Seasonal and inter-individual variation in testosterone levels in badgers <Emphasis Type="Italic">Meles meles</Emphasis>: evidence for the existence of two endocrinological phenotypes

Elevated testosterone levels can lower condition and increase parasites. We analysed testosterone in 84 blood samples of wild European badgers Meles meles collected at regular intervals (winter = mating season; spring = end of mating season; summer = minor mating peak; autumn = reproductive quiescence), and related variation to body condition, subcaudal gland secretion, parasite burden, and bite wounding. All males showed elevated levels in winter and low levels in autumn. In neither season did testosterone correlate with fitness-related parameters. However, two different endocrinological phenotypes existed in spring and summer. Whilst some males lowered their testosterone to levels comparable to autumnal quiescence (Type 1), others maintained elevated levels comparable to those during winter (Type 2). In spring and summer high levels were correlated with lower body condition and increased parasite burden, and Type 2 males tended to suffer higher mortality rates than Type 1. No animals older than 6 years adopted phenotype 2, indicating that males either switch phenotypes with age or that Type 2 results in lower life expectancy, evidencing the costs of male reproduction in badgers.     

Net costs of group living in a solitary forager, the Eurasian badger (Meles meles)

Group living is expected to evolve under two extreme conditions:when there are net benefits to the individual of living in agroup and when there are net costs to living in a group togetherwith strong ecological constraints on dispersal and independentbreeding. A third condition may facilitate group formation:when the territorial defense of resources that are dispersedwidely or renewed at high rates allows groups to form at nocost to group members. Eurasian badgers are solitary over alarge part of their geographic distribution and forage aloneeven where diey live in territorial groups. To determine whichof the three conditions best explains group living in badgers,we analyzed dispersal and breeding patterns. Using these datawe describe the mechanism of group formation and the net costsor benefits of group living in 16 badger groups in one population.Groups form primarily by the retention of young on their natalterritory. Typically, groups contain one or more sexually maturebut nonbreeding females in addition to one or more breedingfemales. Females do not benefit from group living as indicatedby the lack of relationships, or perhaps negative relationships,between the proportion of adult females that bred in a groupand mean reproductive success, on the one hand, and group sizeand components of group size, on the other. A high reproductivefailure rate among females in this and other populations ofsocial badgers, as compared with a population of solitary badgers,suggests that there is a cost of group living to females. Wepropose that if badgers defend resources whose spatial distributionor high renewal rates allow groups to form on a territory atlitde or no cost to group members, weak ecological constraintson dispersal and independent breeding are sufficient to explainthe formation of groups. Badgers appear to have not evolvedcooperative breeding in response to these ecological conditions,perhaps because badger groups represent an early stage in theevolution of carnivore sociality.     

Helminth parasites of the Eurasian badger (<Emphasis Type="Italic">Meles meles</Emphasis> L.) in the Basque Country (Spain)

The helminthological study of 26 Eurasian badgers (Meles meles L.) in the Basque Country (northern Spain) revealed the presence of two trematode (Euryhelmis squamula and Brachylaima sp.), three cestode (Atriotaenia incisa, Mesocestoides sp. and Taenia sp.) and five nematode (Aonchotheca putorii, Physaloptera sp., Molineus patens, Uncinaria criniformis and Strongyloides sp.) species. All 15 individuals analysed for Trichinella sp. were negative. The coprological analysis (flotation and migration) revealed the excretion of strongylid, capillariid and trematode eggs, and Crenosoma sp. and Angiostrongylus sp. larvae. No sex- or age-related differences were found in the parasite burden or egg and larvae excretion. A. incisa and M. patens abundances were positively correlated, both species being negatively correlated with badger weight. The presence of adults of U. criniformis and strongylid eggs in faeces was not independent. Badgers excreting Angiostrongylus larvae were in poorer condition than those not excreting.     

The Ectoparasites of the European Badger, Meles meles, and the Behavior of the Host-Specific Flea, Paraceras melis

The badger-specific flea, Paraceras melis, jumps repeatedly when separated from its host Meles meles; thereafter fleas settled into sheltered positions. After separation from badgers, some 42% of fleas (n = 63) voided their gut contents; this was associated with a significant increase in mean jumping distance. The maximum longevity of fleas away from the host was 89 days, with 50% mortality at around 35 days. Badger lice, Trichodectes melis, survived for up to 3 days postcapture. We conclude that the badger's habit of frequently swapping dens with a mean period of return of 6 days is unlikely to bring about significant mortality of adult fleas but may effectively eradicate lice. Fleas abandoned in bedding in a simulated badger sett were mobile, being drawn toward light and moving upward. This response would draw the fleas to the den entrance, which may be a suitable site to intercept returning badgers. The fleas responded to stimuli which might signal the proximity of the host: they jumped toward sources of carbon dioxide and of carbon dioxide in air current directed at the flea. The strongest response was seen when a mixture of stimuli consisting of carbon dioxide, a dark circle of card, and movement were tested; the majority of fleas jumped toward the mixed stimulus. Finally, fleas separated from the host responded to exhaled air by running and jumping; this is in marked contrast to their response to those stimuli when on the host, when fleas run downward and very rarely jump. These contrasting observations find adaptive explanation in the two contexts.     

The effect of seasonality on oxidative metabolism in Nacella (Patinigera) magellanica

We studied the seasonal variation on aerobic metabolism and the response of oxidative stress parameters in the digestive glands of the subpolar limpet Nacella (P.) magellanica. Sampling was carried out from July (winter) 2002 to July 2003 in Beagle Channel, Tierra del Fuego, Argentina. Whole animal respiration rates increased in early spring as the animals spawned and remained elevated throughout summer and fall (winter: 0.09 ± 0.02 μmol O₂ h^− 1 g^− 1; summer: 0.31 ± 0.06 μmol O₂ h^− 1 g^− 1). Oxidative stress was assessed at the hydrophilic level as the ascorbyl radical content / ascorbate content ratio (A / AH⁻). The A / AH⁻ ratio showed minimum values in winter (3.7 ± 0.2 10^− 5 AU) and increased in summer (18 ± 5 10^− 5 AU). A similar pattern was observed for lipid radical content (122 ± 29 pmol mg^− 1 fresh mass [FW] in winter and 314 ± 45 pmol mg^− 1 FW in summer), iron content (0.99 ± 0.07 and 2.7 ± 0.6 nmol mg^− 1 FW in winter and summer, respectively) and catalase activity (2.9 ± 0.2 and 7 ± 1 U mg^− 1 FW in winter and summer, respectively). Since nitrogen derived radicals are thought to be critically involved in oxidative metabolism in cells, nitric oxide content was measured and a significant difference in the content of the Fe–MGD–NO adduct in digestive glands from winter and summer animals was observed. Together, the data indicate that both oxygen and nitrogen radical generation rates in N. (P.) magellanica are strongly dependent on season.     

A survey of helminth infection in Eurasian badgers (Meles meles) in relation to their foraging behaviour in a Mediterranean environment in southwest Portugal

This study provides the first data on the helminth fauna of the Eurasian badger in the southwestern edge of its range (Grândola Mountain, Portugal) and interprets the results in relation to badger diet and feeding behaviour. By examination of 163 badger faecal samples, faecal developmental stages (eliminative forms) of four helminth species and one genus were identified: one cestode (Atriotaenia incisa) and four nematodes (Mastophorus muris, Molineus patens, Uncinaria criniformis and Strongyloides sp.). The overall prevalence of parasites was 62%, with limited seasonal variation. Single parasite excretions were dominant and Strongyloides sp. excretion was the most common. Diet assessment based on 450 faecal samples revealed that badgers consumed mainly insects and fruits. No correlation was detected between helminth prevalence and diet. Apparently, diet (mainly insects) and feeding behaviour (fossorial), together with the species’ social behaviour (anal scent marking of group members), facilitate the infection with helminths. The helminth fauna of Eurasian badgers in Grândola Mountain has isolationist characteristics, apparently indicating low host colonisation.     

Sexual dimorphism of craniological characters in Eurasian badgers, Meles spp. (Carnivora, Mustelidae)

An analysis of 30 craniological characters of Eurasian badgers (Meles spp.) revealed different levels of sexual size dimorphism (SSD) and geographic variation in the three different species. SSD is displayed mostly in the general size of the skull (condylobasal length, zygomatic width, width of rostrum, and cranial height) and mandible (height of the vertical mandibular ramus, total length of the mandible, and length between the angular process and infradentale), and in some dental characters (length of the upper molar M¹). The most stable size dimorphism is manifested in the size of the canines, which is pronounced in all studied samples. SSD is not apparent in the length of the auditory bulla, the postorbital width, the minimum palatal width, the length of the lower molar M₂, and the talonid length of the lower carnassial tooth M₁.In both the European badgers, Meles meles, and the Asian badgers, Meles leucurus, two geographic forms that differ in the degree of SSD have been found. The most pronounced SSD of cranial characters is found in the Transcaucasian form of Meles meles and the Far-Eastern form of Meles leucurus. In the large European form of Meles meles, SSD is less pronounced in both absolute and relative criteria than in the smaller Transcaucasian form. An analogous situation is observed in the larger Siberian and smaller Far-Eastern forms of Meles leucurus. In the Japanese badgers, Meles anakuma, a downsizing of the skull is accompanied by a decrease in SSD (except in canine size) in comparison to the continental species. The significant differences in the manifestation of SSD in the Eurasian badgers support an earlier hypothesis (Abramov, 2001. Proc. Zool. Inst. Russ. Acad. Sci. 288, 221-233; Abramov, 2002. Russ. J. Theriol. 1 (1), 57-60; Abramov, 2003. Small Carnivore Conserv. 29, 5-7) that Meles meles, Meles leucurus, and Meles anakuma are separate species. The differences in the level of SSD among and within these three species of badgers may be attributed not to differences in the diet or social structure, but to the history of speciation events and formation of intraspecific distribution ranges.     

Probing the Drosophila retinal determination gene network in Tribolium (II): The Pax6 genes eyeless and twin of eyeless

The Pax6 genes eyeless (ey) and twin of eyeless (toy) are upstream regulators in the retinal determination gene network (RDGN), which instructs the formation of the adult eye primordium in Drosophila. Most animals possess a singleton Pax6 ortholog, but the dependence of eye development on Pax6 is widely conserved. A rare exception is given by the larval eyes of Drosophila, which develop independently of ey and toy. To obtain insight into the origin of differential larval and adult eye regulation, we studied the function of toy and ey in the red flour beetle Tribolium castaneum. We find that single and combinatorial knockdown of toy and ey affect larval eye development strongly but adult eye development only mildly in this primitive hemimetabolous species. Compound eye-loss, however, was provoked when ey and toy were RNAi-silenced in combination with the early retinal gene dachshund (dac). We propose that these data reflect a role of Pax6 during regional specification in the developing head and that the subsequent maintenance and growth of the adult eye primordium is regulated partly by redundant and partly by specific functions of toy, ey and dac in Tribolium. The results from embryonic knockdown and comparative protein sequence analysis lead us further to conclude that Tribolium represents an ancestral state of redundant control by ey and toy.     

The phylogenetic placement of the Leucogastrales, including Mycolevis siccigleba (Cribbeaceae), in the Albatrellaceae using morphological and molecular data

The morphology of many hypogeous fungi converges on a homogeneous reduced form, suggesting that disparate lineages are subject to a uniform selection pressure. The primary goal of this study was to evaluate the morphology and infer the phylogeny of the Leucogastrales with Mycolevis siccigleba using a Bayesian methodology. A comprehensive morphological assessment was used for an a priori phylogenetic inference to guide the sequencing effort. All structures except spore ornamentation pointed to the Albatrellaceae as the most likely sister taxon. Polyporoletus sublividus, a close relative of Albatrellus, produces ornamented basidiospores with a similar structure to M. siccigleba basidiospores. The ITS from 30 taxa was used for the molecular phylogenetic analysis. P. sublividus was found sister to Mycolevis. Leucophleps spinispora and L. magnata formed a group sister to the Polyporoletus/Mycolevis group, whereas Leucogaster was polyphyletic with respect to the core of the Leucogastrales and sister to A. caeruleoporus. This relationship was expected as previously undescribed chlamydospores produced by members of Albatrellus had a similar morphology to the basidiospores of L. rubescens.     

The phylogenetic placement of Ostropales within Lecanoromycetes (Ascomycota) revisited

Results of molecular studies regarding the phylogenetic placement of the order Ostropales and related taxa within Lecanoromycetes were thus far inconclusive. Some analyses placed the order as sister to the rest of Lecanoromycetes, while others inferred a position nested within Lecanoromycetes. We assembled a data set of 101 species including sequences from nuLSU rDNA, mtSSU rDNA, and the nuclear protein-coding RPB1 for each species to examine the cause of incongruencies in previously published phylogenies. MP, minimum evolution, and Bayesian analyses were performed using the combined three-region data set and the single-gene data sets. The position of Ostropales nested in Lecanoromycetes is confirmed in all single-gene and concatenated analyses, and a placement as sister to the rest of Lecanoromycetes is significantly rejected using two independent methods of alternative topology testing. Acarosporales and related taxa (Acarosporaceae group) are basal in Lecanoromycetes. However, if the these basal taxa are excluded from the analyses, Ostropales appear to be sister to the rest of Lecanoromycetes, suggesting different ingroup rooting as the cause for deviating topologies in previously published phylogenies.     

Growth of Phragmites australis and Phalaris arundinacea in constructed wetlands for wastewater treatment in the Czech Republic

Common reed (Phragmites australis) and reed canarygrass (Phalaris arundinacea) are two most commonly used plant species in constructed wetlands for wastewater treatment in the Czech Republic. Growth characteristics of both plants (biomass, stem count, and length) have been measured in 13 horizontal sub-surface flow constructed wetlands since 1992. The results revealed that while Phalaris usually reaches its maximum biomass as early as during the second growing season, Phragmites usually reaches its maximum only after three to four growing seasons. The maximum biomass of both species varies widely among systems and the highest measured values (5070 g m⁻² for Phragmites and 1900 g m⁻² for Phalaris) are similar to those found in eutrophic natural stands. The shoot count of Phragmites decreases after the second growing season while length and weight of individual shoots increases over time due to self-thinning process. Number of Phalaris shoots is the highest during the second season and then the shoot count remains about the same. Also the shoot length remains steady over years of constructed wetland operation.     

Biological control of black vine weevil Otiorhynchus sulcatus in Ireland using Heterorhabditis megidis

Heterorhabditis megidis (UK211) was applied against black vine weevil (BVW, Otiorhynchus sulcatus) in potted plants in a polyethylene (2002) or glasshouse (2003) and in field planted strawberries (2003). Both potted and field strawberries were artificially infested with BVW larvae. In a 2002 pot planting in the polyethylene house, a single drench application of 25,000 H. megidis infective juveniles per plant in 50 ml of water in mid September, reduced the number of BVW larvae to 1.8/20 plants. A second application in early October gave a reduction of 0.2/20 plants and in the third application, the following March no live weevils were recovered, compared to the control which had 8.2 larvae/20 plants. In a 2003 pot planting in a glasshouse, similar treatments gave a reduction of 5.2, 5.4 and 0.8 larvae/20 plants, respectively, compared to the control where 26.2 larvae/20 plants were recovered. In an artificially, BVW infested field trial, similar treatments gave a reduction to 2.2 larvae/20 plants in the single September treatment, and 2 larvae/20 plants in the single October treatment. The double (September and October) application reduced BVW larvae further to 1.6/20 plants and the triple (September, October and April) application to 0.4 larvae/20 plants, compared to the control where four larvae corresponded to every 20 plants. There was, therefore, little difference between the single and double autumn treatments indoors or in the field, and it mattered little whether the single application in the field was made in September or October under the conditions of 2003. Early spring application gave a significant reduction in BVW in each of the three experiments.     

The diet of the Alpine mouse Apodemus alpicola in the Swiss Alps

In this study, we used faecal analysis to determine the diet of the alpine mouse Apodemus alpicola in the field for the first time. This species consumes mainly insects in spring and fruits and seeds of small herbaceous dicotyledons in summer and autumn. Compared to the two congeneric species A. flavicollis and A. sylvaticus, which also occur in the Alps, the diet of A. alpicola is rich in contrasts, with a very pronounced difference between spring and summer. The absence of tree seeds also suggests a mostly terrestrial behaviour. We explain these facts by the specificity of the habitat of A. alpicola: the extreme weather conditions produce great seasonal changes in the vegetation, and the rocky ground favours the adaptation to rock climbing rather than to arboreal living.

Zusamenfassung

Nahrungszusammensetzung bei der Alpenwaldmaus Apodemus alpicola in den Schweizer AlpenDie Nahrungszusammensetzung der Alpenwaldmaus Apodemus alpicola wurde erstmals an Wildfängen und anhand von Kotanalysen qualitativ und quantitativ untersucht. Die Alpenwaldmaus konsumierte im Frühjahr hauptsächlich Insekten, im Sommer und Herbst Früchte und Samen kleiner Dicotyledonen der Krautschicht. Verglichen mit der Gelbhalsmaus A. flavicollis und der Waldmaus A. sylvaticus, die ebenfalls in den Alpen vorkommen, ist die Nahrungspalette von A. alpicola kontrastreicher, mit größeren Unterschieden zwischen Frühjahrs- und Sommerkost. Wir erklären dies durch extreme Klimabedingungen, die zu ausgeprägten jahreszeitlichen Änderungen in der Vegetation führen. Das Fehlen von Baumsamen läßt auf ein vorwiegend terrestrisches Futtersuchverhalten schließen. Große Hinterfüße und langer Schwanz sind offenbar Anpassungen ans Felsklettern und nicht an arboricoles Verhalten.     

Ontogenetic diet shifts and resource partitioning among piscivorous fishes in the Venezuelan ilanos

Synopsis Resource utilization by nine abundant piscivores from a diverse tropical fish assemblage was examined over the course of a year. All nine species exhibited peak reproduction during the early wet season and a similar sequence of size-dependent shifts from a diet composed primarily of microcrustacea, to aquatic insects, and finally fishes. Three piranha species specialized on fish fins, particularly at subadult size classes (SL 30–80 mm). Gradual dessication of the floodplain during the transition season was associated with fish growth, increased fish density, and decreased aquatic primary productivity and availability of invertebrate prey. Based on 118 resource categories, average pairwise diet overlap was low during all three seasons: wet, transition, and dry. Of 72 species pairings, only one pair of fin-nipping piranhas exhibited high overlap simultaneously on three niche dimensions: food type, food size, and habitat. Adults of two species, a gymnotid knifefish and pimelodid catfish, were largely nocturnal. Patterns of habitat utilization indicate that piranhas may restrict diurnal use of the open-water region by other piscivores. Collective diet overlap of individual piscivore species with the other eight feeding guild members and collective overlaps with the entire fish community each revealed two basic seasonal trends. Four species that showed an early switch to piscivory also showed a high degree of diet separation with both the guild and community at large on a year-round basis. The five remaining species showed lowest collective diet overlaps during the transition season when availability of invertebrates was reduced and fish densities were maximal. Whereas predation may play a role in habitat separation, diffuse competition for food resources during the approximately four-month transition season probably is the principal factor yielding patterns of diet specialization.