Reproductive Patterns and Tidal Effects on Spat Settlement of Mytilus Edulis Populations in Dundrum Bay, Northern Ireland

The gametogenic and spat settlement patterns of two Mytihis edulis beds were studied in Dundrum Inner Bay, Northern Ireland. There was evidence of gonad development throughout the year with the main development period between November and March. Spawning was protracted, lasting from May to November. Slight inter-annual and inter-population differences in the riming of the phases were observed but the cycles at both beds were broadly similar to each other and to those of other British and Irish sites. Settlement occurred throughout the year and there was evidence of both primary and secondary spat settlement at both sites. Although the reproductive cycles were similar, distinct seasonal and inter-site differences in spatfall were apparent. At the Downshire Bridge bed, settlement peaked during summer and was dominated by spat in the 0•;5-1•0 mm size range. At Ballykinler, settlement levels were highest in the winter months and larger (>1 mm) spat dominated the samples. The orientation of spat collection pads also significantly affected numbers of the larger (>1 mm) spat. Collectors facing the flood tide attracted significantly more secondary settlers than ebb-facing collectors. This effect varied seasonally and was greater at the Ballykinler bed. It is suggested that hydrodynamic regimes may be an important factor in the differences in settlement patterns of M. edulis.

Population dynamics of the liver fluke, Fasciola hepatica: the effect of time and spatial separation on the genetic diversity of fluke populations in the Netherlands

An evaluation of the genetic diversity within Fasciola hepatica (liver fluke) may provide an insight into its potential to respond to environmental changes, such as anthelmintic use or climate change. In this study, we determined the mitochondrial DNA haplotypes of >400 flukes from 29 individual cattle, from 2 farms in the Netherlands, as an exemplar of fasciolosis in a European context. Analysis of this dataset has provided us with a measure of the genetic variation within infrapopulations (individual hosts) and the diversity between infrapopulations within a herd of cattle. Temporal sampling from one farm allowed for the measurement of the stability of genetic variation at a single location, whilst the comparison between the two farms provided information on the variation in relation to distance and previous anthelmintic regimes. We showed that the liver fluke population in this region is predominantly linked to 2 distinct clades. Individual infrapopulations contain a leptokurtic distribution of genetically diverse flukes. The haplotypes present on a farm have been shown to change significantly over a relatively short time-period.

Does infection by Nosema ceranae cause "Colony Collapse Disorder" in honey bees (Apis mellifera)?

Nosema ceranae is an emergent and potentially virulent pathogen of the honey bee (Apis mellifera) that has spread across the world in the last 10 or so years. Its precise origin and timing of spread are currently unclear because of a lack of appropriate genetic markers and inadequate sampling in putative Asian source populations. Though it has been dismissed as a cause of CCD in the USA based on correlational analyses of snapshot sampling of diseased hives, observations of naturally infected colonies suggest that it leads to colony collapse in Spain. Experiments are sorely needed to investigate its impact on individuals and colonies, and to pin down a causal relationship between N. ceranae and colony collapse. Whether N. ceranae is displacing N. apis is uncertain. For temperate zone apiculturalists, global climate change may mean that N. ceranae presents more of a challenge than has hitherto been considered the case.

The conservation of bees: a global perspective

Bees are major pollinators of Angiosperms and therefore their apparent decline is of importance for humans and biodiversity. We synthesise results of 12 recent reviews to provide a global picture of the threats they face. Habitat loss is the major threat to bee diversity, whilst invasive species, emerging diseases, pesticide use, and climate change also have the potential to impact bee populations. We suggest that future conservation strategies need to prioritise (i) minimising habitat loss, (ii) making agricultural habitats bee-friendly, (iii) training scientists and the public in bee taxonomy and identification, (iv) basic autecological and population genetic studies to underpin conservation strategies, (v) assessing the value of DNA barcoding for bee conservation, (vi) determining the impact of invasive plants, animals, parasites and pathogens, and (vii) integrating this information to understand the potential impact of climate change on current bee diversity.

Estimation of survival rate and extinction probability for stage-structured populations with overlapping life stages

The development of methods providing reliable estimates of demographic parameters (e. g., survival rates, fecundity) for wild populations is essential to better understand the ecology and conservation requirements of individual species. A number of methods exist for estimating the demographics of stage-structured populations, but inherent mathematical complexity often limits their uptake by conservation practitioners. Estimating survival rates for pond-breeding amphibians is further complicated by their complex migratory and reproductive behaviours, often resulting in nonobservable states and successive cohorts of eggs and tadpoles. Here we used comprehensive data on 11 distinct breeding toad populations (Bufo calamita) to clarify and assess the suitability of a relatively simple method [the Kiritani-Nakasuji-Manly (KNM) method] to estimate the survival rates of stage-structured populations with overlapping life stages. The study shows that the KNM method is robust and provides realistic estimates of amphibian egg and larval survival rates for species in which breeding can occur as a single pulse or over a period of several weeks. The study also provides estimates of fecundity for seven distinct toad populations and indicates that it is essential to use reliable estimates of fecundity to limit the risk of under- or overestimating the survival rates when using the KNM method. Survival and fecundity rates for B. calamita populations were then used to define population matrices and make a limited exploration of their growth and viability. The findings of the study recently led to the implementation of practical conservation measures at the sites where populations were most vulnerable to extinction. © 2010 The Society of Population Ecology and Springer.

Recent mumps outbreaks in vaccinated populations: no evidence of immune escape.

Recently, numerous large-scale mumps outbreaks have occurred in vaccinated populations. Clinical isolates sequenced from these outbreaks have invariably been of genotypes distinct from those of vaccine viruses, raising concern that certain mumps virus strains may escape vaccine-induced immunity. To investigate this concern, sera obtained from children 6 weeks after receipt of measles, mumps, and rubella (MMR) vaccine were tested for the ability to neutralize a carefully selected group of genetically diverse mumps virus strains. Although the geometric mean neutralizing antibody titer of the sera was lower against some virus strains than others, all viruses were readily neutralized, arguing against immune escape.

Deformed wing virus and drone mating flights in the honey bee (Apis mellifera): implications for sexual transmission of a major honey bee virus

Deformed wing virus (DWV) represents an ideal model to study the interaction between mode of transmission and virulence in honey bees since it exhibits both horizontal and vertical transmissions. However, it is not yet clear if venereal-vertical transmission represents a regular mode of transmission for this virus in natural honey bee populations. Here, we provide clear evidence for the occurrence of high DWV titres in the endophallus of sexually mature drones collected from drone congregation areas (DCAs). Furthermore, the endophallus DWV titres of drones collected at their maternal hives were no different from drones collected at nearby DCAs, suggesting that high-titre DWV infection of the endophallus does not hinder the ability of drones to reach the mating area. The results are discussed within the context of the dispersal of DWV between colonies and the definition of DWV virulence with respect to the transmission route and the types of tissues infected.

Larval Transport Modeling of Deep-Sea Invertebrates Can Aid the Search for Undiscovered Populations

Background: Many deep-sea benthic animals occur in patchy distributions separated by thousands of kilometres, yet because deep-sea habitats are remote, little is known about their larval dispersal. Our novel method simulates dispersal by combining data from the Argo array of autonomous oceanographic probes, deep-sea ecological surveys, and comparative invertebrate physiology. The predicted particle tracks allow quantitative, testable predictions about the dispersal of benthic invertebrate larvae in the south-west Pacific. Principal Findings: In a test case presented here, using non-feeding, non-swimming (lecithotrophic trochophore) larvae of polyplacophoran molluscs (chitons), we show that the likely dispersal pathways in a single generation are significantly shorter than the distances between the three known population centres in our study region. The large-scale density of chiton populations throughout our study region is potentially much greater than present survey data suggest, with intermediate ‘stepping stone’ populations yet to be discovered. Conclusions/Significance: We present a new method that is broadly applicable to studies of the dispersal of deep-sea organisms. This test case demonstrates the power and potential applications of our new method, in generating quantitative, testable hypotheses at multiple levels to solve the mismatch between observed and expected distributions: probabilistic predictions of locations of intermediate populations, potential alternative dispersal mechanisms, and expected population genetic structure. The global Argo data have never previously been used to address benthic biology, and our method can be applied to any non-swimming larvae of the deep-sea, giving information upon dispersal corridors and population densities in habitats that remain intrinsically difficult to assess.