452 research outputs found
Unanchored to the World: Displacement and Alienation in Anil's Ghost and the Prose of Michael Ondaatje
Special Issue of CRNLE Journal - Sri Lankan and Indian Diasporic Writin
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Evolution of nectar spur length in a clade of Linaria reflects changes in cell division rather than in cell expansion.
BACKGROUND AND AIMS: Nectar spurs (tubular outgrowths of a floral organ which contain, or give the appearance of containing, nectar) are hypothesized to be a 'key innovation' which can lead to rapid speciation within a lineage, because they are involved in pollinator specificity. Despite the ecological importance of nectar spurs, relatively little is known about their development. We used a comparative approach to investigate variation in nectar spur length in a clade of eight Iberian toadflaxes. METHODS: Spur growth was measured at the macroscopic level over time in all eight species, and growth rate and growth duration compared. Evolution of growth rate was reconstructed across the phylogeny. Within the clade we then focused on Linaria becerrae and Linaria clementei, a pair of sister species which have extremely long and short spurs, respectively. Characterization at a micromorphological level was performed across a range of key developmental stages to determine whether the difference in spur length is due to differential cell expansion or cell division. KEY RESULTS: We detected a significant difference in the evolved growth rates, while developmental timing of both the initiation and the end of spur growth remained similar. Cell number is three times higher in the long spurred L. becerrae compared with L. clementei, whereas cell length is only 1.3 times greater. In addition, overall anisotropy of mature cells is not significantly different between the two species. CONCLUSIONS: We found that changes in cell number and therefore in cell division largely explain evolution of spur length. This contrasts with previous studies in Aquilegia which have found that variation in nectar spur length is due to directed cell expansion (anisotropy) over variable time frames. Our study adds to knowledge about nectar spur development in a comparative context and indicates that different systems may have evolved nectar spurs using disparate mechanisms
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The evo-devo of plant speciation
Speciation research bridges the realms of macro- and microevolution. Evolutionary developmental biology (evo-devo) has classically dealt with macroevolutionary questions through a comparative approach to distantly related organisms, but the field later broadened in focus to address recent speciation and microevolution. Here we review available evidence of the power of evo-devo approaches to understand speciation in plants at multiple scales. At a macroevolutionary scale, evidence is accumulating for evolutionary developmental mechanisms giving rise to key innovations promoting speciation. At the macro microevolution transition, we review instances of evo-devo change underlying both the origin of reproductive barriers and phenotypic changes distinguishing closely related species. At the microevolutionary scale, the study of developmental variation within species provides insight into the processes that generate the raw material for evolution and speciation. We conclude by advocating a strong interaction between developmental biology and evolutionary biology at multiple scales to gain a deeper understanding of plant speciation.M.F.-M. has been supported by the Marie Curie Intra-European Fellowship LINARIA-SPECIATION (FP7-PEOPLE-2013-IEF, project reference 624396 to M.F.-M and B.J.G) and an Isaac Newton Trust Research Grant (Trinity College, Cambridge)
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A synopsis of the Iberian clade of Linaria subsect. Versicolores (Antirrhineae, Plantaginaceae) based on integrative taxonomy
Integrative taxonomy, based on the combination of multiple lines of evidence, provides the foundations for a robust species delimitation. Here we provide a taxonomic synopsis of the Iberian clade of Linaria subsect. Versicolores based on recently published morphometric and phylogenomic data. This clade radiated in the Iberian Peninsula (western Mediterranean)during the Quaternary, and is being intensively studied from phylogenetic, evolutionary, biogeographic, ecological and developmental standpoints. Eight morphologically and genetically distinct species are recognized in the clade: L. algarviana, L. becerrae, L.
clementei, L. incarnata, L. onubensis, L. salzmannii, L. spartea and L. viscosa. For each accepted species, the type material and notes on diagnostic characters, distribution, habitat and intraspecific variability are provided. Five names are typified (four neotypes and one lectotype are designated), and references to previous typifications are also presented. A distribution map and an identification key are presented. This synopsis will provide the basis for future research on speciation and evolution of the clade
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The effect of the ‘Bee Gym™’ grooming device on Varroa destructor mite fall from honey bee (Apis mellifera) colonies
Grooming is a honey bee behavior that has the potential to minimize and manage the detrimental effects of . Here we tested the efficacy of the Bee Gym™, a device hypothesized to increase honey bee auto-grooming and increase mite removal from colonies. Natural mite fall from 20 colonies was counted for 14 days, after which half the colonies were fitted with a Bee Gym and half with a control object. Mite fall and the proportion of damaged mites were then recorded for another 14 days. Total mite fall was generally higher over the second 14 days, but this increase was not significantly higher for the Bee Gym colonies than for the control colonies. There was also no difference in the proportion of damaged mites between the two treatments. Mite fall and damage to mites may be influenced by other factors, and this is discussed; however, given that we found no effect of the Bee Gym, we conclude that there is no evidence from this study of its efficacy as a management strategy for .
El aseo es un comportamiento de la abeja de la miel que tiene el potencial de minimizar y de manejar los efectos perjudiciales de . Aquí hemos probado la eficacia del Bee Gym ™, un dispositivo que hipotéticamente aumenta el auto-aseo en la abeja de la miel y aumentar la eliminación de ácaros de las colonias. La caída natural de ácaros de 20 colonias se contó durante 14 días, tras lo cual la mitad de las colonias fueron equipadas con un Bee Gym y la otra mitad con un objeto de control. La caída de ácaros y la proporción de ácaros dañados se registraron durante otros 14 días. La caída total de ácaros fue generalmente mayor durante los segundos 14 días, pero este aumento no fue significativamente mayor para las colonias con Bee Gym que para las colonias de control. Tampoco hubo diferencias en la proporción de ácaros dañados entre los dos tratamientos. La caída de ácaros y el daño a los ácaros pueden estar influidos por otros factores, lo cual se discute; sin embargo, dado que no encontramos ningún efecto del Bee Gym, concluimos que no hay evidencia en este estudio de su eficacia como estrategia de manejo para .Stuart Roweth supplied the Bee Gyms and control frames and provided funding for equipment and travel costs. JGP was funded by a Biotechnology and Biological Sciences Research Council Doctoral Training Partnership studentship under Grant [BB/J014540/1]
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Spur length evolution in Linaria reflects changes in cell division
Background and aims
Nectar spurs (tubular outgrowths of a floral organ which contain or give the appearance of containing nectar) are hypothesized to be a ‘key innovation’ which can lead to rapid speciation within a lineage, because they are involved in pollinator specificity. Despite the ecological importance of nectar spurs, relatively little is known about their development. We used a comparative approach to investigate variation in nectar spur length in a clade of eight Iberian toadflaxes.
Methods
Spur growth was measured at the macroscopic level over time in all eight species, and growth rate and growth duration compared. Evolution of growth rate was reconstructed across the phylogeny. Within the clade we then focused on Linaria becerrae and Linaria clementei, a pair of sister species which have extremely long and short spurs, respectively. Characterisation at a micromorphological level was performed across a range of key developmental stages to determine whether the difference in spur length is due to differential cell expansion or cell division.
Key results
We detected a significant difference in the evolved growth rates, while developmental timing of both the initiation and the end of spur growth remained similar. Cell number is 3 times higher in the long spurred Linaria becerrae compared to Linaria clementei, whereas cell length is only 1.3 times greater. In addition, overall anisotropy of mature cells is not significantly different between the two species.
Conclusions
We found that changes in cell number and therefore in cell division largely explain evolution of spur length. This contrasts with previous studies in Aquilegia which have found that variation in nectar spur length is due to directed cell expansion (anisotropy) over variable timeframes. Our study adds to knowledge about nectar spur development in a comparative context and indicates that different systems may have evolved nectar spurs using disparate mechanisms
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How have advances in comparative floral development influenced our understanding of floral evolution?
Evolutionary developmental biology has come to prominence in the past two decades, in both the plant kingdom and the animal kingdom, particularly following the description of homeotic genes linked to key morphological transitions. A primary goal of evolutionary developmental biology (“evo-devo”) is to define how developmental programs are modified to generate novel or labile morphologies. This requires an understanding of the molecular genetic basis of these programs and of the evolutionary changes they have undergone. The past decade has seen the establishment of a common language and common standards, and these changes have greatly improved the integration of evo-devo. Recently, a more comparative approach has been added to mechanistic developmental biology. In this review we attempt to show how, by using this “next-generation evo-devo” approach, insights into both developmental biology and evolutionary biology can be gained. Although the concepts we discuss are more broadly applicable, we have focused our examples on traits of the angiosperm flower, a structure that has undergone enormous morphological and developmental evolution since its relatively recent appearance in the fossil record.Work in the Glover laboratory on these topics is funded by the BBSRC, EU Marie Curie Actions, Isaac Newton Trust, Leverhulme Trust, NERC and the NSF, and we gratefully acknowledge all support.This is the accepted manuscript of a paper published in the International Journal of Plant Sciences (Glover BJ, Airoldi CA, Brockington SF, Fernández-Mazuecos M, Martínez-Pérez C, Mellers G, Moyroud E, Taylor L, International Journal of Plant Sciences, 2015, 176, 4, 307-323, doi:10.1086/681562). The final version is available at http://dx.doi.org/10.1086/68156
Structural colour from helicoidal cell-wall architecture in fruits of Margaritaria nobilis
The bright and intense blue-green coloration of the fruits of Margaritaria nobilis (Phyllanthaceae) was investigated using polarization-resolved spectroscopy and transmission electron microscopy. Optical measurements of freshly collected fruits revealed a strong circularly polarized reflection of the fruit that originates from a cellulose helicoidal cell wall structure in the pericarp cells. Hyperspectral microscopy was used to capture the iridescent effect at the single-cell level.This work was supported by the Leverhulme Trust (F/09-
741/G) and a BBSRC David Phillips fellowship (BB/K014617/1).
P.V. acknowledges support from the US Air Force Office of Scientific
Research under award number FA9550-10-1-0020. U.S. acknowledges
support from the Adolphe Merkle foundation and the Swiss National
Science Foundation through the National Centre of Competence in
Research Bio-Inspired Materials
Determining the Contribution of Epidermal Cell Shape to Petal Wettability Using Isogenic Antirrhinum Lines
This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
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