A new species of Daphniopsis (Crustacea: Anomopoda: Daphniidae) from Australian salt lakes

A new species of the genus Daphniopsis found in Australian salt lakes is described and illustrated. A differential diagnosis and short taxonomic remarks are presented.     

Breeding behaviour, relatedness and sex-investment ratios inLeptothorax tuberum Fabricius

The ant speciesLeptothorax tuberum was shown to be predominantly monogynous. Queens usually mate once only but some nests may have a multiply-mated queen or are partially or serially polygynous. As expected from these results, within nest relatedness between workers and between workers and alate queens was found to be high. Almost fifty percent of nests had no nest queen which may indicate high queen mortality, queens leaving to found new nests or nest fragmentation. Observed female investment frequencies (IF _o ) were not significantly different from those expected on the basis of worker control of sexual production and the relatedness estimates of workers to alate queens and workers to males calculated from isozyme data (IF _E ). These values were not consistent with queen control. There was no evidence for lower IF _o s in queenless nests nor for higher IF _o s in larger nests classified by worker number. When nests were classified by sexual productivity, however, there was a strong rank correlation between productivity and female bias. This is the first study of an ant species to test observed IF against expected IF calculated without inferring between caste relatedness from worker data or pooling of data from different castes.     

Development of a transient expression system in grapevine via agro-infiltration

Transient expression of genes using Agrobacterium is a powerful tool for the analysis of gene function in plants. We have developed this method for the analysis of genes involved in disease resistance in grapevine leaves. Our research showed that the quality of the plant material, the plant genotype used for agro-infiltration and the presence of additional virulence factors (carried on plasmid pCH32) in the Agrobacterium strain are all important factors for success of the procedure. After optimising these factors, we consistently achieve sufficient acceptable levels of expression of the markers beta-glucuronidase (GUS) and green fluorescent protein (GFP) using vacuum infiltration of grapevine leaves from plants grown in vitro. We used this procedure to investigate the proposed role of stilbenes in defense against grapevine downy mildew (Plasmopara viticola) by transiently overexpressing stilbene synthase in grapevine leaves, before infection with P. viticola. We found that agro-infiltration itself induces the synthesis of stilbenes in grapevine leaves, thus preventing us to test the effect of the overexpression of stilbene synthase in defense. However, our results revealed that agro-infiltration before P. viticola inoculation had an effect on the development of the infection. Further research is required to show whether stilbenes or some other factor are the causal agent restricting pathogen development. The method described here provides and excellent tool to exploit at the many grapevine genomic resources now available, and will contribute to a better understanding of many areas of grapevine biology.     

Living in a Phaeocystis colony: a way to be a successful algal species

Evidence is provided showing that in two species of Phaeocystis (P. globosa and P. pouchetii) the colonial cells possess a much higher growth rate than the single cells when grown under identical conditions. Based on the DNA-cell-cycle method gross growth rate of colony cells exceeded those of co-occurring single cells by a factor 1.5 up to 3.8. The dominance of colonies in blooms of Phaeocystis can therefore be primarily due to their significantly high growth rate allowing a rapid bloom formation.Both Phaeocystis species showed ultradian growth but differed in timing of the initiation of the second DNA replication phase. In both species the first DNA-replication period started at the end of the (local) light period and was completed in the early dark period. In P. globosa this was immediately followed by the second DNA-replication period (first half of the dark period). In P. pouchetii this process was delayed by ca. 12 h until the middle of the light period (local noon).Flow cytometric analysis of the cell size and chlorophyll fluorescence showed little variation in colony and single cells of P. pouchetii. In contrast, colonies of P. globosa showed often the presence of two cell morphs, co-occurring in the same colony. The size of both morphs was identical but they differed in chlorophyll fluorescence up to a factor 4. In general the high chlorophyll cell morph dominated (>70% of the total colony cells). Both colony cell morphs were observed in cultures, mesocosms differing in N/P ratio but also in the field.     

Morphology and defensive structures in the predator-prey interaction: an experimental study of Parabroteas sarsi (Copepoda,Calanoida) with different cladoceran prey

Parabroteas sarsi is a predaceous calanoid copepod commonly found in South Andes lakes. Feeding experiments were carried out in order to estimate the predation rates and attack patterns on different cladoceran prey. Predation rates were related with prey sizes. The smallest prey, Bosmina longirostris, was ingested up to 5 prey pred^–1 h^–1 while the largest, Daphnia middendorffiana, only at 0.12 prey pred^–1 h^–1. The functional response of P. sarsi differed when confronted with different prey although in all cases, the number of kills increased with prey density. A saturation of ingestion rates at high prey densities was only observed for B. longirostris and Ceriodaphnia dubia juveniles. Remains seldom appeared at the end of the experiments, implying that the predator consumed prey totally. Yet, in all experiments carried out with Daphnia ambigua and D. middendorffiana, remains, including soft parts, were found. Direct observations of attack and of number and types of remains showed interference of handling by tail, helmet, and size of the prey.     

Breeding system of a plesiomorphic floral type: an investigation of small flowered Streptocarpus (Gesneriaceae) species

Six different floral morphologies can be found among the ca. 146 species of Streptocarpus occurring in Africa and Madagascar. One of these, a simple, small pouch type, was found to be plesiomorphic for the genus after mapping these floral types onto a molecular phylogeny. The breeding systems and population structure of three species possessing the plesiomorphic small floral morphology, S. micranthus, S. ibityensis and S. lanatus, have been investigated using nuclear microsatellite markers. Significant deviations from panmixia were found both at the between and within population level (S. micranthus θ = 0.708, f = 0.786; S. ibityensis, θ = 0.173, f = 0.138; S. lanatus, θ=0.539, f = 0.646). As a florally diverse genus, Streptocarpus is unusual in having a predominantly selfing, mixed mating breeding system as a plesiomorphic condition.     

Breeding system and seed set inEuonymus europaeus (Celastraceae)

The seed set and breeding system in a naturalized population ofEuonymus europaeus is described. The average seed set is lower (5.7%) and more variable in male than in female plants (9.3%). Some male plants set little or no seed. The results are compared with those ofDarwin, who describedE. europaeus as polygamous and trioecious; it is concluded that the species is better described as gynodioecious.     

Daphniopsis australis nov.sp. (Crustacea: Cladocera), a further daphniid in Australian salt lakes

Daphniopsis australis, a new species of cladoceran in Australian salt lakes, is described, and some brief comments on its distribution are given.     

Breeding aye-ayes: an aid to preserving biodiversity

In August 1992 an aye-aye Daubentonia madagascariensis (Primates) was bred in captivity for the first time. This species is the only living representative of a monotypic family and is endangered in its native Madagascar. A brief history of the captive breeding effort and a summary of the conservation problems facing the fauna, flora, and people of Madagascar is given. The role that a captive breeding programme for aye-ayes can fulfil as an aid to preserving biodiversity is discussed.     

Subgeneric differentiation within Kurzia (Crustacea: Anomopoda: Chydoridae) and a new species from Central America

The genus Kurzia is divided into two subgenera: Kurzia s. str. and Rostrokurzia n. subg. Subgenus Kurzia includes Kurzia (K.) latissima Kurz, 1874, with a palearctic -, Kurzia (K.) polyspina n. sp. with a neotropic - , and Kurzia (K.) cf. media (Birge, 1879) with a nearctic distribution. Rostrokurzia includes Kurzia (R.) longirostris Daday, 1898 (pantropical distribution), and Kurzia (R.) brevilabris Rajapaksa & Fernando, 1986, from subtropical and tropical Asia. Kurzia latissima Kurz, 1874, from Central Europe is redescribed in detail.     

PEG-mediated plastid transformation: a new system for transient gene expression assays in chloroplasts

Summary Evidence is presented for the introduction of functional copies of the GUS-reporter gene with plastid regulatory signals into chloroplasts after treatment of Nicotiana plumbaginifolia leaf protoplasts with PEG. GUS-activity is found in cells derived from protoplasts treated with PEG in the presence of plasmids harbouring the GUS-gene under the control of plastid promoter and terminator signals (plastid-specific reporter gene constructions). The activity is maintained after chloroplast isolation and incubation with the protease thermolysin under conditions sufficient to completely remove the much higher transient nuclear/cytoplasmic expression of a GUS-gene carrying the CaMV 35S-promoter. Likewise, GUS-activity derived from a plasmid coding for the nuclear/cytoplasmic expression of the reporter gene with a plastid transit presequence is also maintained after these procedures. These results indicate that PEG-treatment is a suitable protocol by which to introduce DNA into chloroplasts for the study of transient gene expression.     

Daphnia (Cienodaphnia) menucoensis (Anomopoda; Daphniidae): a new species from athalassic saline waters in Argentina

Daphnia (Ctenodaphnia) menucoensis n. sp. is described from various localities in arid and semiarid Argentina. D. menucoensis has no ocellus, and a characteristic head, fornices, ephippium and denticular arrangement of postabdomen in females and males. The species belongs to a group, along with D. mediterranea, D. dolichocephala Negrea 1984, and D. salina, sharing ecological and morphological characteristics.     

Sexual reproduction in Daphnia: interspecific differences in a hybrid species complex

To investigate whether reproductive variation in the Daphnia galeata-cucullata-hyalina hybrid species complex can explain the occurrence of hybrids and backcrosses, a total of 43 clones from three north German lakes were tested for allocation to sexual reproduction under equal stress conditions. Six replicates per clone were followed until the seventh adult instar. I used the following cues to promote sexual reproduction: short photoperiod, water from a crowded Daphnia culture, fish-conditioned water and low food concentration. For each animal, clutch size and clutch sex were recorded. Ephippia, which were empty since the animals were cultured individually, were only produced by D. cucullata and D. cucullata x hyalina (26% and 6% of the broods, respectively), whereas almost all taxa produced males (the range was 2–15%). Intraspecific variation for male and ephippial production was also found. The fact that the taxa tested show different responses to the stimuli of-fered may indicate that there is reproductive isolation between them. This is supported by field data from the Tjeukemeer (The Netherlands) which shows that D. galeata mostly produces ephippia in spring and D. cucullata in autumn. The presence of hybrids with ephippia in both seasons, however, shows that backcrossing is also possible.     

The fern as a model system to study photomorphogenesis

The fern gametophyte is a good model system for studying cell biological, physiological, and photobiological aspects of the fundamental processes of plant development and physiological phenomena, because of its autotrophic characteristics and its simple structure. The cells, moreover, are not surrounded by tissue, so observation and manipulation of the cells are very easy. Here I summarize a part of my knowledge of fern systems, which I have studied for nearly 40 years. Masamitsu Wada is the recipient of the BSJ Research Award for 2004.     

Breeding suppression in the bank vole as antipredatory adaptation in a predictable environment

Summary In northern Fennoscandia, microtine rodent populations fluctuate cyclically. The environment of an individual vole can be considered to be predictable when the risks of predation and intra- and interspecific competition change with the cycle, such that both are high during the population highs of voles. The risk of predation is also high during the vole crash. After the crash, the vole population is characterized by low intra- and interspecific competition and low predation pressure. The main predators affecting voles during the crash are the small mustelids, least weasel and stoat. The density of these specialist predators declines drastically during the winter after the vole crash. We studied experimentally the impact of the perceived presence of stoats on the breeding and mating behaviour of voles. In a series of breeding experiments with bank voles,Clethrionomys glareolus, both old and young females suppressed breeding when exposed to the odour of stoats,Mustela erminea. The weights of females decreased in both experimental and control groups, but more among the voles under odour exposition. It seems that females actively avoided copulations under high predation risk and that breeding suppression is mediated by a change in female mating behaviour. There was no change in male behaviour or physical condition between the experimental and control treatments. An alternative mechanism for the observed breeding suppression could be the one caused by decreased feeding in females mediated with low energy intake which does not allow breeding. Regardless of its mechanism, delay of breeding should increase the probability of non-breeding females to survive to the next breeding season. The females surviving the crash should gain a strong selective advantage in a predator-free environment of the subsequent breeding season, which could explain the adaptive function of this antipredatory strategy.     

Breeding system and reproductive skew in a highly polygynous ant population

Factors affecting relatedness among nest members in ant colonies with high queen number are still poorly understood. In order to identify the major determinants of nest kin structure, we conducted a detailed analysis of the breeding system of the ant Formica exsecta. We estimated the number of mature queens by mark-release-recapture in 29 nests and dissected a sub-sample of queens to assess their reproductive status. We also used microsatellites to estimate relatedness within and between all classes of nestmates (queens, their mates, worker brood, queen brood and male brood). Queen number was very high, with an arithmetic mean of 253 per nest. Most queens (90%) were reproductively active, consistent with the genetic analyses revealing that there was only a minimal reproductive skew among nestmate queens. Despite the high queen number and low reproductive skew, almost all classes of individuals were significantly related to each other. Interestingly, the number of resident queens was a poor predictor of kin structure at the nest level, consistent with the observation that new queens are produced in bursts leading to highly fluctuating queen number across years. Queen number also varied tremendously across nests, with estimates ranging from five to several hundred queens. Accordingly, the harmonic mean queen number (40.5) was six times lower than the arithmetic mean. The variation in queen number was the most important factor of the breeding system contributing to a significant relatedness between almost all classes of nestmates despite a high average number of queens per nest. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Received 12 November 2007; revised 4 May 2008; accepted 8 May 2008.     

Change of adaptations from entomophily to autogamy inParahebe linifolia (Scrophulariaceae)

Measurements of 16 inflorescence and floral characters from 5 populations ofParahebe linifolia (3 of entomophilous subsp.linifolia; 2 of autogamous subsp.brevistylis) were analysed. Discontinuous variation of three characters associated with the mechanisms of pollination suggests these are under strong selection towards different optima in each subspecies. Variation which is continuous and associated with the type of pollination in 4 characters mostly concerned with display is thought to result from selection for metabolic economies, counteracted strongly in subsp.linifolia, but less so in subsp.brevistylis, by selection for display. Nine more characters vary in a way not known to be associated with the two pollination systems.     

Phylogeny and habitat adaptations within a monophyletic group of wetland moss genera (Amblystegiaceae)

Genus level phylogenetic patterns within a monophyletic group of wetland mosses consisting ofTomentypnum, Hamatocaulis, Scorpidium, Conardia, Calliergon, Warnstorfia, Straminergon, andLoeskypnum (Amblystegiaceae) are cladistically analysed, usingPalustriella and partlyCratoneuron as outgroups. The ingroup consists of two clades, one withTomentypnum, Hamatocaulis andScorpidium, the other with the other ingroup genera. The second clade gets completely resolved only with the inclusion of habitat data. The adaptation to relatively dry wetland habitats probably evolved in the ancestor ofStraminergon andLoeskypnum, the species ofCalliergon andWarnstorfia, which are more ancestral, growing in wetter habitats. The more primitive taxa of the ingroup, as well asPalustriella species, occur in relatively mineral-rich habitats and adaptations to poorer habitats occurred several times in the two clades.