Phylogenetic and phenotypic divergence of an insular radiation of birds

Evolutionary divergence of lineages is one of the key mechanisms underpinning large scale patterns in biogeography and biodiversity. Island systems have been highly influential in shaping theories of evolutionary diversification and here I use the insular Zosteropidae of the south west Pacific to investigate the roles of ecology and biogeography in promoting evolutionary divergence. Initially I build a phylogenetic tree of the study group and use it to reveal the pattern of colonisation and diversification. My results suggest a complex history of dispersal with the observed pattern most likely a result of repeated bouts of colonisation and extinction. I then use the new phylogeny to quantify the diversification rates of the Zosteropidae. I find a very high rate of lineage divergence and suggest the most likely explanation relates to extensive niche availability in the south west Pacific. I also find evidence for an overall slowdown in diversification combined with repeated bursts of accelerated speciation, consistent with a model of taxon cycles. I do not find evidence for sympatric speciation, however. Finally I combine morphological and phylogenetic data to investigate the mode of evolution, evidence for character displacement and influence of biogeography on trait evolution. I find little support for the traditional theory of character displacement in sympatric species. I do, however, find some support for biogeographic theories. Taken together my results do not support traditional theories on the ecological and biogeographical basis of divergence, even in those cases where Zosterops have been used as exemplars. This appears to be because those theories assume rather simple patterns of colonisation and a static ecological system. Instead, my results suggest that evolutionary diversification is dominated by recurrent waves of colonisation and extinction, which, viewed at any particular moment, tend to obscure any underlying ecological rules

Trade Liberalization, Technical Change and Firm Level Restructuring in the South African Automotive Component Sector

This paper examines the interplay between trade liberalization and the processes of learning, technical change and capability development in the South African automotive component sector. Using case studies based on firm level interviews conducted at various points since 1992, it illustrates how the technological capabilities of the industry were shaped by protection, and how this in turn mediated responses to trade liberalization initially via internal restructuring and more recently in the phase of internationalization and growing foreign ownership. In essence, the paper presents a ‘before and after’ picture of firm level responses to liberalization.- auto-parts, foreign direct investment, industrial policy, South Africa, technology, trade

The Impact of the Financial Crisis on the Bond Market

The Australian bond market functioned well during the financial crisis. Changes in investor sentiment and issuer behaviour led to a slowing in issuance and an increase in the average credit quality of new issuance. While the average bond term shortened and spreads widened, these trends have since reversed somewhat as market conditions have improved.bond issuance; financial crisis; bond spreads

Tilting the playing field: labour absorbing growth and the role of industrial policy

South Africa faces a severe problem of persistent structural unemployment. This results not only from low growth but more importantly from the pattern of growth over many decades. The recent recession aside, there has for the past several years been a significant improvement in South Africa?s growth performance. However, although new jobs have been created, this has been at a frustratingly slow pace and it would be difficult to argue that there has been a structural shift to a more labour demanding growth path. The data remain controversial but even the more optimistic projections show that very large scale unemployment will remain a major problem even under quite optimistic growth scenarios. If it were not for increased social payments, poverty would have continued to increase over the period

Integrating theory and practice : a guided mentoring research process for licensed ministers in the West Michigan district of the Wesleyan Church

https://place.asburyseminary.edu/ecommonsatsdissertations/1847/thumbnail.jp

What are the implications of the SADC Protocol for the Automotive Industry in Southern Africa?

This policy brief is a shortened version of the following paper: Implications of the SADC Trade and Investment Protocol for the Automotive Industry in Southern Africa, By Samson Muradzikwa and Anthony Black

De novo prediction of PTBP1 binding and splicing targets reveals unexpected features of its RNA recognition and function.

The splicing regulator Polypyrimidine Tract Binding Protein (PTBP1) has four RNA binding domains that each binds a short pyrimidine element, allowing recognition of diverse pyrimidine-rich sequences. This variation makes it difficult to evaluate PTBP1 binding to particular sites based on sequence alone and thus to identify target RNAs. Conversely, transcriptome-wide binding assays such as CLIP identify many in vivo targets, but do not provide a quantitative assessment of binding and are informative only for the cells where the analysis is performed. A general method of predicting PTBP1 binding and possible targets in any cell type is needed. We developed computational models that predict the binding and splicing targets of PTBP1. A Hidden Markov Model (HMM), trained on CLIP-seq data, was used to score probable PTBP1 binding sites. Scores from this model are highly correlated (ρ = -0.9) with experimentally determined dissociation constants. Notably, we find that the protein is not strictly pyrimidine specific, as interspersed Guanosine residues are well tolerated within PTBP1 binding sites. This model identifies many previously unrecognized PTBP1 binding sites, and can score PTBP1 binding across the transcriptome in the absence of CLIP data. Using this model to examine the placement of PTBP1 binding sites in controlling splicing, we trained a multinomial logistic model on sets of PTBP1 regulated and unregulated exons. Applying this model to rank exons across the mouse transcriptome identifies known PTBP1 targets and many new exons that were confirmed as PTBP1-repressed by RT-PCR and RNA-seq after PTBP1 depletion. We find that PTBP1 dependent exons are diverse in structure and do not all fit previous descriptions of the placement of PTBP1 binding sites. Our study uncovers new features of RNA recognition and splicing regulation by PTBP1. This approach can be applied to other multi-RRM domain proteins to assess binding site degeneracy and multifactorial splicing regulation