 individuals in the mid 20th century. Since then, Pinzón's tortoise population has recovered through an ex situ head-start programme in which eggs or pre-emergent individuals were collected from natural nests on the island, reared ex situ in captivity until they were 4-5 years old and subsequently repatriated. We found that the extent and distribution of genetic variation in the historical and contemporary samples were very similar, with the latter group not exhibiting the characteristic genetic patterns of recent population decline. No population structure was detected either spatially or temporally. We estimated an effective population size (N e) of 58 (95% CI = 50-69) for the postbottleneck population; no prebottleneck Ne point estimate was attainable (95% CI = 39-infinity) likely due to the sample size being lower than the true N e. Overall, the historical sample provided a valuable benchmark for evaluating the head-start captive breeding programme, revealing high retention of genetic variation and no skew in representation despite the documented bottleneck event. Moreover, this work demonstrates the effectiveness of head-starting in rescuing the Pinzón giant tortoise from almost certain extinction.
 

Taco*mom

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Amazing that they all have their own preferences! Love your detailed posts. It brings me to imagine how it's like at your place!


Presently it is about 6 am, still dark and our temperature is 69 degrees F. The ground (and water ) is still warm and will not worry much about short minor dips in temp at present. This is warmer and less windy than the caldera rim on of volcano Alcedo at times. The three year olds have a heated night house. A few older animals choose to go in a shelter overnight year-round. It will probably be another month before transfer of some the tortoises back to their winter yards ( in which I am currently workin). They will quickly demolish the grasses near the heated buildings and much prefer to spread out over space. When they sleep outside in cooler nights, they typically will find a sheltered area to which they return each evening and where they get first sun in the am. Although some readily go into the heated buildings in the winter areas, moving them can be challenging, takes time, and frequently involves bribery. Big males prefer not to share a building with another male (at least when females are present). It takes many hours to get all the stragglers inside when it becomes cold. Ideally they are confined to small yards next to the heated structures when there are several days of cold but most of those confinement yards were destroyed by falling trees with Hurricane Irma.
 

Taco*mom

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How's Tuscon Kid? Miss him (and his stories) already

I heard stories how Galaps are a lot more aggressive when compared to Aldabra. A couple of Aldabras kept together with Galaps were bitten and things like that. Kinda hard to believe.. yours seem to be very gentle especially Tuscon Kid.
 

Olddog

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Morning stirrings....

IMG_3579.jpg
IMG_3581.jpg





Giant tortoise genomes provide insights into longevity and age-related disease.

Quesada V, Freitas-Rodríguez S, Miller J, Pérez-Silva JG, Jiang ZF, Tapia W, Santiago-Fernández O, Campos-Iglesias D, Kuderna LFK, Quinzin M, Álvarez MG, Carrero D, Beheregaray LB, Gibbs JP, Chiari Y, Glaberman S, Ciofi C, Araujo-Voces M, Mayoral P, Arango JR, Tamargo-Gómez I, Roiz-Valle D, Pascual-Torner M, Evans BR, Edwards DL, Garrick RC, Russello MA, Poulakakis N, Gaughran SJ, Rueda DO, Bretones G, Marquès-Bonet T, White KP, Caccone A, López-Otín C.
Abstract
Giant tortoises are among the longest-lived vertebrate animals and, as such, provide an excellent model to study traits like longevity and age-related diseases. However, genomic and molecular evolutionary information on giant tortoises is scarce. Here, we describe a global analysis of the genomes of Lonesome George-the iconic last member of Chelonoidis abingdonii-and the Aldabra giant tortoise (Aldabrachelys gigantea). Comparison of these genomes with those of related species, using both unsupervised and supervised analyses, led us to detect lineage-specific variants affecting DNA repair genes, inflammatory mediators and genes related to cancer development. Our study also hints at specific evolutionary strategies linked to increased lifespan, and expands our understanding of the genomic determinants of ageing. These new genome sequences also provide important resources to help the efforts for restoration of giant tortoise populations.

PMID: 30510174

DOI: 10.1038/s41559-018-0733-x


 

Olddog

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About the farm earlier this month...

IMG_3579.jpg IMG_3581.jpg

Mobray, the oler tortoise on the right, was imported to Bermuda in one of the Townsend expeditions. She does not have much use for the youngsters. Peanut hay under the food was ignored.
IMG_3657.jpg




The Aldabras appeared to enjoy the peanut hay.
IMG_3670.jpg


Moving some of the ladies to winter enclosures..
IMG_3685.jpg


Herpetological History of the Jacksonville Zoo and Gardens

Herpetological Review, 2018, 49(3), 573–587.
© 2018 by Society for the Study of Amphibians and Reptiles

https://repository.si.edu/bitstream...ksonville Zoo 2018.pdf?sequence=1&isAllowed=y

An interesting read regarding reptile accomplishments of the 104 yo facility. Includes selected longevity records for reptiles and amphibians kept by the Jacksonville Zoo and Gardens. Throughout the 1980s, JZG hatched at least seven species of tortoise, which included the first captive breeding of Aldabra tortoises (A. gigantean) in the western hemisphere. Additional noteworthy chelonians bred at the zoo include the Indian Star Tortoise (Geochelone elegans), Pancake Tortoise (Malacochersus tournieri), and Yellow-headed Temple Turtle (Heosemys annandalii).



For the more academic.. Discussion of turtle embryology and the role of the Hox genes in the formation of the Turtle Shell. Mentions role of Hoxd 11 and Hoxa 13 in Temperature Sex Determination of the olive ridley sea turtle.

Hox Genes in Reptile Development, Epigenetic Regulation, and Teratogenesis

Rodolfo Martín-del-Campoa Itzel Sifuentes-Romerob Alejandra García-Gascaa

a Laboratory of Molecular Biology, Centro de Investigación en Alimentación y Desarrollo (CIAD), Mazatlán, Mexico; b Department of Biological Sciences, Florida Atlantic University, Boca Raton, FL, USA

https://www.karger.com/Article/Pdf/495712

Abstract

Reptiles are ancestral organisms presenting a variety of shapes, from the elongated vertebral column of the snake to the turtle dorsalized ribs or retractile neck. Body plans are specified by a conserved group of homeobox-containing genes (Hoxgenes), which encode transcription factors important in cell fate and vertebral architecture along the anteroposterior axis during embryonic development; thus, dysregulation of these genes may cause congenital malformations, from mild-sublethal to embryonic-lethal. The genetic pool, maternal transfer, and environmental conditions during egg incubation affect development; environmental factors such as temperature, moisture, oxygen, and pollution may alter gene expression by epigenetic mechanisms. Thus, in this review, we present information regarding Hox genes and development in reptiles, including sex determination and teratogenesis. We also present some evidence of epigenetic regulation of Hox genes and the role of the environment in epigenetic modulation of gene expression. So far, the evidence suggests that the molecular instructions encoded by Hox genes to build a snake, a lizard, or a turtle represent the interplay between genome and epigenome after years of evolution, with occasional environmentally induced molecular mistakes leading to abnormal body shapes.
 

Olddog

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How's Tuscon Kid? Miss him (and his stories) already

I heard stories how Galaps are a lot more aggressive when compared to Aldabra. A couple of Aldabras kept together with Galaps were bitten and things like that. Kinda hard to believe.. yours seem to be very gentle especially Tuscon Kid.

Tuscon

Tuscon is doing fine. Recently moved from the summer pastures. Requied two slices of watermelon to load on trailer.
Tuscon tends to sleep wherever he feels like. Just tends to plop down wherever he might be. this is not ideal if it is cold. Placed in a winer yard with a group of young males in hopes he would go into the heated shelter at night. Been warm and so far no interest. After all know where shelter and water is, will open gate for this group so thery can spread out more. IMO, this is not really enough room for a group of young males.
IMG_3893.jpg
IMG_3894.jpg

Really do not see aggression except mild disagreements when food is involved. Some individuals will like to take the food out of another's mouth rather than from the ground. Usually they will both stand and tortoise who stands tallest wins. Then they will usually continue to eat side by side. In the video one post above with Mobray and friends, the elderly Mowbray nipped at the neck of the younger tortoise eating from the community feedbowl although I think I cut it for brevity. On page 1, about the 8th video down, you can see the interplay when a young female decides to take food from a elderly male.
 

Reptilony

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Is this your personnal animals or is this a company or a sanctuary/rescue? In any case how did you get so many?
 
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