How Do Infanticidal Male Bank Voles (Myodes glareolus) Find the Nest with Pups?

Infanticide, the killing of conspecific young, occurs in most mammal species, like in our study species, the bank vole (Myodes glareolus). Infanticide by adult males is regarded as a strong factor affecting recruitment of young into population. It is considered as an adaptive behaviour, which may increase male fitness via resource gain or an increased access to mates. When an intruder is approaching the nest, the mother should not be present, as her nest guarding is very aggressive and successful. Pups use ultrasonic vocalisation to call their mother when mother leaves nest for foraging but it is not know which cues do infanticidal males use to find the nest with vulnerable pups to commit infanticide? We studied whether the pups' sounds or the olfactory cues of the nest guide the males of known infanticidal behavioural trait towards the nest with vulnerable pups. Four nest boxes in a large indoor arena offered different nesting cues: nest odour, pup vocalisation, both odour and sound or control with no cue. The result showed that infanticidal males were more active in their searching behaviour than non‐infanticidal males and seemed to target the nest providing only acoustic cues. Four of the males, all infanticidal, intruded the nest box. Infanticidal males seem to actively search for nests with vulnerable pups by eavesdropping pup begging calls for absent mother. However, under natural conditions, mother presence and aggressive nest protection may be an effective counter strategy against strange male infanticide. When trapping study voles from the wild, we monitored occurrence of male infanticide across the breeding season from early to late summer. Proportion of infanticidal males was between 25 and 29% of all males tested along the breeding season. Our results suggest that male infanticide seems to cause a stable threat for pup mortality in increasing breeding season density.     

Pre-implantation Pregnancy Disruption in Female Meadow Voles Microtus pennsylvanicus (Rodentia: Muridae): Male Competition or Female Mate Choice?

I investigated alternative hypotheses concerning the functions of pre-implantation male-induced pregnancy disruption in meadow voles. Disruptions may be viewed as: 1. Postcopulatory male competition; 2. A mechanism for postcopulatory mate choice by females; and 3. A means of benefitting females by terminating investment in litters that may be harmed by new males. Female voles were paired with a second male 3 d after mating with their first mate. Behavioural interactions between the female and each male were compared for females that disrupted or retained the pregnancy sired by the first male. Whether they were the females' first or second mates, males siring litters showed similar high levels of approach and moderately high aggression, behaviour that differed from the females' other mates. Disrupted females huddled sooner with their second mates than females that retained their original pregnancies, and females tended to approach males that approached them. These results suggest that females influence whether a disruption occurs by the amount of contact they initiate with the second male, and thus pregnancy disruption may facilitate postcopulatory mate choice by females. This pre-implantation disruption did not enhance female reproductive success: pup survival was the same whether or not a disruption occurred, and males living with pups they had sired (after a disruption) spent as much time with them as males with unrelated pups (females did not disrupt).     

The Sex Specific Genetic Variation of Energetics in Bank Voles,Consequences of Introgression?

Interaction between mitochondrial and nuclear genomes is expected to affect energetic phenotypes of traits linked to mitochondrial physiology, further influencing the fitness. A rodent, the bank vole (Myodes glareolus), has a population structure completely or partially introgressed with mitochondria from its relative, the red vole (M. r utilus). Females that carried either bank vole mitochondria or mitochondria from the introgressed species were repeatedly mated with males of both mtDNA types. We found that in males, but not in females, morpho-physiological phenotypes are affected by sire type, causing decreases in body mass (BM) and basal metabolic rate (BMR; including BM corrected, rBMR) in individuals sired by fathers carrying introgressed mitochondria. Higher effect sizes for the proportion of additive genetic variation (and 5.6, 1.9 and 3.6 times higher narrow sense heritability for BM, BMR and rBMR, respectively), and lower for proportion of environmental variation were detected in progeny of non-introgressed males. Our data indicate that co-adapted and possibly co-introgressed nuclear genes related to energetic physiology have an important role in adaptation to the northern conditions in bank voles, and that sex linked nuclear genes are a potential source for variation in basal metabolic rate.     

Parasites in biodiversity conservation: friend or foe?

Parasites stabilise food webs and facilitate species coexistence but can also lead to population- or species-level extinctions. So, in biodiversity conservation, are parasites friends or foes? This question is misleading: it implies that parasites are not part of biodiversity. Greater integration of parasites into global biodiversity and ecosystem conservation efforts is required.     

Egorov’s narrow-skulled vole (Rodentia,Arvicolinae) from the Late Pleistocene of Eastern Siberia,a North American immigrant

A comparative study of the Late Pleistocene Egorov’s narrow-skulled vole from the Indigirka River basin is performed. The taxon was previously regarded as a subspecies of Microtus (Stenocranius) gregalis (Pallas, 1779). Based on a number of morphological characters, it is shown that this vole is closer to the American species Mynomes (Vocalomys) miurus (Osgood, 1901). It is proposed that Mynomes (V.) miurus egorovi (Fejgin in Baranova et Fejgin, 1980) penetrated into northeastern Siberia during the Zyryanian glacial.     

Time trends in the prevalence of birth defects in Texas 1999–2007: Real or artifactual?

BACKGROUND: Few studies have reported time trends for total birth defects or for a comprehensive range of phenotypes. METHODS: We examined data from the Texas Birth Defects Registry (TBDR) from 1999 through 2007. Poisson regression was used to fit trend lines to birth prevalence over time for total birth defects (each infant/fetus counted once), for every birth defect collected by the TBDR, and for subsets of cases or defects grouped various ways. RESULTS: From 1999 through 2007, birth prevalence of total birth defects in Texas increased 3.6% per year. Increases were observed in all population groups, persisted after adjustment for demographic characteristics, and were strongest in regions of Texas that were more urban. There was a wide variety of different defects showing significant increases. The trends of several defects were driven by their mild cases. Perhaps the most compelling finding was that larger upward trends were observed in defects that had been rated as more susceptible to diagnostic variation. One notable exception to that was gastroschisis, which showed an average increase of over 5% per year, the total birth defects rate in TBDR increased at 3.6% per year, similar to 3.7% per year in birth certificate check boxes. CONCLUSIONS: In our opinion, the weight of evidence in our study suggests that the observed increase over time in total birth defects and in many specific birth defects is artifactual. This likely reflects increased awareness, referral, detection, or documentation in health care facilities visited by TBDR staff, resulting in more complete ascertainment by the registry, rather than a true change over time in the occurrence of most birth defects. Birth Defects Research (Part A), 2011. © 2011 Wiley‐Liss, Inc.     

Are the dot-like chromosomes in Trinomys iheringi (Rodentia, Echimyidae) B chromosomes?

In this article we review the existing cytogenetic information on the polymorphic dot-like chromosomes in Trinomys iheringi, the only species in the family Echimyidae harboring them, and provide new data on the frequency, banding properties, meiotic behavior and DNA composition of these minute chromosomes. Since no individuals lacking these chromosomes have hitherto been found, one of the main properties of B chromosomes, i.e. dispensability, has not yet been tested, so that some reasonable doubt might exist on whether they are true B chromosomes. The dot-like chromosomes were also present in the twelve new individuals analyzed, showed intraindividual variation in number, most likely due to mitotic instability during development, failed to show C-bands, showed late-replication, paired among them in meiosis, but not with the large chromosomes, and appeared to be mainly composed of telomeric DNA. These results suggest that these dot-like chromosomes might actually be mitotically unstable micro B chromosomes showing very high frequency in the natural populations thus far analyzed. But, to be confident of this conclusion, individuals lacking the dot-like chromosomes should actively be searched in future research to test their dispensability.     

Ectoparasites of the zokor Myospalax myospalax (Rodentia) in northern Altaĭ

Following ectoparasites have been recorded on the zokor in the Northern Altay: specific fleas--Ctenophthalmus dilatatus, Rhadinopsylla ioffi, Brachyctenonotus myospalacis; a flea distributed on various rodents; ixodid ticks--Ixodes crenulatus, I. persulcatus; gamasid mites--Hirstionyssus myosplalacis. The C. dilatatus carried hypopi of acaroid mites.     

Tyrophagus putrescentiae (Sarcoptiformes: Acaridae) in the in vitro cultures of slime molds (Mycetozoa): accident,contamination, or interaction?

Experimental and Applied Acarology - Tyrophagus putrescentiae (Schrank), commonly known as the cereal mite, cheese mite, or ham mite, is a cosmopolitan species reported from various environments in...     

Parasites in hybridizing communities: the Red Queen again?

Over the past two decades, infection levels in hybrids have frequently been compared with those in their progenitor species to find out whether parasites favour or penalize hybridization. Four static infection scenarios are possible, depending on whether hybrid resistance differs from that of one or both parental species. All four alternatives have been supported by some empirical data, but any potential dynamics might have been overlooked because of limited sampling or experimental designs. However, coevolutionary oscillations generated by frequency-dependent selection might provide a better explanation for the observed results than does a static genetic perspective of host resistance.     

Parasites in sexual and asexual mollies (Poecilia, Poeciliidae, Teleostei): a case for the Red Queen?

The maintenance of sexual reproduction in the face of its supposed costs is a major paradox in evolutionary biology. The Red Queen hypothesis, which states that sex is an adaptation to fast-evolving parasites, is currently one of the most recognized explanations for the ubiquity of sex and predicts that asexual lineages should suffer from a higher parasite load if they coexist with closely related sexuals. We tested this prediction using four populations of the sexual fish species Poecilia latipinna and its asexual relative Poecilia formosa. Contrary to expectation, no differences in parasite load could be detected between the two species.     

Diet of the capybara Hydrochaeris hydrochaeris (Rodentia: Hydrocharidae) in Caño Limón, Arauca, Colombia

We studied the composition and seasonal variation of the diet of the capybara (Hydrochaeris hydrochaeris) in the flooded savannas of Ca?o Limón, Colombia. This was achieved by direct observation of the consumption patterns of these animals. The capybaras only consumed plants, and their diet included 89 species of 22 families. Sixty three percent of these plant species had not been reported before. The most commonly consumed plants (94% of the diet), belonged to the Poaceae, Cyperaceae, Leguminosae and Pontederiaceae. Only seven species represented 60% of the total diet: the grasses Hymenachne amplexicaulis (16.9%), Digitaria bicornis (4.5%) and Panicum maximum (4.4%) and the Cyperaceae Rynchospora corymbosa (4.4%). There was seasonal variation in the diet composition of capybaras.     

Parasites of the superorganism: are they indicators of ecosystem health?

The concept of ecosystem health is derived from analogies with human health, which subsequently leads to the implication that the ecosystem has organismal properties, a 'superorganism' in the Clementsian sense. Its application and usefulness has been the subject of a contentious debate; yet, the term 'ecosystem health' has captured the public's imagination and woven its way into the current lexicon, even incorporated into public policy. However, the application of parasites as bioindicators of ecosystem health poses a curious conundrum. Perceptions of parasites range from mild distaste to sheer disgust among the general public, the media, environmental managers and non-parasitologists in the scientific community. Nevertheless, the biological nature of parasitism incorporates natural characteristics that are informative and useful for environmental management. The helminths in particular have evolved elegant means to ensure their transmission, often relying on complex life cycle interactions that include a variety of invertebrate and vertebrate hosts. The assemblage of these diverse parasites within a host organism potentially reflect that host's trophic position within the food web as well as the presence in the ecosystem of any other organisms that participate in the various parasite life cycles. Perturbations in ecosystem structure and function that affect food web topology will also impact upon parasite transmission, thus affecting parasite species abundance and composition. As such, parasite populations and communities are useful indicators of environmental stress, food web structure and biodiversity. In addition, there may be useful other means to utilise parasitic organisms based on their biology and life histories such as suites or guilds that may be effective bioindicators of particular forms of environmental degradation. The challenge for parasitology is to convince resource managers and fellow scientists that parasites are a natural part of all ecosystems, each species being a potentially useful information unit, and that healthy ecosystems have healthy parasites.     

Australian Entomology: isolated, or in touch with the rest of the world?

Abstract   Australia is isolated from the rest of the world geographically but not scientifically: Australian entomology has a long and distinguished record of collaboration with a diversity of other countries. Much of the focus relates to keeping new pests out of Australia (biosecurity and quarantine) and managing those that do get in (biological control and insect pest management). Many projects have cooperated with neighbouring countries, to assist them to control pests and thereby reduce threats to Australia. Biological control projects have also had two-way benefits, and examples are given of various collaborations in these fields.     

Cladogenesis and endemism in Tanzanian mole‐rats,genus Fukomys: (Rodentia Bathyergidae): a role for tectonics?

African mole‐rats of the family Bathyergidae are subterranean hystricomorph rodents found throughout sub‐Saharan Africa, where the distributional ranges of the most speciose taxa are divided by the African Rift Valley. In particular, mole‐rats of the genera Heliophobius and Fukomys are distributed widely, and their adaptive radiation appears to have been strongly influenced by the geological process of rifting. As a result, virtually all members of the genus Fukomys occur in locations west of the Rift Valley. However, a small number of isolated populations occur east of the Rift Valley in Tanzania, where Heliophobius is widespread and is the predominant bathyergid rodent. Phylogenetic analysis of mitochondrial cytochrome b sequences of previously unstudied Tanzanian mole‐rats (genus Fukomys) and geographically adjacent populations strongly suggests that vicariance in the Western Rift Valley has subdivided populations of mole‐rats and, together with climatic changes, played a role in the isolation of extralimital populations of Fukomys in Tanzania. Together with molecular clock‐based estimates of divergence times, these results offer strong support for the hypothesis that the observed patterns of cladogenesis are consistent with tectonic activity in the ‘Mbeya triple junction’ and Rungwe volcanic province between Lakes Rukwa and Nyasa. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 337–352.