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Full-Text Articles in Life Sciences

The Larvae Of Eurycea Junaluska (Amphibia: Caudata: Plethodontidae), With Comments On Distribution, Travis Ryan Feb 2015

The Larvae Of Eurycea Junaluska (Amphibia: Caudata: Plethodontidae), With Comments On Distribution, Travis Ryan

Travis J. Ryan

Travis J. Ryan's shorter contribution to Copeia 1997.


The Global Decline Of Reptiles, Deja’ Vu Amphibians, J. Whitfield Gibbons, David E. Scott, Travis J. Ryan, Kurt A. Buhlmann, Tracey D. Tiuberville, Brian S. Metts, Judith L. Greene, Tony Mills, Yale Leiden, Sean Poppy, Christopher T. Winne Feb 2015

The Global Decline Of Reptiles, Deja’ Vu Amphibians, J. Whitfield Gibbons, David E. Scott, Travis J. Ryan, Kurt A. Buhlmann, Tracey D. Tiuberville, Brian S. Metts, Judith L. Greene, Tony Mills, Yale Leiden, Sean Poppy, Christopher T. Winne

Travis J. Ryan

Reptile species are declining on a global scale. Six significant threats to reptile populations are habitat loss and degradation, introduced invasive species, environmental pollution, disease, unsustainable use, and global climate change.


Ultrastructure Of The Reproductive System Of The Black Swamp Snake (Seminatrix Pygaea): Part Ii. Annual Oviducal Cycle, David Sever, Travis Ryan, Deborah Patton, Shannon Swafford Feb 2015

Ultrastructure Of The Reproductive System Of The Black Swamp Snake (Seminatrix Pygaea): Part Ii. Annual Oviducal Cycle, David Sever, Travis Ryan, Deborah Patton, Shannon Swafford

Travis J. Ryan

This article is the first ultrastructural study on the annual oviducal cycle in a snake. The ultrastructure of the oviduct was studied in 21 females of the viviparous natricine snake Seminatrix pygaea. Specimens were collected and sacrificed in March, May, June, July, and October from one locale in South Carolina during 1998–1999. The sample included individuals: 1) in an inactive reproductive condition, 2) mated but prior to ovulation, and 3) from early and late periods of gravidity. The oviduct possesses four distinct regions from cranial to caudal: the anterior infundibulum, the posterior infundibulum containing sperm storage tubules (SSTs), the ...


Does Sex Influence Post-Reproductive Metamorphosis In Ambystoma Talpoideum?, Travis Ryan, Gabrielle Swenson Feb 2015

Does Sex Influence Post-Reproductive Metamorphosis In Ambystoma Talpoideum?, Travis Ryan, Gabrielle Swenson

Travis J. Ryan

Shorter communication in the Journal of Herpetology v. 35.


Growth And The Expression Of Alternative Life Cycles In The Salamander Ambystoma Talpoideum (Caudata: Ambystomatidae), Travis Ryan, Raymond Semlitsch Feb 2015

Growth And The Expression Of Alternative Life Cycles In The Salamander Ambystoma Talpoideum (Caudata: Ambystomatidae), Travis Ryan, Raymond Semlitsch

Travis J. Ryan

Complex life cycles (CLCs) contain larval and adult phases that are morphologically and ecologically distinct. Simple life cycles (SLCs) have evolved from CLCs repeatedly in a wide variety of lineages but the processes that may underlie the transition have rarely been identified or investigated experimentally. We examined the influence of larval growth rate on the facultative expression of alternative life cycles (metamorphosis or maturation as gill-bearing adults [= paedomorphosis]) in the salamander Ambystoma talpoideum. We manipulated growth rates by altering the amount of food individuals received throughout larval development. The expression of alternative life cycles in A. talpoideum is influenced by ...


Evaporative Water Loss In Two Natricine Snakes, Nerodia Fasciata And Seminatrix Pygaea, Christopher Winne, Travis Ryan, Yale Leiden, Michael Dorcas Feb 2015

Evaporative Water Loss In Two Natricine Snakes, Nerodia Fasciata And Seminatrix Pygaea, Christopher Winne, Travis Ryan, Yale Leiden, Michael Dorcas

Travis J. Ryan

Shorter communication in Journal of Herpetology v. 35.


Aspects Of Sex-Specific Differences In The Expression Of An Alternative Life Cycle In The Salamander Ambystoma Talpoideum, Christopher Winne, Travis Ryan Feb 2015

Aspects Of Sex-Specific Differences In The Expression Of An Alternative Life Cycle In The Salamander Ambystoma Talpoideum, Christopher Winne, Travis Ryan

Travis J. Ryan

A recent evolutionary ecological model of facultative paedomorphosis predicts that body size of mature individuals should be larger than immatures of the same cohort. We investigated sex-specific differences in body size and maturation within a single cohort of branchiate (= larval and paedomorphic) mole salamanders, Ambystoma talpoideum. In addition, we also sampled the population after the breeding season, as some individuals began to undergo metamorphosis and leave the pond. The branchiate population was female-biased (62.7%), and mature (paedomorphic) females were significantly smaller than paedomorphic males or immature (larval) females. The majority of male branchiates were mature (86.6%), whereas significantly ...


Effects Of Hydroperiod On Metamorphosis In Rana Sphenocephala, Travis J. Ryan, Christopher T. Winne Feb 2015

Effects Of Hydroperiod On Metamorphosis In Rana Sphenocephala, Travis J. Ryan, Christopher T. Winne

Travis J. Ryan

Hydroperiod, the time a temporary pond holds water, is an important factor influencing recruitment in amphibian populations and structuring amphibian communities. We conducted an experiment to test the effect of hydroperiod on metamorphic traits of the southern leopard frog (Rana sphenocephala), a common amphibian in the southeastern United States. We reared larval R. sphenocephala in artificial ponds at a density of 32 larvae per tank (initial volume = approximately 650 liter). We dried the tanks according to natural patterns, using three different hydroperiods (60, 75 and 90 d). Experimental hydroperiods had a significant effect on the number of metamorphs and the ...


Life History Evolution And Adaptive Radiation Of Hemidactyliine Salamanders, Travis Ryan, R. Bruce Feb 2015

Life History Evolution And Adaptive Radiation Of Hemidactyliine Salamanders, Travis Ryan, R. Bruce

Travis J. Ryan

T.J. Ryan and R.C. Bruce's contribution to: The Biology of Plethodontid Salamanders, R. C. Bruce, R. G. Jaeger, and L. D. Houck, eds. Kluwer Academic/Plenum Publishers, New York.


Ultrastructure Of The Reproductive System Of The Black Swamp Snake (Seminatrix Pygaea). I. Evidence For Oviducal Sperm Storage, David Sever, Travis Ryan Feb 2015

Ultrastructure Of The Reproductive System Of The Black Swamp Snake (Seminatrix Pygaea). I. Evidence For Oviducal Sperm Storage, David Sever, Travis Ryan

Travis J. Ryan

Oviducal sperm storage in the viviparous (lecithotrophic) colubrid snake Seminatrix pygaea was studied by light and electron microscopy. Out of 17 adult snakes examined from May–October, sperm were found in the oviducts of only two specimens. In a preovulatory female sacrificed 14 May, sperm were found in the oviducal lumen and sperm storage tubules (SSTs) of the posterior infundibulum. In a nonvitellogenic female sacrificed 9 June, sperm were found in the lumen and glands of the posterior uterus and anterior vagina, indicating a recent mating. The glands in the posterior infundibulum and vagina were simple or compound tubular, whereas ...


Hatching Asynchrony, Survival, And The Fitness Of Alternative Adult Morphs In Ambystoma Talpoideum, Travis J. Ryan Feb 2015

Hatching Asynchrony, Survival, And The Fitness Of Alternative Adult Morphs In Ambystoma Talpoideum, Travis J. Ryan

Travis J. Ryan

The mole salamander, Ambystoma talpoideum, exhibits both aquatic (gilled) and terrestrial (metamorphosed) adult morphologies. Previous studies have shown the existence of body-size advantages associated with the terrestrial morph in A. talpoideum and other polymorphic salamanders (e.g., A. tigrinum). However, aquatic adult A. talpoideum mature at a younger age and often breed earlier than terrestrial adults. We tested the hypothesis that early maturation and reproduction in aquatic adults increase fitness (irrespective of body size). We reared larval A. talpoideum in mesocosms and varied the timing of hatching, with early-hatching larvae representing the offspring from early-breeding aquatic adults, and late-hatching larvae ...


Intraspecific Heterochrony And Life History Evolution: Decoupling Somatic And Sexual Development In A Facultatively Paedomorphic Salamander, Travis J. Ryan, Raymond D. Semlitsch Feb 2015

Intraspecific Heterochrony And Life History Evolution: Decoupling Somatic And Sexual Development In A Facultatively Paedomorphic Salamander, Travis J. Ryan, Raymond D. Semlitsch

Travis J. Ryan

Morphological features such as size and shape are the most common focus in studies of heterochronic change. Frequently, these easily observed and measured features are treated as a major target of selection, potentially ignoring traits more closely related to fitness. We question the primacy of morphological data in studies of heterochrony, and instead suggest that principal sources of fitness, such as life history characteristics, are not only the chief targets of selection, but changes in them may necessitate changes in other (subordinate) elements of the organism. We use an experimental approach to investigate the timing of metamorphosis and maturation in ...


Larval Life History And Abundance Of A Rare Salamander, Eurycea Junaluska (Plethodontidae), Travis Ryan Feb 2015

Larval Life History And Abundance Of A Rare Salamander, Eurycea Junaluska (Plethodontidae), Travis Ryan

Travis J. Ryan

The larval life history of Eurycea junaluska was studied in three southwestern North Carolina populations. Populations were sampled quarterly over a 13 mo period and size-class analyses were used to evaluate the pattern of larval growth and metamorphosis. Young of the year appeared in the late spring and experienced rapid growth through the first summer. Growth slowed in the second year and metamorphosis usually occured in the summer at about 25.5 mo post-hatching, although some data suggest that either 1yr or 3yr larval periods may be possible. The overall larval growth rate of E. junaluska is estimated at 1 ...


Calf Development: Most Births At Night, Robert H.I. Dale Jun 2014

Calf Development: Most Births At Night, Robert H.I. Dale

Robert H. I. Dale

For many years, field researchers studying both African (Loxodonta africana) and Asian (Elephas maximas) elephants have indicated that they have observed relatively few births in situ, suggesting that most elephant dams give birth at night. For example, according to Cynthia Moss, "Possibly the majority of births occur at night and perhaps those that do take place in the daytime happen in secluded places" (1988, p. 151). Others, for example, Clive Spinage, have referred to "the old beliefs that the cows retreated to 'calving grounds' or that birth took place at night." (Spinage, 1994, p. 90). Although observers in several areas ...


Tribute: In Memoriam, Jeheskel "Hezy" Shoshani, Robert H.I. Dale Jun 2014

Tribute: In Memoriam, Jeheskel "Hezy" Shoshani, Robert H.I. Dale

Robert H. I. Dale

The elephant community has lost one of its great ambassadors, Dr. Jeheskel "Hezy" Shoshani, at the age of 65. A wave of condolences and testimonials from colleagues and friends around the world followed his death on May 21, 2008.


History: The Birth Of "America" In 1882, Robert H.I. Dale Jun 2014

History: The Birth Of "America" In 1882, Robert H.I. Dale

Robert H. I. Dale

This article concerns a New York Times story about the birth of the female Asian elephant calf, named America, at the winter headquarters of the "Greatest Show on Earth" in Bridgeport, Connecticut on February 2, 1882. Phineas T. Barnum, one of the owners of the show, and one prone to self-aggrandizing bluster, claimed that America was the second elephant ever born in captivity. America was born only to months before the arrival in New York of the most famous circus elephant of all time, Jumbo, on Easter Sunday, 1882, and only two years before the origin of a small wagon ...


Variations In Radial Maze Performance Under Different Levels Of Food And Water Deprivation, Robert H.I. Dale, William A. Roberts Jun 2014

Variations In Radial Maze Performance Under Different Levels Of Food And Water Deprivation, Robert H.I. Dale, William A. Roberts

Robert H. I. Dale

Four groups of rats were tested on an eight-arm radial maze under a free-choice procedure. The subjects were maintained at either 80% or 100% of their preexperimental free-feeding weights through restricted access to either food or water. Water-deprived subjects received water in the maze; food-deprived subjects received food. Water-deprived subjects learned the task faster than food-deprived subjects. The four groups developed different response patterns. These were measured by the mean transition size, the average angular distance (in 45° units) between consecutively chosen arms. Rats foraging for food and water developed different search strategies, with water-deprived subjects exhibiting lower mean transition ...


Spatial And Temporal Response Patterns On The Eight-Arm Radial Maze, Robert H.I. Dale Jun 2014

Spatial And Temporal Response Patterns On The Eight-Arm Radial Maze, Robert H.I. Dale

Robert H. I. Dale

Six maze-experienced hooded rats were timed during five trials on which they collected water from all arms of an eight-arm radial maze, then made five more choices. All subjects frequently exhibited a “task-completion pause:” The subjects rarely spent more than 1 sec in the center of the maze between choices until they had entered all eight arms, then stopped in the center of the maze. In contrast, the time spent in each arm gradually increased until all of the water had been obtained, then decreased slightly. Four subjects began every trial by choosing eight consecutive adjacent arms. The task-completion pause ...


Some Children's Books About Elephants (1987-1997), Robert H.I. Dale Jun 2014

Some Children's Books About Elephants (1987-1997), Robert H.I. Dale

Robert H. I. Dale

Literature review of children's books about elephants from the Indianapolis Public Library.


Spatial Memory In Pigeons On A Four-Arm Radial Maze, Robert H.I. Dale Jun 2014

Spatial Memory In Pigeons On A Four-Arm Radial Maze, Robert H.I. Dale

Robert H. I. Dale

Pigeon spatial memory was examined using a four-arm radial maze. The maze had four arms, spaced at 90° intervals, extending radially from a central choice area. Subjects were forced into three arms, then permitted two choices to enter the remaining ann. Five subjects chose accurately (90% correct) with delays of 5 min or less, their choices depended on extramaze cues, and the food in the target arm provided no essential cues. After an incorrect first choice, subjects' second choices were more accurate than chance. These data suggest that, while spatial memory has many similar characteristics in rats and pigeons, pigeon ...


The Locomotor Kinematics Of Asian And African Elephants: Changes With Speed And Size, John R. Hutchinson, Delf Schwerda, Daniel J. Famini, Robert H.I. Dale, Martin S. Fischer, Rodger Kram Jun 2014

The Locomotor Kinematics Of Asian And African Elephants: Changes With Speed And Size, John R. Hutchinson, Delf Schwerda, Daniel J. Famini, Robert H.I. Dale, Martin S. Fischer, Rodger Kram

Robert H. I. Dale

For centuries, elephant locomotion has been a contentious and confusing challenge for locomotion scientists to understand, not only because of technical difficulties but also because elephant locomotion is in some ways atypical of more familiar quadrupedal gaits. We analyzed the locomotor kinematics of over 2400 strides from 14 African and 48 Asian elephant individuals (body mass 116-4632 kg) freely moving over ground at a 17-fold range of speeds, from slow walking at 0.40 m s-1 to the fastest reliably recorded speed for elephants, 6.8 m s-1. These data reveal that African and Asian elephants have some subtle differences ...


A Survey Of The Management And Development Of Captive African Elephant (Loxodonta Africana) Calves: Birth To Three Months Of Age, Nicole L. Kowalski, Robert H.I. Dale, Christa L. H. Mazur Jun 2014

A Survey Of The Management And Development Of Captive African Elephant (Loxodonta Africana) Calves: Birth To Three Months Of Age, Nicole L. Kowalski, Robert H.I. Dale, Christa L. H. Mazur

Robert H. I. Dale

We used four surveys to collect information about the birth, physical growth, and behavioral development of 12 African elephant calves born in captivity. The management of the birth process and neonatal care involved a variety of standard procedures. All of the calves were born at night, between 7PM and 7AM. The calves showed a systematic progression in behavioral and physical development, attaining developmental milestones at least a quickly as calves in situ. This study emphasized birth-related events, changes in the ways that calves used their trunks, first instances of behaviors, and interactions of the calves with other, usually adult, elephants ...


The Relative Attenuation Of Self-Stimulation, Eating And Drinking Produced By Dopamine-Receptor Blockade, E. T. Rolls, B. J. Rolls, P. H. Kelly, S. G. Shaw, R. J. Wood, Robert H.I. Dale Jun 2014

The Relative Attenuation Of Self-Stimulation, Eating And Drinking Produced By Dopamine-Receptor Blockade, E. T. Rolls, B. J. Rolls, P. H. Kelly, S. G. Shaw, R. J. Wood, Robert H.I. Dale

Robert H. I. Dale

Spiroperidol, which blocks dopamine (DA) receptors, attenuated self-stimulation of the nucleus accumbens, septal area, hippocampus, anterior hypothalamus and ventral tegmental area. Dopamine is thus involved in self-stimulation of many sites (in addition to the lateral hypothalamus). The attenuation was not a simple motor impairment of the speed of bar-pressing in that the nucleus accumbens and septal self-stimulation rates were lower than those in treated animals self-stimulating at other sites (Experiment 1). Feeding was partly attenuated, and drinking was much less attenuated by the spiroperidol. Since the rats bar-pressed for brain- stimulation reward, chewed pellets to eat, and licked a tube ...


Limitations On Spatial Memory In Mice, Robert H.I. Dale, Martin Bedard May 2014

Limitations On Spatial Memory In Mice, Robert H.I. Dale, Martin Bedard

Robert H. I. Dale

Rats have an impressive ability to remember locations they have visited. Two experiments used an eight-arm radial maze to determine whether mice showed two important characteristics of this spatial memory: its durability, and its dependence on stimuli outside the maze (extreme stimuli). In Experiment 1, food-deprived mice were allowed to eat from four of the eight arms of the maze then, after delays of 5 sec, 1 min, or 5 min, they were permitted to choose the remaining arms. Choice accuracy declined significantly with the longer delays, but always remained above chance. In Experiment 2, the maze was rotated 180 ...


The Hippocampus As Episodic Encoder: Does It Play Tag?, Robert H.I. Dale May 2014

The Hippocampus As Episodic Encoder: Does It Play Tag?, Robert H.I. Dale

Robert H. I. Dale

Rawlins’s characterization of the hippocampus as a “high-capacity, immediate-term memory store” captures the essential idea in a number of previous models. For example, Gaffan (1974), Gray (1984), Hirsh (1980), Kesner (Bierley, Kesner & Novak 1983), Olton (Olton, Becker & Handelmann 1979), Solomon (1980), and Winocur (1980) all agree that hippocampal animals show memory deficits when required to identify, for whatever reason, one specific event out of a list of recent events. Although these authors disagree on a number of details, Rawlins has identified their models common ground, the core of each model. (It is only fair to note that Gaffan has considerably modified his ideas about the hippocampus; cf. Gaffan, Saunders, Gaffan, Harrison, Shields & Owen 1984.)


Remembrance Of Places Lasts: Proactive Inhibition And Patterns Of Choice In Rat Spatial Memory, William A. Roberts, Robert H.I. Dale May 2014

Remembrance Of Places Lasts: Proactive Inhibition And Patterns Of Choice In Rat Spatial Memory, William A. Roberts, Robert H.I. Dale

Robert H. I. Dale

A series of experiments was carried out to evaluate the notion that rats given a sequence of massed daily trials on the radial maze reset working memory at the end of each trial by deleting its contents. Although curves presented by D. S. Olton [Scientific American, 1977, 236, 82-98: In S. H. Hulse, H. Fowler, & W. K. Honig (Eds.), Cognitive processes in animal behavior, 1978, Hillsdale, N.J.: Erlbaum] show that rats return to errorless performance at the beginning of each trial after the first, the fact that accuracy falls less rapidly over choices on Trial 1 than on subsequent ...


Radial-Maze Performance In The Rat Following Lesions Of Posterior Neocortex, Melvyn A. Goodale, Robert H.I. Dale May 2014

Radial-Maze Performance In The Rat Following Lesions Of Posterior Neocortex, Melvyn A. Goodale, Robert H.I. Dale

Robert H. I. Dale

The present experiment was designed to investigate the role of posterior neocortex (areas 17, 18 and 18a) in the maintenance of performance on the radial maze. Following training to criterion on the 8-arm radial maze, rats received either sham operations, bilateral eye enucleations, lesions of posterior neocortex, or combined enucleations and lesions of posterior neocortex. While the enucleated animals with intact brains showed a slight, but significant performance decrement relative to the sham-operated group, the other two groups, with lesions of areas 17, 18 and 18a, each showed a massive deficit. This large deficit was observed even in the group ...


Parallel-Arm Maze Performance Of Sighted And Blind Rats: Spatial Memory And Maze Structure, Robert H.I. Dale May 2014

Parallel-Arm Maze Performance Of Sighted And Blind Rats: Spatial Memory And Maze Structure, Robert H.I. Dale

Robert H. I. Dale

Sighted and peripherally blinded groups of rats learned to obtain a small reward from each arm of an eight-arm parallel maze, and a sighted group was similarly trained on a radial maze. The parallel-sighted and parallel-blind groups were equally slow, and much slower than the radial-sighted group, to attain criterion performance. The three groups shared several response characteristics: selectively avoiding the most recently entered arms, frequently choosing adjacent arms, and an absence of 'spatial generalization' among the arms. The findings support a simple model proposing how subjects identify and choose among the maze-arms.


Dynamic Effects Of Food Magnitude On Interim-Terminal Interaction, Alliston K. Reid, Robert H.I. Dale May 2014

Dynamic Effects Of Food Magnitude On Interim-Terminal Interaction, Alliston K. Reid, Robert H.I. Dale

Robert H. I. Dale

We tested the assumption of a facilitatory relation between periodic food presentation and schedule-induced drinking by examination of (a) elicited drinking, (b) drinking in anticipation of food delivery, and (c) possible indirect effects of food delivery on drinking. We exposed rats to a fixed-time 60-second schedule in which interfood intervals ended in either one or four food pellets with equal probability. In Phases 1 and 3, a stimulus signaled the magnitude of upcoming food presentation. In Phase 2, the stimulus was eliminated. Changes in drinking and "head-in-feeder" distributions within interfood intervals demonstrated that head-in-feeder was controlled directly by food presentation ...


Interactions Between Response Stereotypy And Memory Strategies On The Eight-Arm Radial Maze, Robert H.I. Dale, Nancy K. Innis May 2014

Interactions Between Response Stereotypy And Memory Strategies On The Eight-Arm Radial Maze, Robert H.I. Dale, Nancy K. Innis

Robert H. I. Dale

Three groups of water-deprived rats collected water from the ends of the 8 arms of an 8-arm radial maze. Sighted subjects, and subjects blinded either with or without pre-enucleation experience on the radial maze, all retrieved the water efficiently. Most of the subjects exhibited the same response stereotypy, regularly choosing 8 adjacent arms of the maze, then stopping in the center of the maze. The strategies underlying this performance were analyzed by interrupting trials and rotating the maze 180° after the subject had made 3 choices. Sighted subjects depended on extramaze stimuli, naive-blind subjects depended on intramaze stimuli and experienced-blind ...