Mosaic pattern of genital divergence in three populations of Schistocerca lineata Scudder, 1899 (Orthoptera: Acrididae: Cyrtacanthacridinae)

Sexual selection theory predicts that genital structures in isolated populations are likely to diverge, but male genitalia are often species-specific, which led to the idea that male genitalia are relatively invariable within species. Previous allometric studies collectively suggested that male genitalia are intraspecifically invariable in size compared with external body parts. We investigated whether male genitalia are invariable in shape in three populations of a grasshopper Schistocerca lineata Scudder, 1899, using two independent methods of geometric morphometric analyses. Specifically, we focused on the idea that male genitalia are complex structures consisting of many functionally different components, and studied how these individual parts diverge among three populations. Individual components of male genitalia show different population-level divergence, resulting in the mosaic pattern of genital divergence. Individual components diverge independently from each other. Body size is positively correlated with genitalia size, but is significantly correlated with the shape of only one of the three genital structures we measured. Thus, different components of male genitalia may be influenced by different evolutionary processes. This study is the first to show that components of complex genitalia evolve separately within a species.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 289–301.     

Differentiation of metallicolous and non‐metallicolous Salix caprea populations based on phenotypic characteristics and nuclear microsatellite (SSR) markers

The Salicaceae family comprises a large number of high‐biomass species with remarkable genetic variability and adaptation to ecological niches. Salix caprea survives in heavy metal contaminated areas, translocates and accumulates Zn/Cd in leaves. To reveal potential selective effects of long‐term heavy metal contaminations on the genetic structure and Zn/Cd accumulation capacity, 170 S. caprea isolates of four metal‐contaminated and three non‐contaminated middle European sites were analysed with microsatellite markers using Wright's F statistics. The differentiation of populations North of the Alps are more pronounced compared to the Southern ones. By grouping the isolates based on their contamination status, a weak but significant differentiation was calculated between Northern metallicolous and non‐metallicolous populations. To quantify if the contamination and genetic status of the populations correlate with Zn/Cd tolerance and the accumulation capacity, the S. caprea isolates were exposed to elevated Cd/Zn concentrations in perlite‐based cultures. Consistent with the genetic data nested anova analyses for the physiological traits find a significant difference in the Cd accumulation capacity between the Northern and Southern populations. Our data suggest that natural populations are a profitable source to uncover genetic mechanisms of heavy metal accumulation and biomass production, traits that are essential for improving phytoextraction strategies.     

Comparative Leaf Epidermal Anatomy of Mutants of Barley (Hordeum vulgare L. 'Himalaya') which Differ in Leaf Length

We wished to determine the nature of differences in epidermalcell numbers and dimensions between leaves of different lengthin mutants of barley (Hordeum vulgare L. ‘Himalaya’).Three comparisons were made: leaf one (L1)vs. leaf four (L4);wild typevs. nine dwarf mutants and wild typevs. a slender mutant.L1 was shorter than L4, and for most lines this was associatedwith a change in epidermal cell number for the blade, and inboth cell number and length for the sheath. Compared to wildtype, the smaller leaves of dwarf plants generally had shorterand fewer cells in both blade and sheath. The blade of slenderplants was the same length (L1) or longer (L4) than wild type,while the sheath was longer than that of wild type for bothL1 and L4. Slender plants had longer but fewer cells than thewild type along the blade of L1, and shorter but more cellsfor the blade of L4. In the sheath, slender plants had longerand more (L1) or fewer (L4) cells than did the wild type. ForL1, variation in blade width amongst the barley lines was associatedwith a change in file width and file number. For L4, blade widthvaried only with file number, except for slender plants wherenarrow blades were associated with reduced file width. Hencethere was no consistent correlation between changes in cellsize or cell (or file) number with changes in leaf length orwidth. Differences depended on the leaf (L1vs. L4), leaf part(bladevs. sheath), and the nature of the mutation (dwarfvs.slender). Barley (Hordeum vulgare L. ‘Himalaya’); leaf epidermis; dwarf mutant; slender mutant     

Regeneration of Mesophyll Protoplasts Isolated from Dihaploid Clones of Solanum tuberosum

Protoplasts have been isolated from leaves of shoot cultures of six dihaploid clones of Solanum tuberosum L. (2n = 2x = 24). In the KM medium (Kao and Michayluk 1975), sustained cell divisions were obtained in up to 50% of the plated protoplasts of four clones, whereas only a few divisions occurred in the other two clones. The first mitosis appeared 2–8 days after plating, dependent on the clones. In the clones showing sustained cell divisions, a protoplast titre of about 5 × 10³ per ml turned out to be optimal. The culture conditions for protoplasts of one of the poorly growing clones, clone H² 140, have been improved using modified KM media, plating at a concentration of as high as 5 × 10⁴ cells per ml, and subsequent diluting at intervals 5 days. The dilutions were carried out with media containing 0.25% agar. Up to 60% of the plated protoplasts underwent divisions within 10 days under these conditions. After about 15 days, the regenerants were transferred onto media inducing organogenesis. Shoots and roots were formed on modified media MS (Murashige and Skoog 1962) and B5 (Gamborg et al. 1968). Plants have been regenerated in four of the investigated clones. Countings of chromosomes revealed a satisfactory stability of the karyotype in shoot culture and protoplast regeneration.     

Caste in the swarming wasps: 'queenless' societies in highly social insects

Morphometric data for 30 species of swarming wasps (Vespidae: Polistinae: Epiponini) are presented, representing all currently recognized genera. Data are coded according to whether females that were shown by dissection to be egglayers are larger, similar, or smaller for each dimension than non-egglayers. These data are analysed in a phylogenetic framework with primitively social Polistes and Mischocyttarus as outgroups. Representative measurements are illustrated to show that most genera of Epiponini appear to have ancestry in a lineage that has no queen caste comparable with either the primitively social outgroups, or the more derived species of the tribe. This analysis indicates that a conspiracy of workers that operates without a queen characterizes the societies of many Epiponini, or their recent ancestors.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 509–522.     

Survival,growth and reproduction of Daphnia galeata feeding on single and mixed Pseudomonas and Rhodomonas diets

1. Bacteria can be an important resource for zooplankton production in aquatic food webs, although the degree to which bacteria sustain zooplankton growth and reproduction is not clear. We performed a growth experiment with Daphnia galeata feeding on different ratios of P‐replete Pseudomonas and Rhodomonas, ranging from a 100% bacterial to a 100% algal diet. 2. A pure bacterial diet did not support survival, growth or reproduction of D. galeata. While a 20% share of Rhodomonas in the food allowed survival of daphniids, the occurrence of offspring on a 50% algal diet indicated that the threshold for successful reproduction was between those two proportions of algal food. Increasing the proportion of the alga further increased growth and reproductive output, indicating that Rhodomonas was a higher‐quality food than Pseudomonas. 3. A subsequent labelling experiment demonstrated that D. galeata incorporated phosphorus from Pseudomonas and Rhodomonas with similar efficiency, whereas carbon was incorporated more efficiently from Pseudomonas than from Rhodomonas. 4. we hypothesise that inadequate levels of essential biochemicals in pure bacterial diets led to decreased Daphnia performance. Concentrations of fatty acids in general, and especially of polyunsaturated fatty acids, were much lower in Pseudomonas than in Rhodomonas. This difference could explain the different growth and reproduction responses, although limitation by other essential biochemicals (e.g. sterols) cannot be ruled out. 5. Hence, where they dominate, bacteria may provide a significant part of the elemental flux to species feeding higher in the food web on the short term. However, the performance of consumers may be constrained by essential biochemicals.