Solving the taxonomic identity of Hipposideros cineraceus sensu lato (Chiroptera: Hipposideridae) in the Thai-Malay Peninsula, with the description of a new species

A new species of small Hipposideros in the bicolor group is described based on specimens from Thailand and Malaysia. It can be distinguished from other small Hipposideros in Southeast Asia by a combination of external, craniodental, and bacular morphology, as well as echolocation call frequency. The new species has a distinct rounded swelling on the internarial septum of the noseleaf, with a forearm length of 35.3-42.6 mm, greatest skull length of 15.94-17.90 mm, and a call frequency of maximum energy of 132.3-144.0 kHz. Although clearly different in morphology, the new species forms a sister clade with H. kunzi and H. bicolor in the phylogenetic trees based on mitochondrial DNA. In addition, this study reports echolocation and genetic data, with a confirmed record of H. einnaythu from Thailand for the first time. The new species most closely resembles H. einnaythu. However, it differs in the details of the noseleaf and craniodental morphology, and it has a genetic distance of 9.6% and 10.4% based on mitochondrial COI and ND2, respectively. It is currently documented from five localities: two in peninsular Thailand, at Hala Forest in Yala Province, and Phru To Daeng Swamp Forest in Narathiwat Province, one from peninsular Malaysia at Krau Wildlife Reserve in Pahang, and another two in Sabah, Malaysian Borneo at Gunung Kinabalu, and near Madai Caves. However, it is likely that many previous records of "H. cineraceus" from Borneo refer to this species. Most records of the species are from lowland evergreen rainforest, though one record from Sabah was at 1800m. The roosting sites for this new species are currently unknown. Future research with a combination of data such as genetics, echolocation and morphology would be necessary to further determine the species geographic distribution in Southeast Asia.

Out of thin air: surveying tropical bat roosts through air sampling of eDNA

Understanding roosting behaviour is essential to bat conservation and biomonitoring, often providing the most accurate methods of assessing bat population size and health. However, roosts can be challenging to survey, e.g., physically impossible to access or presenting risks for researchers. Disturbance during monitoring can also disrupt natural bat behaviour and present material risks to the population such as disrupting hibernation cycles. One solution to this is the use of non-invasive monitoring approaches. Environmental (e)DNA has proven especially effective at detecting rare and elusive species particularly in hard-to-reach locations. It has recently been demonstrated that eDNA from vertebrates is carried in air. When collected in semi-confined spaces, this airborne eDNA can provide remarkably accurate profiles of biodiversity, even in complex tropical communities. In this study, we deploy novel airborne eDNA collection for the first time in a natural setting and use this approach to survey difficult to access potential roosts in the neotropics. Using airborne eDNA, we confirmed the presence of bats in nine out of 12 roosts. The identified species matched previous records of roost use obtained from photographic and live capture methods, thus demonstrating the utility of this approach. We also detected the presence of the white-winged vampire bat (Diaemus youngi) which had never been confirmed in the area but was long suspected based on range maps. In addition to the bats, we detected several non-bat vertebrates, including the big-eared climbing rat (Ototylomys phyllotis), which has previously been observed in and around bat roosts in our study area. We also detected eDNA from other local species known to be in the vicinity. Using airborne eDNA to detect new roosts and monitor known populations, particularly when species turnover is rapid, could maximize efficiency for surveyors while minimizing disturbance to the animals. This study presents the first applied use of airborne eDNA collection for ecological analysis moving beyond proof of concept to demonstrate a clear utility for this technology in the wild.

Expert range maps of global mammal distributions harmonised to three taxonomic authorities

AIM

Comprehensive, global information on species' occurrences is an essential biodiversity variable and central to a range of applications in ecology, evolution, biogeography and conservation. Expert range maps often represent a species' only available distributional information and play an increasing role in conservation assessments and macroecology. We provide global range maps for the native ranges of all extant mammal species harmonised to the taxonomy of the Mammal Diversity Database (MDD) mobilised from two sources, the Handbook of the Mammals of the World (HMW) and the Illustrated Checklist of the Mammals of the World (CMW).

LOCATION

Global.

TAXON

All extant mammal species.

METHODS

Range maps were digitally interpreted, georeferenced, error-checked and subsequently taxonomically aligned between the HMW (6253 species), the CMW (6431 species) and the MDD taxonomies (6362 species).

RESULTS

Range maps can be evaluated and visualised in an online map browser at Map of Life (mol.org) and accessed for individual or batch download for non-commercial use.

MAIN CONCLUSION

Expert maps of species' global distributions are limited in their spatial detail and temporal specificity, but form a useful basis for broad-scale characterizations and model-based integration with other data. We provide georeferenced range maps for the native ranges of all extant mammal species as shapefiles, with species-level metadata and source information packaged together in geodatabase format. Across the three taxonomic sources our maps entail, there are 1784 taxonomic name differences compared to the maps currently available on the IUCN Red List website. The expert maps provided here are harmonised to the MDD taxonomic authority and linked to a community of online tools that will enable transparent future updates and version control.

Bat selfies: photographic surveys of flying bats

The recent pandemic and other environmental concerns have resulted in restrictions on research and surveys involving capture and handling bats. While acoustic surveys have been widely used as an alternative survey method, in this study, we show how photographic surveys can offer an important contribution to study and survey bats. We outline approaches, using high speed flash and automated trip beams to obtain photos of flying bats of sufficient quality for reliable identification of species. We show, through a series of examples of setups and photographs, that photography is effective for surveying bats at a variety of sites, where bats roost, drink, and forage. We note, however, that photographic surveys cannot replace capture in all situations. In addition, although photographing bats is less invasive than capturing them, it can involve disturbance, so we stress the importance of minimizing the impact of such operations on bats.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42991-022-00233-7.

Bridging research and practice in conservation

Calls for biodiversity conservation practice to be more evidence based are growing, and we agree evidence use in conservation practice needs improvement. However, evidence-based conservation will not be realized without improved access to evidence. In medicine, unlike in conservation, a well-established and well-funded layer of intermediary individuals and organizations engage with medical practitioners, synthesize primary research relevant to decision making, and make evidence easily accessible. These intermediaries prepare targeted evidence summaries and distribute them to practitioners faced with time-sensitive and value-laden decisions. To be effective, these intermediaries, who we refer to as evidence bridges, should identify research topics based on the priorities of practitioners; synthesize evidence; prepare and distribute easy-to-find and easy-to-use evidence summaries; and develop and maintain networks of connections with researchers and practitioners. Based on a review of the literature regarding evidence intermediaries in conservation and environmental management, as well as an anonymous questionnaire searching for such organizations, we found few intermediaries that met all these criteria. Few evidence bridges that do exist are unable to reach most conservation practitioners, which include resource managers in government and industry, conservation organizations, and farmers and other private landowners. We argue that the lack of evidence bridges from research to practitioners contributes to evidence complacency and limits the use of evidence in conservation action. Nevertheless, several existing organizations help reduce the gap between evidence and practice and could serve as a foundation for building additional components of evidence bridges in conservation. Although evidence bridges need expertise in research and evidence synthesis, they also require expertise in identifying and communicating with the community of practitioners most in need of clear and concise syntheses of evidence. Article Impact Statement: Evidence-based conservation will not be realized without improved access to evidence. We call for intermediary evidence bridges.

Bridging research and practice in conservation

Calls for biodiversity conservation practice to be more evidence based are growing, and we agree evidence use in conservation practice needs improvement. However, evidence-based conservation will not be realized without improved access to evidence. In medicine, unlike in conservation, a well-established and well-funded layer of intermediary individuals and organizations engage with medical practitioners, synthesize primary research relevant to decision making, and make evidence easily accessible. These intermediaries prepare targeted evidence summaries and distribute them to practitioners faced with time-sensitive and value-laden decisions. To be effective, these intermediaries, who we refer to as evidence bridges, should identify research topics based on the priorities of practitioners; synthesize evidence; prepare and distribute easy-to-find and easy-to-use evidence summaries; and develop and maintain networks of connections with researchers and practitioners. Based on a review of the literature regarding evidence intermediaries in conservation and environmental management, as well as an anonymous questionnaire searching for such organizations, we found few intermediaries that met all these criteria. Few evidence bridges that do exist are unable to reach most conservation practitioners, which include resource managers in government and industry, conservation organizations, and farmers and other private landowners. We argue that the lack of evidence bridges from research to practitioners contributes to evidence complacency and limits the use of evidence in conservation action. Nevertheless, several existing organizations help reduce the gap between evidence and practice and could serve as a foundation for building additional components of evidence bridges in conservation. Although evidence bridges need expertise in research and evidence synthesis, they also require expertise in identifying and communicating with the community of practitioners most in need of clear and concise syntheses of evidence. Article Impact Statement: Evidence-based conservation will not be realized without improved access to evidence. We call for intermediary evidence bridges.

NABat: A top-down, bottom-up solution to collaborative continental-scale monitoring

Collaborative monitoring over broad scales and levels of ecological organization can inform conservation efforts necessary to address the contemporary biodiversity crisis. An important challenge to collaborative monitoring is motivating local engagement with enough buy-in from stakeholders while providing adequate top-down direction for scientific rigor, quality control, and coordination. Collaborative monitoring must reconcile this inherent tension between top-down control and bottom-up engagement. Highly mobile and cryptic taxa, such as bats, present a particularly acute challenge. Given their scale of movement, complex life histories, and rapidly expanding threats, understanding population trends of bats requires coordinated broad-scale collaborative monitoring. The North American Bat Monitoring Program (NABat) reconciles top-down, bottom-up tension with a hierarchical master sample survey design, integrated data analysis, dynamic data curation, regional monitoring hubs, and knowledge delivery through web-based infrastructure. NABat supports collaborative monitoring across spatial and organizational scales and the full annual lifecycle of bats.

Long-distance migratory shorebirds travel faster towards their breeding grounds, but fly faster post-breeding

Long-distance migrants are assumed to be more time-limited during the pre-breeding season compared to the post-breeding season. Although breeding-related time constraints may be absent post-breeding, additional factors such as predation risk could lead to time constraints that were previously underestimated. By using an automated radio telemetry system, we compared pre- and post-breeding movements of long-distance migrant shorebirds on a continent-wide scale. From 2014 to 2016, we deployed radio transmitters on 1,937 individuals of 4 shorebird species at 13 sites distributed across North America. Following theoretical predictions, all species migrated faster during the pre-breeding season, compared to the post-breeding season. These differences in migration speed between seasons were attributable primarily to longer stopover durations in the post-breeding season. In contrast, and counter to our expectations, all species had higher airspeeds during the post-breeding season, even after accounting for seasonal differences in wind. Arriving at the breeding grounds in good body condition is beneficial for survival and reproductive success and this energetic constraint might explain why airspeeds are not maximised in the pre-breeding season. We show that the higher airspeeds in the post-breeding season precede a wave of avian predators, which could suggest that migrant shorebirds show predation-minimizing behaviour during the post-breeding season. Our results reaffirm the important role of time constraints during northward migration and suggest that both energy and predation-risk constrain migratory behaviour during the post-breeding season.

Forest surveys extend the range of the Krau woolly bat (Kerivoula krauensis) in the Malay-Thai Peninsula, Borneo and Sumatra

was formally described in 2007 and until recently was only known from tropical forest in central peninsular Malaysia. We report four new records, which, together with recent published collections, extend the known range for this species to peatswamps, lowland and montane forests in Borneo and Sumatra (Brunei and Indonesia), and further north on the Malay peninsula, including Thailand. External body measurements and cranial data match well with those from the type locality, although echolocation call parameters differ – most likely due to technological improvements in recording devices. The species remains patchily distributed and rarely encountered, despite substantial sampling effort.

Response to letter regarding article "How far north are migrant birds transporting the tick Ixodes scapularis in Canada? Insights from stable hydrogen isotope analyses of feathers"

In this letter we respond to correspondence and clarify the intent and importance of our article.

How far north are migrant birds transporting the tick Ixodes scapularis in Canada? Insights from stable hydrogen isotope analyses of feathers

Lyme disease is emerging in Canada because of northward range expansion of the tick vector Ixodes scapularis. It is hypothesised that I. scapularis feeding on passerine birds migrating north in spring are important in founding new I. scapularis populations leading to northward range expansion. However, there are no studies on how far north I. scapularis may be carried, only inferences from passive tick surveillance. We used stable hydrogen isotope (δ(2)H) analysis of rectrices collected from northward migrating, I. scapularis-carrying, passerine birds captured in Canada to estimate how far north I. scapularis may be carried. Rectrices are usually grown close to breeding sites and their δ(2)H values reflect those in the environment, which vary strongly with latitude in North America. Passerines usually return to their breeding or natal sites so δ(2)H values of rectrices of northward migrating birds can identify the likely latitudinal bands of their intended destinations. In 2006 we analysed δ(2)H from rectrices of 73 I. scapularis-carrying birds captured at five migration monitoring stations, mainly from southern Ontario. Values of δ(2)H ranged from -33 to -124‰, suggesting 19/71 (26.7%) birds were destined for latitude band B (the most southerly part of Ontario), 40/71 (56.3%) birds were destined for band C (which extends from southern Ontario, Quebec and the Maritimes to southern James Bay) and 12/71 (16.9%) birds were destined for bands D and E (which extend from northern Ontario and Quebec into the southern Canadian Arctic). This indicates that many I. scapularis-carrying migratory birds in spring have destinations far north in Canada, including some farther north than the current region of climatic suitability for I. scapularis. These findings support the hypothesis that I. scapularis may continue to be spread north by spring migrating passerines. Some thrush species may be particularly implicated in far northward dispersion of I. scapularis.

Estimating breeding bird survey trends and annual indices for Canada: how do the new hierarchical Bayesian estimates differ from previous estimates?

Canadian data from the North American Breeding Bird Survey (BBS) provide information on the population status and trends for over 300 species that regularly breed in Canada. Since the first assessments were made in the mid-1970s, both the dataset and the suite of statistical tools and techniques available to researchers have grown. As a result, Canadian BBS trend estimates have been derived from numerous statistical models. Because the BBS data are relatively complex, different statistical models can generate different trend and status estimates from the same data. In 2013, Environment Canada’s Canadian Wildlife Service began producing BBS status and trend estimates using a hierarchical Bayesian model. To give users of BBS trends and annual indices of abundance a better understanding of these estimates, we demonstrate and explain some of the similarities and differences between the new hierarchical Bayesian estimates and those from the previous model; discuss the philosophical and inferential consequences of estimating trends with the new model; and describe how the hierarchical Bayesian model differs from the model currently used in the United States. Overall, trends and annual indices from the new model are generally similar to estimates from the previous model; however, they are more precise, less variable among years, better represent the spatial variation across Canada in population status, and allow for more intuitive and useful assessments of uncertainty.

Molecular phylogenetic reconstructions identify East Asia as the cradle for the evolution of the cosmopolitan genus Myotis (Mammalia, Chiroptera)

Sequences of the mitochondrial cytochrome b (1140 bp) and nuclear Rag 2 (1148 bp) genes were used to assess the evolutionary history of the cosmopolitan bat genus Myotis, based on a worldwide sampling of over 88 named species plus 7 species with uncertain nomenclature. Phylogenetic reconstructions of this comprehensive taxon sampling show that most radiation of species occurred independently within each biogeographic region. Our molecular study supports an early divergence of species from the New World, where all Nearctic and Neotropical species plus a lineage from the Palaearctic constitute a monophyletic clade, sister to the remaining Old World taxa. The major Old World clade includes all remaining Eurasian taxa, most Oriental species, one Oceanian, and all Ethiopian species. Another lineage, including M. latirostris from Taiwan, appears at the base of these two major biogeographic clades and, because it bears nyctalodont molars, could be considered as a distinct genus. However, this molar configuration is also found in crown-group species, indicating that these dental characters are variable in the genus Myotis and may confound interpretation of the fossil record. Molecular datings suggest an origin of all recent Myotis in the early Miocene (about 21MYA with 95% highest posterior density interval 23-20MYA). This period was characterized by a global climatic cooling that reduced the availability of tropical habitats and favoured the development of more temperate vegetation. This sharp climatic change might have triggered the evolution of Myotis in the Northern continents, because Myotis ancestors seem to have been well adapted and successful in such temperate habitats. Ancestral area reconstructions based on the molecular phylogeny suggest that the eastern portion of the Asian continent was an important center of origin for the early diversification of all Myotis lineages, and involved relatively few subsequent transcontinental range expansions.

Molecular phylogeny of hipposiderid bats from Southeast Asia and evidence of cryptic diversity

Old World leaf-nosed bats (Hipposideridae) are among the most widespread and ecologically diverse groups of insectivorous bats in the Old World tropics. However, phylogenetic relationships in Hipposideridae are poorly resolved at both the generic and species levels, and deep genetic divergence within several Southeast Asian species suggests that current taxonomy underestimates hipposiderid diversity in this region. We used mitochondrial and nuclear sequence data to conduct the first extensive molecular phylogenetic analysis of Southeast Asian hipposiderid bats. Inclusion of multiple samples per taxon allowed testing for evidence of evolutionarily distinct lineages within taxa currently defined as single species. In contrast to earlier phylogenies based on morphometrics, molecular data support monophyly of Hipposideros, but are ambiguous regarding the monophyly of Hipposideridae. With a few exceptions, molecular data also support currently recognized species groups classified by qualitative morphological characters. Widespread paraphyly and polyphyly within many currently recognized species of Hipposideros indicates that evolutionary diversity in the genus is underrepresented by current nomenclature. Comparison of available morphological and echolocation data suggest that both geographic isolation and ecological selection have contributed to the diversification of Southeast Asian hipposiderid bats.

The role of DNA barcodes in understanding and conservation of mammal diversity in southeast Asia

Background

Southeast Asia is recognized as a region of very high biodiversity, much of which is currently at risk due to habitat loss and other threats. However, many aspects of this diversity, even for relatively well-known groups such as mammals, are poorly known, limiting ability to develop conservation plans. This study examines the value of DNA barcodes, sequences of the mitochondrial COI gene, to enhance understanding of mammalian diversity in the region and hence to aid conservation planning.

Methodology and Principal Findings

DNA barcodes were obtained from nearly 1900 specimens representing 165 recognized species of bats. All morphologically or acoustically distinct species, based on classical taxonomy, could be discriminated with DNA barcodes except four closely allied species pairs. Many currently recognized species contained multiple barcode lineages, often with deep divergence suggesting unrecognized species. In addition, most widespread species showed substantial genetic differentiation across their distributions. Our results suggest that mammal species richness within the region may be underestimated by at least 50%, and there are higher levels of endemism and greater intra-specific population structure than previously recognized.

Conclusions

DNA barcodes can aid conservation and research by assisting field workers in identifying species, by helping taxonomists determine species groups needing more detailed analysis, and by facilitating the recognition of the appropriate units and scales for conservation planning.

Risk maps for range expansion of the Lyme disease vector, Ixodes scapularis, in Canada now and with climate change

BACKGROUND

Lyme disease is the commonest vector-borne zoonosis in the temperate world, and an emerging infectious disease in Canada due to expansion of the geographic range of the tick vector Ixodes scapularis. Studies suggest that climate change will accelerate Lyme disease emergence by enhancing climatic suitability for I. scapularis. Risk maps will help to meet the public health challenge of Lyme disease by allowing targeting of surveillance and intervention activities.

RESULTS

A risk map for possible Lyme endemicity was created using a simple risk algorithm for occurrence of I. scapularis populations. The algorithm was calculated for each census sub-division in central and eastern Canada from interpolated output of a temperature-driven simulation model of I. scapularis populations and an index of tick immigration. The latter was calculated from estimates of tick dispersion distances by migratory birds and recent knowledge of the current geographic range of endemic I. scapularis populations. The index of tick immigration closely predicted passive surveillance data on I. scapularis occurrence, and the risk algorithm was a significant predictor of the occurrence of I. scapularis populations in a prospective field study. Risk maps for I. scapularis occurrence in Canada under future projected climate (in the 2020s, 2050s and 2080s) were produced using temperature output from the Canadian Coupled Global Climate Model 2 with greenhouse gas emission scenario enforcing 'A2' of the Intergovernmental Panel on Climate Change.

CONCLUSION

We have prepared risk maps for the occurrence of I. scapularis in eastern and central Canada under current and future projected climate. Validation of the risk maps provides some confidence that they provide a useful first step in predicting the occurrence of I. scapularis populations, and directing public health objectives in minimizing risk from Lyme disease. Further field studies are needed, however, to continue validation and refinement of the risk maps.

Comprehensive DNA barcode coverage of North American birds

DNA barcoding seeks to assemble a standardized reference library for DNA-based identification of eukaryotic species. The utility and limitations of this approach need to be tested on well-characterized taxonomic assemblages. Here we provide a comprehensive DNA barcode analysis for North American birds including 643 species representing 93% of the breeding and pelagic avifauna of the USA and Canada. Most (94%) species possess distinct barcode clusters, with average neighbour-joining bootstrap support of 98%. In the remaining 6%, barcode clusters correspond to small sets of closely related species, most of which hybridize regularly. Fifteen (2%) currently recognized species are comprised of two distinct barcode clusters, many of which may represent cryptic species. Intraspecific variation is weakly related to census population size and species age. This study confirms that DNA barcoding can be effectively applied across the geographical and taxonomic expanse of North American birds. The consistent finding of constrained intraspecific mitochondrial variation in this large assemblage of species supports the emerging view that selective sweeps limit mitochondrial diversity.

The influence of climate on the timing and rate of spring bird migration

Ecological processes are changing in response to climatic warming. Birds, in particular, have been documented to arrive and breed earlier in spring and this has been attributed to elevated spring temperatures. It is not clear, however, how long-distance migratory birds that overwinter thousands of kilometers to the south in the tropics cue into changes in temperature or plant phenology on northern breeding areas. We explored the relationships between the timing and rate of spring migration of long-distance migratory birds, and variables such as temperature, the North Atlantic Oscillation (NAO) and plant phenology, using mist net capture data from three ringing stations in North America over a 40-year period. Mean April/May temperatures in eastern North America varied over a 5 degrees C range, but with no significant trend during this period. Similarly, we found few significant trends toward earlier median capture dates of birds. Median capture dates were not related to the NAO, but were inversely correlated to spring temperatures for almost all species. For every 1 degrees C increase in spring temperature, median capture dates of migratory birds averaged, across species, one day earlier. Lilac (Syringa vulgaris) budburst, however, averaged 3 days earlier for every 1 degrees C increase in spring temperature, suggesting that the impact of temperature on plant phenology is three times greater than on bird phenology. To address whether migratory birds adjust their rate of northward migration to changes in temperature, we compared median capture dates for 15 species between a ringing station on the Gulf Coast of Louisiana in the southern USA with two stations approximately 2,500 km to the north. The interval between median capture dates in Louisiana and at the other two ringing stations was inversely correlated with temperature, with an average interval of 22 days, that decreased by 0.8 days per 1 degrees C increase in temperature. Our results suggest that, although the onset of migration may be determined endogenously, the timing of migration is flexible and can be adjusted in response to variation in weather and/or phenology along migration routes.

Identification of Birds through DNA Barcodes

Short DNA sequences from a standardized region of the genome provide a DNA barcode for identifying species. Compiling a public library of DNA barcodes linked to named specimens could provide a new master key for identifying species, one whose power will rise with increased taxon coverage and with faster, cheaper sequencing. Recent work suggests that sequence diversity in a 648-bp region of the mitochondrial gene, cytochrome c oxidase I (COI), might serve as a DNA barcode for the identification of animal species. This study tested the effectiveness of a COI barcode in discriminating bird species, one of the largest and best-studied vertebrate groups. We determined COI barcodes for 260 species of North American birds and found that distinguishing species was generally straightforward. All species had a different COI barcode(s), and the differences between closely related species were, on average, 18 times higher than the differences within species. Our results identified four probable new species of North American birds, suggesting that a global survey will lead to the recognition of many additional bird species. The finding of large COI sequence differences between, as compared to small differences within, species confirms the effectiveness of COI barcodes for the identification of bird species. This result plus those from other groups of animals imply that a standard screening threshold of sequence difference (10x average intraspecific difference) could speed the discovery of new animal species. The growing evidence for the effectiveness of DNA barcodes as a basis for species identification supports an international exercise that has recently begun to assemble a comprehensive library of COI sequences linked to named specimens.

Sexual size dimorphism and timing of spring migration in birds

Sexually selected traits are limited by selection against those traits in other fitness components, such as survival. Thus, sexual selection favouring large size in males should be balanced by higher mortality of larger males. However, evidence from red-winged blackbirds (Agelaius phoeniceus) indicates that large males survive better than small males. A survival advantage to large size could result from males migrating north in early spring, when harsh weather favours large size for energetic reasons. From this hypothesis we predicted that, among species, sex differences in body size should be correlated with sex differences in timing of spring migration. The earlier males migrate relative to females, the larger they should be relative to females. We tested this prediction using a comparative analysis of data collected from 30 species of passerine birds captured on migration. After controlling for social mating system, we found that sexual size dimorphism and difference in arrival dates of males and females were significantly positively correlated. This result is consistent with the hypothesis that selection for survival ability promotes sexual size dimorphism (SSD), rather than opposes SSD as is the conventional view. If both natural selection and sexual selection favour large adult males, then limits to male size must be imposed before males become adults.

The effects of selective logging on nest-site selection and productivity of hooded warblers (Wilsonia citrina) in Canada

We examined nest-site selection by hooded warblers (Wilsonia citrina) in two forests differing in composition (extensive pine plantation versus largely deciduous) and management (recent selective logging versus minimal logging). We measured habitat at 52 nests and 66 controls in one forest and 57 nests and 41 controls in the second. Nests had denser ground vegetation, fewer tree stems, less basal area due to small trees and greater basal area due to large trees than controls in both forests. In the managed forest with extensive pine plantations, hooded warblers were in coniferous and logged stands more often than expected by chance, nests had more stumps and greater canopy height than controls, and 91% (52/57) of all nests were found in gaps, 84% of which were created by harvest. Gap age was 6.2 ± 0.9 years (mean ± SE) in 1999, and 7.6 ± 0.6 years in 2000. In the managed forest, 52% of 24 nests were parasitized in 1999 and 39% of 33 nests were parasitized in 2000. The daily survival rate was 0.936 ± 0.019 in 1999 and 0.944 ± 0.014 in 2000. Successful nests did not differ from unsuccessful nests in any habitat variable. To benefit hooded warblers, forest managers should mimic natural gap creation by using selective logging to create gaps no larger than 0.05 ha, and should leave a residual basal area of mature trees (>38 cm diameter at breast height) of at least 12 m2/ha.

Survey of provision of echocardiography in Scottish district general hospitals

A telephone survey of echocardiography services in district general hospitals in Scotland was carried out in 1999. The study showed wide variation in the echocardiography services among the district hospitals in terms of equipment, personnel and service provision. The number of echocardiograms performed by a centre is partly dependent on the demand but is more critically influenced by the local provision of service. In particular, sufficient numbers of trained technicians hold the key to efficient high output services. The survey has provided a platform for comparison of echocardiography services among the district general hospitals in Scotland. We hope that this will encourage individual district hospitals to audit their echocardiography service with a special emphasis on the role of the technician.

Should we screen for asymptomatic left ventricular dysfunction to prevent heart failure?

A programme to detect and treat asymptomatic left ventricular dysfunction would seem to fulfil all five principles of screening. Indeed, such a programme would appear to be at least as firmly based as those already in existence for, for example, cervical and breast cancer. Further evaluation of the screening of high risk groups to detect asymptomatic left ventricular systolic dysfunction with the aim of giving treatment to prevent the development of heart failure is merited.

The prevalence of left ventricular diastolic filling abnormalities in patients with suspected heart failure

AIMS

It is reported that one third of patients with heart failure have normal left ventricular systolic function, and may or may not have left ventricular diastolic dysfunction. We sought to define the prevalence of left ventricular diastolic filling abnormalities in a large unselected group of patients, unlike the diagnosis by exclusion in the small highly selected groups of patients studied previously.

METHODS AND RESULTS

Patients were referred by general practitioners to an open-access echocardiography service for assessment of possible heart failure. Echocardiography included a Doppler study of transmitral flow at the tips of the mitral leaflets and calculation of an E/A ratio. Of 534 patients referred and assessed, 371 patients had normal systolic function and a measurable E/A ratio. These were compared with age-adjusted reference ranges to give 9 above the reference range and 19 below. This is only 10 more than would be expected if our patients were normal. In the same group of patients we found 96 cases of left ventricular systolic dysfunction, or 52 amongst the 423 with a measurable E/A ratio.

CONCLUSION

Either left ventricular diastolic filling abnormalities are very much less common than previously supposed or the E/A ratio is almost useless for their detection.

Assessing diagnosis in heart failure: which features are any use?

We assessed the value of symptoms, past history, medications and signs in the evaluation of patients who might have heart failure secondary to left ventricular systolic dysfunction. An open-access echocardiography service was set up to help identify patients with left ventricular systolic dysfunction who might benefit from treatment with an angiotensin-converting-enzyme inhibitor. History and examination were recorded for each of these patients. The patients were divided into groups according to whether left ventricular systolic function was preserved or not and whether various clinical features were present or not. Of 259 consecutive patients studied, 41 had impairment of left ventricular systolic function as assessed by echocardiography. Past history of myocardial infarction and displaced apex beat were the best single predictors of left ventricular systolic dysfunction as assessed by echocardiography. The combination of past history of myocardial infarction and displaced apex had the best positive predictive value of all. Patients with such clinical features or combinations of clinical features may not need echocardiography, and where access to this resource is limited, it could be reserved for patients without such diagnostic features.

Effects of digoxin on time domain measures of heart rate variability in patients with stable chronic cardiac failure: withdrawal and comparison group studies

The effect on heart rate variability of adding digoxin to a diuretic and ACE inhibitor was studied in patients with chronic stable cardiac failure. Digoxin was found to increase heart rate variability, especially those measures of heart rate variability thought to represent parasympathetic activity. The withdrawal of digoxin led to a decrease in heart rate variability to pre-treatment levels. Whilst digoxin in standard doses does not alter prognosis in chronic cardiac failure, it does have potentially beneficial neurohumoral effects. If the increase in heart rate variability, which represents beneficial neurohumoral modulation, can be divorced from the potentially detrimental effects, perhaps by using smaller doses, then there may be a role for digoxin in the treatment of chronic cardiac failure.

The glutamate-enriched cortical and thalamic input to neurons in the subthalamic nucleus of the rat: convergence with GABA-positive terminals

Neurons of the subthalamic nucleus play a key role in the normal physiology and the pathophysiology of the basal ganglia. In order to understand better how the activity of subthalamic neurons and hence the output of the basal ganglia are controlled, we have reexamined the topography and examined in detail the synaptology and neurochemical nature of the two major excitatory projections to the subthalamic nucleus, that from the cortex and from the parafascicular nucleus of the thalamus. The approach was to use anterograde neuronal tracing and postembedding immunocytochemistry for amino acid transmitters. In confirmation of previous findings the cortical and thalamic projections were topographically organized, although the topography was more finely organized, and the projections more extensive, than previously demonstrated. Cortical and thalamic terminals made asymmetrical synaptic contacts with the dendrites and spines of subthalamic neurons. The thalamic terminals contacted larger postsynaptic targets, and therefore presumably more proximal regions of subthalamic neurons, than did the cortical terminals. Quantitative analysis of the postembedding immunolabelled sections revealed that the cortical and thalamic terminals were significantly enriched in glutamate-immunoreactivity when compared to identified gamma-aminobutyric acid (GABA)-positive terminals, supporting physiological studies that suggest that these projections use glutamate as their neurotransmitter. In addition a small population of nonanterogradely labelled terminals that formed asymmetrical synapses and were immunopositive for GABA were identified. A larger population of terminals that formed symmetrical synapses were also immunopositive for GABA and were probably derived from the globus pallidus. The latter type of terminal was found to make convergent synaptic input with cortical or thalamic terminals on the dendrites and spines of subthalamic neurons, indicating that the "indirect pathways" by which information flows through the basal ganglia converge at the level of individual neurons in the subthalamic nucleus.