The moss mites of the Cheviot (Acari: Oribatei)

A faunal list of oribatid mites collected from the summit of the Cheviot, Northumberland, is given, together with notes on the taxonomy and distribution of several of the species. Special attention is paid to the Arctic-alpine and European-alpine species and the list provides further support for the view that the upland areas of Britain are characterized by a common group of oribatid species. It is suggested that these species may be cold hardy or cold tolerant with relatively high supercooling points, enabling them to survive the winter at these higher altitudes.     

Phonetic Ability and Related Anatomy of the Newborn and Adult Human, Neanderthal Man, and the Chimpanzee

The sounds of human speech make human language a rapid medium of communication through a process of speech "encoding." The presence of sounds like the vowels [a], [i], and [u] makes this process possible. The supralaryngeal vocal tracts of newborn Homo sapiens and chimpanzee are similar and resemble the reconstructed vocal tract of the fossil La Chapelle-aux-Saints Neanderthal man. Vocal tract area functions that were directed toward making best possible approximations to the human vowels [a], [i], and [u], as well as certain consonantal configurations, were modeled by means of a computer program. The lack of these vowels in the phonetic repertories of these creatures, who lack a supralaryngeal pharyngeal region like that of adult Homo sapiens, may be concomitant with the absence of speech encoding and a consequently linguistic ability inferior to modern man.     

Towards a monophyletic genus Albinaria (Gastropoda, Pulmonata): the first molecular study into the phylogenetic position of eastern Albinaria species

Recent molecular phylogenetic studies of the terrestrial snail genus Albinaria have caused a radical reassessment of its taxonomy. These studies, however, were limited to western species. This paper examines mitochondrial 12S sequences and nuclear ITS1 & 2 sequences of both eastern and western species, and demonstrates that Albinaria, in its most recent definition, is not monophyletic. Both molecular datasets place ' Albinaria ' hedenborgi from Lebanon in a well-supported clade with species of the genus Cristataria , distributed south-east of the vicariant range of Albinaria . The remaining species from Cyprus, Turkey and Greece constitute a well-supported monophyletic group. These two clades form geographical clusters, whereas Albinaria in the current definition (including ' A. '  hedenborgi ) has a disjunct distribution. ' A.' hedenborgi should therefore be classified with Cristataria , together with the morphologically similar and geographically close ' A. '  nadimi .  © 2005 The Linnean Society of London, Zoological Journal of the Linnean Society , 2005, 143 , 531−542.     

Carbon exchange in biological soil crust communities under differential temperatures and soil water contents: implications for global change

Biological soil crusts (biocrusts) are an integral part of the soil system in arid regions worldwide, stabilizing soil surfaces, aiding vascular plant establishment, and are significant sources of ecosystem nitrogen and carbon. Hydration and temperature primarily control ecosystem CO₂ flux in these systems. Using constructed mesocosms for incubations under controlled laboratory conditions, we examined the effect of temperature (5–35 °C) and water content (WC, 20–100%) on CO₂ exchange in light (cyanobacterially dominated) and dark (cyanobacteria/lichen and moss dominated) biocrusts of the cool Colorado Plateau Desert in Utah and the hot Chihuahuan Desert in New Mexico. In light crusts from both Utah and New Mexico, net photosynthesis was highest at temperatures >30 °C. Net photosynthesis in light crusts from Utah was relatively insensitive to changes in soil moisture. In contrast, light crusts from New Mexico tended to exhibit higher rates of net photosynthesis at higher soil moisture. Dark crusts originating from both sites exhibited the greatest net photosynthesis at intermediate soil water content (40–60%). Declines in net photosynthesis were observed in dark crusts with crusts from Utah showing declines at temperatures >25 °C and those originating from New Mexico showing declines at temperatures >35 °C. Maximum net photosynthesis in all crust types from all locations were strongly influenced by offsets in the optimal temperature and water content for gross photosynthesis compared with dark respiration. Gross photosynthesis tended to be maximized at some intermediate value of temperature and water content and dark respiration tended to increase linearly. The results of this study suggest biocrusts are capable of CO₂ exchange under a wide range of conditions. However, significant changes in the magnitude of this exchange should be expected for the temperature and precipitation changes suggested by current climate models.     

ALTITUDINAL VARIATION AND ADAPTIVE ZONES IN ARIANTA ARBUSTORUM: A NEW LOOK AT A WIDESPREAD SPECIES

Arianta arbustorum is a European land snail, occurring in bothlowland and mountainous regions. Its shell is usually globular,which makes the species aberrant among the Campylaeinae in shellshape, habitat, and wide, not exclusively montane range. Withincreasing altitudes, the shells usually decrease in size andbecome more conical. However, in some mountain stocks thereare populations with depressed shells, provided with an openumbilicus. This form (subspecies) is only known from formerPleistocene refugia. It is hypothesized that in the Pliocene, the primary montaneA. arbustorum, with a depressed shell, entered an additional,adaptive zone, while conquering damp lowland habitats. Thisresulted in an enormous range extension. In the new habitata different (globular) shell shape evolved and the species becamepolytypic. The subsequent glaciations wiped out most of theoriginal montane A. arbustorum with depressed shells. Wherethis had occurred, post-Pleistocene re-colonizing conspecificsnails with globular shells, found vacant territory and coulddevelop the dines mentioned before. The invading populationsdid not regain the original, montane, depressed shell shape.This shape was only retained in a few refugia, where the populationssurvived amidst the glaciers. (Received 9 February 1990; accepted 31 May 1990)     

Phylogeography of the land snail Albinaria hippolyti (Pulmonata: Clausiliidae) from Crete, inferred from ITS-1 sequences

The polytypic Cretan land snail Albinaria hippolyti has a range that is partly fragmented and partly subdivided by hybrid zones. For this reason, it has served as a model species for investigating speciation and radiation in Mediterranean Clausiliidae. The first internal transcribed spacer ( ITS-1 ) of the nuclear ribosomal DNA was sequenced in 20 populations of A. hippolyti and phylogenetically analysed using maximum parsimony. We employed a novel method involving logarithmic weighting of gaps and topological constraints based on bootstrap values. The resulting phylogeography suggests that the species has undergone a recent cycle of range expansion and range reduction. Speciation cannot be linked to major geological vicariance events in the Miocene and Pliocene, as has been suggested previously. The subspecies A. h. arthuriana appears unrelated to other A. hippolyti subspecies, which supports recent suggestions, based on morphology, to regard it as a separate species.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 83 , 317–326.     

Determinants of savanna vegetation structure: Insights from Colophospermum mopane

Abstract Savannas are structurally heterogeneous at the local, community‐level scale due to fine‐scale floristic heterogeneity as well as the responses of individual species to underlying environmental variation. The structure of mopane woodland, an arid savanna of southern Africa, is dictated largely by local variation in the relative dominance of tall, single‐stemmed and shorter, multi‐stemmed forms of the dominant tree species, Colophospermum mopane (Kirk ex Benth) Léonhard. Here we evaluate the hypothesis that the existence of these alternative forms of C. mopane, as well as the factors that dictate their distribution at a local scale, are driven by fine‐scale environmental variability in available water. We surveyed trees at four sites in the Kruger National Park of South Africa, in each instance surveying both forms of the species, from both riparian and non‐riparian zones. A survey of genetic variation across our sample (n = 80 individuals), using inter‐simple sequence repeat (ISSR) amplification profiles, indicates that the two forms are not genetically distinct, instead being environmentally determined. While measurements of xylem pressure potentials, determined using a Scholander pressure chamber, show a significant difference between riparian and non‐riparian zones, there is no significant difference between the two growth forms. Although this seems paradoxical in view of the prevalence of tree and shrub form mopane at riparian and non‐riparian sites, respectively, we speculate that such a pattern may emerge through the interaction of moisture stress and top‐down controls, such as those imposed by large mammal browsing and fire.     

Studies on the moss mites of Snowdonia (Acari: Oribatei). 2. The Cnicht

A faunal list of oribatid mites collected from the summit of the Cnicht, Snowdonia, at 2265 ft is given, together with critical notes on the taxonomy and distribution of several of the species. The list provides further evidence of the presence of arctic-alpine and European-alpine species of Oribatei on the mountain peaks of Britain. A comparison of the faunal list with lists of species recorded by the author on another peak in Snowdonia and on high ground in other parts of Britain (Peak District, Lake District) and by Block in Westmorland, provides evidence of a group of additional species which can be regarded as characteristic of upland areas in general of Britain and Europe.     

Environment and food of the budgerigar Melopsittacus undulatus

Budgerigars range and breed over most of the interior of Australia. During a year, budgerigars may experience a maximal change in day length of about 5 h, and temperatures range from well below to above their zone of thermo-neutrality. In the north of the budgerigar's range there is growth of pastures in summer and autumn and in the south there is growth in spring and early summer. In the arid interior, growth is irregular from year-to-year and varies from site-to-site. However, in northern arid regions growth tends to occur in summer and autumn; in southern arid regions in spring and early summer; and over most of the arid regions in most years there is some growth in run-on areas. In inland mid-eastern Australia budgerigars ate only seeds of ground vegetation. These seeds were from about 0.5 to 2.5 mm in length, weighed between about 0.3 and 1.3 mg and had an energy content of about 18.9 kJ g^-1. Ata site on Mitchell grass plains Astrebla spp. were the main seeds eaten. At a site further inland the diet was more diverse: in the hot months of 1973–74 they ate mainly Boerhavia diffusa, Atriplex spp. and Astrebla pectinata, during the cold months of 1974 mainly Iseilema and an unidentified seed, and in spring 1974 mainly Atriplex spp. There was no evidence of special dietary requirements for breeding; in particular no requirements of soft, unripened seed or insect food to feed young. Males and females, adults and juveniles, and individuals in the same flock had similar diets. Information from the literature and my data suggest there is considerable stability and seasonal regularity in the budgerigar's food supply.