Recognition by Population and Genetic Similarity in the Mountain Dusky Salamander,Desmognathus ochrophaeus (Amphibia: Plethodontidae)

Adult males and females of Desmognathus ochrophaeus were tested in two-choice substrate discrimination trials in which salamanders were given a choice of the marked substrates of opposite-sex individuals from their own population and from a geographically distinct population. Females exhibited a significant preference for the marked substrates of extrapopulation males, whereas there was no evidence that males made any such discrimination of the marked substrates of females. We suggest that females may utilize substrate cues to make initial assessments of potential mates. We compared data from substrate discrimination trials to random amplified polymorphic DNA (RAPD) profiles generated for each individual. There was no evidence that females made any distinction of substrate odours based on our assessment of genetic similarity. The estimated genetic differences between the two populations were minimal.     

Male Mating Success in the Mountain Dusky Salamander,Desmognathus ochrophaeus: Are Small,Young, Inexperienced Males at a Disadvantage?

Young, small, sexually-inexperienced males suffer lower mating success than older, larger, more experienced males in many species of animals. I compared the mating success of male Desmognathus ochrophaeus (Amphibia: Caudata: Plethodontidae) reared to maturity in the laboratory with that of males collected as adults in the field. Courtship trials were staged in the laboratory between single males and females. Laboratory-reared males were significantly smaller in body size than adult males collected in the field, were certainly inexperienced sexually and were probably younger. No difference was found between laboratory-reared males and field-collected males in any measure of mating success, although the former apparently produced smaller sperm masses. I conclude that newly-mature male D. ochrophaeus are not discriminated against by females in the context of mate choice, and do not need to “rehearse” courtship in order to obtain successful inseminations. However, newly-mature males are probably at a disadvantage in terms of aggressive and sperm competition with larger males.     

Time courses of thermal acclimation for critical thermal minima in the salamanders Desmognathus quadramaculatus, Desmognathus monticola, Desmognathus ochrophaeus, and Plethodon jordani

1. We examined the time courses of thermal acclimation for critical thermal minima (CTMin) in the salamanders Desmognathus quadramaculatus, D. monticola, D. ochrophaeus, and Plethodon jordani. 2. D. quadramaculatus showed no annual differences in their time courses, but we noted seasonal differences in the CTMin with these salamanders having lower CTMin in the spring. 3. Gain in CTMin (25 degrees C to 5 degrees C transfer) was faster than its corresponding loss (5 degrees C to 25 degrees C transfer) in D. quadramaculatus. 4. Comparison of all three Desmognathus species revealed no differences in the CTMin for the 5 degrees C to 25 degrees C time courses, but P. jordani had lower CTMin than corresponding D. quadramaculatus. 5. Our results indicate that the pattern of CTMin acclimation correlates with the constraints acting on salamanders in their natural environment.     

Hydric constraints upon foraging in a terrestrial salamander,Desmognathus ochrophaeus (Amphibia: Plethodontidae)

Summary The time until salamanders voluntarily abandoned foraging (the water time limit) and the amount of water lost when salamanders abandoned foraging (dehydration deficit) were determined for terrestrial plethodontid salamanders, Desmognathus ochrophaeus, foraging at various vapor pressure gradients in the laboratory. Salamander activity was correlated with the rate of water loss and was inversely related to the water time limit. Animals at 0.35–0.86 kPa vapor pressure gradients abandoned foraging and returned to moist retreats significantly sooner than animals in water-saturated air. The early retreat of animals in dry air was related in part to high rates of water loss and in part to the modest dehydration deficit (3.8%) at which animals abandoned foraging. Locomotor performance and foraging ability were unaffected by dehydration until dehydration deficits exceeded 12%. This suggests that salamanders in unsaturated air abandoned foraging at a low dehydration deficit to conserve and replenish water reserves rather than to avoid outright incapacitation or death. Present address: Department of Zoology, University of Guelph, Guelph, Ontario N1G 2W1, Canada     

Evolution of Courtship Behaviour Patterns and Reproductive Isolation in the Desmognathus ochrophaeus Complex

The extent to which differences in courtship behaviour patterns act as mechanisms of reproductive isolation is critical to understanding both speciation and the evolution of these behaviour patterns. While numerous studies have investigated intraspecific and interspecific differences in courtship, fewer interpret results in a phylogenetic framework. We describe and analyse geographic variation in the courtship behaviour patterns of the Allegheny Dusky salamander ( Desmognathus ochrophaeus ). We then examine courtship among closely related species in the D. ochrophaeus complex in a phylogenetic context. We found that populations of D. ochrophaeus separated by extensive geographic distances show little variation in courtship behaviour patterns and are sexually compatible. This contrasts with significant levels of sexual isolation between D. ochrophaeus and other species in the complex. Mapping behaviour patterns onto a phylogeny that we generated from cytochrome b sequences indicates that two behaviour patterns present in the courtship sequence of other members in the complex have either been lost in D. ochrophaeus or gained independently in other species in the complex. Loss of these behaviour patterns may result in reproductive isolation between D. ochrophaeus and its sister taxon, D. orestes .     

Dusky salamanders (Desmognathus, Plethodontidae) from the Coastal Plain: multiple independent lineages and their bearing on the molecular phylogeny of the genus

Recent phylogenetic reassessment of the lungless salamanders (Plethodontidae) confirmed a major life-history reversal-from direct development to an aquatic larval stage-in the dusky salamanders (Desmognathus) of eastern North America. This reversal initiated high rates of lineage accumulation, reputedly generating the species richness and ecological breath that now characterize Desmognathus. Certain important aspects of the radiation, e.g., ecomorphological evolution, have been identified through intense sampling effort of Appalachian Highland lineages. However, the research preoccupation on montane species has left overlooked a significant component of dusky salamander distribution-the Coastal Plain. We present the first molecular phylogeny for Desmognathus to incorporate extensive coverage from the Atlantic and Gulf coastal plains. We examined 38 Coastal Plain populations in conjunction with 45 additional populations, representing 16 of the 19 nominal species. Bayesian analysis of 88 mitochondrial cox1 haplotypes diagnosed eight independent population lineages within the Coastal Plain, a number at odds with the region's three currently recognized species. Desmognathus has apparently experienced a complex biogeographic history in this physiographic region, one involving multiple invasions and several ecological transitions from lotic to lentic habitats.     

Population differentiation in plethodontid salamanders: divergence of allozymes and sexual compatibility among populations of Desmognathus imitator and D. ochrophaeus (Gaudata: Plethodontidae)

Plethodontid salamanders of the genus Desmognathus exhibit varying levels of genetic differentiation among and within both allopatric and sympatric taxa. This provides excellent opportunities to study population differentiation and speciation. Two morphologically similar species in this genus, D. imitator and D. ochrophaeus, are genetically well-differentiated from one another and occur in sympatry with no evidence of hybridization and introgression. We report that the degree of sexual isolation between these two species is very high, regardless of whether the populations under comparison are allopatric or sympatric with one another. Neither reinforcement nor reproductive character displacement are required to explain the evolution of sexual incompatibility in sympatry. Sexual behaviour apparently diverges while populations are allopatric with one another. Preliminary study indicates that D. imitator consists of populations among which there may be significant sexual isolation in the absence of detectable genetic differentiation.     

Effects of size,caudal autotomy,and predator kairomones on the foraging behavior of Allegheny Mountain dusky salamanders (<Emphasis Type="Italic">Desmognathus ochrophaeus</Emphasis>)

Prey must balance the conflicting demands of foraging and defensive behavior. Foraging under the threat of predation may be further complicated among species that engage in caudal autotomy, the loss of a portion of the tail at preformed breakage planes, because the tail may serve as an important energy storage organ and contribute to motility, culminating in a trade-off between foraging and predator avoidance. As a result of the advantages conferred by the presence of a tail, individuals that have recently undergone autotomy may be more motivated to forage despite elevated levels of threat indicated by predator kairomones. We used a full factorial design to evaluate the combined effects of body size, exposure to predator kairomones, and experience with autotomy on the latency to strike at Drosophila prey, number of strikes, and prey captured per strike by Allegheny Mountain dusky salamanders (Desmognathus ochrophaeus). In our study, caudal autotomy was the only significant main effect and influenced both the latency to attack prey and the number of strikes attempted. In terms of latency to attack prey, there was a significant interaction between body size and autotomy such that “small” salamanders (≤3.2 cm SVL) without tails delayed their foraging behavior. In terms of the number of strikes toward prey, there was a significant interaction between autotomy and exposure to predator kairomones such that individuals with intact tails exhibited a greater number of strikes, with the exception of the “large” (>3.2 cm SVL) salamanders, which performed fewer strikes when exposed to the snake kairomones. There was no significant effect on foraging efficiency, although the trend in the data suggests that autotomized individuals forage more efficiently. This study was designed to evaluate the confluence of factors related to size, caudal autotomy, and exposure to stimuli from predators and hints at the magnitude of caudal autotomy on antipredator decision-making. Our data suggest that despite the importance of tail tissue for energy storage, locomotion, and mating, salamanders without tails are cautious when foraging under elevated risk.     

Lack of Evidence for Encystment in the Parasitic Amoeba Hydramoeba hydroxena (Entz)

SYNOPSIS. It is known that hydras infected with H. hydroxena commonly disintegrate and release scores of amoebae. Spherical resting bodies found among the free amoebae have been described as cysts and it has been suggested that they give rise to amoebulae. Using Hydra pseudoligactis as the host, a study was made of the history of the free amoebae and of the structure, nature, and fate of the so-called cysts. All such amoebae transformed into spherical bodies that resembled cysts, even to the presence of an external membrane. These bodies invariably disintegrated after 2–3 days and they never produced amoebulae. They were called pseudocysts. The external membrane proved to be a layer of gelated cytoplasm. Unlike a true cyst membrane, it dissolved in KOH and it underwent solation when the pseudocyst disintegrated. It is concluded that the pseudocysts are actually weakened, starved, moribund amoebae. At present there is no evidence that H. hydroxena is capable of producing true cysts; its transmission from host to host appears to be solely by means of the amoeboid trophozoite.     

Osseous pathologies in the lungless salamander Desmognathus fuscus (Plethodontidae)

The majority of reported pathologies in lissamphibians (salamanders, caecilians and frogs) include limb deformities such as missing limbs, multiple extra limbs and digits, or incomplete limb formation. However, comparatively little is known about congenital vertebral malformations or posttraumatic pathologies (e.g. injuries, infections) in the vertebral column of salamanders. In the present study, we describe eight vertebral deformities in three cleared and stained specimens of Desmognathus fuscus. Two specimens display developmental deformities which range from a potential non-segmented wedge vertebra to fully segmented hemivertebrae. The vertebral pathology in the third specimens possibly results from a parasitic infection. Apparently, these osseous deformities were not severe enough to prohibit survival of the specimens.     

Olfactory metamorphosis in the Coastal Giant Salamander (Dicamptodon tenebrosus)

This study examined the gross morphology and ultrastructure of the olfactory organ of larvae, neotenic adults, and terrestrial adults of the Coastal Giant Salamander (Dicamptodon tenebrosus). The olfactory organ of all aquatic animals (larvae and neotenes) is similar in structure, forming a tube extending from the external naris to the choana. A nonsensory vestibule leads into the main olfactory cavity. The epithelium of the main olfactory cavity is thrown into a series of transverse valleys and ridges, with at least six dorsal and nine ventral valleys lined with olfactory epithelium, and separated by ridges of respiratory epithelium. The ridges enlarge with growth, forming large flaps extending into the lumen in neotenes. The vomeronasal organ is a diverticulum off the ventrolateral side of the main olfactory cavity. In terrestrial animals, by contrast, the vestibule has been lost. The main olfactory cavity has become much broader and dorsoventrally compressed. The prominent transverse ridges are lost, although small diagonal ridges of respiratory epithelium are found in the lateral region of the ventral olfactory epithelium. The posterior and posteromedial wall of the main olfactory cavity is composed of respiratory epithelium, in contrast to the olfactory epithelium found here in aquatic forms. The vomeronasal organ remains similar to that in large larvae, but is now connected to the mouth by a groove that extends back through the choana onto the palate. Bowman's glands are present in the main olfactory cavity at all stages, but are most abundant and best developed in terrestrial adults. They are lacking in the lateral olfactory epithelium of the main olfactory cavity. At the ultrastructural level, in aquatic animals receptor cells of the main olfactory cavity can have cilia, short microvilli, a mix of the two, or long microvilli. Supporting cells are of two types: secretory supporting cells with small, electron-dense secretory granules, and ciliated supporting cells. Receptor cells of the vomeronasal organ are exclusively microvillar, but supporting cells are secretory or ciliated, as in the main olfactory cavity. After metamorphosis two distinct types of sensory epithelium occur in the main olfactory cavity. The predominant epithelium, covering most of the roof and the medial part of the floor, is characterized by supporting cells with large, electron-lucent vesicles. The epithelium on the lateral floor of the main olfactory cavity, by contrast, resembles that of aquatic animals. Both types have both microvillar and ciliated receptor cells. No important changes are noted in cell types of the vomeronasal organ after metamorphosis. A literature survey suggests that some features of the metamorphic changes described here are characteristic of all salamanders, while others appear unique to D. tenebrosus.     

Lack of Evidence for Energetic Costs of Mate-Guarding in Wild Male Assamese Macaques (Macaca assamensis)

Mate-guarding is a widespread and efficient male strategy for increasing paternity success. The inability to guard entire female receptive phases or complete lack of mate-guarding has been explained by energetic constraints posed on males. The energetic costs per unit time a male can afford to suffer are thought to be lowest in year-round breeding species in marginal habitats and highest in seasonally breeding species in rich habitats. Here we test the prediction that mate-guarding is energetically costly in seasonal breeders in marginal habitats. We observed all males in one group of wild Assamese macaques (Macaca assamensis) for two 4-mo mating seasons and recorded activity and travel paths via focal animal sampling, physical condition via visual inspection, and collected feces for analysis of glucocorticoid levels. Generalized linear mixed model (GLMM) analyses did not reveal an effect of mate-guarding on time spent feeding or moving or on distance traveled, travel speed, directedness of travel, or glucocorticoid levels. This lack of mate-guarding costs was consistent with the lack of a relationship between individual time spent mate-guarding and change in physical condition over the mating season. Within the limitations of our study the results do not support the idea that seasonally breeding males in marginal habitats face energetic costs of mate-guarding. With others we suggest instead that though these costs may be found in species where strength, size, and mass predict rank, mating, and reproductive success, males may not engage in costly mate-guarding in species such as Assamese macaques where also smaller, weaker males may attain high social status via political coalitions or other routes alternative to direct contest over guarded females.     

河北塞罕坝褐柳莺鸣唱特征分析

2014年7月至8月,在天气良好的情况下,每天上午5:00至10:00时,利用TASCAM DR-680型录音机外接Sennheiser ME67话筒,录制了河北塞罕坝林场处于繁殖期的褐柳莺(Phylloscopus fuscatus)鸣声。录音的采样精度为16 bit,采样频率设置为44.1 k Hz。共获得41只个体清晰可供分析的录音,平均每只个体录到(47±16)句录音。利用Raven pro分析软件测量鸣唱参数,如每个句子和音节的最低频率、最高频率、起始频率及终止频率、持续时间和音节(音素)个数。进行统计分析后,发现河北地区褐柳莺鸣唱语句包含两种类型,句型较单一不变的S-song和句型多变的V-song。褐柳莺鸣唱句子的最高频率为(7.04±0.89)k Hz,最低频率为(1.75±0.30)k Hz,起始频率为(4.53±2.00)k Hz,终止频率(3.22±1.43)k Hz,句子的持续时间(1.24±0.32)s,由(6.50±1.91)个音节组成。基于语图上音节形态的差异,共发现49种不同的音节类型,每只个体鸣唱中使用2到30种音节类型。     

Formation and fate of the corpus luteum in the Dusky leaf monkey (Presbytis obscura)

The formation and fate of the corpus luteum have been described for a previously un researched species of South-east Asian colobine, the Dusky leaf monkey, Presbytis obscura. Histological material from 44 wild female monkeys collected at various stages of the menstrual cycle, pregnancy and lactation over a 12-month period was available for study. The corpus luteum of the menstrual cycle was a cystic structure and consisted of a thin rim of luteal tissue surrounding a central cavity filled with a meshwork of fibrin. At the end of the luteal phase the corpus luteum either degenerated into a corpus albicans, or became transformed into a corpus aberrans. Corpora aberrantia have previously only been described in the ovaries of the rhesus monkey, where they may persist for many months. Ultimately the corpus aberrans may also degenerate into a corpus albicans. Small corpora lutea atretica were observed during early pregnancy but there was no evidence of corpora lutea accessoria. Anovulatory cycles were common amongst the females included in this study and may play a role in limiting the growth of troops in their natural environment. Comparisons have been drawn between the findings presented here and those published for other species of catarrhine primate.