5,670 research outputs found
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
Migration, Poverty Reduction Strategies and Human Development
This paper focuses on the specific question of how Poverty Reduction Strategy Papers (PRSPs) address migration and its potential to enhance human development at the national level. Based on a review of PRSPs completed since 1999, it argues that migration often remains poorly recognised or analysed in poorer countries in terms of its impacts on poverty reduction, whilst attitudes towards migration in these countries are often highly negative and/or based on limited evidence, especially in relation to internal migration. Analysis of how both internal and international migration are treated in PRSPs is also placed in the context of a broader understanding of the purpose of, and constraints faced by the PRS process. The paper goes on to highlight the extent to which in Sub-Saharan African countries, successive drafts of PRSPs have shown increasing attention to migration. It also considers how analysis of the problems and opportunities associated with different types of migration are converted into policy initiatives, highlighting the lack of good practice in terms of the incorporation of migration into human development policy.Poverty Reduction Strategy Papers (PRSPs), internal migration, international migration, sub-Saharan Africa, analysis of migration
Endothelial and smooth muscle cell interactions with a PCL-PU composite vascular scaffold with potential for bioactive release
Paper discussing endothelial and smooth muscle cell interactions with a PCL-PU composite vascular scaffold with potential for bioactive release
How the credit channel works: differentiating the bank lending channel and the balance sheet channel
The credit channel of monetary policy transmission operates through changes in lending. To examine this channel, we explore how movements in the real federal funds rate affect bank lending. Using data on individual loans from the Survey of Terms of Bank Lending, we are able to differentiate two ways the credit channel can work: by affecting overall bank lending (the bank lending channel) and by affecting the allocation of loans (the balance sheet channel). We find evidence consistent with the operation of both internal credit channels. During periods of tight monetary policy, banks adjust their stock of loans by reducing the maturity of loan originations and they reallocate their short-term loan supply from small firms to large firms. These results are stronger for large banks than for small banks.Monetary policy ; Bank loans
The Role of School Counselors in Meeting Students\u27 Mental Health Needs: Examining Issues of Professional Identity
The professional identity of school counselors has evolved over time. This article traces the historical context driving this evolution, and suggests it is time for the profession to conjoin the roles of educational leader and mental health professional. This proposal is prompted by heightened awareness of unmet student mental health needs, referrals that go unmet, school counselors displaced by other mental health providers in schools, the potential loss of the unique school counselor role, and the natural link between the mental health professional role and the array of personal-social factors that impact student achievement. A conjoint professional school counselor identity that includes the roles of both educational leader and mental health professional positions school counselors to better respond to all students, including those with mental health needs. This article discusses potential roadblocks and offers suggestions for action
The labor problem in the coal mining industry of Kansas
Thesis (M.A.)--University of Kansas, Economics, 1920. ; Includes bibliographical references
Populations 'trapped' at times of crisis
A focus on those who are trapped challenges both theoretical and practical approaches to mobility and crisis, which prioritise movement. Those who have lost control of the decision to move away from potential danger have inevitably lost a lot more too
Poblaciones “atrapadas” en épocas de crisis
Centrarse en aquellos que están atrapados desafĂa los enfoques teĂłricos y prácticos basados en la movilidad y la crisis, que priorizan los traslados de la poblaciĂłn. Aquellos que no pueden decidir sobre si mudarse a otra parte para huir de un potencial peligro, inevitablemente son los que más pierden
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