The Experts below are selected from a list of 171 Experts worldwide ranked by ideXlab platform
William F Towne - One of the best experts on this subject based on the ideXlab platform.
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The depth of the honeybee's backup sun-Compass systems.
The Journal of experimental biology, 2013Co-Authors: Katelyn M Dovey, Jordan R Kemfort, William F TowneAbstract:Honeybees have at least three Compass mechanisms: a magnetic Compass; a celestial or sun Compass, based on the daily rotation of the sun and sun-linked skylight patterns; and a backup celestial Compass based on a memory of the sun's movements over time in relation to the landscape. The interactions of these Compass systems have yet to be fully elucidated, but the celestial Compass is primary in most contexts, the magnetic Compass is a backup in certain contexts, and the bees' memory of the sun's course in relation to the landscape is a backup system for cloudy days. Here we ask whether bees have any further Compass systems, for example a memory of the sun's movements over time in relation to the magnetic field. To test this, we challenged bees to locate the sun when their known celestial Compass systems were unavailable, that is, under overcast skies in unfamiliar landscapes. We measured the bees' knowledge of the sun's location by observing their waggle dances, by which foragers indicate the directions toward food sources in relation to the sun's Compass Bearing. We found that bees have no celestial Compass systems beyond those already known: under overcast skies in unfamiliar landscapes, bees attempt to use their landscape-based backup system to locate the sun, matching the landscapes or skylines at the test sites with those at their natal sites as best they can, even if the matches are poor and yield weak or inconsistent orientation.
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The connection between landscapes and the solar ephemeris in honeybees
Journal of Experimental Biology, 2008Co-Authors: William F Towne, Heather MoscripAbstract:SUMMARY Honeybees connect the sun9s daily pattern of azimuthal movement to some aspect of the landscape around their nests. In the present study, we ask what aspect of the landscape is used in this context – the entire landscape panorama or only sectors seen along familiar flight routes. Previous studies of the solar ephemeris memory in bees have generally used bees that had experience flying a specific route, usually along a treeline, to a feeder. When such bees were moved to a differently oriented treeline on overcast days, the bees oriented their communicative dances as if they were still at the first treeline, based on a memory of the sun9s course in relation to some aspect of the site, possibly the familiar route along the treeline or possibly the entire landscape or skyline panorama. Our results show that bees lacking specific flight-route training can nonetheless recall the sun9s Compass Bearing relative to novel flight routes in their natal landscape. Specifically, we moved a hive from one landscape to a differently oriented twin landscape, and only after transplantation under overcast skies did we move a feeder away from the hive. These bees nonetheless danced accurately by memory of the sun9s course in relation to their natal landscape. The bees9 knowledge of the relationship between the sun and landscape, therefore, is not limited to familiar flight routes and so may enCompass, at least functionally, the entire panorama. Further evidence suggests that the skyline in particular may be the bees9 preferred reference in this context.
Charles-andré Bost - One of the best experts on this subject based on the ideXlab platform.
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A Space Oddity: Geographic and Specific Modulation of Migration in Eudyptes Penguins
PloS one, 2013Co-Authors: Jean-baptiste Thiebot, Yves Cherel, Philip N. Trathan, Robert J. M. Crawford, Azwianewi B. Makhado, David Pinaud, Charles-andré BostAbstract:Post-breeding migration in land-based marine animals is thought to offset seasonal deterioration in foraging or other important environmental conditions at the breeding site. However the inter-breeding distribution of such animals may reflect not only their optimal habitat, but more subtle influences on an individual’s migration path, including such factors as the intrinsic influence of each locality’s paleoenvironment, thereby influencing animals’ wintering distribution. In this study we investigated the influence of the regional marine environment on the migration patterns of a poorly known, but important seabird group. We studied the inter-breeding migration patterns in three species of Eudyptes penguins (E. chrysolophus, E. filholi and E. moseleyi), the main marine prey consumers amongst the World’s seabirds. Using ultra-miniaturized logging devices (light-based geolocators) and satellite tags, we tracked 87 migrating individuals originating from 4 sites in the southern Indian Ocean (Marion, Crozet, Kerguelen and Amsterdam Islands) and modelled their wintering habitat using the MADIFA niche modelling technique. For each site, sympatric species followed a similar Compass Bearing during migration with consistent species-specific latitudinal shifts. Within each species, individuals breeding on different islands showed contrasting migration patterns but similar winter habitat preferences driven by sea-surface temperatures. Our results show that inter-breeding migration patterns in sibling penguin species depend primarily on the site of origin and secondly on the species. Such site-specific migration Bearings, together with similar wintering habitat used by parapatrics, support the hypothesis that migration behaviour is affected by the intrinsic characteristics of each site. The paleo-oceanographic conditions (primarily, sea-surface temperatures) when the populations first colonized each of these sites may have been an important determinant of subsequent migration patterns. Based on previous chronological schemes of taxonomic radiation and geographical expansion of the genus Eudyptes, we propose a simple scenario to depict the chronological onset of contrasting migration patterns within this penguin group.
A S Edwards - One of the best experts on this subject based on the ideXlab platform.
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A landscape-scale study of bumble bee foraging range and constancy, using harmonic radar
Journal of Applied Ecology, 1999Co-Authors: J L Osborne, J R Riley, D R Reynolds, R. J. Morris, S J Clark, I H Williams, A D Smith, A S EdwardsAbstract:1. Bumble bees play a vital role in the pollination of many crops and wild flowers, and plans for their conservation require a knowledge of the dynamics and spatial scale of their foraging flights, which are, at present, poorly understood. 2. We investigated the foraging range and constancy of two colonies of bumble bees Bombus terrestris L. on a mixed arable farm using harmonic radar, which has a unique capability to record the trajectories of insects flying at low altitude in the field. 3. Foraging bees were fitted with lightweight radar transponders and tracked as they flew to and from the nest to forage. The resulting tracks gave information on length, direction and straightness of foraging routes. Superimposition onto a map of the foraging landscape allowed interpretation of the bees’ destinations in relation to the spatial distribution of forage. 4. Outward tracks had a mean length of 275·3 ± 18·5 m (n = 65) and a range of 70–631 m, and were often to forage destinations beyond the nearest available forage. Most bees were constant to Compass Bearing and destination over successive trips, although one bee was tracked apparently switching between forage patches. Both outward and return tracks had a mean straightness ratio of 0·93 ± 0·01 (n = 99). The bees’ ground speeds ranged from 3·0 m s–1 to 15·7 m s–1 (n = 100) in a variety of wind conditions. 5. The results support the hypothesis that bumble bees do not necessarily forage close to their nest, and illustrate that studies on a landscape scale are required if we are to evaluate bee foraging ranges fully with respect to resource availability. Such evaluations are required to underpin assessments of gene flow in bee-pollinated crops and wild flowers. They are also required when making decisions about the management of bees as pollinators and the conservation of bee and plant biodiversity.
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A landscape‐scale study of bumble bee foraging range and constancy, using harmonic radar
Journal of Applied Ecology, 1999Co-Authors: J L Osborne, J R Riley, D R Reynolds, R. J. Morris, S J Clark, I H Williams, A D Smith, A S EdwardsAbstract:Summary 1. Bumble bees play a vital role in the pollination of many crops and wild flowers, and plans for their conservation require a knowledge of the dynamics and spatial scale of their foraging flights, which are, at present, poorly understood. 2. We investigated the foraging range and constancy of two colonies of bumble bees Bombus terrestris L. on a mixed arable farm using harmonic radar, which has a unique capability to record the trajectories of insects flying at low altitude in the field. 3. Foraging bees were fitted with lightweight radar transponders and tracked as they flew to and from the nest to forage. The resulting tracks gave information on length, direction and straightness of foraging routes. Superimposition onto a map of the foraging landscape allowed interpretation of the bees’ destinations in relation to the spatial distribution of forage. 4. Outward tracks had a mean length of 275·3 ± 18·5 m (n = 65) and a range of 70–631 m, and were often to forage destinations beyond the nearest available forage. Most bees were constant to Compass Bearing and destination over successive trips, although one bee was tracked apparently switching between forage patches. Both outward and return tracks had a mean straightness ratio of 0·93 ± 0·01 (n = 99). The bees’ ground speeds ranged from 3·0 m s–1 to 15·7 m s–1 (n = 100) in a variety of wind conditions. 5. The results support the hypothesis that bumble bees do not necessarily forage close to their nest, and illustrate that studies on a landscape scale are required if we are to evaluate bee foraging ranges fully with respect to resource availability. Such evaluations are required to underpin assessments of gene flow in bee-pollinated crops and wild flowers. They are also required when making decisions about the management of bees as pollinators and the conservation of bee and plant biodiversity.
Jean-baptiste Thiebot - One of the best experts on this subject based on the ideXlab platform.
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A Space Oddity: Geographic and Specific Modulation of Migration in Eudyptes Penguins
PloS one, 2013Co-Authors: Jean-baptiste Thiebot, Yves Cherel, Philip N. Trathan, Robert J. M. Crawford, Azwianewi B. Makhado, David Pinaud, Charles-andré BostAbstract:Post-breeding migration in land-based marine animals is thought to offset seasonal deterioration in foraging or other important environmental conditions at the breeding site. However the inter-breeding distribution of such animals may reflect not only their optimal habitat, but more subtle influences on an individual’s migration path, including such factors as the intrinsic influence of each locality’s paleoenvironment, thereby influencing animals’ wintering distribution. In this study we investigated the influence of the regional marine environment on the migration patterns of a poorly known, but important seabird group. We studied the inter-breeding migration patterns in three species of Eudyptes penguins (E. chrysolophus, E. filholi and E. moseleyi), the main marine prey consumers amongst the World’s seabirds. Using ultra-miniaturized logging devices (light-based geolocators) and satellite tags, we tracked 87 migrating individuals originating from 4 sites in the southern Indian Ocean (Marion, Crozet, Kerguelen and Amsterdam Islands) and modelled their wintering habitat using the MADIFA niche modelling technique. For each site, sympatric species followed a similar Compass Bearing during migration with consistent species-specific latitudinal shifts. Within each species, individuals breeding on different islands showed contrasting migration patterns but similar winter habitat preferences driven by sea-surface temperatures. Our results show that inter-breeding migration patterns in sibling penguin species depend primarily on the site of origin and secondly on the species. Such site-specific migration Bearings, together with similar wintering habitat used by parapatrics, support the hypothesis that migration behaviour is affected by the intrinsic characteristics of each site. The paleo-oceanographic conditions (primarily, sea-surface temperatures) when the populations first colonized each of these sites may have been an important determinant of subsequent migration patterns. Based on previous chronological schemes of taxonomic radiation and geographical expansion of the genus Eudyptes, we propose a simple scenario to depict the chronological onset of contrasting migration patterns within this penguin group.
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A space oddity: geographic and specific modulation of migration in Eudyptes penguins
2013Co-Authors: Jean-baptiste Thiebot, Yves Cherel, Philip N. Trathan, Robert J. M. Crawford, Azwianewi B. Makhado, David Pinaud, Charles-andre ́ BostAbstract:Post-breeding migration in land-based marine animals is thought to offset seasonal deterioration in foraging or other important environmental conditions at the breeding site. However the inter-breeding distribution of such animals may reflect not only their optimal habitat, but more subtle influences on an individual’s migration path, including such factors as the intrinsic influence of each locality’s paleoenvironment, thereby influencing animals ’ wintering distribution. In this study we investigated the influence of the regional marine environment on the migration patterns of a poorly known, but important seabird group. We studied the inter-breeding migration patterns in three species of Eudyptes penguins (E. chrysolophus, E. filholi and E. moseleyi), the main marine prey consumers amongst the World’s seabirds. Using ultra-miniaturized logging devices (light-based geolocators) and satellite tags, we tracked 87 migrating individuals originating from 4 sites in the southern Indian Ocean (Marion, Crozet, Kerguelen and Amsterdam Islands) and modelled their wintering habitat using the MADIFA niche modelling technique. For each site, sympatric species followed a similar Compass Bearing during migration with consistent species-specific latitudinal shifts. Within each species, individuals breeding on different islands showed contrasting migration patterns but similar winter habitat preferences driven by sea-surface temperatures. Our results show that inter-breeding migration patterns in sibling penguin species depend primarily on the site of origin and secondly on the species. Such site-specific migration Bearings, together with similar wintering habitat used b
Martin White - One of the best experts on this subject based on the ideXlab platform.
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using natural experimental studies to guide public health action turning the evidence based medicine paradigm on its head
Journal of Epidemiology and Community Health, 2020Co-Authors: David Ogilvie, Jean Adams, Adrian Bauman, Edward W Gregg, Jenna Panter, Karen R Siegel, Nicholas J Wareham, Martin WhiteAbstract:Despite smaller effect sizes, interventions delivered at population level to prevent non-communicable diseases generally have greater reach, impact and equity than those delivered to high-risk groups. Nevertheless, how to shift population behaviour patterns in this way remains one of the greatest uncertainties for research and policy. Evidence about behaviour change interventions that are easier to evaluate tends to overshadow that for population-wide and system-wide approaches that generate and sustain healthier behaviours. Population health interventions are often implemented as natural experiments, which makes their evaluation more complex and unpredictable than a typical randomised controlled trial (RCT). We discuss the growing importance of evaluating natural experiments and their distinctive contribution to the evidence for public health policy. We contrast the established evidence-based practice pathway, in which RCTs generate ‘definitive’ evidence for particular interventions, with a practice-based evidence pathway in which evaluation can help adjust the Compass Bearing of existing policy. We propose that intervention studies should focus on reducing critical uncertainties, that non-randomised study designs should be embraced rather than tolerated and that a more nuanced approach to appraising the utility of diverse types of evidence is required. The complex evidence needed to guide public health action is not necessarily the same as that which is needed to provide an unbiased effect size estimate. The practice-based evidence pathway is neither inferior nor merely the best available when all else fails. It is often the only way to generate meaningful evidence to address critical questions about investing in population health interventions.
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Using natural experimental studies to guide public health action: turning the evidence-based medicine paradigm on its head
2019Co-Authors: David Ogilvie, Jean Adams, Adrian Bauman, Jenna Panter, Edward Gregg, Karen Siegel, Nick Wareham, Martin WhiteAbstract:Despite smaller effect sizes, interventions delivered at population level to prevent non-communicable diseases generally have greater reach, impact and equity than those delivered to high risk groups. Nevertheless, how to shift population behaviour patterns in this way remains one of the greatest uncertainties for research and policy. Evidence about behaviour change interventions that are easier to evaluate tends to overshadow that for population- and system-wide approaches that generate and sustain healthier behaviours. Population health interventions are often implemented as natural experiments, which makes their evaluation more complex and unpredictable than a typical randomised controlled trial (RCT). We discuss the growing importance of evaluating natural experiments, and their distinctive contribution to the evidence for public health policy. We contrast the established evidence-based practice pathway, in which RCTs generate ‘definitive’ evidence for particular interventions, with a practice-based evidence pathway in which evaluation can help adjust the Compass Bearing of existing policy. We propose that intervention studies should focus on reducing critical uncertainties, that non-randomised study designs should be embraced rather than tolerated, and that a more nuanced approach to appraising the utility of diverse types of evidence is required. The complex evidence needed to guide public health action is not necessarily the same as that which is needed to provide an unbiased effect size estimate. The practice-based evidence pathway is neither inferior, nor merely the best available when all else fails. It is often the only way to generate meaningful evidence to address critical questions about investing in population health interventions.