No abstract

Human activities often replace native forests with warmer, modified habitats that represent novel thermal environments for biodiversity. Reducing biodiversity loss hinges upon identifying which species are most sensitive to the environmental conditions that result from habitat modification. Drawing on case studies and a meta-analysis, we examined whether observed and modelled thermal traits, including heat tolerances, variation in body temperatures, and evaporative water loss, explained variation in sensitivity of ectotherms to habitat modification. Low heat tolerances of lizards and amphibians and high evaporative water loss of amphibians were associated with increased sensitivity to habitat modification, often explaining more variation than non-thermal traits. Heat tolerances alone explained 24-66% (mean = 38%) of the variation in species responses, and these trends were largely consistent across geographic locations and spatial scales. As habitat modification alters local microclimates, the thermal biology of species will likely play a key role in the reassembly of terrestrial communities.

Habitat conversion is driving biodiversity loss and restructuring species assemblages across the globe. Responses to habitat conversion vary widely, however, and little is known about the degree to which shared evolutionary history underlies changes in species richness and composition. We analyzed data from 48 studies, comprising 438 species on five continents, to understand how taxonomic and phylogenetic diversity of amphibian assemblages shifts in response to habitat conversion. We found that evolutionary history explains the majority of variation in species' responses to habitat conversion, with specific clades scattered across the amphibian tree of life being favored by human land uses. Habitat conversion led to an average loss of 139 million years of amphibian evolutionary history within assemblages, high species and lineage turnover at landscape scales, and phylogenetic homogenization at the global scale (despite minimal taxonomic homogenization). Lineage turnover across habitats was greatest in lowland tropical regions where large species pools and stable climates have perhaps given rise to many microclimatically specialized species. Together, our results indicate that strong phylogenetic clustering of species' responses to habitat conversion mediates nonrandom structuring of local assemblages and loss of global phylogenetic diversity. In an age of rapid global change, identifying clades that are most sensitive to habitat conversion will help prioritize use of limited conservation resources.

Aim: Habitat modification is causing widespread declines in biodiversity and the homogenization of biotas. Amphibians are especially threatened by habitat modification, yet we know little about why some species persist or thrive in the face of this threat whereas others decline. Our aim was to identify intrinsic factors that explain variation among amphibians in their sensitivity to habitat modification (SHM), factors that could help target groups of species for conservation.Location: Global. Time period: 1986-2015Major taxon studied: Amphibians. Methods:We quantified SHM using species abundances in natural and altered habitats as reported in published field surveys. We first examined associations between local SHM and rangewide threatened status, population trends and invasiveness. We then evaluated the importance of intrinsic and extrinsic variables in explaining species SHM using multiple comparative methods.Our analyses included over 200 species that could be ranked with confidence from 47 studies across five continents.Results: Amphibians species varied considerably in local SHM. High SHM was associated with elevated range-wide extinction risk and declining population trends. Species that were tolerant of habitat modification were most likely to be invasive outside their native range. Geographical range size was the most important intrinsic predictor and was negatively associated with SHM. Larval habitat was also an important predictor, but was tightly coupled with phylogenetic position.Main conclusions: Narrowly distributed species whose larvae develop on land or in lotic habitats are most sensitive to habitat modification. However, other unmeasured, phylogenetically constrained traits could underlie the effect of larval habitat. Species range size is frequently correlated with global extinction risk in vertebrates, and our analysis extends this macroecological pattern to the sensitivity of amphibians to local habitat loss, a proximate driver of extinction. These general patterns of SHM should help identify those groups of amphibians most at risk in an era of rapid habitat loss and scarce conservation resources. K E Y W O R D Sbiodiversity, conservation, habitat loss, land use, life history, matrix tolerance, specialization, species traits, susceptibility, threatened 700 |

The histomorphologic characteristics and chemical composition of the crystals associated with suspected pet food-induced nephrotoxicosis in 3 dogs are described. Kidney specimens from 2 dogs, a 3-year-old Parson Russell Terrier and a 3-year-old Bernese Mountain Dog, were examined. Both developed acute renal failure after eating canned pet food on the 2007 Menu Foods recall list. The third case was a kidney specimen from a 1-year-old mixed-breed dog from a similar 2004 outbreak of canine renal failure in Taiwan, which occurred after eating a commercial dog food. Hematoxylin and eosin (HE), 72-hour Oil Red O (ORO72h), Alizarin Red S (pH 4.1-4.3), and Von Kossa stains; infrared (IR) spectroscopy; and scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDXA) were performed to determine the histomorphologic characteristics and chemical composition of the crystals observed in each case. Histomorphologic findings in each case included acute, marked tubular degeneration and necrosis with many intratubular birefringent crystals, and lymphoplasmacytic interstitial nephritis. In each case, most of the crystals were rough, pale brown, and stained with ORO72h but did not stain with Alizarin Red S (pH 4.1-4.3) or Von Kossa stains; these features were consistent with a plastic or lipid. IR spectroscopy and SEM/EDXA results were consistent with melamine-containing crystals. A second crystal type identified in each case was smooth and platelike with staining characteristics and IR spectroscopy and SEM/EDXA results consistent with calcium oxalate crystals. Melamine-containing crystals have distinct light microscopic, histochemical, and SEM/EDXA characteristics that facilitate their identification in tissue.