13,267 research outputs found
Pattern of population structuring between Belgian and Estonian bumblebees
Several population genetic studies investigated the extent of gene flow and population connectivity in bumblebees. In general, no restriction in gene flow is considered for mainland populations of common bumblebee species. Whether this assumption holds true for all species is not known. An assessment of bumblebee genetic structure in the context of their geographic distribution is needed to prioritize conservation and management needs. Here, we conducted a genetic study on seven bumblebee species occurring in Belgium and Estonia. Using 16 microsatellite markers, we investigated genetic diversity and population structuring in each species. This is the first study investigating population structuring of both declining and stable bumblebee species on both small and large geographic scales. Our results showed no or only low population structuring between the populations of the restricted and declining bumblebee species on both scales, while significant structuring was found for populations of the common species on the larger scale. The latter result, which may be due to human or environmental changes in the landscape, implies the need for the conservation of also widespread bumblebee species. Conservation strategies to improve gene flow and connectivity of populations could avoid the isolation and future losses of populations of these important species
Radiative corrections in bumblebee electrodynamics
We investigate some quantum features of the bumblebee electrodynamics in flat
spacetimes. The bumblebee field is a vector field that leads to a spontaneous
Lorentz symmetry breaking. For a smooth quadratic potential, the massless
excitation (Nambu-Goldstone boson) can be identified as the photon, transversal
to the vacuum expectation value of the bumblebee field. Besides, there is a
massive excitation associated with the longitudinal mode and whose presence
leads to instability in the spectrum of the theory. By using the
principal-value prescription, we show that no one-loop radiative corrections to
the mass term is generated. Moreover, the bumblebee self-energy is not
transverse, showing that the propagation of the longitudinal mode can not be
excluded from the effective theory.Comment: Revised version: contains some more elaborated interpretation of the
results. Conclusions improve
A game demonstrating aspects of bumblebee natural history
The Bumblebee Game is an exciting outdoor game, which demonstrates aspects of bumblebee natural history
including food chains, food webs and competition for food, predation by crab spiders, parasitism by Conopidae
(Diptera) and brood parasitism by cuckoo bees. It has been played successfully with groups of 10-25 people.
Although most suitable for 6-14 year olds, adults have had a lot of fun playing this game
Spontaneous Lorentz and Diffeomorphism Violation, Massive Modes, and Gravity
Theories with spontaneous local Lorentz and diffeomorphism violation contain
massless Nambu-Goldstone modes, which arise as field excitations in the minimum
of the symmetry-breaking potential. If the shape of the potential also allows
excitations above the minimum, then an alternative gravitational Higgs
mechanism can occur in which massive modes involving the metric appear. The
origin and basic properties of the massive modes are addressed in the general
context involving an arbitrary tensor vacuum value. Special attention is given
to the case of bumblebee models, which are gravitationally coupled vector
theories with spontaneous local Lorentz and diffeomorphism violation. Mode
expansions are presented in both local and spacetime frames, revealing the
Nambu-Goldstone and massive modes via decomposition of the metric and bumblebee
fields, and the associated symmetry properties and gauge fixing are discussed.
The class of bumblebee models with kinetic terms of the Maxwell form is used as
a focus for more detailed study. The nature of the associated conservation laws
and the interpretation as a candidate alternative to Einstein-Maxwell theory
are investigated. Explicit examples involving smooth and Lagrange-multiplier
potentials are studied to illustrate features of the massive modes, including
their origin, nature, dispersion laws, and effects on gravitational
interactions. In the weak static limit, the massive mode and
Lagrange-multiplier fields are found to modify the Newton and Coulomb
potentials. The nature and implications of these modifications are examined.Comment: 27 pages two-column REVTeX, accepted in Physical Review
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