Will climate change be beneficial or detrimental to the invasive swede midge in North America? Contrasting predictions using climate projections from different general circulation models

Climate change may dramatically affect the distribution and abundance of organisms. With the world's population size expected to increase significantly during the next 100 years, we need to know how climate change might impact our food production systems. In particular, we need estimates of how future climate might alter the distribution of agricultural pests. We used the climate projections from two general circulation models (GCMs) of global climate, the Canadian Centre for Climate Modelling and Analysis GCM (CGCM2) and the Hadley Centre model (HadCM3), for the A2 and B2 scenarios from the Special Report on Emissions Scenarios in conjunction with a previously published bioclimatic envelope model (BEM) to predict the potential changes in distribution and abundance of the swede midge, Contarinia nasturtii, in North America. The BEM in conjunction with either GCM predicted that C. nasturtii would spread from its current initial invasion in southern Ontario and northwestern New York State into the Canadian prairies, northern Canada, and midwestern United States, but the magnitude of risk depended strongly on the GCM and the scenario used. When the CGCM2 projections were used, the BEM predicted an extensive shift in the location of the midges' climatic envelope through most of Ontario, Quebec, and the maritime and prairie provinces by the 2080s. In the United States, C. nasturtii was predicted to spread to all the Great Lake states, into midwestern states as far south as Colorado, and west into Washington State. When the HadCM3 was applied, southern Ontario, Saskatchewan, and Washington State were not as favourable for C. nasturtii by the 2080s. Indeed, when used with the HadCM3 climate projections, the BEM predicted the virtual disappearance of ‘very favourable’ regions for C. nasturtii. The CGCM2 projections generally caused the BEM to predict a small increase in the mean number of midge generations throughout the course of the century, whereas, the HadCM3 projections resulted in roughly the same mean number of generations but decreased variance. Predictions of the likely potential of C. nasturtii spatial spread are thus strongly dependent on the source of climate projections. This study illustrates the importance of using multiple GCMs in combination with multiple scenarios when studying the potential for spatial spread of an organism in response to climate change.     

Discovery of a large clonal patch of a social amoeba: implications for social evolution

Studies of genetic population structures of clonally reproducing macro-organisms have revealed large areas where only one clone is found. These areas, referred to as clonal patches, have not been shown to occur in free-living microbes until now. In free-living microbes, high genetic diversity at local scales is usually maintained by high rates of dispersal. We report, however, a highly dense, 12-m clonal patch of the social amoeba Dictyostelium discoideum in a cattle pasture located in a Texas Gulf Coast prairie. We confirm the presence of only one clone by the analysis of 65 samples and amplification of 10 polymorphic microsatellite loci. Samplings of additional cattle pastures nearby showed higher clonal diversity, but with a density of D. discoideum isolates lower than in the clonal patch. These findings show that high rates of microbial dispersal do not always produce genetic diversity at local scales, contrary to the findings of previous studies. The existence of clonal patches may be particularly important for microbial social evolution.     

THE MANTLE AND SHELL OF SOLEMYA PARKINSONI (PROTOBRANCHIA: BIVALVIA)

The shell of Solemya exhibits considerable flexibility which is further enhanced by the marked extension of the periostracum beyond the calcareous portions of the valves. This fcature, more than any other, has made possible the habit, unique among bivalves, of burrowing deep within the substrate without direct contact with the water above. The inner calcareous layer of tho valves is restricted to a small area near the umbones while the outer calcareous layer is thin and contains a high proportion of organic material. The shell conchiolin consists mainly of protein, varying in composition, but much of it strengthcned by quinone-tanning, and in ccrtain regions probably by the presence of appreciable quantities of chitin. The ligament, although superficially resembling an amphidetic structure, is opisthodetic, the extcnsion anterior to the umbones consisting of anterior outer layer only.
The mantle is characterized by an extension of the outer fold of the mantle margin which has effected equally both the inner and outer surfaces of this fold. The secretory epithelium and the modified pallial musculature, contraction of which results in the intucking and plaiting of the periostracum, is dcscribed. Simple tubular oil glands open at the mantlo margin and are responsible for the water-repellent nature of the periostracum.
The form of the mantlelshell and that of the enclosed body are discussed and compared with those of other bivalves in which elongation of the mantle/shell is achieved in a different way. It is concluded that the mantlelshell of Solemya is of little value in determining its relationships, and that the greatly elongatod ligament, the edentulous hinge and the flexible shell are all adaptations to a specialized mode of life.     

A route to recovery: The early Silurian shallow-water shelly fauna in the northern Oslo basin

The shelly fauna of the lowest part of the Sælabonn Formation in the Hadeland district of the Oslo Region provides a rare insight into the shallow-water biota of the earliest Silurian and hence the start of biotic recovery after the end Ordovician extinction event. It is dominated by the brachiopods Dalmanella cf. pectinoides Bergström, Coolinia cf. columbana (Reed), Leptaena cf. haverfordensis Bancroft and Zygospiraella scotica (Salter) together with the trilobite Acernaspis elliptifrons (Esmark). The first three species in this unique association belong to eurytopic Ordovician survivor genera which were also present in the underlying unit in Hadeland and continued to thrive during the Silurian. Significantly, Zygospiraella and Acernaspis have no unequivocal Ordovician record but diversified rapidly and became common during the early Silurian (Rhuddanian) in many parts of the world. Moreover, Acernaspis and Zygospiraella were highly eurytopic, pioneer taxa that were among the first elements of the Rhuddanian shelly fauna to appear in many parts of the world especially around the margins of the remnant Iapetus Ocean, following the drowning of areas previously emergent during the late Ordovician sea-level lowstand. The Hadeland fauna provides evidence of a previously undocumented route (among several) by which life ultimately returned to the global diversity plateau established in the mid-Ordovician.     

Probing the deep shelf: a Lagerstätte from the Upper Ordovician of Girvan, southwestern Scotland

A deep‐water Konservat Lagerstätte from the lower Caradoc (Sandbian) at Girvan is dominated by the trilobite Diacanthaspis trippi, the carpoids Anatifopsis n. sp.? and a new genus of ctenocystoid together with the polyplacophoran Solenocaris solenoides and the brachiopod Onniella williamsi. Most of these are multi‐element organisms, with many specimens preserved in an articulated state in finely laminated rocks, indicating minimal disturbance and suggesting that the fauna is largely an in situ association. It contains few of the species known from other deep‐water sites of similar age at Girvan which contain diverse assemblages of trilobites and brachiopods absent from the Lagerstätte. The taphonomy of the site indicates preservation by rapid burial followed by early diagenesis under dysaerobic conditions. It provides a ‘taphonomic window’ on otherwise unknown faunas from distal shelf facies on the Ordovician Laurentian margin, and, moreover, is an important reminder of the hidden biodiversity that resided in thin‐shelled, multi‐element organisms.     

Interpopulation variation and selective predation in the meadow brown butterfly, Maniola jurtina (L.) (Lepidoptera: Satyridae) in the Canary Islands

Samples of the meadow brown butterfly, Maniola jurtina , were collected from all five of the Canary Islands where it occurs. The butterflies were scored for several spotting characters on both fore- and hindwings and assessed for damage from predators.
The analysis reveals considerable interisland heterogeneity for spotting characters and suggests that the populations fall into two relatively distinct, homogeneous groups, which inhabit the islands of Gran Canaria and La Gomera, on the one hand, and Tenerife, El Hierro and La Palma, on the other.
The main predators are lizards and insectivorous birds. Predator damage is non-random in the following respects: males are more damaged than females; high spot male phenotypes are more damaged than low ones early in the flight period (April-May); symmetrical damage, probably acquired while resting, is commoner in females, while asymmetrical damage is more characteristic of males. Damage generally increases in both sexes through the flight period.
Comparison of the bulked Canary Island samples with museum material from North Africa and Iberia suggests that the former area is the more likely source of the island populations. However, samples from two islands more resemble Iberian stock and it is suggested that the butterfly may have colonized the islands, either by introduction or immigration, on two occasions.     

THE EFFECTS OF INFECTION WITH TOBACCO MOSAIC VIRUS ON THE PHOTOSYNTHESIS OF TOBACCO LEAVES

The rate of photosynthesis of tobacco leaves infected with the Rothamsted type culture of tobacco mosaic virus was lower than that of comparable healthy tobacco leaves. The lower rate was inferred from Net Assimilation Rates of whole plants and confirmed by direct comparisons of photosynthetic rates of inoculated and healthy leaves. The effect began within 1 hr. of inoculation. It was not caused by an effect of the virus on the stomata, and inactivated virus inoculum did not change the rates. The results indicate either a more rapid movement of virus from the epidermis into the chlorenchyma than has been previously recorded or an effect of virus infection at a site distant from the cells containing virus.     

FURTHER OBSERVATIONS ON THE PATHOGENICITY OF CALONECTRIA RIGIDIUSCULA (BERK. & BR.) SACC. TO THEOBROMA CACAO L

Quantitative data are provided for the occurrence of Calonectria rigidiuscula and other fungi in occluded Mirid lesions and other sites in shoots of cacao plants. Mirid lesions appear to be particularly favourable for the development of C. rigidiuscula. The fungus also occurs as a saprophyte on cacao pods, and as a wound parasite in woody plants other than cacao; it was successfully introduced into plants of varied affinities by inoculation. C. rigidiuscula spreads from inoculations in cacao stems much more rapidly than other fungi. The results confirm that it is the most important fungus infecting Mirid lesions and causing dieback of cacao in West Africa.
Inoculation tests with a range of Amelonado and Trinitario clones suggested that the clones vary in their susceptibility to C. rigidiuscula , but the plant-to-plant variation was too great to conclude that any one is highly resistant. Various types of introduced cacao were also tested; preliminary experiments indicate that certain types of Upper Amazon cacao may be resistant, but they need further investigation.     

Influences of Light Quality, Growth Regulators and Inhibitors of Protein Synthesis on Respiration of Protoplasts from Meristematic Cells in Barley Seedlings

The influences of light of different wavelengths and plant growthregulators on the respiration of protoplasts isolated from tissue0 to 5 mm above the basal intercalary meristem of barley (Hordeumvulgare L. cv. Patty) leaves were studied. Respiration was measuredusing oxygen electrodes and a Cartesian-diver technique. Red,far-red and blue light all stimulated respiration in the protoplastsbut not in mitochondria isolated from them. Gibberellic acid stimulated respiration in protoplasts but abscisicacid had the opposite effect. Physiological concentrations ofindole-3-acetic acid and kinetin had no influence in eitherdirection. Combinations of gibberellic acid with light of anywavelength always increased respiration. Red or far-red light treatments in the presence of abscisicacid decreased dark respiration and only blue light significantlyreversed the inhibitory effect of abscisic acid. Cycloheximidemarkedly increased dark respiratory activity; chloramphenicolwas without effect. These results indicate that mitochondrialactivity in the leaf basal intercalary meristem was partiallycontrolled through phytochrome and a blue light receptor, andby gibberellic and abscisic acids. Changes in cytosolic proteinsynthesis were important for the initiation of enhanced mitochondrialactivity in meristems. Hordeum vulgare L., barley, abscisic acid, Cartesian-diver microrespirometry, gibberellic acid, meristematic respiration, protoplasts