Eastern Red-Backed Salamanders: A Comprehensive Review of an Undervalued Model in Evolution, Ecology, and Behavior

A multicenter random forest model for effective prognosis prediction in collaborative clinical research network.

Terrestrial salamanders are sensitive to forest disturbance associated with even-aged management. We studied the distribution of redback salamanders (Plethodon cinereus) for 4 yr at edges between even-aged northern hardwood stands along three replicate transects in each of three edge contrast types: regeneration/mature, sapling/mature, and poletimber/mature in northern New Hampshire. We used 2 m2 coverboard clusters at the edge, and at 5, 10, 20, and 40 m into the younger and mature stands. Salamanders were surveyed 12 times per year from May to October, approximately once every 2 wk, usually within 24 hr of a rain event. Habitat variables included board station soil temperature, litter depth, organic layer depth, depth to soil mottling, herbaceous cover, down log cover, three classes of understory hardwood stem density [0.5–1m tall, 1–2 m tall and <10 cm dbh, and >2 m tall], softwood stem density, Rubus/other stem density, and overstory basal area (ba) and mean dbh. A total of 4,038 redback salamanders were detected during 432 transect counts. The mean salamander density was 0.41/m2 across regenerating stand transects, 0.47m2 across sapling transects, and 0.69 m2 across poletimber transects. We analyzed salamander distribution by edge type, replicate, year, station (distance from edge), and their interactions. There were significant differences in salamander detections among edge types, replicates, station, and years for both counts across entire younger forest/mature forest transects and across the younger forest transect sections. There were significant interactions between edge type and distance from edge. Salamander detections were greater (P < 0.001) in pole/mature edges than in sapling/mature and regeneration/mature edges in all years. Counts in sapling and regeneration stands were not different. The pattern of salamander abundance was similar across all edge types: low abundance 40 m out in the younger stand, increased abundance near or at the edge, a decrease just inside the edge, peak abundance in the mature stand (20 m inside the edge), and decline at 40 m in the mature stand. Salamander counts differed among years across all transects, tracking yearly precipitation differences. Counts also varied seasonally; early spring and late summer counts were higher (P < 0.001) than counts in early to mid-summer and fall. Salamander counts were negatively related to total understory stem density, density of hardwood stems >2 cm tall and <10 cm dbh, and percent herb cover, and positively related to soil organic layer depth (P values <0.10). A stepwise regression model included percent herbaceous ground cover, number of hardwood stems >2 m tall and <10 cm dbh, and organic soil layer depth, and explained 29% of the variation in redback salamander counts. Our findings are consistent with reported recovery times for redback salamanders after clearcut harvesting; recovery rates even along edges may take about 30 yr. Seasonal and yearly variation must be taken into account if terrestrial salamanders are used in monitoring programs. FOR. SCI. 48(2):351–363.

To avoid or not to avoid? Factors influencing the discrimination of predator diet cues by a terrestrial salamander

Research and development is considered a main source of knowledge and innovation in the Gulf countries and Arab region. Therefore, building a Collaborative Research Network (CRN) in the Gulf is necessary for high quality and sustainable research. In this paper, the authors examine the role of CRN in improving Gulf countries’ performance in research and innovation. Four objectives have been set: investigate the current situation regarding scientific research and CRN in the Gulf countries, identify factors that influence the building of a CRN, identify the impact and contribution of CRN in improving the Gulf countries’ performance, and develop a model. To achieve these objectives, a quantitative method was adopted. A questionnaire was developed and distributed to 100 participants. The current paper presents the first stage of research that investigates the role of building CRN in improving the Gulf countries’ performance in research and innovation. The next stage will examine the model of building CRN.

Balancing timber production and conservation in forest management requires an understanding of how timber harvests affect wildlife species. Terrestrial salamanders are useful indicators of mature forest ecosystem health due to their importance to ecosystem processes and sensitivity to environmental change. However, the effects of timber harvests on salamanders, though often researched, are still not well understood. To further this understanding, we used artificial cover objects to monitor the relative abundance of terrestrial salamanders for two seasons (fall and spring) pre-harvest and five seasons post-harvest in six forest management treatments, and for three seasons post-harvest across the edge gradients of six recent clearcuts. In total, we recorded 19,048 encounters representing nine species of salamanders. We observed declines in mean encounters of eastern red-backed salamanders (Plethodon cinereus) and northern slimy salamanders (P. glutinosus) from pre- to post-harvest in group selection cuts and in clearcuts. However, we found no evidence of salamander declines at shelterwoods and forested sites adjacent to harvests. Edge effects induced by recent clearcuts influenced salamanders for approximately 20 m into the forest, but edge influence varied by slope orientation. Temperature, soil moisture, and canopy cover were all correlated with salamander counts. Our results suggest silvicultural techniques that remove the forest canopy negatively affect salamander relative abundance on the local scale during the years immediately following harvest, and that the depth of edge influence of clearcuts on terrestrial salamanders is relatively shallow (<20 m). Small harvests (<4 ha) and techniques that leave the forest canopy intact may be compatible with maintaining terrestrial salamander populations across a forested landscape. Our results demonstrate the importance of examining species-specific responses and monitoring salamanders across multiple seasons and years. Long-term monitoring will be necessary to understand the full impacts of forest management on terrestrial salamanders.

I determined whether variation in diet related to variation in head and/or body size and whether ontogenetic size change was associated with dietary shifts in the terrestrial red-backed salamander, Plethodon cinereus. No ontogenetic shift was found in the diet of P. cinereus, nor was there an apparent relationship between head size and prey size in larger salamanders. However, prey size was related to juvenile head size, indicating that overall body size constrains prey selection in small individuals. Juvenile P. cinereus have proportionally broader heads than adults, indicating an ontogenetic change in head shape. I hypothesize that head shape is attained by a heterochronic change in development that enables hatchlings to utilize a wide range of prey-i.e., broad head shape in small salamanders is a mechanism for generalized feeding. I also suggest that terrestrial salamanders may exhibit combinations of ontogenetic changes in head morphology and diet.

To describe pediatric severe asthma care, complications, and outcomes to plan for future prospective studies by the Collaborative Pediatric Critical Care Research Network. Retrospective cohort study. : Pediatric intensive care units in the United States that submit administrative data to the Pediatric Health Information System. Children 1-18 yrs old treated in a Pediatric Health Information System pediatric intensive care unit for asthma during 2004-2008. None. Thirteen-thousand five-hundred fifty-two children were studied; 2,812 (21%) were treated in a Collaborative Pediatric Critical Care Research Network and 10,740 (79%) were treated in a non-Collaborative Pediatric Critical Care Research Network pediatric intensive care unit. Medication use in individual Collaborative Pediatric Critical Care Research Network centers differed widely: ipratropium bromide (41%-84%), terbutaline (11%-74%), magnesium sulfate (23%-64%), and methylxanthines (0%-46%). Complications including pneumothorax (0%-0.6%), cardiac arrest (0.2%-2%), and aspiration (0.2%-2%) were rare. Overall use of medical therapies and complications at Collaborative Pediatric Critical Care Research Network centers were representative of pediatric asthma care at non-Collaborative Pediatric Critical Care Research Network pediatric intensive care units. Median length of pediatric intensive care unit stay at Collaborative Pediatric Critical Care Research Network centers was 1 to 2 days and death was rare (0.1%-3%). Ten percent of children treated at Collaborative Pediatric Critical Care Research Network centers received invasive mechanical ventilation compared to 12% at non-Collaborative Pediatric Critical Care Research Network centers. Overall 44% of patients who received invasive mechanical ventilation were intubated in the pediatric intensive care unit. Children intubated outside the pediatric intensive care unit had significantly shorter median ventilation days (1 vs. 3), pediatric intensive care unit days (2 vs. 4), and hospital days (4 vs. 7) compared to those intubated in the pediatric intensive care unit. Among children who received mechanical respiratory support, significantly more (41% vs. 25%) were treated with noninvasive ventilation and significantly fewer (41% vs. 58%) were intubated before pediatric intensive care unit care when treated in a Pediatric Health Information System hospital emergency department. Marked variations in medication therapies and mechanical support exist. Death and other complications were rare. More than half of patients treated with mechanical ventilation were intubated before pediatric intensive care unit care. Site of respiratory mechanical support initiation was associated with length of stay.

Research and development is considered a main source of knowledge and innovation in the Gulf countries and Arab region. Therefore, building a Collaborative Research Network (CRN) in the Gulf is necessary for high quality and sustainable research. In this paper, the authors examine the role of CRN in improving Gulf countries’ performance in research and innovation. Four objectives have been set: investigate the current situation regarding scientific research and CRN in the Gulf countries, identify factors that influence the building of a CRN, identify the impact and contribution of CRN in improving the Gulf countries’ performance, and develop a model. To achieve these objectives, a quantitative method was adopted. A questionnaire was developed and distributed to 100 participants. The current paper presents the first stage of research that investigates the role of building CRN in improving the Gulf countries’ performance in research and innovation. The next stage will examine the model of building CRN.

The effects of roads and trails on terrestrial salamanders, primarily plethodontids, can be important. The abundance of terrestrial salamanders often increases with distance from roads. Less is known about the effects of recreational or hiking trails on terrestrial salamanders than is known about the effects of roads. We explored how low and high traffic trails in a suburban biological reserve affect the relative abundance of Eastern Red-backed Salamanders (Plethodon cinereus). We found more salamanders under cover objects next to low traffic trails compared to either high traffic trails or wooded areas without trails. At wooded sites, we found only striped morphs whereas at high traffic sites we found only unstriped morphs. Low traffic sites included a range of color morph frequencies. The proportion of females found in each site did not differ, nor did the mean size of the salamanders. Our results suggest that the impact of recreational walking trails needs to be examined more closely to see how and why the distributions of P. cinereus, and potentially other woodland salamanders, are affected and what trail characteristics are important in driving the apparent effects. Such information will contribute to the design and maintenance of walking trails in natural areas that minimize effects on terrestrial salamanders, and likely other organisms.

Roads through forest habitats reduce the abundance of many animal species. These reductions are often referred to as edge effects and their causes include roadkill, degradation of forest habitat, and changes in biotic interactions. Which of these causes are operating can have important implications for management. Terrestrial salamanders in the southern Appalachians have previously been shown to be subject to edge effects from forest roads that are open to traffic. In this study, I examined edge effects on red‐backed salamanders ( Plethodon cinereus ) along forest roads that were either open or gated to prevent vehicle entry. I also included roads that varied in the width of the gravel surface, the width of the roadside verge, and the magnitude of habitat gradients at the forest edge. I found that ungated roads were associated with consistent edge effects on salamanders, whereas no detectable edge effects were found for gated roads. Road width was as good a predictor of the magnitude of edge effects as was the presence of a gate, though the width of the roadside verge was largely unrelated to the magnitude of edge effects. Gradients in habitat variables (soil moisture, temp, leaf litter thickness) were not closely related to the magnitude of edge effects. These results demonstrate that narrow, gated roads do not typically produce edge effects on terrestrial salamanders of the same magnitude as wider, ungated roads. In addition, the apparent importance of road type or road width and the relative unimportance of habitat characteristics suggest that traffic‐related factors may be a substantial contributor to edge effects on terrestrial salamanders. These findings provide some support for the closing of redundant forest roads as a low‐cost method for diminishing the negative effects of roads on forest ecosystems.

Although thinning of young, even-aged forests may accelerate the development of characteristics associated with mature forests, in the short term it may negatively affect some taxa, including terrestrial salamanders. Preexisting site conditions, including down wood, and forest management measures, such as riparian buffers, may moderate these effects, but these relationships are poorly understood. To explore whether down wood and riparian buffer widths might influence short-term responses to thinning, we sampled salamanders using ground searches before and during the first 2 years after experimental thinning at two 45- to 65-year-old headwater forest sites in western Oregon that differed in down wood volume. Prethinning distributions of terrestrial salamanders overlapped one- and two-tree height riparian buffers, and except for red-backed salamanders, overlapped very little with narrower streamside or variable-width buffers. At the site where down wood volume was low, captures of ensatina (Ensatina eschscholtzii Gray) and western red-backed salamanders (Plethodon vehiculum Cooper) both declined by 40% in thinned areas. In contrast, captures of ensatina and Oregon slender salamanders (Batrachoseps wrighti Bishop) were not significantly affected by thinning at the site where down wood volume was high. Our results suggest that site conditions, such as down wood volume, and riparian buffers may influence the effect of thinning on terrestrial salamanders, and demonstrate the tight linkage among management of aquatic, riparian, and upslope resources in headwater forests.

Several recent studies have shown that amphibian populations may exhibit high genetic subdivision in areas with recent fragmentation and urban development. Less is known about the potential for genetic differentiation in continuous habitats. We studied genetic differentiation of red-backed salamanders (Plethodon cinereus) across a 2-km transect through continuous forest in Virginia, USA. Mark-recapture studies suggest very little dispersal for this species, whereas homing experiments and post-Pleistocene range expansion both suggest greater dispersal abilities. We used six microsatellite loci to examine genetic population structure and differentiation between eight subpopulations of red-backed salamanders at distances from 200 m to 2 km. We also used several methods to extrapolate dispersal frequencies and test for sex-biased dispersal. We found small, but detectable differentiation among populations, even at distances as small as 200 m. Differentiation was closely correlated with distance and both Mantel tests and assignment tests were consistent with an isolation-by-distance model for the population. Extrapolations of intergenerational variance in spatial position (sigma(2)<15 m(2)) and pair-wise dispersal frequencies (4 Nm < 25 for plots separated by 300 m) both suggest limited gene flow. Additionally, tests for sex-biased dispersal imply that dispersal frequency is similarly low for both sexes. We suggest that these low levels of gene flow and the infrequent dispersal observed in mark-recapture studies may be reconciled with homing ability and range expansion if dispersing animals rarely succeed in breeding in saturated habitats, if dispersal is flexible depending on the availability of habitat, or if dispersal frequency varies across the geographic range of red-backed salamanders.

In the terrestrial salamander (Plethodon cinereus), previous work has shown that mother's body size is positively correlated to offspring size at the time of hatching even after controlling for the effects of egg size. This study was designed to determine whether maternal body size affects offspring size via pre-oviposition factors (e.g., yolk quality, jelly coat composition, or maternal genes) or post-oviposition factors (e.g., parental care behaviors, parental modification of environment). Gravid females were captured and induced to lay eggs in experimental chambers in which the environment was standardized. Fifteen clutches were exchanged, or cross-fostered, between female pairs differing in body size. Ten females whose eggs were taken away and then returned served as controls for the crossing treatment. Foster mothers did not significantly differ from control mothers in the time spent with eggs, body position, or number of egg movements during brooding. Average egg mass measured midway through development was not significantly correlated to the body size of either the genetic or foster mother, but was correlated to pre-oviposition oocyte size. At hatching, offspring body length was positively correlated to egg size and the foster mother's body size. This correlation suggests that in P. cinereus post-oviposition maternal effects have a greater impact on offspring size than other maternal factors incorporated into the egg prior to oviposition. While our study showed that larger mothers moved their eggs less often and tended to spend more time in contact with their eggs, further work needs to be done to identify the specific mechanisms through which larger mothers influence the body size of their offspring. This is the first experimental demonstration of post-oviposition maternal effects for any amphibian with parental care.

The osmoregulatory response of the red-backed salamander, Plethodon cinereus, to acidic substrates was studied. In the laboratory, animals exposed to low pH exhibited elevated sodium eflux rate constants. The efflux rate constant was elevated in two other plethodontid species under acidic conditions but was not elevated in efts of the red-spotted newt. Red-backed salamanders maintained on substrate of low pH for 14 d had reduced body sodium and body water levels and lost more mass than did salamanders maintained on substrate of higher pH. These results are consistent with earlier studies that have linked field distributions of P. cinereus and other salamanders to soil pH. However, in the field, body sodium levels of red-backed salamanders were not correlated with soil pH of the collection microsite, suggesting greater complexity of field than of laboratory conditions. Disruption of sodium balance by acidic conditions is well documented for aquatic amphibians but has not been demonstrated previously for terrestrial forms.

BackgroundCollaborative research networks are often touted as a solution for enhancing the translation of knowledge, but questions remain about how to evaluate their impact on health service delivery. This pragmatic scoping study explored the enabling factors for developing and supporting a collaborative imaging network in a metropolitan university in Australia.MethodsAn advisory group was established to provide governance and to identify key informants and participants. Focus group discussions (n = 2) and semi-structured interviews (n = 22) were facilitated with representatives from a broad range of disciplines. In addition, a survey, a review of relevant websites (n = 15) and a broad review of the literature were undertaken to elicit information on collaborative research networks and perceived needs and factors that would support their involvement in a multi-disciplinary collaborative research network. Findings were de-identified and broad themes were identified.ResultsParticipants identified human factors as having priority for developing and sustaining a collaborative research network. In particular, leadership, a shared vision and a communication plan that includes social media were identified as crucial for sustaining an imaging network in health research. It is important to develop metrics that map relationships between network members and the role that communication tools can contribute to this process.ConclusionsThis study confirms that human factors remain significant across a range of collaborative endeavours. The use of focus group discussions, interviews, and literature and website reviews means we can now strongly recommend the primacy of human factors. More work is needed to identify how the network operates and what specific indicators or metrics help build the capacity of clinicians and scientists to participate in translational research.