14 research outputs found
The grand challenges of migration ecology that radar aeroecology can help answer
Many migratory species have experienced substantial declines that resulted from rapid and massive expansions of human structures and activities, habitat alterations and climate change. Migrants are also recognized as an integral component of biodiversity and provide a multitude of services and disservices that are relevant to human agriculture, economy and health. The plethora of recently published studies reflects the need for better fundamental knowledge on migrations and for better management of their ecological and humanârelevant effects. Yet, where are we in providing answers to fundamental questions and societal challenges?
Engaging a broad network of researchers worldwide, we used a horizonâscan approach to identify the most important challenges which need to be overcome in order to gain a fuller understanding of migration ecology, and which could be addressed using radar aeroecological and macroecological approaches. The top challenges include both longâstanding and novel topics, ranging from fundamental information on migration routes and phenology, orientation and navigation strategies, and the multitude of effects migrants may have on resident communities, to societal challenges, such as protecting or preventing migrant services and disservices, and the conservation of migrants in the face of environmental changes. We outline these challenges, identify the urgency of addressing them and the primary stakeholders â researchers, policy makers and practitioners, or funders of research.
Visual ecology of aphids â a critical review on the role of colours in host finding
We review the rich literature on behavioural responses of aphids (Hemiptera: Aphididae) to stimuli of different colours. Only in one species there are adequate physiological data on spectral sensitivity to explain behaviour crisply in mechanistic terms.
Because of the great interest in aphid responses to coloured targets from an evolutionary, ecological and applied perspective, there is a substantial need to expand these studies to more species of aphids, and to quantify spectral properties of stimuli rigorously. We show that aphid responses to colours, at least for some species, are likely based on a specific colour opponency mechanism, with positive input from the green domain of the spectrum and negative input from the blue and/or UV region.
We further demonstrate that the usual yellow preference of aphids encountered in field experiments is not a true colour preference but involves additional brightness effects. We discuss the implications for agriculture and sensory ecology, with special respect to the recent debate on autumn leaf colouration. We illustrate that recent evolutionary theories concerning aphidâtree interactions imply far-reaching assumptions on aphid responses to colours
that are not likely to hold. Finally we also discuss the
implications for developing and optimising strategies
of aphid control and monitoring
The scleritome of Paterimitra: an Early Cambrian stem group brachiopod from South Australia
Early Cambrian tommotiids are problematic fossil metazoans with external organophosphatic sclerites that have been considered to be basal members of the lophophorate stem group. Tommotiids are almost exclusively known from isolated or rarely fused individual sclerites, which made previous reconstructions of the actual organism highly conjectural. However, the recent discovery of the first articulated specimens of the tommotiid Eccentrotheca revealed a tubular sclerite arrangement (scleritome) that limited the possible life habit to sessile filter feeding and thus further supported a lophophorate affinity. Here, we report the first articulated specimens of a second tommotiid taxon, Paterimitra from the Early Cambrian of the Arrowie Basin, South Australia. Articulated specimens of Paterimitra are composed of two bilaterally symmetrical sclerite types and an unresolved number of small, asymmetrical and irregular crescent-shaped sclerites that attached to the anterior margin of the symmetrical sclerites. Together, the sclerites form an open cone in which the symmetrical sclerites are joined together and form a small posterior opening near the base of the scleritome, while the irregular crescent-shaped sclerites defined a broad anterior opening. The coniform scleritome of Paterimitra is interpreted to have attached to hard substrates via a pedicle that emerged through the small posterior opening (sometimes forming a tube) and was probably a sessile filter feeder. The scleritome of Paterimitra can be derived from the tubular scleritome of Eccentrotheca by modification of basal sclerites and reduction in tube height, and probably represents a more derived member of the brachiopod stem group with the paired symmetrical sclerites possibly homologous to brachiopod valves
Reproducing the indigenous: John MĂžllerâs studio portraits of Greenlanders in context
Between 1889 and 1922, John MĂžller (1867â1935), the first professional Greenlandic photographer, produced more than 3000 glass plate negatives documenting life in Western Greenland around the turn of the twentieth century. Rooted in an internal understanding of self, MĂžllerâs photographs played an important part in the formation of a contemporary image of Greenlandic indigenous identity. At the same time, MĂžllerâs photographic practice was arguably entangled in and delimited by a historical reality that was structured by colonial relations of power. This paper examines the social and art- historical contexts of MĂžllerâs work, focusing in particular on a selection of his formal studio portraits. My reading of these portraits suggests a case in which conflicting impulses coincide. On the one hand, MĂžller produced images that played out the âethnographic conventionâ, a European form of representation dating back to the sixteenth century used for the documentation of non-Western indigenous peoples as specimens. However, in acting out that convention, MĂžllerâs photographs hint at a subtle, progressive building-up of identity that reclaimed images of Greenlanders for themselves, and turned an originally negative, external image of indigeneity into a positive sense of self
ILC Reference Design Report Volume 1 - Executive Summary
The International Linear Collider (ILC) is a 200-500 GeV center-of-mass high-luminosity linear electron-positron collider, based on 1.3 GHz superconducting radio-frequency (SCRF) accelerating cavities. The ILC has a total footprint of about 31 km and is designed for a peak luminosity of 2x10^34 cm^-2s^-1. This report is the Executive Summary (Volume I) of the four volume Reference Design Report. It gives an overview of the physics at the ILC, the accelerator design and value estimate, the detector concepts, and the next steps towards project realization.The International Linear Collider (ILC) is a 200-500 GeV center-of-mass high-luminosity linear electron-positron collider, based on 1.3 GHz superconducting radio-frequency (SCRF) accelerating cavities. The ILC has a total footprint of about 31 km and is designed for a peak luminosity of 2x10^34 cm^-2s^-1. This report is the Executive Summary (Volume I) of the four volume Reference Design Report. It gives an overview of the physics at the ILC, the accelerator design and value estimate, the detector concepts, and the next steps towards project realization