| 1. |
- Tierney, Simon M., et al.
(författare)
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Consequences of evolutionary transitions in changing photic environments
- 2017
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Ingår i: Austral Entomology. - : Wiley. - 2052-174X. ; 56:1, s. 23-46
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Forskningsöversikt (refereegranskat)abstract
- Light represents one of the most reliable environmental cues in the biological world. In this review we focus on the evolutionary consequences to changes in organismal photic environments, with a specific focus on the class Insecta. Particular emphasis is placed on transitional forms that can be used to track the evolution from (1) diurnal to nocturnal (dim-light) or (2) surface to subterranean (aphotic) environments, as well as (3) the ecological encroachment of anthropomorphic light on nocturnal habitats (artificial light at night). We explore the influence of the light environment in an integrated manner, highlighting the connections between phenotypic adaptations (behaviour, morphology, neurology and endocrinology), molecular genetics and their combined influence on organismal fitness. We begin by outlining the current knowledge of insect photic niches and the organismal adaptations and molecular modifications that have evolved for life in those environments. We then outline concepts and guidelines for future research in the fields of natural history, ethology, neurology, morphology and particularly the advantages that high throughput sequencing provides to these aspects of investigation. Finally, we highlight that the power of such integrative science lies in its ability to make phylogenetically robust comparative assessments of evolution, ones that are grounded by empirical evidence derived from a concrete understanding of organismal natural history.
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| 2. |
- Baird, Emily, et al.
(författare)
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Flight control and landing precision in the nocturnal bee Megalopta is robust to large changes in light intensity.
- 2015
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Ingår i: Frontiers in Physiology. - : Frontiers Media SA. - 1664-042X. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Like their diurnal relatives, Megalopta genalis use visual information to control flight. Unlike their diurnal relatives, however, they do this at extremely low light intensities. Although Megalopta has developed optical specializations to increase visual sensitivity, theoretical studies suggest that this enhanced sensitivity does not enable them to capture enough light to use visual information to reliably control flight in the rainforest at night. It has been proposed that Megalopta gain extra sensitivity by summing visual information over time. While enhancing the reliability of vision, this strategy would decrease the accuracy with which they can detect image motion-a crucial cue for flight control. Here, we test this temporal summation hypothesis by investigating how Megalopta's flight control and landing precision is affected by light intensity and compare our findings with the results of similar experiments performed on the diurnal bumblebee Bombus terrestris, to explore the extent to which Megalopta's adaptations to dim light affect their precision. We find that, unlike Bombus, light intensity does not affect flight and landing precision in Megalopta. Overall, we find little evidence that Megalopta uses a temporal summation strategy in dim light, while we find strong support for the use of this strategy in Bombus.
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| 3. |
- Berry, Richard P., et al.
(författare)
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Ocellar adaptations for dim light vision in a nocturnal bee
- 2011
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 1477-9145 .- 0022-0949. ; 214:8, s. 1283-1293
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Tidskriftsartikel (refereegranskat)abstract
- Growing evidence indicates that insect ocelli are strongly adapted to meet the specific functional requirements in the environment in which that insect lives. We investigated how the ocelli of the nocturnal bee Megalopta genalis are adapted to life in the dim understory of a tropical rainforest. Using a combination of light microscopy and three-dimensional reconstruction, we found that the retinae contain bar-shaped rhabdoms loosely arranged in a radial pattern around multi-layered lenses, and that both lenses and retinae form complex non-spherical shapes reminiscent of those described in other ocelli. Intracellular electrophysiology revealed that the photoreceptors have high absolute sensitivity, but that the threshold location varied widely between 109 and 10(11) photons cm(-2) s(-1). Higher sensitivity and greater visual reliability may be obtained at the expense of temporal resolution: the corner frequencies of dark-adapted ocellar photoreceptors were just 4-11 Hz. Spectral sensitivity profiles consistently peaked at 500 nm. Unlike the ocelli of other flying insects, we did not detect UV-sensitive visual pigments in M. genalis, which may be attributable to a scarcity of UV photons under the rainforest canopy at night. In contrast to earlier predictions based on anatomy, the photoreceptors are not sensitive to the e-vector of polarised light. Megalopta genalis ocellar photoreceptors possess a number of unusual properties, including inherently high response variability and the ability to produce spike-like potentials. These properties bear similarities to photoreceptors in the compound eye of the cockroach, and we suggest that the two insects share physiological characteristics optimised for vision in dim light.
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| 4. |
- Frederiksen, Rikard, et al.
(författare)
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Visual reliability and information rate in the retina of a nocturnal bee.
- 2008
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Ingår i: Current Biology. - : Elsevier BV. - 1879-0445 .- 0960-9822. ; 18:5, s. 349-353
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Tidskriftsartikel (refereegranskat)abstract
- Nocturnal animals relying on vision typically have eyes that are optically and morphologically adapted for both increased sensitivity and greater information capacity in dim light [1]. Here, we investigate whether adaptations for increased sensitivity also are found in their photoreceptors by using closely related and fast-flying nocturnal and diurnal bees as model animals. The nocturnal bee Megalopta genalis is capable of foraging and homing by using visually discriminated landmarks at starlight intensities [2, 3]. Megalopta's near relative, Lasioglossum leucozonium, performs these tasks only in bright sunshine. By recording intracellular responses to Gaussian white-noise stimuli [4, 5], we show that photoreceptors in Megalopta actually code less information at most light levels than those in Lasioglossum. However, as in several other nocturnal arthropods [6-13], Megalopta's photoreceptors possess a much greater gain of transduction, indicating that nocturnal photoreceptors trade information capacity for sensitivity. By sacrificing photoreceptor signal-to-noise ratio and information capacity in dim light for an increased gain and, thus, an increased sensitivity, this strategy can benefit nocturnal insects that use neural summation to improve visual reliability at night.
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| 5. |
- Greiner, Birgit, et al.
(författare)
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Anatomical and physiological evidence for polarisation vision in the nocturnal bee Megalopta genalis
- 2007
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Ingår i: Journal of Comparative Physiology A. - : Springer Science and Business Media LLC. - 1432-1351 .- 0340-7594. ; 193:6, s. 591-600
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Tidskriftsartikel (refereegranskat)abstract
- The presence of a specialised dorsal rim area with an ability to detect the e-vector orientation of polarised light is shown for the first time in a nocturnal hymenopteran. The dorsal rim area of the halictid bee Megalopta genalis features a number of characteristic anatomical specialisations including an increased rhabdom diameter and a lack of primary screening pigments. Optically, these specialisations result in wide spatial receptive fields (Delta rho = 14 degrees), a common adaptation found in the dorsal rim areas of insects used to filter out interfering effects (i.e. clouds) from the sky. In this specialised eye region all nine photoreceptors contribute their microvilli to the entire length of the ommatidia. These orthogonally directed microvilli are anatomically arranged in an almost linear, anterior-posterior orientation. Intracellular recordings within the dorsal rim area show very high polarisation sensitivity and a sensitivity peak within the ultraviolet part of the spectrum.
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| 6. |
- Leray, Matthieu, et al.
(författare)
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Natural experiments and long-term monitoring are critical to understand and predict marine host–microbe ecology and evolution
- 2021
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Ingår i: PLoS biology. - : Public Library of Science (PLoS). - 1544-9173 .- 1545-7885. ; 19:8, s. e3001322-e3001322
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Tidskriftsartikel (refereegranskat)abstract
- Marine multicellular organisms host a diverse collection of bacteria, archaea, microbial eukaryotes, and viruses that form their microbiome. Such host-associated microbes can significantly influence the host’s physiological capacities; however, the identity and functional role(s) of key members of the microbiome (“core microbiome”) in most marine hosts coexisting in natural settings remain obscure. Also unclear is how dynamic interactions between hosts and the immense standing pool of microbial genetic variation will affect marine ecosystems’ capacity to adjust to environmental changes. Here, we argue that significantly advancing our understanding of how host-associated microbes shape marine hosts’ plastic and adaptive responses to environmental change requires (i) recognizing that individual host–microbe systems do not exist in an ecological or evolutionary vacuum and (ii) expanding the field toward long-term, multidisciplinary research on entire communities of hosts and microbes. Natural experiments, such as time-calibrated geological events associated with well-characterized environmental gradients, provide unique ecological and evolutionary contexts to address this challenge. We focus here particularly on mutualistic interactions between hosts and microbes, but note that many of the same lessons and approaches would apply to other types of interactions.
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| 7. |
- Mitko, Lukasz, et al.
(författare)
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Olfactory specialization for perfume collection in male orchid bees
- 2016
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 219:10, s. 1467-1475
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Tidskriftsartikel (refereegranskat)abstract
- Insects rely on the olfactory system to detect a vast diversity of airborne molecules in their environment. Highly sensitive olfactory tuning is expected to evolve when detection of a particular chemical with great precision is required in the context of foraging and/or finding mates. Male neotropical orchid bees (Euglossini) collect odoriferous substances from multiple sources, store them in specialized tibial pouches and later expose them at display sites, presumably as mating signals to females. Previous analysis of tibial compounds among sympatric species revealed substantial chemical disparity in chemical composition among lineages with outstanding divergence between closely related species. Here, we tested whether specific perfume phenotypes coevolve with matching olfactory adaptations in male orchid bees to facilitate the location and harvest of species-specific perfume compounds. We conducted electroantennographic (EAG) measurements on males of 15 sympatric species in the genus Euglossa that were stimulated with 18 compounds present in variable proportions in male hind tibiae. Antennal response profiles were species-specific across all 15 species, but there was no conspicuous differentiation between closely related species. Instead, we found that the observed variation in EAG activity follows a Brownian motion model of trait evolution, where the probability of differentiation increases proportionally with lineage divergence time. However, we identified strong antennal responses for some chemicals that are present as major compounds in the perfume of the same species, thus suggesting that sensory specialization has occurred within multiple lineages. This sensory specialization was particularly apparent for semi-volatile molecules ('base note' compounds), thus supporting the idea that such compounds play an important role in chemical signaling of euglossine bees. Overall, our study found no close correspondence between antennal responses and behavioral preferences/tibial contents, but confirms the utility of EAG profiling for discovering certain behaviorally active compounds.
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