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The Holarctic land snail genus Perpolita was used to explore the influence of past and current biogeography on diversification. The number of empirically-supported species was determined using a consensus between mtDNA sequence, nDNA sequence, conchology, and geographic and ecological range with five valid temperate-boreal species (Perpolita binneyana , Perpolita electrina , Perpolita hammonis , Perpolita petronella , and Perpolita radiatella) being recognized. Only P. petronella was unchanged in both nomenclature and diagnostic characteristics with the remainder requiring alterations. Perhaps the most important of these was elevation of P. radiatella to a valid species, with its populations having been previously lumped either under European P. hammonis or North American P. electrina. Divergence times of 18.7–10.0 Mya were suggested through genome-wide SNPs in combination with the fossil record, indicating a pre-Pleistocene origin for all Perpolita species. Using genetically-confirmed diagnostic shell characters, we accumulated > 2000 valid occurrences and used these to estimate appropriate modern and Last Glacial Maximum climate extents for all species. These models suggest that modern intra-specific gene pool diversity may generally reflect Pleistocene palaeoclimatology. [ABSTRACT FROM AUTHOR]

Pyramidula saxatilis and P. pusilla are two Central European rock-dwelling snail species that frequently co-occur and show substantial overlap in overall shell morphology. The two species can be separated from each other by differences in mitochondrial and nuclear DNA (mtDNA and nDNA) sequences. Recent studies have not shown consistent differences between these species in shell shape but have suggested possible species-specific features in shell microstructure. We investigated this issue by studying variation in the microsculpture of the upper shell surface (based on five shells per population from a total of nine populations for each species) and by analysing the geometric morphometrics of shell shape (based on 51 individuals and 12 populations of P. saxatilis and 54 individuals and 14 populations of P. pusilla), with species identifications based on mtDNA and nDNA markers. While geometric morphometrics and canonical variance analysis did reveal some statistical differences in overall shell shape, these differences were too subtle to be consistently detected by the eye. However, the density and development of growth ridges on the upper shell surface of the two species were found to be statistically different, with P. saxatilis having denser and very regular ridges. As a final verification of the utility of shell miscrosculpture, we were able to separate these two species even in two mixed populations with highly overlapping shell phenotypes, the shell-based identifications being confirmed by cytochrome c oxidase subunit I sequence data for all of the collected individuals. We therefore recommend using shell microsculpture to distinguish these two species. [ABSTRACT FROM AUTHOR]

A noted impact of urbanization is the tendency for biotic homogenization, or the increase of similarity of geographically disparate communities. On the other hand, some urban habitats harbor biodiversity native to their region, a role potentially important in xeric landscapes, with irrigation increasing the coverage and availability of mesic habitats in an otherwise water-limited landscape. We assessed the relative importance of urban yards as agents of biotic homogenization or riparian refugia by characterizing community composition of Tamaulipan thornforest land snail assemblages across a pronounced precipitation gradient in far south Texas, USA. We quantified α- and β-diversity and assessed whether the land snail fauna of urban yards are more similar to each other across a precipitation gradient than they are to their wild counterparts, as well as determined the significance of moisture in driving Tamaulipan thornforest β-diversity, both in terms of turnover (changing species composition) and nestedness (species loss). Sites with both the wild and wet conditions had the highest values of species richness and abundance. Urban land snail communities were significantly homogenized, outweighing the influence of the precipitation gradient. We did not find urban yards served as a refuge for native, moisture-dependent, riparian snails. Our analyses find that turnover, not nestedness, is the largest contributor to β-diversity in these assemblages. Studies of urbanization should address regional spatial scales to quantify how urbanization modifies regional biodiversity arising from background environmental gradients. Such an approach could lead to improved understanding of how large metroplex areas could be used to maintain and even promote biodiversity. [ABSTRACT FROM AUTHOR]

Human societies have always faced temporal and spatial fluctuations in food availability. The length of time that food remains edible and nutritious depends on temperature, moisture, and other factors that affect the growth rates of organisms that cause spoilage. Some storage techniques, such as drying, salting, and smoking, date back to ancient hunter-gatherer and early agricultural societies and use relatively low energy inputs. Newer technologies developed since the industrial revolution, such as canning and compressed-gas refrigeration, require much greater energy inputs. Coincident with the development of storage technologies, the transportation of food helped to overcome spatial and temporal fluctuations in productivity, culminating in today's global transport system, which delivers fresh and preserved foods worldwide. Because most contemporary humans rely on energy-intensive technologies for storing and transporting food, there are formidable challenges for feeding a growing and increasingly urbanized global population as finite supplies of fossil fuels rapidly deplete. [ABSTRACT FROM AUTHOR]

Using the Pupilla faunas of Europe, North America, the Altai region of central Asia and eastern Asia, we consider whether the existing taxonomy based primarily on shell apertural characteristics correlates with relationships established on the basis of mitochondrial and nuclear DNA-sequence data. We obtained DNA sequence from nuclear ITS1 and ITS2 and mitochondrial COI and CytB from 80 specimens across 22 putative Pupilla taxa. The sequence data were analysed using maximum likelihood, maximum parsimony, Bayesian and neighbour-joining phylogenetic tree reconstruction, as well as base-pair substitution and insertion-deletion analysis. Revised species-level concepts were generated by identifying reciprocally monophyletic clades that exhibited unique conchological features. These analyses document that, although many previously described taxa have biological merit, the highly plastic nature of shell apertural features makes them unreliable indicators of species identity in several independent lineages. However, shell surface sculpture and architecture appear to provide more reliable diagnoses. Because of the traditional reliance of species-level taxonomy in Pupilla on plastic apertural features, too many species-level entities have been described in Europe and the Altai. Also, because taxonomically useful shell sculpture features have tended to be ignored, too few species have been described in eastern Asia and North America. As a result, confusion exists about species ranges, ecological tolerances and interpretation of Quaternary fossils within the genus. Based on these analyses three new species are described: P. alaskensis, P. hudsonianum and P. hokkaidoensis. [ABSTRACT FROM AUTHOR]

Some suggest that because of scale independence major biodiversity metrics can be estimated at large scales from analysis of a well chosen suite of individual sites. Others have attempted to estimate individual site patterns from analysis of the continental pool. But does such cross-scale extrapolation work? This issue is addressed for the North American terrestrial gastropod fauna by comparison of family representation, species richness and body-size patterns across site to continental scales. These data demonstrate profound differences: while the continental fauna is dominated by large body-size families such as the Polygyridae, Helminthoglyptidae, Oreohelicidae, Succineidae and Urocoptidae, average site faunas are most frequently represented by small body-sized families like the Vertiginidae, Gastrodontidae, Oxychilidae, Euconulidae, Punctidae, Valloniidae, Strobilopsidae and Ellobiidae. Species richness within sites tends to be 2–7 times smaller than random draws of individuals of the same number from regional or continental pools, indicating the potential for strong bias in the construction of site faunas. And, while the body-size spectrum for average site faunas is strongly right-skewed, the continental pool is strongly left-skewed. Thus, although taxa with biovolumes >16 mm3 dominate the continental fauna (79.4% of total), they make up only a small average fraction (4.1%) of individual site species lists. Within most regions, site faunas are overrepresented in species with biovolumes <4 mm3 and underrepresented in species with biovolumes >128 mm3 as compared with the regional pool. As a result, assumptions of self-similarity between observational scales in terrestrial gastropods are inappropriate. [ABSTRACT FROM AUTHOR]

The human population and economy have grown exponentially and now have impacts on climate, ecosystem processes, and biodiversity far exceeding those of any other species. Like all organisms, humans are subject to natural laws and are limited by energy and other resources. In this article, we use a macroecological approach to integrate perspectives of physics, ecology, and economics with an analysis of extensive global data to show how energy imposes fundamental constraints on economic growth and development. We demonstrate a positive scaling relationship between per capita energy use and per capita gross domestic product (GDP) both across nations and within nations over time. Other indicators of socioeconomic status and ecological impact are correlated with energy use and GDP. We estimate global energy consumption for alternative future scenarios of population growth and standards of living. Large amounts of energy will be required to fuel economic growth, increase standards of living, and lift developing nations out of poverty. [ABSTRACT FROM AUTHOR]

Habitats with soil pH < 4 and Ca < 100 ppm, such as pocosins, Sphagnum bogs and heathlands, would appear inimical to land-snail biodiversity. Nevertheless, a survey of 1,356 sites, c. 1/2 million individuals and over 240 species (c. 1/5 of the continental fauna) across North America shows that c. 10% of species appear to favour such highly or moderately acidic sites, spread from subtropical forests of the Gulf of Mexico coast to the arctic tundra. Nonmetric multidimensional scaling ordination of faunas from 292 sites that support at least five co-occurring species documents that the principal axis of compositional variation in highly and moderately acidic habitats is significantly (P < 0.0005) correlated with latitude, while the second axis is significantly (P < 0.0005) correlated with moisture level. Composition was found to vary continuously along both axes, implying that discrete acidophilic communities are not present. While highly and moderately acidic sites were shown to have significantly (P < 0.000000005) lower richness and abundance compared with neutral/calcareous habitats, even the most acidic sites still typically supported 5–10 species. Abundance distributions in highly acidic habitats were found to be more uneven those of neutral/calcareous sites. The greater richness of the North American acidophilic land snail fauna compared with that in Europe has allowed communities to display replacement-driven compositional turnover. These results demonstrate that it is vitally important for biodiversity surveys of North American land snails not to ignore acidic habitats, because they harbour an important and surprisingly diverse fauna. [ABSTRACT FROM PUBLISHER]