Our data mostly support the environmental change hypothesis. The results of the previous models may be affected by imperfect detection. Humidity inside caves was strongly related to external humidity, month, depth and to the time of survey. (A)–(B): results of regression models analyzing all individuals encountered; (C)–(D) results of models analyzing adults only (E)–(F) results of models analyzing juveniles only. During surveys, for each cave we recorded monthly environmental data both inside and outside caves. Seasonal change led to thermal inversion inside caves: from late autumn to early spring temperature increased with depth, while from late spring to early autumn temperature decreased in the deep sectors (Fig. The interior of each cave was divided into sectors of 3-m length, starting from the entrance and extending to the deepest explored area: our exploration was conducted until the end of the caves, or until the deepest sector reachable without speleological equipment. At the time of surveys, in each sector we recorded four parameters known to influence cave salamanders. Nevertheless, habitat preferences and requirements may change across seasons, as in the case of juveniles that select microhabitats with slightly different conditions in different times (Figs. which salamanders exploit microhabitat refugia will facilitate. Salamanders have already attained the adult color pattern. They have a fairly slender build and a light-colored ridge running from the eye to the tip of the snout.Coloration varies from salmon to yellowish brown with hints of red, and quite often there is a mottled or cloudy appearance with small dark spots. Conversely, if adults only were analyzed, none of similarity tests were rejected (Table 5). GFF was funded by Labex OSUG@2020 (Investissements d’avenir—ANR10 LABX56). Multiple, non-exclusive explanations are possible for such selection change. The spring salamander (Gyrinophilus porphyriticus) is a species of salamander in the family Plethodontidae It is found in Canada and the United States. 2016, Ficetola et al. Gentile Francesco Ficetola conceived and designed the experiments, analyzed the data, contributed reagents/materials/analysis tools, wrote the paper, prepared figures and/or tables, reviewed drafts of the paper. All individuals were immediately released at the collection point. Note: You are now also subscribed to the subject areas of this publication The violin plots for temperature are available in. Microhabitat showed strong seasonal variation, with the highest variability in the superficial sectors. If you are following multiple publications then we will send you Pacific giant salamander larvae (Dicamptodon tenebrosus) inhabit headwater streams and are sensitive to heavy sedimentation and stream degradation. If salamanders always select the same optimal temperature (about 10–15 °C; Fig. This suggests a higher tolerance for dry sectors during winter, and supports the selection change hypothesis. Description: Spring salamanders are one of the largest stream salamanders in our region (5 - 7.5 in; 12 - 19 cm). Furthermore, all cave abiotic features (temperature, humidity and light) followed the variation of external conditions, which indeed were the major cause of fluctuations of internal microhabitats. microhabitat around a breeding site is also likely to influence the distribution of individual salamanders . If possible, salamanders were measured. The model assuming constant detection probability across sectors showed a lower AIC value (AIC: 53.3) than the model assuming that detection probability is related to distance from the entrance (AIC: 53.9). As lungless salamanders exchange gasses mainly through their skin, and the efficiency of this skin function increases with high level of moisture (Spotila, 1972), during the cold season the individuals could be more tolerant to low humidity because of their lower respiration needs. The trade-offs between tolerance and resources requirement are major determinant of such variation. Not detecting a species during a survey does not necessarily mean that species is absent, as most species have detection probability <1 (MacKenzie et al., 2006). Specifically, in winter periods salamanders were associated with warmest sectors, while in summer periods they were associated with coldest and most humid sectors (Figs. In subterranean environments microclimatic features are often considered to remain approximately stable, giving organisms the opportunity to inhabit caves constantly. The peculiar physiology of plethodontids forces these salamanders to live within very narrow typologies of habitat. We used the MacKenzie & Kendall (2002) approach to test detection probability of cave salamanders, on the basis of data collected in 22 sectors from three different caves. Results were nearly identical in the analysis of adults-only (Table S1B; Figs. There also may be a dark line above the white line, often conspicuous. First, we used generalized linear mixed models (GLMM) assuming binomial error to identify the relationships between the presence of salamanders and environmental features (air temperature, humidity, illuminance and spider abundance) of each sector, throughout the 12 months of sampling. Salamanders were detected throughout the year with 13% of detections in winter, 39% in spring, 30% in summer and 18% in autumn months. Both selection changes and environmental changes may influence the possibility of predicting species distribution in different time periods. Study species.—Gyrinophilus porphyriticus is in the What do calves choose to eat and how do preferences affect behaviour? Individuals often require different resources depending on their life stage, and thus must shift their habitat selection to exploit different environments to satisfy their needs (Cox & Cresswell, 2014; Dittmar et al., 2014; Webb et al., 2014). These sectors represent the area in which microclimate variability is higher; at 21 m illuminance was constantly 0 lux. thank you in advance for your patience and understanding. Surface density was not correlated with amount of rainfall, but microhabitat choice was so correlated: the percentage of salamanders under rocks and logs increased and the percentage in the leaf litter decreased with decreasing rainfall. The microhabitat selection pattern was similar if adults only were considered. For these sectors, two surveys were performed 9–14 days apart, therefore we assumed constant occupancy in this interval and estimated detection probability using single-season closed population occupancy models with the unmarked package in R (Fiske & Chandler, 2011). 2). Standard approaches to the analysis of detection probability assume that sites are closed to changes in the state of occupancy for the duration of sampling (MacKenzie et al., 2006). We then used AIC to identify the best detection probability model. We considered as dependent variable the presence of (A) the species, (B) presence of Adults and (C) presence of Juveniles. The model assuming constant detection probability across sectors showed a lower AIC value (AIC: 53.3) than the model assuming that detection probability is related to distance from the entrance (AIC: 53.9). 2D). Salamanders select the microhabitats with abiotic conditions (e.g. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. 2). Internal light incidence was related to depth and external humidity (Tables 1C and 2C). Common use cases Among amphibians, plethodontid salamanders represent a very interesting study case. Breeding occurs from late fall through early spring. We merged data from two-months periods respectively into winter (January–February) and summer (June–July), and repeated the analyses using the same variables of the best-AICc models obtained from the analyses of full dataset. salamanders, this study also has opportunity to contribute to the understanding of Van Dyke’s salamander, ... Amphibian Microhabitat Study (SAMS) and their Riparian Ecosystem Management Study (REMS). Furthermore, the negative consequences of low humidity may be stronger in summer. Juveniles were associated with the coldest sectors during winter and with warmer sectors during spring (Fig. We also included the time of survey (hour and minute in which we began the survey) as an additional independent variable. On the one hand, Meta spiders are major predators of juvenile salamanders (Lanza et al., 2006). The Shenandoah Salamander is only found on high elevation peaks within the Shenandoah National Park. The cool habitats that the salamander requires are only at these higher elevations. The SAMS study program is an attempt to characterize microhabitats of ... spring season of 2003. Seasonal variation in microhabitat of salamanders: environmental variation or shift of habitat selection? and will receive updates in the daily or weekly email digests if turned on. However, in the analyses of humidity considering all individuals and juveniles only, niche equivalency was significantly lower than expected by chance between February and June, and between February and July. To assess the robustness of habitat models to imperfect detection, we also repeated the GLMM analysis by comparing two contrasting periods seasons: January–February and June–July. The study was conducted under authorization of Apuan Alps Regional Park (no 5, 4/04/2013), District of Prato (no 448, 2013), District of Pistoia (no 0022597/2013/P) and District of Lucca (no 731, 21/02/2013). Furthermore, species are easily detectable inside the delimited cave environments (Ficetola, Pennati & Manenti, 2012), allowing a reliable identification of occupied and unoccupied sectors. We used niche equivalency tests to assess whether salamanders select sectors with similar environmental features in different months, after taking into account differences for the availability of microhabitat conditions (Broennimann et al., 2012). The subspecies G. p. danielsi and G. p. dunni can be 5–7.5 in (13–19 cm). The following information was supplied regarding the deposition of related data: Raw data can be found in the Supplemental Information. NewScientist.com: Salamanders formed new species despite interbreeding, https://en.wikipedia.org/w/index.php?title=Spring_salamander&oldid=921556000, Creative Commons Attribution-ShareAlike License, This page was last edited on 16 October 2019, at 12:29. PeerJ promises to address all issues as quickly and professionally as possible. Cave depth represented the major gradient along with microhabitat features varied: as expected, humidity always increased and light decreased in the deepest sectors. Parameters related to presence/absence of salamanders. For each independent variable, we report the first five best models. The following information was supplied relating to field study approvals (i.e., approving body and any reference numbers): Apuan Alps Regional Park (no 5, 4/04/2013). The Shenandoah Salamander is generally found within moist microhabitats in otherwise dry talus areas on the very tops of Shenandoah's mountains . Hatching occurs four to six weeks later. 1A). How should detection probability be incorporated into estimates of relative abundance? Adults were associated with relatively cold sectors during summer, while in winter they were associated with warmer sectors (Fig. Existing studies indicate that multiple physical habitat characteristics can affect the abundance and distribution of larval stream salamanders. The peculiar features of both caves and plethodontid salamanders make them an excellent system for species-habitat association studies. In principle, it might be also possible that in certain periods juveniles are forced to move toward suboptimal areas because of competition with adults. They are known to rub heads as part of courtship behavior. Such fluctuations mostly affect areas near the entrance of caves (twilight zone) and can strongly influence cave communities (Ficetola, Pennati & Manenti, 2013; Camp et al., 2014; Lunghi, Manenti & Ficetola, 2014). Since six pairwise tests were performed for each group and for each variable, significance values were corrected using sequential Bonferroni’s correction (Rice, 1989). The white line from eye to nostril, bordered below by a conspicuous black or dark brown line, is distinctive. Occupancy changed with the annual life cycle and was higher in autumn than in spring, when females were found closer to the stream in the study area. Our study explores the complexity of habitat use patterns under variable conditions, and highlights difficulties in determining habitat selection processes. Occupancy changed with the annual life cycle and was higher in autumn than in spring, when females were found closer to the stream in the study area. This suggests that tolerance for suboptimal abiotic conditions may change through time, depending on the required resources. Season strongly affected the presence of salamanders; furthermore, we detected a significant interaction between temperature and season; the interaction between humidity and season was marginally not significant (Table S1A). Model selection and model averaging in behavioural ecology: the utility of the IT-AIC framework, Macroevolutionary consequences of profound climate change on niche evolution in marine molluscs over the past three million years, Movement and microhabitat use of a terrestrial amphibian (, Optimising biodiversity assessments by volunteers: the application of occupancy modelling to large-scale amphibian surveys, Niches and distributional areas: concepts, methods, and assumptions, Role of temperature and water in the ecology of lungless salamanders, Environmental heterogeneity as a universal driver of species richness across taxa, biomes and spatial scales, A call for statistical pluralism answered, Using ecological niche modelling to evaluate niche stability in deep time. Effects of food restriction across stages of juvenile and early adult development on body weight, survival and adult life history, Predicting to new environments: tools for visualizing model behaviour and impacts on mapped distributions. In these rainy nights of early spring, salamanders migrate to ponds to breed. The equivalency test was repeated for the two environmental variables (temperature and humidity) for which habitat models suggested differences among months. Such heterogeneity in habitat selection may occur both because individuals select different conditions during different times or life stage (selection change hypothesis) or because of the strong variability of available microhabitat conditions (environmental change hypothesis). ext (external temperature), Hum. Its skin is orange/red with random black spots. Seasonal variation also occurs for the distribution of cave spiders but was not analyzed here as it will be the focus of a separate study. No doubt, the strong seasonal variation of salamander distribution was mostly dictated by the fluctuations of microhabitats. Differences in habitat use are jointly determined by environmental variation through time, and by changes in the preferred habitat. Best AIC models explaining the variation in microhabitat features of caves. Unmarked: an R package for fitting hierarchical models of wildlife occurrence and abundance, An R and S-PLUS companion to applied regression, Thermal regulation and habitat use of the eastern box turtle in southwestern Virginia, I can’t define the niche but I know it when I see it: a formal link between statistical theory and the ecological niche, Predicting species distribution: offering more than simple habitat models, Evaluation of terrestrial and streamside salamander monitoring techniques at Shenandoh National Park, Mechanistic niche modelling: combining physiological and spatial data to predict species ranges, Balancing heat, water and nutrients under environmental change: a thermodynamic niche framework, A review of systematics, taxonomy, genetics, biogeography and natural history of the genus. Counts of E. naufragia on the surface were made monthly or bimonthly at Swinbank Spring near Georgetown, Williamson County, Texas, over a period of 1 year. First, the temperature gradient showed a clear inversion through the seasons (Fig. Therefore, in the following winter, acquiring energy is a major priority for juveniles. salamanders. The analysis was performed on all individuals together and for each age category (juveniles only and adults only). Such models are based on the assumptions that species presence is associated with favorable environmental features (species-habitat association) (Godsoe, 2010). The order of cave survey was chosen randomly, and the time interval between successive visits was 9–45 days. We used as independent variables: Month of survey, Time in which the survey began, Depth of sector, External Temperature, External Humidity and interaction between Month and Depth (Prof : M). Scarce access to food resources during juvenile stages poses major constraints on development, and may have prolonged consequences and even impact lifetime fitness (Wong & Kölliker, 2014). Habitat/Range: Spring salamanders may be found in and around headwater streams, caves, springs, and seepages. We used the Akaike’s Information Criterion corrected for small sample size (AICc) to identify the combination of parameters that better explain the variation of microclimatic features inside caves (Stephens et al., 2007). In each graph, colored plots represent sectors located at different distance from the entrance (from 3 to 21 m). For temperature and humidity, the trend of the respective external feature is also shown, represented by a continuous red line. However, patterns of species-habitat association may be not consistent during time. The similarity of the habitat selection pattern in two distinct seasons was assessed using Schoener’s D, a metric of niche similarity (Warren, Glor & Turelli, 2008; Saupe et al., 2014). Body Evaluating whether habitat association pattern changes through time, and the factors determining such variation, is extremely important to assess the transferability and generality of conclusions drawn from habitat modeling. We built all possible model combinations, and ranked them using AICc. Internal variables are (A) temperature, (B) humidity and (C) illuminance (lux). Parameters related to microclimatic change of caves through the year: best-AICc models. S1A and S1B). Spatial and temporal variability in microhabitat use greatly inﬂuence individual detectability, which is always a challenge for terrestrial salamanders. Inferring patterns and dynamics of species occurrence, The distribution of cave twilight-zone spiders depends on microclimatic features and trophic supply, Predicting the past distribution of species climatic niches, Ecological niches and geographic distributions. We quantified seasonal patterns of microhabitat use by larval southern two-lined salamanders (Eurycea cirrigera) and microhabitat availability in two Georgia Piedmont streams from April 2000 to April 2001. Research Article Prescribed Fire and Timber Harvest Effects on Terrestrial Salamander Abundance, Detectability, and Microhabitat Use KATHERINE M. O’DONNELL,1,2 Division of Biological Sciences, University of Missouri, 105 Tucker Hall, Columbia, MO 65211, USA FRANK R. THOMPSON III, Northern Research Station, U.S.D.A. Most Cope's giant salamanders become sexually mature in the larval stage. For both categorical variables and interactions, + indicates their presence into the model. 2A and 2B). If all individuals were pooled, salamanders were associated with the darkest sectors. Actually, most of equivalency tests were not significantly different from random expectations, indicating that the species consistently selected the same microhabitat. In spring 2007, we initiated a low-impact ecological study of E. naufragia with the goal of better understanding the ecology of salamanders within flows of surface springs. We used as independent variables: internal humidity (Humid), Month of survey, illuminance (Lux), The dependent variables were the presence of (A) Species, (B) Adults only and (C) Juveniles only. Females lay 60 to 110 eggs on the undersides of rocks in water and leave after laying. For 12 months (from January 2013 to December 2013) we monitored 15 caves occupied by Hydromantes italicus in the North of Tuscan Apennines (Central Italy, between 43°52′42″N, 11°07′18″E and 43°59′51″N, 10°13′48″E). Cave and sector identity were considered as random categorical variables, as they shows a typical combination of variables (both biotic and abiotic) independently from their position and location. In principle, only sampling the whole spectrum of potential habitat conditions may allow a full reconstruction of habitat preferences, but this is not feasible in the real world, because the available environmental gradients generally cover a limited range of conditions (Soberon & Nakamura, 2009; Elith, Kearney & Phillips, 2010). Second, we assessed whether the temporal variation in microhabitat occurs because the species selects different environmental features through the year, or because habitat features are affected by seasonal variation (i.e., we evaluated the support of the environmental changes vs. selection change hypotheses). See, The area of violin plots represents the distribution of cave sectors according to microclimate feature. Immobility times for Shenandoah Salamanders averaged 5.9 s (range 1–36 s) and were significantly lower from times for seven other species of eastern Plethodon. We used a likelihood ratio test to assess the significance of terms in the best-AICc model. First, we used habitat models to identify the relationships between the distribution of salamanders and microhabitat features, evaluating if the pattern of microhabitat association is constant through time. Approaches assuming open populations also exist but, in this study case, their implementation would require assumptions on population dynamics for which no data were available (Dail & Madsen, 2011). nymphs also were important predictors of salamander microhabitats. The abundance of Meta menardi spiders was considered as a biotic variable. In a good salamander year, hundreds of these critters will be in the edges of ponds, seemingly dancing in the water. Although many studies have shown negative effects of anthropogenic disturbances on woodland salamanders, such as timber harvest and tree canopy removal, (Petranka et al., 1993; Ash and Bruce, … The light line from eye to nostril is bordered below by gray pigment, but the markings are not always conspicuous. predictions regarding potential changes to species distribu-tion or ecology. Dodd (1989) determined the length of time salamanders remained immobile when disturbed in the field by close approach, through disturbance of nearby microhabitat, or when touched. Presence of H. italicus was strongly related to month, and was generally associated with sectors characterized by high humidity, low light and abundant M. menardi spiders (Tables 3A and 4A). You can add specific subject areas through your profile settings. 2E and 2F). Such models help understanding the factors determining species occurrence, and may allow predicting potential areas of occupancy, with important consequences for planning adequate conservation actions (Domíguez-Vega et al., 2012; Bogaerts et al., 2013). Actually, in our study caves, the potential prey richness (calculated as the summed N of species of Araneae (excluding M. menardi) and Diptera, as these taxa are the major food items for cave salamanders (Vignoli, Caldera & Bologna, 2006; Crovetto, Romano & Salvidio, 2012)) quickly decreases with depth (generalized linear model with Poisson error, taking into account month of survey: B ± SE = − 0.024 ± 0.006, χ12=201.3, P < 0.0001). However, incident light increased in summer and during periods characterized by low humidity (Fig. The nominate subspecies, G. p. porphyriticus, occupies the remainder of the geographical range of this species. However, such “ideal” conditions are rarely available in the real world, and species have to deal with environmental variability, which causes frequent changes of habitat conditions and resources availability (Seebacher & Alford, 1999; Araújo et al., 2010; Fredericksen, 2014). Most of equivalency tests were not significant, suggesting that habitat selection pattern was consistent through months (Table 5). Some studies have shown that cave salamanders are associated with caves having specific environmental features, such as low temperature, high humidity and presence of prey (Ficetola, Pennati & Manenti, 2012; Lunghi, Manenti & Ficetola, 2014), but these studies have been often performed during summer, when outdoor conditions are particularly unsuitable for salamanders, and abundance in cave is highest. While this influence was strongest in the first meters of the caves, it remained clearly detectable at depths >20 m (Fig. Surveys were conducted during day-time. Furthermore, the significant interaction between month and depth indicated that the humidity gradient was not constant through the year (Tables 1B and 2B). Nevertheless, the few studies analyzing the seasonal variation in the distribution of European cave salamanders (Salvidio et al., 1994; Vignoli, Caldera & Bologna, 2008) did not test whether habitat selection changes through time. 2F). In laboratory trials, salamanders used lower quality microhabitat and consumed fewer flies in the presence of earthworms. The spring salamander (Gyrinophilus porphyriticus) is a species of salamander in the family Plethodontidae It is found in Canada and the United States. Spring salamanders also have a line that extends from each eye to the tip of the snout. S2), they can only find such conditions in the deepest sectors of caves, in which temperature is relatively warm during winter, and coolest during summer. Understanding patterns of woodland salamander microhabitat use is important for predicting their response to natural and anthropogenic disturbances such as land use and climate change. The generic name, Gyrinophilus, means "tadpole lover" and refers to the long period of time it spends as a gilled larva before maturing. G. p. dunni is distributed through the southern portion of the Blue Ridge Province and the Piedmont from southwest North Carolina to eastern to central Alabama. Most of variation in species-habitat relationships was likely caused by the seasonal variation of temperature and humidity. Cave salamanders (genus Hydromantes) may live both in surface and subterranean environments, but must move underground during the arid and hot Mediterranean summer, when the surface conditions become hot and dry (Lanza et al., 2006; Ficetola, Pennati & Manenti, 2012). Salamanders were associated to relatively cold and humid sectors in summer, but not during winter. We assessed the pattern and role of niche variation along a hybrid zone, by investigating differences in microhabitat selection between terrestrial cave salamander species (Hydromantes Relationships between species and their habitats are not always constant. Complex models with AICc values higher than the simpler, nested models were not considered as candidate models (Richards, Whittingham & Stephens, 2011). Furthermore, significant interactions between month and temperature and between month and humidity indicated different microhabitat selection patterns among months (Table 4A). Through the 180 cave surveys, we obtained 1,087 detections of cave salamanders (289 adult males, 393 adult females, 49 not sexed adults and 356 juveniles). For equivalency tests, salamander occurrences from different months were pooled and then randomly split in two datasets, maintaining the same number of occurrences of the original datasets; Schoener’s D was then calculated. Spring Salamanders can also be found under stones and logs near stream edges (Wild Portraits, 2000). The observation of H. italicus was strongly related to time of survey. Correlative models combine data on species occurrence (e.g., presence/absence, presence-only, abundance) with information on environmental features, identifying statistical relationships which represent the basis for model predictions (Guisan & Thuiller, 2005). The subspecies G. p. porphyriticus and G. p. duryi can be 4.75–7.5 in (12.1–19.1 cm) long. Reproduction in long-tailed salamanders is not well documented. Therefore, in certain months, young salamanders exploit superficial sectors with more stressful abiotic conditions, but they receive enough food input from the outdoor environment to offset the risk. Cave environments are dominated by few, simple environmental gradients, such as light, depth, temperature, humidity and food availability (Romero, 2009), affording simplistic habitat characterization. I looked at levels of sedimentation within and between plots in a headwater stream, and salamander use of substrate types to determine if they were selecting against sediment. In summer, adults were associated with the most humid sectors; however, they showed a clear preference for the most humid sectors also in February (Fig. Forest Service, 202 Natural Resources Building, Columbia, MO 65211, USA The analysis of detection probability was repeated twice: assuming constant detection across sectors, and assuming that detection probability is related to distance from cave entrance. G. p. duryi is present in southern Ohio, eastern Kentucky, West Virginia, and western Virginia. days during spring and summer, even during seven-day periods without rain. The distribution range of G. p. danielsi is the southern Appalachian Mountains and the adjacent Piedmont from North Carolina to Alabama. In addition to insects, worms, and other small invertebrates, the fairly large spring salamander may also consume smaller stream dwelling salamanders such as two-lined and dusky salamanders. monticola), and spring salamanders (Gyrinophilus p. porphyriticus). Do cave features affect underground habitat exploitation by non-troglobite species? Detection probability of salamanders within sectors was high (detection probability ± SE: 0.75 ± 0.12). This indicates that juveniles may trade-off microclimatic optima for food availability (Vlachos et al., 2014). We flagged trees every 5 m along the stream for accurate estimation of salamander capture locations. Analyses (see results) showed a per-visit detection probability of 0.75, i.e., two surveys allow to ascertain presence/absences with 94% confidence (Sewell, Beebee & Griffiths, 2010). These caves were surveyed in late June-early July: during this interval, Hydromantes movements among sectors are expected to be limited (Lanza et al., 2006). We The dorsal coloration can be clear reddish, salmon, or orange-yellow marked with black or brown spots or flecks. Furthermore, Meta spiders are associated with areas showing high invertebrate abundance, and have been proposed as an indicator of prey abundance in cave environments (Manenti, Lunghi & Ficetola, in press). Habitat selection studies are often based on data collected over temporal snapshots. An analysis with. ing of niche evolution, but information on microhabitat differences between paren‐ tal species and hybrids is extremely scarce for animal populations. The spotted salamander (Ambystoma maculatum) is a large (adults are, on average, 6 to 7 inches long with some individuals reaching 9 inches), distinctively colored (dark gray or blue-black on its back with two, full body length rows of round, orange or yellow spots) salamander found on our Nature Trail. no more than one email per day or week based on your preferences. For each continuous variable, the regression coefficient is reported if the variable is included into a given model. Furthermore, differences among months were strong, and the interactions between month and both humidity and temperature were significant. Are niche-based species distribution models transferable in space? Independent variables were: Month of survey, Depth of sector, Temp. Efficient exploitation of seasonal peaks of food resources may be a key of fast development during the first years. The ground color has a cloudy appearance, and the darker markings are vague. based on availability of microhabitat conditions (Smith & Grossman, 2003) or a ... For example, larger Gryonophilus porphyriticus (spring salamander) salamanders have greater predatory influence on Eurycea cirrigera (southern two-lined salamander) (Gustafson, 1994). We focused on univariate rather than multivariate tests because we were interested on variation of habitat selection due to change of specific variables (Saupe et al., 2014). The aim of our study was to assess whether cave salamanders change their habitat association pattern through the year, and to test whether such changes are determined by environmental changes or by changes in preferences. However, this explanation is unlikely: previous studies explicitly testing this hypotheses have found evidence that juveniles are not displaced by adults (Ficetola, Pennati & Manenti, 2013), while behavioral analyses suggested lack of competition for territories (Berti & Corti, 2010). Corresponding Author. Maintenance of subsurface microhabitats and microclimates are essential to their survival because they have a very limited period of surface activity in the spring and fall when We used visual encounter surveys to assess the presence/absence of H. italicus and M. menardi spiders in each sector. We thank two reviewers for constructive comments on a previous version of this manuscript. Air temperature, humidity and incident light (illuminance, measured using a Velleman DVM1300 light meter, minimum recordable light: 0.1 lux) represented the abiotic conditions of caves, which influence metabolism, water balance and activity (Kearney et al., 2013). Its distribution ranges from southern Quebec to northern Alabama and extremely northeast Mississippi. Outside caves, we registered air temperature (accuracy: 0.1 °C) and humidity (accuracy: 0.1%) using a thermo-hygrometer Lafayette TDP92, in a shaded area 5–10 m from the entrance. However, under certain circumstances, individuals may select conditions that are closer to their physiological limits (Kearney et al., 2013). Preliminary surveys performed in 2012 indicated the presence of H. italicus at all sites. Salamanders were most com- monly found in shallow (<10 mm), slowly moving (usually <10 cm/s) water with medium-sized rocks (65-256 mm diameter), moderate degrees of embeddedness (about 50%), … Internal temperature was strongly related to external temperature and humidity, month, depth and interaction between month and depth: all variables except depth were significant (Tables 1A and 2A). As observed in other studies (Ficetola, Pennati & Manenti, 2012; Lunghi, Manenti & Ficetola, 2014), salamanders were strongly associated with sectors characterized by specific microhabitat features, such as high humidity, low light and abundant spiders. We considered as dependent variables inner abiotic features of caves: (A) Temperature, (B) Humidity and (C) Illuminance. From late winter until spring, juveniles were associated with sectors characterized by lower humidity, while during summer this apparent preference shifted in favor of most humid sectors (Fig. You can also choose to receive updates via daily or weekly email digests. In the long term, temporal variation for habitat association in a given species may also occur due to evolution of novel adaptations (Nogués-Bravo, 2009; Stigall, 2012). Description: A small, slender salamander (2.5 to 4.0 inches in length) with two color morphs, striped and lead-backed. 1B). Adults were associated with the wettest microclimates, while juveniles were present in apparently more stressful sectors as they were also present in sectors with lower humidity and less suitable temperatures. This analysis was performed on four months (January, February, June and July) showing contrasting patterns of habitat association (see results), and during which we do not expect major movements among cave sectors (i.e., within these intervals the quasi-equilibrium assumption is more likely to be hold than when seasonal migrations occur). The record length is 8.06 in (20.5 cm). S1E and S1F). In practice, selection of the same habitat resulted in regression coefficients that were remarkably different among seasons (Fig. The most superficial cave sectors are the ones with driest microclimate (Table 2), but show the highest abundance of prey. They use cutaneous respiration, and for that reason, must live in moist habitats (Petranka 1998). Universität Trier Fachbereich VI Raum- und Umweltwissenschaften Biogeographie, Campus I, Gebäude N Universitätsring, Museo di Storia Naturale dell’Università di Firenze, Sezione di Zoologia “La Specola,”, Dipartimento di Bioscienze, Università degli Studi di Milano, Dipartimento di Scienze dell’Ambiente e del Territorio e di Scienze della Terra, Università degli Studi di Milano-Bicocca, Laboratoire d’Ecologie Alpine (LECA), Université Grenoble-Alpes, This is an open access article distributed under the terms of the. According to the environmental change hypothesis, temporal variation that exists for the many biotic and abiotic features can affect species distribution (Kearney et al., 2013). Dodd (1989) determined the length of time salamanders remained immobile when disturbed in the field by close approach, through disturbance of nearby microhabitat, or when touched. Underground environments suffer constant food scarcity (Romero, 2009), but juveniles require consistent food supply in order to grow and reach maturity. Sector and cave identity were included as random categorical factors. Similar to other giant salamander species, most activity is probably nocturnal and much time is spent in subterranean microhabitats. 1A). 2018, 2019). However, seasonality is a pervasive feature of natural environments, highlighting the importance to always take into account the potential seasonal variation and considering the interactions between the requirement of individuals and the variability of habitats. We categorized a salamander as moving away from a good microhabitat if it was migrating out of upland forest, whereas a salamander migrating out of the old field (poor canopy cover) or out of the red maple swamp (poorly drained soil) was considered to be moving from a poor microhabitat (Downs, 1989; Windmiller, 1996). spring salamanders. Cave salamanders are able to exploit the whole cave; therefore, if salamanders just require optimal abiotic conditions they can remain in farthest sectors where suitable microclimate is more stable. Results for December were not reported due to small sample size. Actually, the end of winter may be a particularly important period, as in this period many invertebrates end their winter latency (Bale & Hayward, 2010). Raoul Manenti conceived and designed the experiments, contributed reagents/materials/analysis tools, wrote the paper, reviewed drafts of the paper. Enrico Lunghi conceived and designed the experiments, performed the experiments, analyzed the data, contributed reagents/materials/analysis tools, wrote the paper, prepared figures and/or tables, reviewed drafts of the paper. Placing a log upside down can destroy the microhabitat found below. This standardized technique allows to verify the presence of species in an area during a defined time (Crump & Scott Jr, 1994; Jung et al., 2000). These updates will appear in your home dashboard each time you visit PeerJ. This procedure was repeated 300 times to assess whether niche similarity was significantly lower than expected by chance. In LMM, we considered cave features (temperature, humidity, illuminance) as dependent factors, while outdoor features (temperature and humidity), linear distance from the cave entrance (hereafter, depth) and month of survey were considered as independent factors. Like all members of the family Plethodontidae these salamanders have a nasolabial groove. Katherine M. O'Donnell. The deepest sectors always showed lower light than the superficial ones. External humidity was particularly high in autumn and spring, determining an increase of humidity in the first sector of caves (Fig. There is also an isolated colony in Hamilton County, Ohio. Our approach provides fine-grained parameters of microhabitat suitability and elucidates many aspects of the salamander's terrestrial ecology. Juvenile Blue-spotted and Jefferson salamanders have light-blue flecking that might be mistaken for the silvery-gray flecking of juvenile Marbled Salamanders, In the analysis of juveniles, only the interaction between season and temperature remained significant (Table S1C, Figs. For instance, many species show seasonal activities, and select different environments depending on the activities performed (e.g., nesting, foraging, wintering) (Seebacher & Alford, 1999; Brambilla & Saporetti, 2014). Individuals showed differences in their response to abiotic features, which resulted in a different distribution of salamanders inside caves (Ficetola, Pennati & Manenti, 2013). During our surveys, detection probability of Hydromantes italicus was high, allowing us to obtain many observations, which are a necessary prerequisite for any habitat association study. The red salamander (Pseudotriton ruber) is a species of salamander in the family Plethodontidae endemic to the eastern United States. The average size at maturity is 2.6 to 3 inches snout to vent length. Caves are often described as stable environments (Romero, 2012), but their features and the distribution of their inhabitants shows strong fluctuations through the year, particularly in the superficial sectors. TypoMissing or incorrect metadataQuality: PDF, figure, table, or data qualityDownload issuesAbusive behaviorResearch misconductOther issue not listed above. For all models, Variance Inflation Factor was <5, confirming lack of collinearity issues (Fox, 2002). 2C). We also considered the interaction between depth and month of survey. 3). Salamanders showing total length >6.5cm or with male secondary characters were considered adults (Lanza et al., 2006), the remaining salamanders were considered juveniles. Such apparent shift in habitat preferences mostly occurred because the environmental gradient changed through the year, while individuals generally selected similar conditions. As detection probability was imperfect, we repeated the analysis by focusing on the comparison between two contrasting seasons (winter/summer), in which migration of salamanders is probably limited. In cohabitation trials, we predicted earthworms would exclude salamanders from high quality microhabitat (beneath artificial COs), resulting in salamanders using high quality microhabitat less frequently when paired with an earthworm than when alone. The following information was supplied relating to ethical approvals (i.e., approving body and any reference numbers): University of Florence approved the project by regular department’s application and we followed our institutional guidelines. , Its natural habitats are temperate forests, rivers, swamps, freshwater marshes, freshwater springs, inland karsts, and caves. Juveniles were more frequent in sectors with high humidity and abundant M. menardi spiders; furthermore the effect of month, and the interactions humidity-month and temperature-month were significant (Tables 3C and 4C). In a natural field experiment, conducted on salamander populations from “non-invaded” and “pheretimoid invaded” sites in Ohio, salamanders and earthworms shared cover objects ~60% less than expected. The aim of this study was analyzing the variation through time of species-habitat association in the Italian cave salamander (Hydromantes italicus). 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