Size isn’t everything:rates of genome size evolution, not C value, correlate with speciation in angiosperms

Angiosperms represent one of the key examples of evolutionary success, and their diversity dwarfs other land plants; this success has been linked, in part, to genome size and phenomena such as whole genome duplication events. However, while angiosperms exhibit a remarkable breadth of genome size, evidence linking overall genome size to diversity is equivocal, at best. Here, we show that the rates of speciation and genome size evolution are tightly correlated across land plants, and angiosperms show the highest rates for both, whereas very slow rates are seen in their comparatively species-poor sister group, the gymnosperms. No evidence is found linking overall genome size and rates of speciation. Within angiosperms, both the monocots and eudicots show the highest rates of speciation and genome size evolution, and these data suggest a potential explanation for the megadiversity of angiosperms. It is difficult to associate high rates of diversification with different types of polyploidy, but it is likely that high rates of evolution correlate with a smaller genome size after genome duplications. The diversity of angiosperms may, in part, be due to an ability to increase evolvability by benefiting from whole genome duplications, transposable elements and general genome plasticity

Constructing ‘good teaching’ through written lesson observation feedback

This paper explores the ways in which ‘good teaching’ is constructed through mentors’ written lesson observation feedback during Initial Teacher Education (ITE). Written lesson observation feedback has received little research attention, yet represents a potentially powerful activity for teachers’ development. It is also an important aspect of direct university-school-beginning teacher collaboration which is common across diverse programmes and ITE partnerships internationally. Data were collected from written lesson observation feedback given to beginning teachers (n=127) on one ITE programme in England across one year to a total of 508 lessons, and analysed through a typology of competing conceptions of teaching defined by Winch et al.; craft, executive technician, and extended professional. This data suggests that teaching is predominantly constructed through mentors’ written feedback as a craft or technical activity. In response, we argue that there is scope to broaden the evidence considered, in particular, by bringing observed insights about beginning teachers’ practice into dialogue with research evidence in order to construct a more expansive vision of teaching as a professional endeavour. Using this theoretical framework highlights the important contribution written lesson observation feedback might offer to broader attempts seeking to improve teachers’ engagement with research evidence

A critical account of what ‘geography’ means to primary trainee teachers in England

Research on trainee teachers’ conceptions of geography has criticised their views for being limited, and failing to appreciate the breadth or depth of geography. A body of research in this area has developed over the past two decades, producing well-established classifications through which to analyse conceptions of geography. This contribution breaks from these classifications by offering a critical review of the existing literature and then, drawing on critical theory, distinguishing between geography as knowing, understanding, and acting. Findings from a survey of first year undergraduate primary trainee teachers (n = 42) are analysed through this critical framework, and it is argued that there is a distinct Cartesian duality in the way that respondents see the world as an object of study for learners as cognising subjects. This is argued to be problematic and, in response, a moral vision for school geography is outlined that represents geography in terms of a critical praxis

Thermal stability of dialkylimidazolium tetrafluoroborate and hexafluorophosphate ionic liquids: ex situ bulk heating to complement in situ mass spectrometry

Thermal decomposition (TD) products of the ionic liquids (ILs) [CnC1Im][BF4] and [CnC1Im][PF6] ([CnC1Im]+ = 1-alkyl-3-methylimidazolium, [BF4]- = tetrafluoroborate, and [PF6]- = hexafluorophosphate) were prepared, ex situ, by bulk heating experiments in a bespoke setup. The respective products, CnC1(C3N2H2)BF3 and CnC1(C3N2H2)PF5 (1-alkyl-3-methylimidazolium-2-trifluoroborate and 1-alkyl-3-methylimidazolium-2-pentafluorophosphate), were then vaporized and analyzed by direct insertion mass spectrometry (DIMS) in order to identify their characteristic MS signals. During IL DIMS experiments we were subsequently able, in situ, to identify and monitor signals due to both IL vaporization and IL thermal decomposition. These decomposition products have not been observed in situ during previous analytical vaporization studies of similar ILs. The ex situ preparation of TD products is therefore perfectly complimentary to in situ thermal stability measurements. Experimental parameters such as sample surface area to volume ratios and heating rates are consequently very important for ILs that show competitive vaporization and thermal decomposition. We have explained these experimental factors in terms of Langmuir evaporation and Knudsen effusion-like conditions, allowing us to draw together observations from previous studies to make sense of the literature on IL thermal stability. Hence, the design of experimental setups are crucial and previously overlooked experimental factors

Right Ventricular Dysfunction in the R6/2 Transgenic Mouse Model of Huntington's Disease is Unmasked by Dobutamine

Background: Increasingly, evidence from studies in both animal models and patients suggests that cardiovascular dysfunction is important in HD. Previous studies measuring function of the left ventricle (LV) in the R6/2 mouse model have found a clear cardiac abnormality, albeit with preserved LV systolic function. It was hypothesized that an impairment of RV function might play a role in this condition via mechanisms of ventricular interdependence.Objective: To investigate RV function in the R6/2 mouse model of Huntington's disease (HD).Methods: Cardiac cine- magnetic resonance imaging (MRI) was used to determine functional parameters in R6/2 mice. In a first experiment, these parameters were derived longitudinally to determine deterioration of cardiac function with disease progression. A second experiment compared the response to a stress test (using dobutamine) of wildtype and early-symptomatic R6/2 mice. Results: There was progressive deterioration of RV systolic function with age in R6/2 mice. Furthermore, beta-adrenergic stimulation with dobutamine revealed RV dysfunction in R6/2 mice before any overt symptoms of the disease were apparent.Conclusions: This work adds to accumulating evidence of cardiovascular dysfunction in R6/2 mice, describing for the first time the involvement of the right ventricle. Cardiovascular dysfunction should be considered, both when treatment strategies are being designed, and when searching for biomarkers for HD

Bayesian methods outperform parsimony but at the expense of precision in the estimation of phylogeny from discrete morphological data

Different analytical methods can yield competing interpretations of evolutionary history and, currently, there is no definitive method for phylogenetic reconstruction using morphological data. Parsimony has been the primary method for analysing morphological data, but there has been a resurgence of interest in the likelihood-based Mk-model. Here, we test the performance of the Bayesian implementation of the Mk-model relative to both equal and implied-weight implementations of parsimony. Using simulated morphological data, we demonstrate that the Mk-model outperforms equal-weights parsimony in terms of topological accuracy, and implied-weights performs the most poorly. However, the Mk-model produces phylogenies that have less resolution than parsimony methods. This difference in the accuracy and precision of parsimony and Bayesian approaches to topology estimation needs to be considered when selecting a method for phylogeny reconstruction

Student teachers’ beliefs about diversity: analysing the impact of a ‘diversity week’ during initial teacher education

This article reports findings from a week of enrichment placements framed around ‘diversity’ within a secondary Initial Teacher Education (ITE) programme in England. The authors outline the demographics of the county – a largely rural, White county in the East Midlands of England – and describe the challenges this presents for ITE. A mixed-methods approach was used to study student teachers’ (n = 56) beliefs about diversity, generating data through: pre- and post-survey of beliefs and attitudes; student-created reflective videos; journaling; and one pre- and post-diversity week interview. The findings reveal shifts in student teachers’ perceptions about gender, race and sexuality, and these attitudinal shifts were more significant in those attending all week than those attending only the first day. This is particularly interesting because for some topics the only formal input was on the first day, and so the authors argue for the importance of time and space for creative reflection in beginning teachers’ professional development