Cryptic complexity in felid vertebral evolution: shape differentiation and allometry of the axial skeleton

Members of the mammalian family Felidae (extant and extinct cats) are grossly phenotypically similar, but display a 300-fold range in body size, from less than 1 kg to more than 300 kg. In addition to differences in body mass, felid species show dietary and locomotory specializations that correlate to skull and limb osteological measurements, such as shape or cross-sectional area. However, ecological correlates to the axial skeleton are yet untested. Here, we build on previous studies of the biomechanical and morphological evolution of the felid appendicular skeleton by conducting a quantitative analysis of morphology and allometry in the presacral vertebral column across extant cats. Our results demonstrate that vertebral columns of arboreal, scansorial and terrestrial felids significantly differ in morphology, specifically in the lumbar region, while no distinction based on dietary specialization was found. Body size significantly influences vertebral morphology, with clear regionalization of allometry along the vertebral column, suggesting that anterior (cervicals and thoracics) and posterior (lumbar) vertebrae may be independently subjected to distinct selection pressures

Regional differentiation of felid vertebral column evolution: a study of 3D shape trajectories

Recent advances in geometric morphometrics provide improved techniques for extraction of biological information from shape and have greatly contributed to the study of ecomorphology and morphological evolution. However, the vertebral column remains an under-studied structure due in part to a concentration on skull and limb research, but most importantly because of the difficulties in analysing the shape of a structure composed of multiple articulating discrete units (i.e. vertebrae). Here, we have applied a variety of geometric morphometric analyses to three-dimensional landmarks collected on 19 presacral vertebrae to investigate the influence of potential ecological and functional drivers, such as size, locomotion and prey size specialisation, on regional morphology of the vertebral column in the mammalian family Felidae. In particular, we have here provided a novel application of a method—phenotypic trajectory analysis (PTA)—that allows for shape analysis of a contiguous sequence of vertebrae as functionally linked osteological structures. Our results showed that ecological factors influence the shape of the vertebral column heterogeneously and that distinct vertebral sections may be under different selection pressures. While anterior presacral vertebrae may either have evolved under stronger phylogenetic constraints or are ecologically conservative, posterior presacral vertebrae, specifically in the post-T10 region, show significant differentiation among ecomorphs. Additionally, our PTA results demonstrated that functional vertebral regions differ among felid ecomorphs mainly in the relative covariation of vertebral shape variables (i.e. direction of trajectories, rather than in trajectory size) and, therefore, that ecological divergence among felid species is reflected by morphological changes in vertebral column shape

Relationship among fibre type, myosin ATPase activity and contractile properties

At least two types of skeletal muscle myosin have been described which differ in ATPase activity and stability in alkaline or acidic media. Differences in ATPase characteristics distinguish Type I and Type II fibres histochemically. In this study, ATPase activity of myosin from muscles of several species with known histochemical and contractile properties has been determined to test the hypothesis that (1) myosin ATPase activity, (2) histochemical determination of fibre types and (3) maximum shortening velocity, all provide equivalent estimates of contractile properties in muscles of mixed fibre types. Maximum shortening velocity appears to be proportional to ATPase activity as expected from previous reports by Barany. However, both myosin ATPase and the maximum shortening velocity exhibit curvilinear relationships to the fraction of cross-sectional area occupied by Type II fibres. Therefore, we reject the hypothesis and conclude that histochemically determined myofibrillar ATPase does not accurately reflect the intrinsic ATPase activity or shortening velocity in muscles of mixed fibre types. Our data are consistent with the presence of more than two myosin isozymes or with a mixture of isozymes within single muscle fibres.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42851/1/10735_2005_Article_BF01005238.pd

‘Letting the right one in’: Provider contexts for recruitment to initial teacher education in the United Kingdom

We exploit policy differences within the UK to investigate provider context and recruitment to initial teacher education (ITE). We identify three dimensions of variation: conceptions of professionalism, universal or context specific preparation and costs and benefits to providers. University-led ITE programmes used similar criteria and processes in each jurisdiction, but there were differences between university-led and school-led recruitment. Our study suggests that the current shortfall in recruitment to ITE in England may be a product of the contextual constraints which schools experience. It also suggests that school-led recruitment may tend to emphasise short-term and school-specific needs

The Dependability of the Updated NSSE: A Generalizability Study

This study utilized generalizability theory to assess the context where the National Survey of Student Engagement’s (NSSE) summary measures, the Engagement Indicators, produce dependable group-level means. The dependability of NSSE group means is an important topic for the higher education assessment community given its wide utilization and usage in institutional assessment and accreditation. We found that the Engagement Indicators produced dependable group means for an institution derived from samples as small as 25 to 50 students. Furthermore, we discuss how the assessment community should use NSSE data

National student feedback surveys in distance education: An investigation at the UK Open University

National student feedback surveys are administered in a number of countries, and several encompass both campus-based and distance-learning students. The UK Open University achieves a high ranking in the annual National Student Survey (NSS), but there are some anomalies in the results. The NSS questionnaire was administered to three samples of students to explore the origins of these anomalies. The reliability and the validity of the questionnaire were satisfactory, but a substantial proportion of the respondents did not produce valid data. There was a high proportion of ‘not applicable’ responses to items concerned with learning resources and personal development. Other students responded ‘neither agree nor disagree’ to these items when ‘not applicable’ would have been more appropriate. This would have led to low rankings on these scales in the national surveys. Distance-learning institutions need to advise their students about the importance of only rating items they have actually experienced or to negotiate changes to the questionnaires themselves if they are to ensure that their activities and achievements are properly represented in national student feedback surveys