Parasites affect song complexity and neural development in a songbird

There is now considerable evidence that female choice drives the evolution of song complexity in many songbird species. However, the underlying basis for such choice remains controversial. The developmental stress hypothesis suggests that early developmental conditions can mediate adult song complexity by perturbing investment in the underlying brain nuclei during their initial growth. Here, we show that adult male canaries (Serinus canaria), infected with malaria (Plasmodium relictum) as juveniles, develop simpler songs as adults compared to uninfected individuals, and exhibit reduced development of the high vocal centre (HVC) song nucleus in the brain. Our results show how developmental stress not only affects the expression of a sexually selected male trait, but also the structure of the underlying song control pathway in the brain, providing a direct link between brain and behaviour. This novel experimental evidence tests both proximate and ultimate reasons for the evolution of complex songs and supports the Hamilton–Zuk hypothesis of parasite-mediated sexual selection. Together, these results propose how developmental costs may help to explain the evolution of honest advertising in the complex songs of birds.

Social capital : an analytical tool for exploring lifelong learning and community development

In her recent contribution to the British Educational Research Journal, Pauline McClenaghan identified the link between social capital and community development, particularly community development education, as a core area where scholarly and policy interests overlap. She concluded that the concept of social capital is unable to grapple with the complex social divisions that characterise contemporary Europe. The authors of this article question her account on three main grounds: the definition of social capital, which they hold is overly narrow, and does not deal with what Woolcock calls the ‘linking’ role of social networks; the presentation of the theoretical foundations of community development, which they believe is flawed in certain key respects; and a lack of clarity in the relationship between the research and the findings reported. The authors then present their own theoretically informed account of social capital as a means of understanding the role of community development, the challenges that it can face and the role of adult education for community development.

NGOs, enterprise and rural development

Non-Government Welfare Organisations (NGOs) in rural areas have traditionally relied upon the state for a large part of their revenue which in turn provides the state with the capacity to impose strict monitoring and evaluation. However the tightening of state funding has either forced NGOs to stretch their own resource to the limit or to become more enterprising and innovative in their desire to provide people with access to an ever increasing range of community-based services and opportunities for connection with their local communities. The term that is often used for these new approaches is ‘social enterprise’ that has been defined as a business with primarily social objectives whose surpluses are principally reinvested for that purpose in the business or the community, rather than being driven by the need to maximise profit for shareholders and owners’ . It is most often seen as an interface between public and private sector, being part of neither but engaging closely with both through partnerships, stakeholding and joint ventures as well as through complex trading and contracting relationships.

Such broad definitions however do not give much guidance to how particular NGOs can shift to a social enterprise model and still remain within their chosen missions. It is the very processes of re-imagining and reforming their enterprise that is a vital element in moving to a successful social enterprise practice. Accordingly this project focuses on two NGOs in different parts of the world (Brophy Family and Youth Services in Warrnambool. Australia and Aberdeen Foyer in Aberdeen, Scotland) that have developed (and are developing) new ways of approaching their roles as service providers and early intervention agents for youth in their local areas. Since both organisations have faced (and are facing) issues associated with depleting state allocated resources they are attempting to break new ground in the ways in which they redevelop their work with youth. Both agencies are leading the way in developing a broader approach that draws together disparate element of a social enterprise model. The project analyses the processes used by these two agencies to develop as social enterprises and how likeminded agencies can use the model for capability enhancement.

Identifying linkages between generations and community development: the effect on residential and retail property

In the analysis of property markets, especially the retail and residential sectors, increasing importance is being given to the role of demography. The impact of economic influences such as interest rate movements, inflation and changes in the labour market are well documented and although these variables are clearly important, they do not incorporate the changing characteristics of the local inhabitants who actually provide the demand. However, demography can provide an invaluable insight into retail and residential property trends, especially over the long term, and are assisted by reliable population datasets with a relatively high level of detail. For example, the emergence of the 'baby boom' generation shift had a substantial effect on demand for retail and housing products, although little consideration has been given to the effect from the subsequent cohorts, namely generations X, Y and Z.

This paper examines the role of demography when researching property markets, with the focus placed on demographic shifts. It discusses trends in a range of demographic variables that have been observed in society. In addition, it highlights linkages with property markets, especially residential and retail property, and draws inferences for long term trends. The study concludes that when conducting research into property markets, it is essential to have a thorough understanding of various demographic variables to predict how they affect demand. An appreciation of the drivers behind generations will assist property researchers to identify future needs, and the subsequent effect this will have on community development involving retail and residential property.

Leptin and the development of obesity

The focus of this thesis was leptin and its role in the development of obesity and non-insulin-dependent diabetes mellitus (NIDDM). Studies in Psammomys obesus, a polygenic animal model of obesity and NIDDM, showed that ob gene expression and plasma leptin concentration correlated significantly with body weight, percentage body fat and plasma insulin concentration. In addition, plasma leptin concentrations were significantly elevated in insulin resistant Psammomys obesus independent of body weight. Dietary energy restriction from weaning in Psammomys obesus prevented excessive body weight gain, hyperleptinemia and hyperglycemia compared with ad libitum fed animals. Interestingly, 19% of the energy-restricted animals still developed hyperinsulinemia and tended to have increased plasma leplin compared with normoinsulinemic energy-restricted Psammomys obesus. Fasting for 24 hours significantly reduced plasma leptin concentration in lean, insulin-sensitive but not obese, insulin-resistant P. obesus, suggesting a dysregulation in the response of leptin to acute caloric deprivation in these animals. The effects of leptin administration to P. obesus were also investigated. Single daily intraperitoneal injection of 5 mg leptin/kg body weight for 14 days had no significant effect in lean or obese P. obesus. This dose had previously been shown to rapidly and significantly reduce food intake and body weight in ob/ob and wild-type mice, suggesting relative leptin resistance in P. obesus. Acute (8 hour) effects of administration of 5 mg leptin/kg body weight were also investigated. No significant effects on food intake or plasma insulin were detected, however blood glucose concentrations were significantly elevated in obese, glucose intolerant P. obexus, suggesting an exacerbation of insulin resistance in susceptible animals. Treatment of lean, healthy P. obesus with 45 mg leptin/kg body weight/day for 7 days resulted in significant decreases in food intake and percentage body fat, showing that the leptin resistance observed in this species could be overcome by the administration of very large doses of leptin. In another study, leplin was shown to significantly inhibit maximal insulin binding to isolated adipocytes, suggesting that leptin may respresent an important link between obesity and NIDDM. Links between aspects of obesity and NIDDM and polymorphisms in the ob and p3-adrencrgic receptor genes were also investigated in two human populations.