Austin J.J. and E.N. Arnold. 2001. Ancient mitochondrial DNA and morphology elucidate an extinct island radiation of Indian Ocean giant tortoises (Cylindraspis). Proc R Soc Lond B Biol Sci 2001 Dec 22;268(1485):2515-23. Contact: Dept. Zool. and Entomology, U. Queensland, St Lucia, Queensland, 4072, Australia.
Casey, M.B. and M.J. Sleigh. 2001. Cross-species investigations of prenatal experience, hatching behavior, and postnatal behavioral laterality. Dev Psychobiol 39(2): 84-91. E-mail: email@example.com.
de Solla S.R. , C.A. Bishop, H. Lickers and K. Jock. 2001. Organochlorine pesticides, PCBs, dibenzodioxin, and furan concentrations in common snapping turtle eggs in Akwesasne, Mohawk Territory, Ontario, Canada. Arch Environ Contam Toxicol 40(3):410-7. Contact: Dept Zool., Univ. of Guelph, Guelph, Ontario, N1G 2W1, Canada.
Holladay S.D., J.C. Wolf, S.A. Smith, D.E. Jones, and J.L. Robertson. 2001. Aural abscesses in wild-caught box turtles (Terrapene carolina): possible role of organochlorine-induced hypovitaminosis A. Ecotoxicol Environ Saf 48(1):99-106. E-mail: firstname.lastname@example.org
Miller, J.K. 2001. Escaping senescence: demographic data from the three-toed box turtle (Terrapene carolina triunguis). Exp Gerontol 36(4-6):829-32. E-mail: email@example.com
Rebęlo, G. H. and L. Lugli. 1996. The conservation of freshwater turtles and the dwellers of the Amazonian Jaú National Park (Brazil). 253-258 In S. K. Jain, (ed.). Ethnobiology in Human Welfare. Deep Publications, New Delhi. E-mail: firstname.lastname@example.org
Reese, S.A., C.E. Crocker, M.E. Carwile, D.C. Jackson, G.R. Ultsch. The physiology of hibernation in common map turtles (Graptemys geographica). Comp Biochem Physiol A Mol Integ Physiol. 130(2):331-40. Contact: Dept. Biol. Sciences, Univ. Alabama, Tuscaloosa, AL 35487 USA.
Willingham, E. 2001. Embryonic exposure to low-dose pesticides: effects on growth rate in the hatchling red-eared slider turtle. J Toxicol Environ Health A 2001 Oct 12: 64. Contact: Division of Biological Sciences, Univ. Texas, Austin 78759, USA.
Wooley, R.E., B.W. Ritchie, M.F. Currin, S.W. Chitwood, S. Sanchez, M.M. Crane, and N. Lamberski. 2001. In vitro inhibition of Salmonella organisms isolated from reptiles by an inactivated culture of microcin-producing Escherichia coli. Am J Vet Res 62(9):1399-401. Contact: Dept. Medical Microbiology & Parasitology, College of Vet. Med., Univ. Georgia, Athens 30602, USA.
The following are dissertation & thesis abstracts from 2000.
Clark, Patricia J. 2000. Reproductive strategies of turtles: Population, latitudinal, and phylogenetic comparisons. Ph.D. 235 pg. Indiana University.
Abstract: A key hypothesis in the study of life history strategies predicts a trade-off between offspring size and number. Previous studies of turtle reproductive strategies and investment focused on variability of egg wet mass (size) and clutch size, generally within one site. This study compared not only the size of eggs and hatchlings but also the more fundamental energetic content of eggs and hatchlings and efficiency of conversion of egg to hatchling material at a variety of levels: within a species among local sites, within two species at widely geographically separated sites, and among a broadly distributed variety of species. Bomb calorimetry was used for energetic determinations. Analyses indicated some significant differences in size and energy content at all levels of comparison. For example, Chelydra serpentina and Trachemys scripta from the southern sites produced significantly larger eggs and hatchlings (both mass and energy) than those from the northern sites. Similarly, tropical cryptodire species with temperature dependent sex determination produced significantly larger eggs and hatchlings (both mass and energy) than did the other groups compared. There were also significant differences in energy density among sites for Sternotherus odoratus and C. serpentina. Additionally, energetic analyses in this study indicated that use of wet mass as a measure of reproductive investment underestimated the differences at all levels of comparison.
This study also addressed the issue of optimal egg size and the constraint on egg size due to the physical morphology of the female S. odoratus shell. Egg width increased with both pelvic girdle opening and caudal aperture. However, comparisons of egg width and pelvic girdle opening and caudal aperture indicated that in this species, the caudal aperture was more constraining than the pelvic opening. This limited eggs to sizes smaller than would otherwise have been optimal save in the largest females.
Duggan, Annemarie E. 2000. Seasonal and Hormonal Regulation of Lipid Homeostasis in the Freshwater Turtle, Chrysemys picta. Ph.D. 165 pg. Boston University.
Abstract: The hypothesis that gonadal steroid hormones have a primary role in the regulation of significant lipid shifts associated with seasonal vitellogenesis and ovarian growth in oviparous species such as the freshwater turtle, Chrysemys picta, was tested. Analysis of the control mechanisms involved may provide insight into sex differences in cardiovascular disease and the cardioprotective role of estrogen in the human. We have described changes in plasma lipid and protein components during the turtle annual ovarian cycle. The distribution of lipids in total plasma and the lipoprotein fractions Very Low Density Lipoprotein, Low Density Lipoprotein, High Density Lipoprotein, and Very High Density Lipoprotein and of the lipid-transporting proteins, apoA-I, apoB, and apoE was assessed. Elevations of plasma triglyceride were associated with spring and fall periods of ovarian growth. Vitellogenin, but not cholesterol was also increased during these periods. ApoA-I, associated with reverse cholesterol transport, was significantly elevated after ovulation. Estradiol administration increased triglyceride and apoA-I levels in females and males, and hypophysectomized females with or without growth hormone. Progesterone followed by estradiol in females, also significantly increased apoA-I and triglyceride levels. Cholesterol levels were not altered. The physiologically relevant receptor for apoA-I, SR-BI (Scavenger Receptor Class B Type I), demonstrated here in non-mammals for the first time, was expressed in turtle tissues (liver, heart, and gonads). A second protein (34 kDa), putative apoE in turtle HDL/VHDL fractions, presumed absent in non-mammalian vertebrates, was also found. A comparative study of other non-mammals demonstrated widespread distribution of a putative apoE in vertebrates, which was reported to be present in the plasma of the lamprey (an agnathan), shark and skate (elasmobranchs), and alligator (another reptile).
These studies suggested that the lipid-transporting proteins, apolipoproteins (A-I and E, were associated with the plasma HDL fractions in the turtle, and that apoE was widely present in vertebrates, as was SR-BI, the receptor for apoA-I. Further, the synthesis/secretion of these lipid-transporting proteins, as well as vitellogenin, may be under endocrine regulation. In this way lipid homeostasis may be maintained despite the massive shifts in lipid reserves associated with seasonal ovarian growth. These studies may provide insight into the cardioprotective role of estrogen in the human female.
Rie, Melanie Tuthill. 2000. Assessment of the Effects of Groundwater Pollution on a Sentinel Species, Chrysemys picta, on Cape Cod, Massachusetts: Tissue Contaminant Levels and Hepatic and Reproductive Bioindicators. Ph.D. 200 pg. Boston Univ.
Abstract: In this study we sought evidence that groundwater pollution containing a low-level mixture of environmental contaminants might negatively impact reproductive processes in the freshwater turtle, Chrysemys picta. The specific geographic focus of the study was the Massachusetts Military Reservation (MMR), a Superfund site on Cape Cod, Massachusetts. We selected several bioindicators of exposure (hepatic cytochrome P4501A [CYP1A], glutathione-S-transferase [GST], metallothionein measurement and plasma vitellogenin) and effect (plasma estrogen and testosterone, sexual maturity, ovarian follicular kinetics (females), sperm counts (males) and testicular histology) to assess responses to groundwater pollution. In addition, the tissue levels of heavy metals were measured in animals trapped seasonally from potentially impacted and non-impacted sites over a period of 4 years. Since cadmium is known to have negative effect on reproduction, we chose to investigate the tissue distribution of an injected dose of radioactive cadmium, and the effect of exposure to non-isotopic cadmium on tissue metallothionein induction in a laboratory study.
Significant seasonal and site related changes were seen in the activity of two hepatic biotransformation enzymes CYP1A/GST, indicative of exposure of animals to organic pollutants. In addition, significant elevations in hepatic metallothionein and tissue heavy metal levels were detected in animals from the impacted site. Assessment of reproductive/endocrine biomarkers of effect indicated significant differences between animals from the contaminant impacted site and the control site. At the impacted site, females appear to be slower to reach sexual maturity and have reduced oocyte numbers. In addition lower plasma levels of estradiol were seen, which correlated with the reduced levels of the estrogen dependent yolk protein precursor vitellogenin and lower reproductive tract weights. Plasma testosterone levels and testis weights were somewhat lower in males from the impacted site. Sperm counts were lower in all Cape Cod nudes than in control males from Wisconsin. Although the primary site of pollutant action in the hypothalamic-pituitary-gonadal axis cannot be determined from these observations, the liver may be related to these responses in as much as hepatic metabolism of gonadal steroids and synthesis of vitellogenin may be altered in animals exposed to xenobiotics.
Rubin, Cory Stuart. 2000. Ecology and Genetics of Blanding’s Turtles in an Urban Landscape. Ph.D. 113 pg. University of Illinois at Urbana-Champaign.
Abstract: The Blanding’s turtle (Emydoidea blandingii) inhabits shallow freshwater habitats in North America and is undergoing population declines throughout its range. The loss of habitat is largely responsible for the demise of this semi-aquatic turtle. Moreover, the subdivision and insularization of remaining habitats through urban development are expected to become major threats to the species’ persistence. Most knowledge to date has been generated in areas where habitats are relatively undisturbed by urban development. Consequently, the potential effects of urbanization on Blanding’s turtles are not well established. To develop a better understanding of how Blanding’s turtles respond to urban development, I initiated an investigation of the ecology and genetics of Blanding’s turtles in the intensely developed Greater Chicago metropolitan area (GCMA) in northeastern Illinois. My findings indicated that populations in the GCMA are small and isolated and have juvenile recruitment problems, though do not appear to be suffering genetically. As expected, Blanding’s turtles relied extensively on wetlands, but during dry periods turtles were often found on land and in permanent residential ponds located on private property adjacent to preserve boundaries. Based on these findings, primary efforts toward the conservation of Blanding’s turtles in the GCMA should aim to increase population sizes and provide permanent wetlands within preserve boundaries and protect those used by turtles on private property. Because adult survival was high in the populations studied, low juvenile recruitment appears to be the major factor resulting in small population sizes. Thus, management interventions need to focus on increasing juvenile recruitment rates to increase the size of Blanding’s turtle populations in the GCMA. Potential strategies to increase juvenile recruitment include “headstarting” or the captive propagation of young turtles that are subsequently released back into the wild and the protection of nesting areas of Blanding’s turtles from predators and human disturbances. Ultimately, however, the fate of Blanding’s turtles in the GCMA will depend upon the protection and proper management of habitat for Blanding’s turtles at all life-stages. Thus, conservation strategies that combine a holistic approach to habitat management with those that increase juvenile recruitment will be the most successful.
Simon, M. Suzanne. 2000. Endocrine Controls and Functional Morphology of the Oviduct of the Slider Turtle, Trachemys scripta. Ph.D. 298 pg. Ohio University.
Abstract: This research sought to elucidate the roles of steroid hormones in the control of the oviduct in turtles by examining the natural hormone cycle, the functional morphology of the oviduct and the effects of specific steroid hormones on the oviduct in the slider turtle, Trachemys scripta. Plasma levels of steroid hormones were measured over a reproductive cycle in a wild population of sliders and their oviducts analyzed histologically. In the laboratory, turtles were treated with specific steroid hormones and the oviducts analyzed histologically.
Wild-caught turtles displayed relatively low levels of estradiol-17beta throughout the reproductive year with no apparent cycle. Testosterone levels, although slightly higher than estrogen, also did not exhibit an annual cycle. Progesterone levels were low and static during most of the year but displayed a distinct peak, possibly representing a spike, around ovulation. Oviductal epithelium, mucosal glands and lamina propria showed no morphometric changes throughout the cycle. However, staining for secretory products in the epithelium and mucosal glands of the tubal and uterine portion of the oviduct was more intense before gravidity and nearly absent in many areas following gravidity.
Estradiol-17beta induced the formation of mucosal glands and had pronounced hypertrophic effects on epithelium, mucosal glands and lamina propria in both tubal and uterine regions of the oviducts of prereproductive female Trachemys. Estradiol also induced the synthesis of secretory products; glycosaminoglycans in secretory epithelium and proteins in mucosal glands. Progesterone enhanced hypertrophic effects in the epithelium but not in other oviductal areas. Progesterone-treated tissues also showed less staining for glycosaminoglycans and proteins. Testosterone induced epithelial hypertrophy and production of glycosaminoglycans, as did dihydrotestosterone to a lesser degree.
Estradiol-17beta appears to have a minor role in control of reproduction in adult Trachemys. It may be responsible for oviductal maturation at puberty and low level maintenance in adults. Testosterone may act as a more primitive and redundant controller of oviductal epithelium. Progesterone is the apparent stimulator for release of secretory products. The periovulatory release of high levels of progesterone suggests that preovulatory follicles are the primary source of progesterone and corpora lutea are a secondary, less important source.
Wilgenbusch, James Charles. 2000. The Influence of Incubation Conditions and Hatchling Body Size on Growth and Survivorship of the Common Snapping Turtle (Chelydra serpentina L.). Ph.D. 144 pg. George Mason University.
Abstract: A comprehensive understanding of how maternal and environmental effects influence offspring phenotype and in-turn how offspring phenotype influences characters directly or indirectly related to fitness is necessary to evaluate current life-history theory. This dissertation represents an examination of the factors affecting hatchling body size and the way that these factors and body size affect post-hatching growth and survival. Specifically, the following hypotheses were tested; (1) clutch identity influences hatchling growth and survivorship independent of body size and incubation condition, (2) incubation of eggs on a wet substrate increase post-hatching growth and survivorship independent of body size and clutch identity, (3) larger hatchlings grow faster and experience lower mortality than smaller hatchlings, and (4) increased body size will be favored when there is greater intraspecific competition. To test these hypotheses 253 eggs from 26 common snapping turtles (Chelydra serpentina) were incubated in the laboratory under wet (-150) and dry (-950 kPa) conditions and the hatchlings from these eggs were reared under variable laboratory conditions to simulate a range of selective pressures.
Clutch identity was a significant source of initial egg size and hatchling body size differences, but did not represent a significant source of variation in models describing post-hatching growth. Post-hatching survivorship in the communal tank was affected by clutch identity, although the effect did not appear to be independent of body size at hatching. Turtles from eggs incubated on wet substrate were significantly larger at hatching than turtles from eggs incubated on a dry substrate. Moisture availability during incubation affected post-hatching growth and survivorship only in as much as moisture affected relative hatchling body size. Size at hatching also affected survivorship regardless of the initial size difference between the paired hatchlings or the condition under which eggs were incubated. Among turtles reared in social isolation, egg size and size at hatching were inversely related to post-hatching growth rates. This finding suggests a possible mechanism that could offset the trade-off typically associated with optimal egg size models in environments where intraspecific competition is low. This study demonstrates that “bigger is better” only under specific post-hatchling rearing conditions.
Feinberg, J.A. 2001. Nesting ecology of diamondback terrapins (Malaclemys terrapin) at Gateway National Recreation Area. Masters Thesis, Hofstra University, Hempstead, NY 116 pp.
Abstract: The nesting ecology of diamondback terrapins (Malaclemys terrapin) was studied in 1998 and 1999 at Gateway National Recreation Area. I found populations of nesting terrapins at three different locations. Most of my research was conducted at the Jamaica Bay Wildlife Refuge. Female terrapins nested from early June through late July, and laid up to two clutches per season, depositing an average of 10.9 eggs per nest. Nesting activity increased with daily high temperature and high tide. The majority of females were captured when there was 25-75% cloud cover. The majority of nests were counted in shrub-land, mixed-grassland, and dune habitats, but nest density was highest on a man-made, sandy trail and also on beaches. Raccoons depredated 92.2% of terrapin nests. Only 5.2% of terrapin nests survived to produce hatchlings. I counted 1,319 and 1,840 depredated nests in 1998 and 1999, respectively, at the Refuge. I also found the carcasses of 23 female terrapins that were apparently killed by raccoons as they came on land to nest. Contact information: J. Feinberg, 348 St. Marks Ave., Apt. 4B, Brooklyn, NY 11238, E-mail: email@example.com