Timing of reproductive behaviour in male musk turtles,Sternotherus odoratus: effects of photoperiod,temperature and testosterone

Although male turtles are usually regarded as having a post-nuptial pattern of gonadogenesis (i.e. gonadal growth dissociated from time of mating), they do mate both in the spring (when testes are regressed, plasma testosterone levels are low, epididymides are enlarged, and temperature and daylength increasing) and in the autumn (testes and epididymides are enlarged, plasma testosterone levels are elevated, and temperature and daylength are decreasing). Therefore different proximate cues may operate in mediating male reproductive behaviour at different times of year. When temperature, photoperiod and testosterone levels were altered in male Sternotherus odoratus during the year in both laboratory and semifield conditions, reproductive behaviour occurred more readily in autumn than in spring (the supposed major breeding period). Short daylength was the key environmental condition stimulating male sexual activity, while temperature changes ‘fine-tuned’ this behaviour. Testosterone was effective in stimulating male behaviour only under certain environmental conditions and males could become refractory to artificially elevated plasma testosterone levels.     

Survival and physiological responses of hatchling blanding's turtles (Emydoidea blandingii) to submergence in normoxic and hypoxic water under simulated winter conditions

Overwintering habits of hatchling Blanding's turtles (Emydoidea blandingii) are unknown. To determine whether these turtles are able to survive winter in aquatic habitats, we submerged hatchlings in normoxic (155 mmHg Po2) and hypoxic (6 mmHg Po2) water at 4 degrees C, recording survival times and measuring changes in key physiological variables. For comparison, we simultaneously studied hatchling softshell (Apalone spinifera) and snapping (Chelydra serpentina) turtles, which are known to overwinter in aquatic habitats. In normoxic water, C. serpentina and A. spinifera survived to the termination of the experiment (76 and 77 d, respectively). Approximately one-third of the E. blandingii died during 75 d of normoxic submergence, but the cause of mortality was unclear. In hypoxic water, average survival times were 6 d for A. spinifera, 13 d for E. blandingii, and 19 d for C. serpentina. Mortality during hypoxic submergence was probably caused by metabolic acidosis, which resulted from accumulated lactate. Unlike the case with adult turtles, our hatchlings did not increase plasma calcium and magnesium, nor did they sequester lactate within the shell. Our results suggest that hatchling E. blandingii are not particularly well suited to hibernation in hypoxic aquatic habitats.     

Effects of experimental anemia on blood ion and acid-base status of turtles during submergence in aerated water at 3 degrees C

The importance of blood hemoglobin to aquatic oxygen uptake by turtles (Chrysemys picta bellii) submerged in aerated water at 3 degrees C was tested by comparing the responses of anemic turtles (hematocrit approximately 6%) to turtles with normal hematocrits (hematocrit approximately 33%). All turtles were submerged for 42 days and blood samples were collected at 0, 7, 21, 32 and 42 days. Blood was analyzed for pH, PCO(2), PO(2), hematocrit, hemoglobin concentration ([Hb]) and plasma was analyzed for concentrations of lactate, glucose, Na(+), K(+), Ca(2+) and Mg(2+). Plasma [HCO(3)(-)] was calculated. [Hb] correlated closely with hematocrit levels. [Lactate] reached higher final values in anemic turtles (34.5+/-5.3 mmol l(-1)) than in normal turtles (14.5+/-4.6 mmol l(-1)) indicating a greater reliance of the anemic animals on anaerobic metabolism. Both groups compensated for acidosis by reduced PCO(2) and anemic turtles also had increased [Ca(2+)] and [Mg(2+)]. Blood pH fell significantly in the anemic turtles but not in the controls. Although the data indicate that the anemic turtles relied more on anaerobic metabolism than the controls, the effect was much less than expected on the basis of the reduced blood O(2) carrying capacity. Possible compensatory mechanisms utilized by the anemic turtles to minimize anaerobic metabolism are discussed.     

A comparison of mtDNA restriction sites vs. control region sequences in phylogeographic assessment of the musk turtle (Sternotherus minor)

A total of nearly 800 base pairs of mitochondrial DNA sequence was assayed in each of 52 musk turtles (Sternotherus minor) collected across the species' range in the south-eastern USA. About one-half of the sequence information in effect was accessed by conventional recognition-site assays of the entire mtDNA molecule; the remainder came from direct sequence assays of a normally hypervariable 5′ section of the noncoding control region. The two assay methods produced essentially nonoverlapping sets of variable character states that were compared with respect to magnitudes and phylogeographic patterns of mtDNA variation. The two assay procedures yielded nearly identical outcomes with regard to: (a) total levels of species-wide mtDNA genetic variation; (b) mean levels of within-locale variation; (c) extremely high population genetic structure; (d) a phylogenetcally significant separation of samples from the north-western half of the species' range vs. those in the south-eastern segment; and (e) considerably lower genetic variability within the north-western clade. The micro- and macro-phylogeographic mtDNA patterns in the musk turtle are consistent with a low-dispersal natural history, and with a suspected longer-term biogeographic history of the species, respectively.     

Blood profiles for a wild population of green turtles (Chelonia mydas) in the southern Bahamas: size-specific and sex-specific relationships.

Blood biochemical profiles and packed cell volumes were determined for 100 juvenile green turtles, Chelonia mydas, from a wild population in the southern Bahamas. There was a significant correlation of body size to 13 of the 26 blood parameters measured. Only plasma uric acid and cholesterol were significantly different between male and female turtles. The relationship between total plasma proteins and plasma refractive index was significant. The equation for converting refractive index (Y) to total plasma proteins (X) is Y = 1.34 + 0.00217(X).     

林麝幼体的换毛序和胎毛、夏毛、冬毛的形态

被毛是哺乳动物最主要的特征之一,有关动物换毛序与环境关系的研究,是动物生态学研究的一个重要方面。从1853年Browne开始研究毛发结构以来,人们对毛发的形态学、分类学和种属关系等方面的研究已开展了大量工作,特别是随着电镜技术的应用,这些方面的工作在逐渐深入(曹汉民等,19     

Canonical discriminant analysis for hematological and serum biochemical changes during pregnancy period in squirrel monkeys (Saimiri sciurea)

Hematological and serum biochemical data obtained from non-pregnant, pregnant and post-partum squirrel monkeys (Saimiri sciurea) were analyzed by canonical discriminant analysis (discriminant analysis with reduction of dimensionality). All animals were of wild origin and had been maintained under uniform environmental conditions at Tsukuba Primate Center for Medical Science, N.I.H., Japan. Months were standardized by the day of parturition. The calculated arithmetic means and standard deviations were listed for each item of measurement performed. Items detected statistically significant difference (p less than 0.01) between months were as follows: red blood cell count (RBC), mean corpuscular volume (MCV), hematocrit value (Ht), hemoglobin concentration (Hb), white blood cell count (WBC), albumin concentration (ALB), blood urea nitrogen concentration (BUN), total cholesterol concentration (T-CHO), triglyceride concentration (TG), alkaline phosphatase activity (ALP) and calcium concentration (Ca). Results of canonical discriminant analysis showed that the value of the first canonical variate (Z1) decreased from the early period of pregnancy to the middle period, and that the second canonical variate (Z2) decreased from the middle period of pregnancy to the end of pregnancy. The meaning of their changes were discussed.     

Glucose oxidation and nonoxidative glucose disposal during prolonged fasts of the northern elephant seal pup (Mirounga angustirostris)

Elephant seal weanlings demonstrate rates of endogenous glucose production (EGP) during protracted fasts that are higher than predicted on the basis of mass and time fasting. To determine the nonoxidative and oxidative fate of endogenously synthesized glucose, substrate oxidation, metabolic rate, glycolysis, and EGP were measured in fasting weanlings. Eight weanlings were sampled at 14 days of fasting, and a separate group of nine weanlings was sampled at 49 days of fasting. Metabolic rate was determined via flow-through respirometry, and substrate-specific oxidation was determined from the respiratory quotient and urinary nitrogen measurements. The rate of glucose disposal (Glu((R)(d))) was determined through a primed, constant infusion of [3-(3)H]glucose, and glycolysis was determined from the rate of appearance of (3)H in the body water pool. Glu((R)(d)) was 1.41 ± 0.27 and 0.95 ± 0.21 mmol/min in the early and late fasting groups, respectively. Nearly all EGP went through glycolysis, but the percentage of Glu((R)(d)) oxidized to meet the daily metabolic demand was only 24.1 ± 4.4% and 16.7 ± 5.9% between the early and late fasting groups. Glucose oxidation was consistently less than 10% of the metabolic rate in both groups. This suggests that high rates of EGP do not support substrate provisions for glucose-demanding tissues. It is hypothesized that rates of EGP may be ancillary to the upregulation of the tricarboxylic acid cycle to meet high rates of lipid oxidation while mitigating ketosis.     

Strongyloides robustus and the northern sympatric populations of northern (Glaucomys sabrinus) and southern (G. volans) flying squirrels

Within North America, northern (Glaucomys sabrinus) and southern (Glaucomys volans) flying squirrels occupy distinct ranges with limited overlap. Sympatry in northern latitudes coincides with northern hardwood vegetation from Minnesota to New England. Strongyloides robustus is an intestinal parasite that infects both species but appears to be deleterious only to northern flying squirrels. As a result, S. robustus could be a critical determinant of flying squirrel population characteristics in at least some areas of sympatry. However, cold weather could potentially limit the distribution of S. robustus in northern climates. Therefore, we assessed fecal samples from both flying squirrel species to determine the presence of the nematode in Wisconsin. Strongyloides robustus was found in 12 flying squirrel scat samples and infected 52% of southern flying squirrels and 11% of northern flying squirrels. Prevalence of S. robustus infection for northern flying squirrels was substantially lower than previously reported from more southern regions. This is the northernmost documentation of S. robustus in flying squirrels and the first documentation of S. robustus parasitizing flying squirrels in Wisconsin.     

Effect of nutrient application and water turbidity on submergence tolerance of rice (Oryza sativa)

Flooding imposes severe selection pressure on plants, principally because excess water in their surroundings deprives the plants from certain basic resources such as oxygen, carbon dioxide and light for photosynthesis. Here, the effects of nitrogen and phosphorus application and their application time, on four Indica rice cultivars and their tolerance to submergence under turbid and clear flood water was studied. Submergence tolerance on metabolic changes, photosynthetic (Pn) rate and ethylene accumulation were evaluated. Submergence substantially reduced survival, chlorophyll, soluble sugars, Pn rate across cultivars with drastic reduction in IR‐20. Sub1 cultivars showed greater Pn rate as compared to sensitive cultivar under submergence because of better protection of chlorophyll, more stomatal conductance leading to higher survival. Turbid water resulted in lower under‐water photosynthesis because of poor light transmission, chlorophyll retention and silt deposition and ultimately poor survival. Foliar spray of N after desubmergence along with basal P improved the chlorophyll, soluble sugars and Pn rate and extenuated ethylene accumulation and shoot elongation resulting in significantly higher survival. To the best of our knowledge, this is the first time that such a study has been performed. Crop establishment could therefore be enhanced in areas where untimely flooding is anticipated by applying basal P and foliar spray of post‐submergence N.     

Availability of water affects organ growth in prenatal and neonatal snapping turtles (Chelydra serpentina)

We manipulated the amount of water that was available to prenatal and neonatal snapping turtles (Chelydra serpentina) in order to assess the impact of water on growth by different organs in these animals. Three treatments were used: (1) turtles that completed their incubation on a wet substrate, (2) turtles that completed their incubation on a dry substrate, and (3) turtles that spent a few days in water after completing incubation on a dry substrate. Turtles hatching on a dry substrate (treatment 2) were smaller than animals in the other two treatments (which did not differ in size), so data for mass of different organs were adjusted by ANCOVA to remove effects of body size. Scaled masses of liver, stomach, lungs, kidneys, and small intestine did not differ between turtles emerging in wet environments and those hatching in dry environments, but hearts of turtles hatching in dry settings were substantially larger than those of animals hatching in wet ones. Thus, the mass of most organs in turtles developing in wet and dry environments scaled to body size, whereas the heart was hypertrophied in embryos developing in dry environments. Turtles that spent a few days in water after hatching from eggs in dry environments grew rapidly in size, and the increase in body size was accompanied by disproportionately rapid growth in the liver, stomach, lungs, kidneys, and small intestine. The heart did not increase in size during this period, despite the substantial increase in body mass over that at hatching. The enlarged heart of turtles hatching on dry substrates may have been caused by a circulatory hypovolemia late in incubation; the rapid growth of organs other than the heart when these animals were placed in water may reflect a release from constraints on growth once circulatory volume was restored. Accepted: 2 November 1999     

Hormonal changes during the mating and conception seasons of wild northern muriquis (Brachyteles arachnoides hypoxanthus)

We investigated hormonal and behavioral changes in wild male and female northern muriquis (Brachyteles arachnoides hypoxanthus) at the Estação Biológica de Caratinga, Minas Gerais, Brazil, during a 6‐mo period that encompassed the onset of the 1998–1999 mating and conception seasons. Individual females resumed mating with the resumption of ovarian cycling, which was not synchronized among them or related to their cortisol levels. Females experienced two to seven cycles prior to conceiving, and the first conception occurred 2 mo after the onset of the group's mating season. There were no differences in female cortisol levels across their premating, mating, and conception conditions. Cortisol levels were significantly higher in females than in males prior to the conception season, consistent with the prediction that energy reserves may be associated with breeding readiness in females, but not males, in this species. The sustained elevation in male cortisol occurred after the peak in their sexual activity, which resulted in the first conception of the year. Male cortisol levels were positively correlated between years that were similar in rainfall, but differed in the timing of sexual and reproductive events. The timing of cortisol elevations in males appears to be generally regulated by environmental cues, but is responsive to fine‐tuning by social and behavioral cues related to the unpredictable timing of reproductive opportunities within their extended mating season. Am. J. Primatol. 61:85–99, 2003. © 2003 Wiley‐Liss, Inc.     

Thermoregulation of spotted turtles (Clemmys guttata) in a beaver-flooded bog in southern Ontario,Canada

Body temperature has a major influence on the physiological processes, growth, reproductive output, and overall survival of ectotherms. When a habitat is altered as a result of natural or anthropogenic influences, the available temperatures in the habitat can change, thus affecting an animal's ability to thermoregulate. We studied thermoregulation in response to habitat change in a population of spotted turtles (Clemmys guttata) in Southern Ontario, Canada. Historically, the study site was ditched to draw down water levels to facilitate peat mining, and the resulting drainage ditches were the only habitat containing surface water and turtles were restricted to these drains. Recent colonization of the site by beaver (Castor canadensis) caused increases in water level and water surface area. We followed spotted turtles (N=16) outfitted with radio transmitters and iButtons to estimate body temperatures (T_b) continuously throughout the active season post-flooding. Turtle models outfitted with iButtons (N=50) were deployed in the nine available habitat types to record environmental temperatures (T_e). Turtles (N=13) were tested in a thermal gradient under laboratory conditions to determine preferred body temperature range (T_set). The T_set for the population ranged from 20 °C to 26 °C. In the field, T_b was within the T_set range 28% of the time from March to October, and 67% of the time from July to August. Efficiency of thermoregulation was calculated to be highest in July and August. The habitat type with the highest thermal quality was the shallow flooded zone created by beaver damming, and the habitat with the lowest thermal quality was the drain bottom, the drains being the only aquatic habitat available prior to flooding. This study confirms that beaver flooding provided a wide variety of preferable thermal opportunities for spotted turtles. Further investigation is needed to determine the effects of flooding on spotted turtle thermoregulation during nesting and hibernation.     

Larval survival of two species of forensically important blowflies (Diptera: Calliphoridae) after submergence in water

Survival of larvae of known ages after 2 to 6 h of submersion under water was assessed by observing pupation and adult emergence in the cases of two blowflies of forensic importance, Chrysomya megacephala (Fabricius) and Chrysomya rufifacies (Macquart). Lowest survival occurred among 10‐h‐old larvae, which could not tolerate more than 2 h of submergence. Even with such a small period of submergence success of survival was only 33%. There were no survivors when 20‐ and 30‐h‐old larvae were submerged for more than 3 and 4 h, respectively. In the cases of 40‐, 50‐, 60‐ and 70‐h‐old larvae there were no survivors if submergence was more than 5 h. The results show that there is an inverse relationship between submergence period and survival rate: the longer the submergence period, the lesser is the survival rate. This study provides data that are potentially useful in estimating the minimum time since submergence (TSS) of a corpse during forensic investigations.     

Nondeep simple morphophysiological dormancy in seeds of Ilex maximowicziana from northern (subtropical) and southern (tropical) Taiwan

In this study, we show that seeds of Ilex maximowicziana collected from northern and southern Taiwan differ in germination responses to temperature. Seeds produced by plants growing in the tropical environment of southern Taiwan were more responsive (in a positive way) to higher incubation temperatures than those produced by plants growing in the subtropical environment of northern Taiwan. On the other hand, seeds produced in northern Taiwan were more responsive (in a positive way) to low incubation temperatures and to cold stratification than those from southern Taiwan. Germination percentages and rates of seeds from northern Taiwan were higher at 20/10°C than at 30/20°C, reaching a plateau of >80% germination after 12 weeks incubation, whereas germination of seeds from southern Taiwan reached >80% at 30/20 and 25°C but not at 20/10°C. Gibberellic acid (GA₃) increased germination rate but not germination percentage of seeds from both southern and northern Taiwan. Freshly matured seeds of I. maximowicziana have rudimentary embryos. During dormancy break, embryo length increased 11.5- and 8.0-fold in northern and southern seeds, respectively, before radicle emergence. Thus, seeds of Ilex maximowicziana have nondeep simple morphophysiological dormancy. This is the first detailed study of the germination requirements of a subtropical/tropical species of the large cosmopolitan genus Ilex.     

Reproductive development of northern and southern strains of plum curculio (Coleoptera: Curculionidae)

Laboratory-reared southern and field-collected northern strains of plum curculio, Conotrachelles nenuphar (Herbst), were sampled to examine the relationship between degree-day (DD) accumulation and female reproductive development, as measured by mating status, oocyte size, and number of oocytes. The overall goal was to generate an objective degree-day model for predicting damage potential that could be applied to various host commodities rather than relying on separate biofix models for each crop. Adult beetles were dissected to measure mating status, maximum oocyte size, and number of oocytes. Southern strain beetles reared at 25 degrees C initiated mating 9 d after eclosion and did not require mating to induce oocyte development. By 20 d posteclosion, unmated females had significantly higher egg loads compared with mated females of the same age. Logistic regression analysis suggests that southern and northern strain beetles had a stable maximum oocyte length of 62 and 72 microm, respectively. Northern strain females mated after overwintering; with approximately 95% of the female population mated after 134 DD (base 10 degrees C), which is before fruit set in many host crops. Oocyte size was the only measured parameter of field reproductive progress that could be linked with confidence to degree-day accumulation. The other two parameters do not share an exclusive relationship with degree-days. Rapid assessment of field-caught female reproductive status could assist in determining the potential for plum curculio damage in high-value commodities and allow for more informed control decisions.     

Effects of acute fresh water exposure on water flux rates and osmotic responses in Kemp's ridley sea turtles (Lepidochelys kempi)

Water flux rates and osmotic responses of Kemp's Ridley sea turtles (Lepidochelys kempi) acutely exposed to fresh water were quantified. Salt-water adapted turtles were exposed to fresh water for 4 d before being returned to salt water. During the initial salt water phase, absolute and relative water flux rates were 1.2+/-0.1 l d(-1) and 123.0+/-6.8 ml kg(-1) d(-1), respectively. When turtles were exposed to fresh water, rates increased by approximately 30%. Upon return to salt water, rates decreased to original levels. Plasma osmolality, Na(+), K(+), and Cl(-) decreased during exposure to fresh water, and subsequently increased during the return to salt water. The Na(+):K(+) ratio was elevated during the fresh water phase and subsequently decreased upon return to salt water. Aldosterone and corticosterone were not altered during exposure to fresh water. Elevated water flux rates during fresh water exposure reflected an increase in water consumption, resulting in a decrease in ionic and osmotic concentrations. The lack of a change in adrenocorticoids to acute fresh water exposure suggests that adrenal responsiveness to an hypo-osmotic environment may be delayed in marine turtles when compared to marine mammals.