Projected Loss of a Salamander Diversity Hotspot as a Consequence of Projected Global Climate Change

Background: Significant shifts in climate are considered a threat to plants and animals with significant physiological limitations and limited dispersal abilities. The southern Appalachian Mountains are a global hotspot for plethodontid salamander diversity. Plethodontids are lungless ectotherms, so their ecology is strongly governed by temperature and precipitation. Many plethodontid species in southern Appalachia exist in high elevation habitats that may be at or near their thermal maxima, and may also have limited dispersal abilities across warmer valley bottoms. Methodology/Principal Findings: We used a maximum-entropy approach (program Maxent) to model the suitable climatic habitat of 41 plethodontid salamander species inhabiting the Appalachian Highlands region (33 individual species and eight species included within two species complexes). We evaluated the relative change in suitable climatic habitat for these species in the Appalachian Highlands from the current climate to the years 2020, 2050, and 2080, using both the HADCM3 and the CGCM3 models, each under low and high CO 2 scenarios, and using two-model thresholds levels (relative suitability thresholds for determining suitable/unsuitable range), for a total of 8 scenarios per species. Conclusion/Significance: While models differed slightly, every scenario projected significant declines in suitable habitat within the Appalachian Highlands as early as 2020. Species with more southern ranges and with smaller ranges had larger projected habitat loss. Despite significant differences in projected precipitation changes to the region, projections did no

Polarization and ideological congruence between parties and supporters in Europe

The relationship between parties and their supporters is central to democracy and ideological representation is among the most important of these linkages. We conduct an investigation of party-supporter congruence in Europe with emphasis on the measurement of ideology and focusing on the role of party system polarization, both as a direct factor in explaining congruence and in modifying the effects of voter sophistication. Understanding this relationship depends in part on how the ideology of parties and supporters is measured. We use Poole’s Blackbox scaling to derive a measure of latent ideology from voter and expert responses to issue scale questions and compare this to a measure based on left–right perceptions. We then examine how variation in the proximity between parties ideological positions and those of their supporters is affected by the polarization of the party system and how this relationship interacts with political sophistication. With the latent ideology measure, we find that polarization decreases party-supporter congruence but increases the effects of respondent education level on congruence. However, we do not find these relationships using the left–right perceptual measure. Our findings underscore important differences between perceptions of left–right labels and the ideological constraint underlying issue positions

Urea treatment decouples intrinsic pH control over N₂O emissions in soils

Soil N₂O emission potential is commonly investigated under idealized denitrifying conditions (e.g. nitrate-N supplied and anaerobic soil), with pH commonly identified as a major determinant of N₂O emission potential. However, under urine patch conditions in grazed pastures soils a more complex series of abiotic and biotic factors may influence emissions due to the complex N transformations that occur following urea hydrolysis. These transformations may decouple native and/or expected controls of N₂O emissions encountered under classic denitrifying conditions. Here, we tracked O₂, CO₂, NO, N₂O and N₂ emissions from urine amended soils (i.e. simulating a urine patch) to determine putative controls of N₂O emissions within 13 different pasture soils from northern (Ireland) and southern hemispheres (New Zealand). Incubations were performed under aerobic conditions±artificial urine (13.3 mg N vial¯¹) equivalent to field ruminant urine deposition rates of 1000 kg N ha¯¹. Results revealed that pH was not an important regulator of the emission ratio (N₂O /(NO + N₂O + N₂)) in urine amended soils. Within urine affected soils, a new set of variables emerged as regulators of N₂O emissions, likely due to the unique environment created within this system. We show that urine results in decoupling of the initial soil pH control of the emission ratio allowing other regulators such as nitrite to dominate. In addition, we observed that the emission ratio of N₂O increased linearly with the rate of N- gas loss (NO + N₂O + N₂ μmol N h¯¹), O₂ consumption was positively associated with ammonia oxidising bacteria (AOB) and that the production of NO and N₂O were also enhanced under urine conditions