Allozymic and morphometric analysis of populations in the Zygaena purpuralis complex (Lepidoptera, Zygaenidae)

In Central Europe and Asia Minor Zygaena purpuralis and Z. minos are two sibling species exhibiting a considerable geographic variation in several features. In this study we examine some populations from the Central and Southern Apennines (Italy) by comparing multivariate analyses of individual allozymic multilocus profiles and of individual morphometric profiles of male genitalia in order to assess their genetic and phenetic relationships.
Results indicate that populations of Z. purpuralis in the Apennines behave in rather different ways with respect to the occurrence of gene exchange with other gene pools. No gene flow appears to occur between two geographically close southern populations; however, extensive introgression, revealable at both the allozymic and morphometric level, seems to occur between some purpuralis and minos -like sympatric populations from Abruzzi. Evolutionary relationships among these peninsular Italy populations are discussed with reference to historical factors, that is, the occurrence of multiple Pleistocene refugia, which could have determined different degrees of isolation among gene pools. This situation is rather different from that previously outlined for Central Europe and present results suggest that the Z. purpuralis complex might include more than two biological species.     

Identification of the Tubulin Gene Family and Sequence Determination of One β-Tubulin Gene in a Cold-Poikilotherm Protozoan, the Antarctic Ciliate Euplotes focardii

ABSTRACT. Four different tubulin genes were identified in the somatic nucleus (macronucleus) of Euplotes focardii , a strictly coldadapted, Antarctic ciliate: one of 1,800 bp for α-tubulin and three of 2,150, 1,900, and 1,600 bp, respectively, for β -tubulin. Preliminarily analysed for restriction fragment length polymorphisms, these genes showed remarkable differences in organisation from tubulin genes of other ciliates which live in temperate areas and were analysed in parallel with E. focardii. The complete coding sequence of the 1,600 bp β -tubulin gene was then determined and shown to contain unique structural features of potential importance for E. focardii microtubule organization and activity. Of eight unique substitutions detected, seven were concentrated in the large amino terminal domain of the molecule that directly interacts with the carboxy terminal region of α-tubulin for heterodimer formation. Sequence analysis of the cloned gene revealed, in addition, a potential new exception in the use of the genetic code by ciliates. A TAG codon was aligned in correspondence with Trp-21 which is strictly conserved in every tubulin sequence so far determined.     

SOURNESS–SWEETNESS INTERACTIONS IN DIFFERENT MEDIA: WHITE WINE,ETHANOL AND WATER*

The aim of this work was to study the sourness–sweetness interactions in water, white wine and alcoholic environment to interpret sweet/sour perception in low concentrations within the range normally encountered in white wine. Nine trained assessors rated sweetness and sourness intensity in mixtures of fructose (11.1, 25.0 and 38.9 mM) and tartaric acid (pH 3.0, 3.4 and 3.8) in water and wine (experiment 1) or ethanol solutions at 2.0, 4.0 and 12.0% v/v (experiment 2). The range of quantitative responses was larger for sourness than for sweetness in the three media. The global sourness intensity perception in wine mixtures was significantly lower than in water and ethanol mixtures, indicating the effect of other wine components. The suppressive effect of tartaric acid on fructose sweetness was stronger than the suppressive effect of fructose on tartaric acid sourness.     

Specialisation of bacterial endosymbionts that protect aphids from parasitoids

1. Infection by the bacterial endosymbiont Hamiltonella defensa is capable of protecting the pea aphid from parasitism by Aphidius ervi and the black bean aphid from parasitism by Lysiphlebus fabarum. Here we investigate protection of a third aphid species, the cowpea aphid, Aphis craccivora, from four parasitoid species: Binodoxys communis, B. koreanus, Lysiphlebus orientalis, and Aphidius colemani. 2. We compared parasitism of A. craccivora lines that were either infected with, or cured of H. defensa separately for the four parasitoid species. Infection by H. defensa almost completely eliminated parasitism of A. craccivora by B. communis and B. koreanus, but had no effect on parasitism by L. orientalis and A. colemani. 3. This indicates at least genus‐level specificity of protective effects by H. defensa and we discuss implications of our findings on the known world‐wide distribution of this host/symbiont interaction.     

Cowpea aphid (Aphis craccivora) associated with different host plants has different facultative endosymbionts

Maternally inherited facultative endosymbiotic bacteria are common among insects, including many polyphagous insect herbivores. To investigate whether symbiont infection is structured by host plant in the polyphagous aphid Aphis craccivora Koch, pyrosequencing and diagnostic PCR were performed on 26 populations from two different host plants, alfalfa (Medicago sativa) or black locust (Robinia pseudoacacia). Results indicated that Aphis craccivora harbours distinctly different microbial communities in alfalfa versus locust. The facultative symbiont Hamiltonella was found only in aphids collected from alfalfa, and the facultative symbiont Arsenophonus was found only in aphids from locust. Hamiltonella is known to protect aphids against hymenopteran parasitoids, whereas the phenotypic effects of Arsenophonus in aphids are unknown. Correspondingly, a screen of the aphid samples for hymenopteran DNA indicated that Hamiltonella‐bearing alfalfa populations of A. craccivora experienced lower parasitism than Arsenophonus‐bearing locust populations. This study contributes to the growing body of evidence that correlative associations between bacterial endosymbionts and host plants may be a common phenomenon in polyphagous herbivores, and suggests that microbial symbionts have the potential to act as drivers for observed ecological differences among host‐associated populations of polyphagous insects.     

A new species of Allium (Alliaceae) from Dalmatia,Croatia

Allium croaticum , a new species from the island of Vis in Central Dalmatia (Croatia) is described and illustrated. Its relationships with allied species belonging to the A. stamineum group (Allium section Codonoprasum) are discussed. It is a diploid species (2n = 16), colonizing calcareous screes and flowering in early summer. Its morphology, leaf anatomy, karyology, palynology, ecology and taxonomic position are examined. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 106–114.     

Sex-specific strategies of dentine depletion in red deer

Worn teeth in herbivore ungulates may be related to lower efficiency in mastication and hence lower performance. However, selection should favour maximal performance in terms of body mass and reproductive capacity during reproductive lifespan, when permanent teeth are already partially worn. We hypothesize that wear rate may respond to a strategy of use of tooth materials (notably dentine), which balances instantaneous wear rate and performance against tooth preservation for future performance and reproduction. In the present study, we investigated 4151 carcasses of Iberian red deer Cervus elaphus hispanicus and show that more worn molars were not related to lower performance throughout age. By comparing between sexes, tooth wear rates were smaller in females than in males, but the relationship between tooth wear and body performance also differed between the sexes: females did not show a significant relationship between tooth wear and performance but males with more worn teeth were in general heavier and had larger antlers until senile age, when more depleted teeth were related to smaller antlers. These results reveal, for the first time, sex-specific lifetime strategies of dentine expenditure: maintenance of performance ability throughout a longer reproductive lifespan in females, compared with maximizing current performance by depleting dentine reserves within a shorter lifespan in males.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 487–497.     

Stipular extranuptial nectaries new to Polygala: morphology and ontogeny

Although taxonomic studies indicate that approximately one‐third of the genera of Polygalaceae have nodal glands, few anatomical data are available on the structure and ontogeny of these secretory organs. We studied the as yet unknown origin, structure and function of such glands in Polygala laureola. During field observations, we detected glucose in the secretion using Glicofita Plus® and visitors were recorded. Vegetative shoot apices and nodal glands were examined using light microscopy and scanning electron microscopy. The presence of glucose in the secretion allowed us to identify these nodal glands as extranuptial nectaries. Secretory cells occupy a medullary position and are surrounded by phloem. Vascular bundles are concentric, and xylem is only observed at the basal region of the nectary. Nectar is released during the daytime through a pore at the top of the nectary. A stipular origin was confirmed by the fact that the procambial strand is connected to the leaf trace, opposite the leaf gap. The occurrence of stipular extranuptial nectaries in a nodal position is new to Polygala. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 166 , 40–50.     

Influence of quantity and lability of sediment organic matter on the biomass of two isoetids,Littorella uniflora and Echinodorus repens

1. Despite real improvement in the water quality of many previously eutrophic lakes, the recovery of submerged vegetation has been poor. This lack of recovery is possibly caused by the accumulation of organic matter on the top layer of the sediment, which is produced under eutrophic conditions. Hence, our objective was to study the combined effects of quantity and lability of sediment organic matter on the biomass of Echinodorus repens and Littorella uniflora and on the force required to uproot plants of L. uniflora. 2. Lake sediments, rich in organic matter, were collected from four lakes, two with healthy populations of isoetids and two from which isoetids had disappeared. The four lake sediments were mixed with sand to prepare a range of experimental sediments that differed in quantity and lability of sediment organic matter. Two isoetid species, E. repens and L. uniflora, were grown in these sediments for 8 weeks. Sediment quality parameters, including elemental composition, nutrient availability and mineralisation rates, were determined on the raw sources of sediment from the lakes. Porewater and surface water were analysed for the chemical composition in all mixtures. At the end of the experiment, plants were harvested and their biomass, tissue nutrient concentration and (for L. uniflora) uprooting force were measured. 3. For both species, all plants survived and showed no signs of stress on all types of sediment. The biomass of E. repens increased as the fraction of organic matter was increased (from 6 to 39% of organic content, depending upon sediment type). However, in some of the sediment types, a higher fraction of organic matter led to a decline in biomass. The biomass of L. uniflora was less responsive to organic content and was decreased significantly only when the least labile sediment source was used to create the gradient of organic matter. The increase in shoot biomass for both species was closely related to higher CO₂ concentrations in the porewater of the sediment. The force required to uproot L. uniflora plants over a range of sediment organic matter fitted a Gaussian model; it reached a maximum at around 15% organic matter and declined significantly above that. 4. Increasing organic matter content of the sediment increased the biomass of isoetid plants, as the positive effects of higher CO₂ production outweighed the negative effects of low oxygen concentration in more (labile) organic sediments. However, sediment organic matter can adversely affect isoetid survival by promoting the uprooting of plants.