Stephanie S. Haan

Bio: Stephanie S. Haan is an academic researcher from New Mexico State University. The author has contributed to research in topics: Species distribution & Endangered species. The author has an hindex of 1, co-authored 1 publications receiving 11 citations.

Influence of Habitat Characteristics on Detected Site Occupancy of the New Mexico Endemic Sacramento Mountains Salamander, Aneides Hardii

Abstract: The Sacramento Mountains Salamander (Aneides hardii) is a state-listed threatened species endemic to three mountain ranges in south-central New Mexico. Information about the ecological requirements of this species is inadequate for managers to make informed conservation decisions, yet changes in management practices are needed throughout the species range because of poor forest health. During summer 2004, we examined patterns of A. hardii distribution in relation to several abiotic and biotic parameters on 36 plots, each of which was 9.6-ha in area and located in mixed conifer forest. We evaluated 18 a priori logistic regression models using Akaike's Information Criterion corrected for small-sample bias (AICc). The model with the highest ranking (lowest AICc value) included soil moisture and soil temperature, and the second highest ranked model (DAICc 5 0.05) included only soil temperature. Soil temperature was lower, and soil moisture was higher on plots where salamanders were detected. The relative importance of canopy cover and log volume was low in this study likely because the study plots, all of which had sufficient canopy cover and log volume, had similar disturbance history. We recommend managers focus on practices that ensure salamander microhabitats remain cool and moist in conservation areas. Resource managers are challenged with bal- ancing human interests and the conservation of threatened and endangered species. This is a current issue in the western United States because of the need to manage forests for catastrophic fire prevention while considering the response of sensitive forest species to silvicultural practices. Fire suppression has

Persistence with Chytridiomycosis Does Not Assure Survival of Direct-developing Frogs

Abstract: The chytrid fungus, Batrachochytrium dendrobatidis (Bd) has been linked to extinction and decline of numerous amphibians. We studied the population-level effects of Bd in two post-decline anuran species, Eleutherodactylus coqui and E. portoricensis, at El Yunque National Forest, Puerto Rico. Data on amphibian abundance was updated to report long-term population trends. Mark–recapture data was used to monitor Bd-infection status and estimate survival probabilities of infected versus uninfected adults. Prevalence of Bd (number of infected/total sampled) and individual infection level (number of zoospores) were compared among age classes at Palo Colorado Forest (661 m) and Elfin Forest (850 m). Results revealed that both species continued to decrease in Palo Colorado Forest, while in the Elfin Forest, E. portoricensis recuperated from drastic declines. Age class, season, and locality significantly predicted zoospore load. Age was also significantly associated with high zoospores loads among Bd-positive frogs, and the prevalence of Bd was higher in juveniles than adults in all populations studied. We suggest that early age represents a critical life stage in the survival of direct-developing frogs infected by this fungus. Survival probability was always higher for uninfected frogs, but recapture rates of infected versus uninfected adults were significantly different only in Palo Colorado, alerting that the negative effect of Bd infection under enzootic conditions is greater at mid-elevations. This work contributes to our understanding of how direct-developing amphibians persist with Bd, pointing to critical life stages and synergistic interactions that may induce fluctuations and/or declines in the wild.

Site-level habitat models for the endemic, threatened Cheat Mountain salamander (Plethodon nettingi): the importance of geophysical and biotic attributes for predicting occurrence

Abstract: The federally threatened Cheat Mountain salamander (Plethodon nettingi; hereafter CMS) is known to occur in approximately 70 small, scattered populations in the Allegheny Mountains of eastern West Virginia, USA. Current conservation and management efforts on federal, state, and private lands involving CMS largely rely on small scale, largely descriptive studies of habitat associations from a few sample sites. To address the critical need for quantitative data, we used an information-theoretic approach to elucidate site-level habitat relationships of CMS relative to a suite of biotic and abiotic habitat variables measured across the species’ range. We collected data on 18 explanatory habitat variables at CMS-occupied (n = 67) and random (n = 37) sites in the summer of 2006 and examined CMS habitat relationships using a priori, logistic regression models with information-theoretic model selection. Overall, results indicated that the probability of CMS occurrence at a fine spatial scale increased in areas with shallower depth to rock, areas proximal to rocky outcrops but distal to seeps, areas with higher densities of bryophytes, and areas with high densities of red spruce (Picea rubens) and eastern hemlock (Tsuga canadensis). Within the Allegheny Mountains, associations between CMS and abiotic habitat features appear to be important predictors of site-level occurrence, although vegetation associations interact to form more precise habitat relationships within forested landscapes. The information gained from our study should increase the capacity of managers to plan for the continued persistence and conservation of Cheat Mountain salamanders in this landscape.

Macrohabitat models of occurrence for the threatened Cheat Mountain salamander, Plethodon nettingi

Abstract: The federally threatened Cheat Mountain salamander (Plethodon nettingi; hereafter CMS) is known to occur at approximately 70 small, scattered sites in the Allegheny Mountains of eastern West Virginia. We used a comparative modeling approach to explain the landscape-level distribution and habitat relationships of CMS in relation to a suite of biotic and abiotic habitat variables measured across the species' range. We collected data on 13 explanatory macrohabitat variables at CMS-occupied (n = 180) and random (n = 180) sites. We then examined CMS-macrohabitat relationships using a priori, logistic regression models with information-theoretic model selection, classification tree modeling, and discriminant function analysis. Among logistic regression models, a model containing the variables elevation, aspect, slope, and lithology received the strongest empirical support, although a model containing these variables and current vegetation type also received limited support. Variable selection within our classification tree and discriminant function modeling was consistent with logistic regression results. Common variables in all three approaches indicated that the probability of finding CMS across the species' range increased in areas at higher elevations and underlain by sandstone. Validation of models with empirical support using reserved data indicated that classification accuracy was ≥80% for all three analytical methods. Finally, we linked model outputs from all three methods to GIS coverage maps that predicted CMS occupancy within the study area. Our results indicate that geophysical and ecological characteristics measured at large spatial scales may be useful for quantifying salamander habitat relationships in forested landscapes, and more specifically increase the capacity of managers to locate and plan for the continued persistence and recovery of CMS.

The role of landscape and history on the genetic structure of peripheral populations of the Near Eastern fire salamander, Salamandra infraimmaculata, in Northern Israel

Abstract: Genetic studies on core versus peripheral populations have yielded many patterns. This diversity in genetic patterns may reflect diversity in the meaning of “peripheral populations” as defined by geography, gene flow patterns, historical effects, and ecological conditions. Populations at the lower latitude periphery of a species’ range are of particular concern because they may be at increased risk for extinction due to global climate change. In this work we aim to understand the impact of landscape and ecological factors on different geographical types of peripheral populations with respect to levels of genetic diversity and patterns of local population differentiation. We examined three geographical types of peripheral populations of the endangered salamander, Salamandra infraimmaculata, in Northern Israel, in the southernmost periphery of the genus Salamandra, by analyzing the variability in 15 microsatellite loci from 32 sites. Our results showed that: (1) genetic diversity decreases towards the geographical periphery of the species’ range; (2) genetic diversity in geographically disjunct peripheral areas is low compared to the core or peripheral populations that are contiguous to the core and most likely affected by a founder effect; (3) ecologically marginal conditions enhance population subdivision. The patterns we found lead to the conclusion that genetic diversity is influenced by a combination of geographical, historical, and ecological factors. These complex patterns should be addressed when prioritizing areas for conservation.