Search

Background: Familial hypercholesterolaemia (FH) is a genetic disorder causing accelerated atherosclerosis and premature cardiovascular disease (CVD). This retrospective observational study examined the clinical characteristics and management of FH subjects in Bulgaria over a 12-month period.

The sea urchins Strongylocentotus pallidus and S. droebachiensis first invaded the Atlantic Ocean from the Pacific following the opening of the Bering seaway in the late Miocene. While trans-Arctic dispersal during the Pleistocene is thought to have maintained species' integrity, a recent genomic analysis identified a reproductively isolated cryptic species within S. droebachiensis . Based on previous studies, the distribution of one of these lineages ( S. droebachiensis W) includes the shallow water habitats of the northwest Atlantic and Pacific, while the other ( S. droebachiensis E) is found throughout the shallow habitat in the northeast but is mostly restricted to deep habitats (>65 m) in the northwest Atlantic. However, since genetic variation within S. droebachiensis has been largely unstudied in the north Pacific and Arctic oceans, the biogeography of the cryptic species is not well known, and it is difficult to identify the mechanisms driving population subdivision and speciation. Here we use population genetic analyses to characterize the distribution of each species, and to test hypotheses about the role of vicariance in the evolution of systematic and genomic divergence within the genus. We collected individuals of all three Strongylocentrotus species ( n  = 365) from 10 previously unsampled locations in the northeast Pacific and north Atlantic (Labrador Sea and Norway), and generated mtDNA sequence data for a 418 bp fragment of cytochrome c oxidase subunit I ( COI ). To assess the biogeography of all three species, we combined our alignment with five previously published data sets (total n  = 789) and used statistical parsimony and maximum likelihood to identify species and characterize their distribution within and among oceans. Patterns of haplotype sharing, pairwise F ST , and hierarchical analyses of molecular variance (AMOVA) identified trans-Arctic dispersal in S. pallidus and S. droebachiensis W, but other than 5 previously reported singletons we failed to detect additional mtDNA haplotypes of S. droebachiensis E in the north Pacific. Within the Atlantic, patterns of habitat segregation suggests that temperature may play a role in limiting the distribution of S. droebachiensis E, particularly throughout the warmer coastal waters along the coast of Nova Scotia. Our results are consistent with the cycles of trans-Arctic dispersal and vicariance in S. pallidus and S. droebachiensis W, but we suggest that the evolution of Atlantic populations of S. droebachiensis E has been driven by persistent trans-Arctic vicariance that may date to the initial invasion in the late Pliocene., Competing Interests: The authors declare there are no competing interests., (©2022 Addison and Kim.)

Background: This paper forms part of an update of the World Health Organization Choosing Interventions that are Cost-Effective (WHO-CHOICE) programmes. It provides an assessment of global health system performance during the first decade of the 21st century (2000-2010) with respect to allocative efficiency in HIV, tuberculosis (TB) and malaria control, thereby shining a spotlight on programme development and scale up in these Millennium Development Goal (MDG) priority areas; and examining the cost-effectiveness of selected best-practice interventions and intervention packages commonly in use during that period., Methods: Generalized cost-effectiveness analysis (GCEA) was used to determine the cost-effectiveness of the selected interventions. Impact modelling was performed using the OpenMalaria platform for malaria and using the Goals and TIME (TB Impact Model and Estimates) models in Spectrum for HIV and TB. All health system costs, regardless of payer, were included and reported in international dollars. Health outcomes are estimated and reported as the gain in healthy life years (HLYs) due to the specific intervention or combination. Analysis was restricted to eastern sub-Saharan Africa and Southeast Asia., Results: At the reference year of 2010, commonly used interventions for HIV, TB and malaria were cost-effective, with cost-effectiveness ratios less than I$ 100/HLY saved for virtually all interventions included. HIV, TB and malaria prevention and treatment interventions are highly cost-effective and can be implemented through a phased approach to full coverage to achieve maximum health benefits and contribute to the progressive elimination of these diseases., Conclusion: During the first decade of the 21st century (2000-2010), the global community has done well overall for HIV, TB, and malaria programmes as regards both economic efficiency and programmatic selection criteria. The role of international assistance, financial and technical, arguably was critical to these successes. As the global community now tackles the challenge of universal health coverage, this analysis can reinforce commitment to Sustainable Development Goal targets but also the importance of continued focus on these critical programme areas., (© 2021 The Author(s); Published by Kerman University of Medical Sciences. This is an open-access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.)

Background The use of drug-eluting stents (DESs), compared with bare-metal stents (BMSs), in percutaneous coronary intervention (PCI) has reduced the rate of restenosis, without an impact on mortality but with an increase in costs. Medical literature lacks randomized studies that economically compare these 2 stent types within the reality of the Brazilian Unified Public Health System (SUS). Objective To estimate the incremental cost-effectiveness ratio (ICER) between DES and BMS in SUS patients with single-vessel coronary artery disease. Methods Over a 3-year period, patients with symptomatic single-vessel coronary artery disease were randomized in a 1:2 ratio to receive a DES or BMS during PCI, with a 1-year clinical follow-up. The evaluation included in-stent restenosis (ISR), target lesion revascularization (TLR), major adverse events, and cost-effectiveness for each group. P-values <0.05 were considered significant. Results In the DES group, of 74 patients (96.1%) who completed the follow-up, 1 developed ISR (1.4%), 1 had TLR (1.4%), and 1 died (1.4%), with no cases of thrombosis. In the BMS group, of 141 patients (91.5%), ISR occurred in 14 (10.1%), TLR in 10 (7.3%), death in 3 (2.1%), and thrombosis in 1 (0.74%). In the economic analysis, the cost of the procedure was R$ 5,722.21 in the DES group and R$ 4,085.21 in the BMS group. The effectiveness by ISR and TLR was 8.7% for DES and 5.9% for BMS, with an ICER of R$ 18,816.09 and R$ 27,745.76, respectively. Conclusions In the SUS, DESs were cost-effective in accordance with the cost-effectiveness threshold recommended by the World Health Organization (Arq Bras Cardiol. 2020; 115(1):80-89).

The same vectors that introduce species to new ranges could move them among native populations, but how human-mediated dispersal impacts native ranges has been difficult to address because human-mediated dispersal and natural dispersal can simultaneously shape patterns of gene flow. Here, we disentangle human-mediated dispersal from natural dispersal by exploiting a system where the primary vector was once extensive but has since ceased. From 10th to 19th Centuries, ships in the North Atlantic exchanged sediments dredged from the intertidal for ballast, which ended when seawater ballast tanks were adopted. We investigate genetic patterns from RADseq-derived SNPs in the amphipod Corophium volutator ( n  = 121; 4,870 SNPs) and the annelid Hediste diversicolor ( n  = 78; 3,820 SNPs), which were introduced from Europe to North America, have limited natural dispersal capabilities, are abundant in intertidal sediments, but not commonly found in modern water ballast tanks. We detect similar levels of genetic subdivision among introduced North American populations and among native European populations. Phylogenetic networks and clustering analyses reveal population structure between sites, a high degree of phylogenetic reticulation within ranges, and phylogenetic splits between European and North American populations. These patterns are inconsistent with phylogeographic structure expected to arise from natural dispersal alone, suggesting human activity eroded ancestral phylogeographic structure between native populations, but was insufficient to overcome divergent processes between naturalized populations and their sources. Our results suggest human activity may alter species' evolutionary trajectories on a broad geographic scale via regional homogenization and global diversification, in some cases precluding historical inference from genetic data., Competing Interests: The authors declare that they have no potential sources of conflict of interest., (© 2020 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.)

Mitochondrial DNA analyses indicate that the Bay of Fundy population of the intertidal tellinid bivalve Macoma petalum is genetically divergent from coastal populations in the Gulf of Maine and Nova Scotia. To further examine the evolutionary forces driving this genetic break, we performed double digest genotype by sequencing (GBS) to survey the nuclear genome for evidence of both neutral and selective processes shaping this pattern. The resulting reads were mapped to a partial transcriptome of its sister species, M. balthica , to identify single nucleotide polymorphisms (SNPs) in protein-coding genes. Population assignment tests, principle components analyses, analysis of molecular variance, and outlier tests all support differentiation between the Bay of Fundy genotype and the genotypes of the Gulf of Maine, Gulf of St. Lawrence, and Nova Scotia. Although both neutral and non-neutral patterns of genetic subdivision were significant, genetic structure among the regions was nearly 20 times higher for loci putatively under selection, suggesting a strong role for natural selection as a driver of genetic diversity in this species. Genetic differences were the greatest between the Bay of Fundy and all other population samples, and some outlier proteins were involved in immunity-related processes. Our results suggest that in combination with limited gene flow across the mouth of the Bay of Fundy, local adaptation is an important driver of intraspecific genetic variation in this marine species with high dispersal potential.

Identifying vulnerable plaque is important in coronary heart disease diagnosis. Recent emerged imaging modality, Intravascular Optical Coherence Tomography (IVOCT), has been proved to be able to characterize the appearance of vulnerable plaques. Comparing with the manual method, automated fibroatheroma identification would be more efficient and objective. Deep convolutional neural networks have been adopted in many medical image analysis tasks. In this paper, we introduce deep features to resolve fibroatheroma identification problem. Deep features which extracted using four deep convolutional neural networks, AlexNet, GoogLeNet, VGG-16 and VGG-19, are studied. And a dataset of 360 IVOCT images from 18 pullbacks are constructed to evaluate these features. Within these 360 images, 180 images are normal IVOCT images and the rest 180 images are IVOCT images with fibroatheroma. Here, one pullback belongs to one patient; leave-one-patient-out cross-validation is employed for evaluation. Data augmentation is applied on training set for each classification scheme. Linear support vector machine is conducted to classify the normal IVOCT image and IVOCT image with fibroatheroma. The experimental results show that deep features could achieve relatively high accuracy in fibroatheroma identification.

This paper presents a method to extract-and-match robust corner features based on connecting edges from the edge maps, mainly formed by coronary vascular junctions in fluoroscopic x-ray sequence images. Such images are challenging due to the aperture problem. To overcome this, existing approaches attempt to extract vessels for registration. However, they are ineffective in poor quality images. Our approach describes the extracted robust corner features in a rotation invariant manner using step patterns, followed by matching them effectively. Experimental results show that our approach performs very well (above 80%) in a dataset of poor quality fluoroscopic x-ray image sequences without extensive processing such as segmentation or learning.

Despite advances in myocardial reperfusion therapies, acute myocardial ischaemia/reperfusion injury and consequent ischaemic heart failure represent the number one cause of morbidity and mortality in industrialized societies. Although different therapeutic interventions have been shown beneficial in preclinical settings, an effective cardioprotective or regenerative therapy has yet to be successfully introduced in the clinical arena. Given the complex pathophysiology of the ischaemic heart, large scale, unbiased, global approaches capable of identifying multiple branches of the signalling networks activated in the ischaemic/reperfused heart might be more successful in the search for novel diagnostic or therapeutic targets. High-throughput techniques allow high-resolution, genome-wide investigation of genetic variants, epigenetic modifications, and associated gene expression profiles. Platforms such as proteomics and metabolomics (not described here in detail) also offer simultaneous readouts of hundreds of proteins and metabolites. Isolated omics analyses usually provide Big Data requiring large data storage, advanced computational resources and complex bioinformatics tools. The possibility of integrating different omics approaches gives new hope to better understand the molecular circuitry activated by myocardial ischaemia, putting it in the context of the human 'diseasome'. Since modifications of cardiac gene expression have been consistently linked to pathophysiology of the ischaemic heart, the integration of epigenomic and transcriptomic data seems a promising approach to identify crucial disease networks. Thus, the scope of this Position Paper will be to highlight potentials and limitations of these approaches, and to provide recommendations to optimize the search for novel diagnostic or therapeutic targets for acute ischaemia/reperfusion injury and ischaemic heart failure in the post-genomic era., (© The Author 2017. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Life-history traits, especially the mode and duration of larval development, are expected to strongly influence the population connectivity and phylogeography of marine species. Comparative analysis of sympatric, closely related species with differing life histories provides the opportunity to specifically investigate these mechanisms of evolution but have been equivocal in this regard. Here, we sample two sympatric sea stars across the same geographic range in temperate waters of Australia. Using a combination of mitochondrial DNA sequences, nuclear DNA sequences, and microsatellite genotypes, we show that the benthic-developing sea star, Parvulastra exigua , has lower levels of within- and among-population genetic diversity, more inferred genetic clusters, and higher levels of hierarchical and pairwise population structure than Meridiastra calcar , a species with planktonic development. While both species have populations that have diverged since the middle of the second glacial period of the Pleistocene, most P. exigua populations have origins after the last glacial maxima (LGM), whereas most M. calcar populations diverged long before the LGM. Our results indicate that phylogenetic patterns of these two species are consistent with predicted dispersal abilities; the benthic-developing P. exigua shows a pattern of extirpation during the LGM with subsequent recolonization, whereas the planktonic-developing M. calcar shows a pattern of persistence and isolation during the LGM with subsequent post-Pleistocene introgression.

This paper presents a novel automatic quantitative measurement method for assessment of the performance of image registration algorithms designed for registering retina fundus images. To achieve automatic quantitative measurement, we propose the use of edges and edge dissimilarity measure for determining the performance of retina image registration algorithms. Our input is the registered pair of retina fundus images obtained using any of the existing retina image registration algorithms in the literature. To compute edge dissimilarity score, we propose an edge dissimilarity measure that we called "robustified Hausdorff distance". We show that our proposed approach is feasible as designed by drawing comparison to visual evaluation results when tested on images from the DRIVERA and G9 dataset.

Marine sediments from the North Pacific document two episodes of expansion and strengthening of the subsurface oxygen minimum zone (OMZ) accompanied by seafloor hypoxia during the last deglacial transition. The mechanisms driving this hypoxia remain under debate. We present a new high-resolution alkenone palaeotemperature reconstruction from the Gulf of Alaska that reveals two abrupt warming events of 4-5 degrees Celsius at the onset of the Bølling and Holocene intervals that coincide with sudden shifts to hypoxia at intermediate depths. The presence of diatomaceous laminations and hypoxia-tolerant benthic foraminiferal species, peaks in redox-sensitive trace metals, and enhanced (15)N/(14)N ratio of organic matter, collectively suggest association with high export production. A decrease in (18)O/(16)O values of benthic foraminifera accompanying the most severe deoxygenation event indicates subsurface warming of up to about 2 degrees Celsius. We infer that abrupt warming triggered expansion of the North Pacific OMZ through reduced oxygen solubility and increased marine productivity via physiological effects; following initiation of hypoxia, remobilization of iron from hypoxic sediments could have provided a positive feedback on ocean deoxygenation through increased nutrient utilization and carbon export. Such a biogeochemical amplification process implies high sensitivity of OMZ expansion to warming.

This paper presents a novel augmented reality assistance platform for eye laser surgery. The aims of the proposed system are for the application of assisting eye doctors in pre-planning as well as providing guidance and protection during laser surgery. We developed algorithms to automatically register multi-modal images, detect macula and optic disc regions, and demarcate these as protected areas from laser surgery. The doctor will then be able to plan the laser treatment pre-surgery using the registered images and segmented regions. Thereafter, during live surgery, the system will automatically register and track the slit lamp video frames on the registered retina images, send appropriate warning when the laser is near protected areas, and disable the laser function when it points into the protected areas. The proposed system prototype can help doctors to speed up laser surgery with confidence without fearing that they may unintentionally fire laser in the protected areas.

This paper presents a novel approach of finding corner features between retinal fundus images. Such images are relatively textureless and comprising uneven shades which render state-of-the-art approaches e.g., SIFT to be ineffective. Many of the detected features have low repeatability (<; 10%), especially when the viewing angle difference in the corresponding images is large. Our approach is based on the finding of blood vessels using a robust line fitting algorithm, and locating corner features based on the bends and intersections between the blood vessels. These corner features have proven to be superior to the state-of-the-art feature extraction methods (i.e. SIFT, SURF, Harris, Good Features To Track (GFTT) and FAST) with regard to repeatability and stability in our experiment. Overall in average, the approach has close to 10% more repeatable detected features than the second best in two corresponding retinal images in the experiment.

The predator-prey interactions within food chains are used to both characterize and understand ecosystems. Conventional methods of constructing food chains from visual identification of prey in predator diet can suffer from poor taxonomic resolution, misidentification, and bias against small or completely digestible prey. Next-generation sequencing (NGS) technology has become a powerful tool for diet reconstruction through barcoding of DNA in stomach content or fecal samples. Here we use multi-locus (16S and CO1) next-generation sequencing of DNA barcodes on the feces of Atlantic puffin (Fratercula arctica) chicks (n=65) and adults (n=64) and the stomach contents of their main prey, Atlantic herring (Clupea harengus, n=44) to investigate a previously studied food chain. We compared conventional and molecular-derived chick diet, tested the similarity between the diets of puffin adults and chicks, and determined whether herring prey can be detected in puffin diet samples. There was high variability in the coverage of prey groups between 16S and CO1 markers. We identified more unique prey with our 16S compared to CO1 barcoding markers (51 and 39 taxa respectively) with only 12 taxa identified by both genes. We found no significant difference between the 16S-identified diets of puffin adults (n=17) and chicks (n=41). Our molecular method is more taxonomically resolved and detected chick prey at higher frequencies than conventional field observations. Many likely planktonic prey of herring were detected in feces from puffin adults and chicks, highlighting the impact secondary consumption may have on the interpretation of molecular dietary analysis. This study represents the first simultaneous molecular investigation into the diet of multiple components of a food chain and highlights the utility of a multi-locus approach to diet reconstruction that is broadly applicable to food web analysis.

We document an extreme example of reproductive trait evolution that affects population genetic structure in sister species of Parvulastra cushion stars from Australia. Self-fertilization by hermaphroditic adults and brood protection of benthic larvae causes strong inbreeding and range-wide genetic poverty. Most samples were fixed for a single allele at nearly all nuclear loci; heterozygotes were extremely rare (0.18%); mitochondrial DNA sequences were more variable, but few populations shared haplotypes in common. Isolation-with-migration models suggest that these patterns are caused by population bottlenecks (relative to ancestral population size) and low gene flow. Loss of genetic diversity and low potential for dispersal between high-intertidal habitats may have dire consequences for extinction risk and potential for future adaptive evolution in response to climate and other selective agents.

Life history plays a critical role in governing microevolutionary processes such as gene flow and adaptation, as well as macroevolutionary processes such speciation. Here, we use multilocus phylogeographic analyses to examine a speciation event involving spectacular life-history differences between sister species of sea stars. Cryptasterina hystera has evolved a suite of derived life-history traits (including internal self-fertilization and brood protection) that differ from its sister species Cryptasterina pentagona, a gonochoric broadcast spawner. We show that these species have only been reproductively isolated for approximately 6000 years (95% highest posterior density of 905-22 628), and that this life-history change may be responsible for dramatic genetic consequences, including low nucleotide diversity, zero heterozygosity and no gene flow. The rapid divergence of these species rules out some mechanisms of isolation such as adaptation to microhabitats in sympatry, or slow divergence by genetic drift during prolonged isolation. We hypothesize that the large phenotypic differences between species relative to the short divergence time suggests that the life-history differences observed may be direct responses to disruptive selection between populations. We speculate that local environmental or demographic differences at the southern range margin are possible mechanisms of selection driving one of the fastest known marine speciation events.

The field of phylogeography has long since realized the need and utility of incorporating nuclear DNA (nDNA) sequences into analyses. However, the use of nDNA sequence data, at the population level, has been hindered by technical laboratory difficulty, sequencing costs, and problematic analytical methods dealing with genotypic sequence data, especially in non-model organisms. Here, we present a method utilizing the 454 GS-FLX Titanium pyrosequencing platform with the capacity to simultaneously sequence two species of sea star (Meridiastra calcar and Parvulastra exigua) at five different nDNA loci across 16 different populations of 20 individuals each per species. We compare results from 3 populations with traditional Sanger sequencing based methods, and demonstrate that this next-generation sequencing platform is more time and cost effective and more sensitive to rare variants than Sanger based sequencing. A crucial advantage is that the high coverage of clonally amplified sequences simplifies haplotype determination, even in highly polymorphic species. This targeted next-generation approach can greatly increase the use of nDNA sequence loci in phylogeographic and population genetic studies by mitigating many of the time, cost, and analytical issues associated with highly polymorphic, diploid sequence markers.

Experiments were conducted to assess the toxicity of methyl tert butyl ether (MTBE) to three species of Collembola (Proisotoma minuta, Folsomia candida, and Onychiurus folsomi) and lettuce (Lactuca sativa L.) using an artificial Organization for Economic Cooperation and Development (OECD) soil and field-collected sandy loam and silt loam soil samples. Soil invertebrate tests were carried out in airtight vials to prevent volatilization of MTBE out of the test units and to allow for direct head-space sampling and gas chromatography-mass spectrometry (GC-MS) analysis for residual MTBE. The use of the airtight vial protocol proved to be very successful, in that the measured MTBE concentrations at the beginning of the experiments were within 95% of nominal concentrations. The test methods used in this study could be used to test the toxicity of other volatile organic compounds to Collembola. The soil invertebrates tested had inhibitory concentration (ICx) and lethal concentration (LCx) values that ranged from 242 to 844 mg MTBE/kg dry soil. When the three test species of Collembola were tested under identical conditions in the artificial OECD soil, O. folsomi was the most sensitive collembolan, with a median inhibitory concentration (IC50; reproduction) of 296 mg MTBE/kg dry soil. The most sensitive endpoint for lettuce was an IC50 for root length of 81 mg MTBE/kg dry soil after 5 d of germination in OECD soil. Data on the loss of MTBE from the three test soils over time indicated that MTBE was retained in the silt loam soil longer than in either the sandy loam or the artificial OECD soil., (Copyright 2009 SETAC.)

Patiria miniata, a broadcast-spawning sea star species with high dispersal potential, has a geographic range in the intertidal zone of the northeast Pacific Ocean from Alaska to California that is characterized by a large range gap in Washington and Oregon. We analyzed spatial genetic variation across the P. miniata range using multilocus sequence data (mtDNA, nuclear introns) and multilocus genotype data (microsatellites). We found a strong phylogeographic break at Queen Charlotte Sound in British Columbia that was not in the location predicted by the geographical distribution of the populations. However, this population genetic discontinuity does correspond to previously described phylogeographic breaks in other species. Northern populations from Alaska and Haida Gwaii were strongly differentiated from all southern populations from Vancouver Island and California. Populations from Vancouver Island and California were undifferentiated with evidence of high gene flow or very recent separation across the range disjunction between them. The surprising and discordant spatial distribution of populations and alleles suggests that historical vicariance (possibly caused by glaciations) and contemporary dispersal barriers (possibly caused by oceanographic conditions) both shape population genetic structure in this species.

The evolution of incompatibilities between eggs and sperm is thought to play important roles in establishing and maintaining reproductive isolation among species of broadcast-spawning marine invertebrates. However, the effectiveness of gametic isolation in initiating the speciation process and/or in limiting the introgression of genes among species at later stages of divergence remains largely unknown. In the present study, we collected DNA sequence data from five loci in four species of Strongylocentrotus sea urchins (S. droebachiensis, S. pallidus, S. purpuratus, and S. franciscanus) to test whether the susceptibility of S. droebachiensis eggs to fertilization by heterospecific sperm results in gene flow between species. Despite the potential for introgression, a small but statistically significant signal of introgression was observed only between the youngest pair of sister taxa (S. pallidus and S. droebachiensis) that was strongly asymmetrical (from the former into the latter). No significant gene flow was observed for either S. purpuratus or S. franciscanus despite the ability of their sperm to readily fertilize the eggs of S. droebachiensis. Our results demonstrate that asymmetrical gamete compatibilities in strongylocentrotids can give rise to asymmetrical patterns of introgression but suggest that gamete traits alone cannot be responsible for maintaining species integrities. The genetic boundaries between strongylocentrotid urchin species in the northeast Pacific appear to be related to postzygotic isolating mechanisms that scale with divergence times and not intrinsic gametic incompatibilities per se.

We tested for genetic differentiation among six populations of California sea mussels (Mytilus californianus) sampled across 4000 km of its geographical range by comparing patterns of variation at four independent types of genetic markers: allozymes, single-copy nuclear DNA markers, and DNA sequences from the male and female mitochondrial genomes. Despite our extensive sampling and genotyping efforts, we detected no significant differences among localities and no signal of isolation by distance suggesting that M. californianus is genetically homogeneous throughout its range. This concordance differs from similar studies on other mytilids, especially in the role of postsettlement selection generating differences between exposed coastal and estuarine habitats. To assess if this homogeneity was due to M. californianus not inhabiting estuarine environments, we reviewed studies comparing allozymes with other classes of nuclear DNA markers. Although both types of markers gave broadly consistent results, there was a bias favouring studies in which allozymes were more divergent than DNA markers (nine to three) and a disproportionate number of these cases involved marine taxa (seven). Furthermore, allozymes were significantly more heterogeneous than DNA markers in three of the four studies that sampled coastal and estuarine habitats. We conclude that the genetic uniformity exhibited by M. californianus may result from a combination of extensive gene flow and the lack of exposure to strong selective gradients across its range.

Phylogeographic studies designed to estimate rates and patterns of genetic differentiation within species often reveal unexpected and graphically striking cases of allele or haplotype sharing between species (introgression) via hybridization and backcrossing. Does introgression between species significantly influence population genetic structure relative to more conventional sources of differentiation (drift) and similarity (dispersal) among populations within species? Here we use mtDNA sequences from four species in two genera of sea urchins and sea stars to quantify the relative magnitude of gene flow across oceans and across species boundaries in the context of the trans-Arctic interchange of marine organisms between the Pacific and Atlantic oceans. In spite of the much smaller distances between sympatric congeners, rates of gene flow between sympatric species via heterospecific gamete interactions were small and significantly lower than gene flow across oceans via dispersal of planktonic larvae. We conclude that, in these cases at least, larvae are more effective than gametes as vectors of gene flow.

Patterns of population genetic variation have frequently been understood as consequences of life history covariates such as dispersal ability and breeding systems (e.g. selfing). For example, marine invertebrates show enormous variation in life history traits that are correlated with the extent of gene flow between populations and the magnitude of differentiation among populations at neutral genetic markers (FST). Here we document an unexpected correlation between marine invertebrate life histories and deviation from Hardy-Weinberg equilibrium (non-zero values of FIS, the inbreeding coefficient). FIS values were significantly higher in studies of species with free-spawned planktonic sperm than in studies of species that copulate or have some form of direct sperm transfer to females or benthic egg masses. This result was robust to several different analytical approaches. We note several mechanisms that might contribute to this pattern, and appeal for more studies and ideas that might help to explain our observations.

We used frequency-based and coalescent-based phylogeographic analysis of sea urchin (Strongylocentrotus droebachiensis) mitochondrial DNA (mtDNA) sequences and previously published microsatellite data to understand the relative influence of colonization and gene flow from older (north Pacific) and younger (northeast Atlantic) sea urchin populations on genetic variation in the northwest Atlantic. We found strong evidence of survival of northwestern Atlantic populations in local Pleistocene glacial refugia: most haplotypes were the same as or closely related to Pacific haplotypes, with deep gene genealogies that reflect divergence times within the northwestern Atlantic that are much older than the last glacial maximum. We detected gene flow across the North Atlantic in the form of haplotypes shared with or recently descended from European populations. We also found evidence of significant introgression of haplotypes from a closely related species (S. pallidus). The relative magnitude of gene flow estimated by coalescent methods (and the effective population size differences among oceanic regions) depended on the genetic marker used. In general, we found very small effective population size in the northeastern Atlantic and high trans-Arctic gene flow between the Pacific and northwestern Atlantic. Both analyses suggested significant back-migration to the Pacific. However, microsatellites more strongly reflected older Pacific migration (with similar effective population sizes across the Arctic), whereas mtDNA sequences appeared to be more sensitive to recent trans- Atlantic dispersal (with larger differences in effective population size). These differences across marker types might have several biological or methodological causes, and they suggest caution in interpretation of the results from a single locus or class of markers.

It has been suggested that an abundance of alternate food early in the spring may be critical to the ability of generalist predaceous mites to suppress spider mite pests. One alternate food that is typically very abundant in spring is wind-dispersed pollen. Here we investigate, at several spatial scales, the heterogeneity in the availability of pollen to predaceous mites on apple. We found pollen to be abundant on apple leaves very soon after they opened (> 100 grains/cm2), and that the dominant pollen types at this time were wind-dispersed tree pollens (Betulaceae and Pinaceae). We found that most of the spatial variation in pollen abundance occurred at either small spatial scales (within trees) or very large spatial scales (among orchard blocks). Variability among orchards was clearly influenced by the surrounding vegetation, and probably also by the management regime (frequency of mowing). Spatial heterogeneity in pollen availability may affect the build-up of predatory mite populations in the spring, as we found early season abundances of Typhlodromus pyri (Phytoseiidae) and Zetzellia mali (Stigmaeidae) to be better correlated with early season pollen density than with abundance of mite prey (Aculus schlechtendali).

Tebufenozide, a new molt-inducing insecticide that mimics the action of ecdysone, is being considered for use to control defoliating lepidoptera in forests in Canada. Soil microcosms, employing substrates and species from the ecosystems in which spraying is likely to occur, were used to evaluate the effects of this compound on soil invertebrates. The forest earthworm (Dendrobaena octaedra Savigny) and four species of Collembola (Folsomia candida Willem, F. nivalis (Packard), Onychiurus parvicornis Mills, and Hypogastrura pannosa Macnamara) were tested. Survival, growth, and reproduction (cocoon production and viability) in the forest earthworm D. octaedra were not affected by exposure to tebufenozide at concentrations up to and including 100x expected environmental concentration (EEC; equivalent to the operational spray rate; 70 g/ha) in leaf litter over a 10-week period. Similarly, population growth over 8-10 weeks in the four species of soil Collembola in LFH material contaminated with tebufenozide at 100x EEC was not affected. Based on the results of these (limited) tests, it therefore appears that, under normal operational conditions, tebufenozide should not pose a hazard to soil invertebrates. The selection of appropriate test species and systems for forestry applications is discussed.

The effects of the organophosphate pesticide fenitrothion on Eisenia fetida Savigny and Dendrobaena octaedra Savigny were studied using the OECD acute toxicity test and microcosms containing forest organic matter. In the acute toxicity study, both species were relatively susceptible to fenitrothion, although D. octaedra (LC50 = 393.9 ml/cm2) was approximately eight times more sensitive than E. fetida (LC50 = 54.1 ml/cm2). E. fetida was unable to utilize oak/maple litter for growth, and attempts to use this species in microcosms were abandoned. In microcosm studies, reproduction of D. octaedra was affected at the expected environmental concentration (EEC), whereas growth and maturation rates did not decrease until 100x the EEC was used. Even at 100x EEC, a significant effect on survival of D. octaedra in microcosms was not demonstrated. The use of microcosm studies to provide insight into possible ecological effects of pesticides is discussed.