A revision of the Haplocheira group of genera (Amphipoda: Aoridae)

The Southern hemisphere aorid amphipod genera Haplocheira Haswell and Kuphocheira Barnard are revised and Anonychocheirus gen. nov. is described from Antarctica. A key is provided to distinguish the three genera and six species currently known. Material attributed to H. barbimana (Thomson, 1879) from Antarctica, South Georgia, Australia, lies de Kerguelen, New Zealand and Auckland Is. has been re-examined. The Antarctic material proves to be separate on the basis of antennal peduncle proportions, shape of lateral cephalic angle and shape and setation of peraeopod bases. Stebbing's species plumosa is re-established for this entity. Haplocheira robusta Barnard is synonymized with H. barbimana and three subspecies are described, viz. H.b. barbimana (Thomson) from New Zealand and Auckland Is., H.b. typica Haswell from Australia and lies de Kerguelen (shallow water) and H.b. robusta Barnard from Magellanic South America and the Falkland islands. Haplocheira balssi Schellenberg remains a separate species. Kuphocheira setimanus Barnard is re-assessed and K. emancipata sp. nov. described from Antarctica. The new genus Anonychocheirus is presently known only from the type species A. richardsoni sp. nov. described herein.     

Phylogeny of Paussus L. (Carabidae: Paussinae): unravelling morphological convergence associated with myrmecophilous life histories

Ant nest beetles (Paussus L.) are ecologically fascinating and phenotypically bizarre. Obligate myrmecophiles, Paussus have undergone extreme adaptations for life with ants and their profound range of phenotypic diversity has been difficult to reconcile in a systematic framework. We conducted a detailed morphological study of Paussus utilizing novel techniques and character systems in order to discover anatomical apomorphies diagnostic of the major clades of Paussus strongly supported by molecular data. Bayesian inference (BI) of molecules alone, morphology alone and varying combinations of the two data types reveal that morphology is informative for placing Paussus species, despite the extreme phenotypic diversity and convergence prevalent in the group. We propose a new classification for Paussus based on this phylogeny. The genus Paussus is revised to include all genera, subgenera and species formerly classified as Paussus by Nagel (2003) in addition to Hylopaussus syn.n. , Hylotorus syn.n. and Granulopaussus syn.n. The following species are transferred to Paussus: Paussus sebakuanus (Péringuey) comb.n. , Paussus gracilis (Reichensperger) comb.n. , Paussus bucephalus Gyllenhal, Paussus caroli (Reichensperger) comb.n. , Paussus uelensis (Reichensperger) comb.n. , Paussus hottentottus (Westwood) comb.n. , Paussus blanchardi (Raffray) comb.n. , Paussus basilewskyi (Luna de Carvalho) comb.n. , Paussus granulatus Westwood, Paussus sankuruensis Reichensperger, Paussus leleupi (Reichensperger) comb.n. , Paussus reichenspergeri (Luna de Carvalho) comb.n. We formally delineate and diagnose the following major subgroups of Paussus: Paussus I series, comprising the subgenera Bohemanipaussus Luna de Carvalho stat. rev. sensu n. , Bathypaussus Wasmann stat. rev. sensu n. , and Edaphopaussus Kolbe stat. rev. sensu n. ; the Paussus II series comprising the subgenera Paussus L. stat. rev. sensu n. , Klugipaussus Kolbe stat. rev. sensu n. , Scaphipaussus Fowler stat. rev. sensu n. , Hylotorus Dalman stat.n. sensu n. , and Anapaussus Wasmann stat. rev. sensu n. ; and the Paussus III series comprising the subgenera Lineatopaussus Kolbe stat. rev. sensu n. and Shuckardipaussus Kolbe stat. rev. sensu n.     

Landscape-Genetic Analysis of Population Structure in the Texas Gray Fox Oral Rabies Vaccination Zone

ABSTRACT In west-central Texas, USA, abatement efforts for the gray fox (Urocyon cinereoargenteus) rabies epizootic illustrate the difficulties inherent in large-scale management of wildlife disease. The rabies epizootic has been managed through a cooperative oral rabies vaccination program (ORV) since 1996. Millions of edible baits containing a rabies vaccine have been distributed annually in a 16-km to 24-km zone around the perimeter of the epizootic, which encompasses a geographic area >4 × 10⁵ km². The ORV program successfully halted expansion of the epizootic into metropolitan areas but has not achieved the ultimate goal of eradication. Rabies activity in gray fox continues to occur periodically outside the ORV zone, preventing ORV zone contraction and dissipation of the epizootic. We employed a landscape-genetic approach to assess gray fox population structure and dispersal in the affected area, with the aim of assisting rabies management efforts. No unique genetic clusters or population boundaries were detected. Instead, foxes were weakly structured over the entire region in an isolation by distance pattern. Local subpopulations appeared to be genetically non-independent over distances >30 km, implying that long-distance movements or dispersal may have been common in the region. We concluded that gray foxes in west-central Texas have a high potential for long-distance rabies virus trafficking. Thus, a 16-km to 24-km ORV zone may be too narrow to contain the fox rabies epizootic. Continued expansion of the ORV zone, although costly, may be critical to the long-term goal of eliminating the Texas fox rabies virus variant from the United States.     

Further studies on the evolution of land and freshwater nemerteans: generic relationships among the paramonostiliferous taxa

The costs and benefits of fighting in bovids are high in terms of injury and reproductive success, respectively. The breakage of a horn would curtail reproductive success permanently. Therefore, the horns of bovids should include sufficient material so that they are strong enough to be unlikely to break in fighting but without being too heavy to carry around. The forces developed during fighting were measured in a computerized analysis of film of blackbuck and bighorn sheep. All possible modes of failure were investigated using a mechanical analysis to see how the horns are most likely to fail.
The maximum possible force developed during fighting is 3400 N for the bighorn sheep and 456 N for the blackbuck. Bending stress, shear stress, deflection, strain energy and critical crack lengths were calculated for the horns of these two bovids. Horns are most likely to fail in bending as indicated by safety factors. Most of the force is taken in compression due to the curvature of horns. Shear stresses are insignificant and deflections are negligible during the most forceful encounters.
The safety factor in bending of the horn of the bighorn sheep is greater (10) than that of the horn of the blackbuck (3.4) because the forces are probably more variable and unpredictable in the fighting of the former.
All of the energy of fighting is absorbed by the body musculature because horns store less than 1% of the energy produced in fighting as strain energy when they bend. Cracks and scratches mustbe more than 60% of the transverse basal dimensions of horns in order for there to be catastrophic failure at the maximum stresses developed during fighting.
The horns of the blackbuck and the bighorn sheep appear to be minimum weight structures given the variability of the forces acting on them and are unlikely to break in fighting given the forces calculated from the analyses of films.     

The Involvement of Glucose-6-Phosphatase in Mucilage Secretion by Root Cap Cells of Zea mays

In order to determine the involvement of glucose-6-phosphatasein mucilage secretion by root cap cells, we have cytochemicallylocalized the enzyme in columella and peripheral cells of rootcaps of Zea mays. Glucose-6-phosphatase is associated with theplasmalemma and cell wall of columella cells. As columella cellsdifferentiate into peripheral cells and begin to produce andsecrete mucilage, glucose-6-phosphatase staining intensifiesand becomes associated with the mucilage and, to a lesser extent,the cell wall. Cells being sloughed from the cap are characterizedby glucose-6-phosphatase staining being associated with thevacuole and plasmalemma. These changes in enzyme localizationduring cellular differentiation in root caps suggest that glucose-6-phosphataseis involved in the production and/or secretion of mucilage byperipheral cells of Z. mays. Zea mays, corn, glucose-6-phosphatase, columella cell, peripheral cell, mucilage, secretion, cytochemistry     

A large-subunit mitochondrial ribosomal DNA sequence translocated to the nuclear genome of two stone crabs (Menippe)

Two DNA sequences that appear to be homologous to large-subunit mitochondrial ribosomal RNA genes have been identified in the stone crabs Menippe mercenaria and M. adina. Amplification from whole genomic DNA by polymerase chain reaction (PCR) with oligonucleotide primers based on conserved portions of large-subunit mitochondrial rRNA genes consistently amplified two products of similar length (565 and 567 bp). These products differed at 3% of their nucleotide bases, and could be distinguished by a HindIII site. Only one of these sequences (designated the A sequence) was detected by PCR in purified mitochondrial DNA. The other (designated the B sequence) hybridized to total genomic DNA at a level consistent with a nuclear genome location. It is unlikely that the type B product would have been recognized as a nuclear copy by examination of its sequence alone. This is the first report of a mitochondrial gene sequence translocated into the nuclear genome of a crustacean.      

Nine-year reciprocal transplant experiment in the gardens of the basin and mountain big sagebrush (Artemisia tridentata: Asteraceae) hybrid zone of Salt Creek Canyon: the importance of multiple-year tracking of f itness

We have studied reciprocal transplant gardens involving the hybrid zone between basin and mountain big sagebrush ( Artemisia tridentata ) in Salt Creek Canyon, Utah, for 9 years. Previously, we showed that the parental taxa and hybrids had superior reproductive and vegetative performance in their native garden. These earlier data supported the Bounded Hybrid Superiority model. Now, after 9 years, we find that the mountain seed source plants have greater relative fitness than middle hybrid zone seed source plants in the middle hybrid zone garden. These results may be due to plant density and climatic factors more conducive to mountain seed source growth than that of either basin or middle hybrid zone seed source plants. On the other hand, these fitness estimates do not take into account the timing of reproduction, which together with the age-specific survival rate, can profoundly affect lifetime fitness. The intrinsic rate of increase ( r ) takes both of these factors into account, providing another estimate of fitness. Middle hybrid zone seed source plants had the greatest rate of increase in both the middle hybrid zone and mountain gardens and a greater rate of increase than either parent in the basin garden. This is most likely due to the greater reproductive performance of middle hybrid zone plants earlier in life than either parental taxon. These results partly support the Bounded Hybrid Superiority model and show the importance of long- term studies of hybrid fitness.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 86 , 213–225.     

Lower Cambrian trace fossil evidence for predation on trilobites

Predation upon trilobites previously has been inferred from large coprolites containing trilobite fragments, and from specimens of trilobites with healed wounds. The discovery of large burrows ( Dolopichnus gulosus , n. ichnogen., n. ichnosp.) in micritic quartz arenite of the Lower Cambrian Poleta Formation in Esmeralda County, Nevada, suggests that sea anemones preyed upon trilobites. Dolopichnus n. ichnogen., vertical cylindrical burrows with a central cylindrical core, is interpreted as dwelling burrows of sea anemones. In the specimens studied, the core contains coarser-grained material, and in one series of burrows, is composed of trilobitc fragments and micrite pellets. cemented with sparite. The central cylinder is interpreted to be a cast of the sea anemone's coelenteron, which in some specimens contains stomach contents.     

Effects of Sucrose on Petiolar Carbohydrate Accumulation and Photosynthesis in Excised Sinapis Cotyledons

Petioles of Sinapis cotyledons cultured in 6x10^–2 M sucrosein the light increased 28-fold in total carbohydrate contentover a 7-d period compared with an 8-fold increase in petiolesof cotyledons cultured on water. The starch and reducing sugarfractions were the major components of this accumulation. Labelledsucrose applied to the petiole base moved quickly up the petioleand into the main veins of the lamina. Some basipetal redistributionoccurred subsequently and after 24 h radioactivity accumulatedstrongly at the petiole base. Culture in sucrose reduced basalaccumulation and increased acropetal movement of the label. Fixation of ¹⁴CO₂ by petioles remained constant when cotyledonswere cultured in water, whereas in sucrose, fixation fell by50 per cent during the first 2 d. The pattern of inhibitionof fixation matched the pattern of sucrose distribution in thepetiole. Petiolar chlorophyll content remained constant in controlsbut fell rapidly after 4 d culture in sucrose. The results are discussed in relation to the role of petiolarcarbohydrate accumulation in the regulation of CO₂ fixation,primordium development, and senescence in this system.