Zsolt Pénzes

In vitro water activity and pH dependence of mycelial growth and extracellular enzyme activities of Trichoderma strains with biocontrol potential

Aims:  Water activity (aw) and pH are probably the most important environmental parameters affecting the activities of mycoparasitic Trichoderma strains. Therefore it is important to collect information on the effects of these factors on mycelial growth and on the in vitro activities of extracellular enzymes involved in nutrient competition (e.g. β‐glucosidase, cellobiohydrolase and β‐xylosidase) and mycoparasitism (e.g. N‐acetyl‐β‐glucosaminidase, trypsin‐like protease and chymotrypsin‐like protease) of Trichoderma strains with biocontrol potential.

Evolution of Genes and Repeats in the Nimrod Superfamily

The recently identified Nimrod superfamily is characterized by the presence of a special type of EGF repeat, the NIM repeat, located right after a typical CCXGY/W amino acid motif. On the basis of structural features, nimrod genes can be divided into three types. The proteins encoded by Draper-type genes have an EMI domain at the N-terminal part and only one copy of the NIM motif, followed by a variable number of EGF-like repeats. The products of Nimrod B-type and Nimrod C-type genes (including the eater gene) have different kinds of N-terminal domains, and lack EGF-like repeats but contain a variable number of NIM repeats. Draper and Nimrod C-type (but not Nimrod B-type) proteins carry a transmembrane domain. Several members of the superfamily were claimed to function as receptors in phagocytosis and/or binding of bacteria, which indicates an important role in the cellular immunity and the elimination of apoptotic cells. In this paper, the evolution of the Nimrod superfamily is studied with various methods on the level of genes and repeats. A hypothesis is presented in which the NIM repeat, along with the EMI domain, emerged by structural reorganizations at the end of an EGF-like repeat chain, suggesting a mechanism for the formation of novel types of repeats. The analyses revealed diverse evolutionary patterns in the sequences containing multiple NIM repeats. Although in the Nimrod B and Nimrod C proteins show characteristics of independent evolution, many internal NIM repeats in Eater sequences seem to have undergone concerted evolution. An analysis of the nimrod genes has been performed using phylogenetic and other methods and an evolutionary scenario of the origin and diversification of the Nimrod superfamily is proposed. Our study presents an intriguing example how the evolution of multigene families may contribute to the complexity of the innate immune response.

Phylogeny and DNA barcoding of inquiline oak gallwasps (Hymenoptera: Cynipidae) of the Western Palaearctic.

We examine phylogenetic relationships within the Synergus complex of herbivorous inquiline gallwasps (Hymenoptera; Cynipidae; Synergini) associated with cynipid host galls on oak, a biologically diverse group whose genus-level morphological taxonomy has long been considered stable but whose species level taxonomy is problematic. We incorporate data for over 70% of recognised Western Palaearctic species in five morphology-based genera (Ceroptres, Saphonecrus, Synergus, Synophrus, Ufo), comprising sequence for two mitochondrial loci (coxI, cytb) and one nuclear locus (28S D2). In particular, we assess the evidence for monophyly of two long-established, morphology-defined sections within the genus Synergus that differ in a range of biological traits. To aid analyses of ecological interactions within oak cynipid communities, we also consider the utility of cytochrome oxidase I (coxI) DNA barcodes in the oak inquilines. In this assessment, we do not assume that species are delineated at a single threshold value of sequence divergence for a single gene, but examine concordance in the composition of molecular operational Taxonomic units (MOTUs) across a range of sequence divergences in each gene and across genes. We also assess the impact of sampling effort on MOTU stability. Phylogenetic reconstructions for all three loci support monophyly for Synergus and Synophrus, but reject monophyly for Saphonecrus and for the two sections within Synergus. The suites of traits associated with the two sections of the genus Synergus are thus homoplasious. All three loci also reject monophyly for three Synergus species (S. hayneanus, S. pallipes, S. umbraculus). Sequences for each locus identify robust MOTUs that are largely concordant across loci for a range of cut-off values. Though many MOTUs correspond to recognised Linnean species, there is significant, multigene disagreement between groupings supported by morphology and sequence data, with both allocation of different morphospecies to the same MOTU and allocation of the same morphospecies to multiple MOTUs, regardless of cut-off value. Our results imply that while DNA barcoding has considerable utility within this group, morphology-based identification needs major revision at both genus and species levels. Further, lifehistory traits currently attributed to single morphospecies probably confound attributes of multiple lineages. Revealing patterns of character state evolution in Synergus requires collection of new host association and life history data explicitly linked to DNA barcode data for the specimens concerned.

Molecular study of arbuscular mycorrhizal fungi colonizing the sporophyte of the eusporangiate rattlesnake fern (Botrychium virginianum, Ophioglossaceae)

The arbuscular mycorrhizal (AM) fungi colonizing the sporophytes of the eusporangiate rattlesnake fern (Botrychium virginianum, Ophioglossaceae) in its Hungarian population were investigated in the present study. Different regions of the nrRNA gene complex were analyzed using two different primer sets. These produced similar results for the detected AM fungi phylotypes. Several AM fungal lineages were associated with sporophytes of B. virginianum. Phylogenetic analyses of different partial small subunit datasets grouped one lineage into the Gigasporaceae, showing similarities with Scutellospora sequences. In addition to unidentified Scutellospora phylotypes, it is possible that S. gregaria also colonized the fern. Several AM fungal phylotypes colonizing the sporophytes grouped into Glomus group A. They did not form distinct clades but grouped with sequences of AM fungi with different geographic and host origins. One main lineage clustered into the widespread G. fasciculatum/G. intraradices group and one into the subgroup GlGrAc, while others had no affinity to the subgroups of Glomus group A. As AM fungal phylotypes associated with B. virginianum seem to belong to widespread AM fungal taxa and show no specificity to this fern, we suppose that the previously described special anatomy of AM of B. virginianum is determined by the plant.

The phylogenetic relationships between Dryocosmus, Chilaspis and allied genera of oak gallwasps (Hymenoptera, Cynipidae: Cynipini)

Abstract Oak gallwasps (Hymenoptera; Cynipidae, tribe Cynipini) are cyclically parthenogenetic insects that induce galls on specific plant hosts in the family Fagaceae. Understanding the processes underlying the evolution of specific oak associations requires knowledge of the phylogenetic relationships among oak gallwasp genera. Although three major lineages of oak gallwasps have been identified, the status and relationships of several species‐poor but biologically significant genera remain unresolved. Two such genera are Chilaspis and Dryocosmus, whose western palaearctic species all gall oaks in the section Cerris. Dryocosmus is particularly significant biologically because it includes: (a) the only palaearctic gallwasp to gall chestnuts, Castanea, and (b) nearctic species. The oak section Cerris is wholly absent from the nearctic, and the relationship between palaearctic and nearctic Dryocosmus is significant for patterns of host plant evolution in the tribe as a whole. We examined the relationships between Chilaspis, Dryocosmus and other oak cynipid genera using cladograms from sequence data for two mitochondrial loci (cytochrome c oxidase subunit I and cytochrome b) and two nuclear loci (the 28S ribosomal gene regions D2 and D3–5). Our analyses support the following conclusions: (1) palaearctic Chilaspis and Dryocosmus species form an intermingled monophyletic group. (2) We propose that Chilaspis Mayr, 1881 is a syn.n. of Dryocosmus Giraud, 1859 and propose the name D. mayri as a comb.rev. for the species previously named C. mayri, and D. nitidus and D. israeli as comb.n. of C. nitida and C. israeli, respectively. (3) We reassess the utility of morphological characters previously regarded as diagnostic for these genera. (4) Two species previously known only from a single generation represent two halves of a single species lifecycle. Dryocosmus nervosus is here designated a syn.n. of D. cerriphilus. (5) The nearctic species D. favus lies outside the palaearctic Chilaspis/Dryocosmus clade, and Dryocosmus as currently recognized is not a monophyletic group. (6) Dryocosmus/Chilaspis is closely related to the other oak gallwasp taxa (Aphelonyx, Plagiotrochus, Pseudoneuroterus, Trichagalma, and some Neuroterus species) galling section Cerris oaks. This implies an early branching evolution of this oak association within this group, and supports previous work showing the rarity of oak gallwasp host shifts.

Dynamics of colony development in Polistes dominulus: a modeling approach

Abstract A simple model based on feedback mechanisms is developed to describe the dynamics of brood production and colony development of primitively eusocial paper wasps. The presence of pupae and empty cells stimulate egg laying, which varies between a basic rate and a physiological maximum. Newly hatched larvae are fed eggs, causing fluctuations in brood demography and forming cohorts of offspring. The basic feedback mechanisms produce emergent colony-level properties such as synchronized development of the brood and mature nest size. Results suggest that it is incorrect to imply colony decline from lack of nest growth, and that production of waves of offspring can be interpreted as the inevitable result of these simple feedback mechanisms rather than the solution to ultimate optimality criteria. Simulations using the parameters estimated in Polistes dominulus Christ are compared to studies of live wasps to test the validity of the model. Comparing simulated results with a perturbation experiment in nature suggests that feedback relationships establish a system that is robust and resilient against severe disturbance.

Systematic re-appraisal of the gall-usurping wasp genus Synophrus Hartig, 1843 (Hymenoptera: Cynipidae: Synergini).

Several unanswered questions remain regarding the taxonomy and phylogeny of inquiline gallwasps (Cynipidae: Synergini), obligate inhabitants of plant galls induced primarily by other gallwasps (Cynipidae: Cynipini and Diplolepidini). Here we use morphological and molecular data to revise the inquiline genus Synophrus, members of which are notable for extensively modifying the structure of galls induced by oak gallwasp hosts on oaks in the section Cerris of Quercus subgenus Quercus in the Western Palaearctic. Previous taxonomic treatments have recognized three Western Palaearctic species of Synophrus: S. pilulae, S. politus and S. olivieri. Our results support the establishment of four additional Western Palaearctic species: Synophrus hungaricussp.n., S. libanisp.n., S. syriacussp.n. and S. hispanicussp.n. We describe and diagnose these new taxa, analyse their phylogenetic relationships, and show that Synophrus inquilines are able to impose their own gall phenotypes on those of their hosts. We provide an updated key to Synophrus.

Morph-specific variation of floral traits associated with reciprocal herkogamy in natural populations of Primula vulgaris and Primula veris

Documenting the morph-specific variation of floral traits associated with reciprocal herkogamy is of special importance for revealing the functional significance of traits in the evolution and maintenance of the heterostylous syndrome. In order to describe the extent and specificity of variation, stigma height, anther height, stigma-anther separation and corolla tube length were measured on 800 flowers collected in two natural populations of Primula vulgaris and P. veris. Beside the almost complete separation of stigma heights between the two morphs, we found appreciable intermorph overlap in anther height and relatively broad range of stigma-anther separation so far reported for heterostylous species. The corolla tube length–stigma-anther separation relationship showed striking difference between the two floral morphs, which supports the hypothesis that length of the corolla tube plays a more important role in positioning the sex-organs in the appropriate distance in the short-styled than in the long-styled morph.

Genetic relatedness in wintering groups of house sparrows (Passer domesticus)

Social behaviour of group‐living animals is often influenced by the relatedness of individuals, thus understanding the genetic structure of groups is important for the interpretation of costs and benefits of social interactions. In this study, we investigated genetic relatedness in feeding aggregations of free‐living house sparrows (Passer domesticus) during the nonbreeding season. This species is a frequent model system for studies of social behaviour (e.g. aggression, social foraging), but we lack adequate information on the kin structure of sparrow flocks. During two winters, we ringed and observed sparrows at feeding stations, and used resightings to identify stable flock‐members and to calculate association indices between birds. We genotyped the birds using seven highly polymorphic microsatellite loci, and estimated pairwise relatedness coefficients and relatedness categories (close kin vs. unrelated) by maximum likelihood method. We found that most birds were unrelated to each other in the flocks (mean ± SE relatedness coefficient: 0.06 ± 0.002), although most individuals had at least a few close relatives in their home flock (14.3 ± 0.6% of flock‐mates). Pairwise association between individuals was not significantly related to their genetic relatedness. Furthermore, there was no difference between within‐flock vs. between‐flock relatedness, and birds had similar proportions of close kin within and outside their home flock. Finally, relatedness among members of different flocks was unrelated to the distance between their flocks. Thus, sparrow flocks were not characterized by association of relatives, nevertheless the presence of some close kin may provide opportunity for kin‐biased behaviours to evolve.

Kinship and aggression: do house sparrows spare their relatives?

Kin-selection theory predicts that relatedness may reduce the level of aggression among competing group members, leading to indirect fitness benefits for kin-favoring individuals. To test this hypothesis, we investigated whether relatedness affects aggressive behavior during social activities in captive house sparrow (Passer domesticus) flocks. We found that sparrows did not reduce their aggression towards kin, as neither the frequency nor the intensity of fights differed between close kin and unrelated flock-mates. Fighting success was also unrelated to kinship and the presence of relatives in the flock did not influence the birds’ dominance rank. These results suggest that the pay-offs of reduced aggression towards kin may be low in non-breeding flocks of sparrows, e.g. due to competition among relatives as predicted by a recent refinement of kin-selection theory. Our findings indicate that the significance of kin selection may be restricted in some social systems such as winter aggregations of birds.