Evolutionary history and leaf succulence as explanations for medicinal use in aloes and the global popularity of Aloe vera

BACKGROUND: Aloe vera supports a substantial global trade yet its wild origins, and explanations for its popularity over 500 related Aloe species in one of the world's largest succulent groups, have remained uncertain. We developed an explicit phylogenetic framework to explore links between the rich traditions of medicinal use and leaf succulence in aloes. RESULTS: The phylogenetic hypothesis clarifies the origins of Aloe vera to the Arabian Peninsula at the northernmost limits of the range for aloes. The genus Aloe originated in southern Africa ~16 million years ago and underwent two major radiations driven by different speciation processes, giving rise to the extraordinary diversity known today. Large, succulent leaves typical of medicinal aloes arose during the most recent diversification ~10 million years ago and are strongly correlated to the phylogeny and to the likelihood of a species being used for medicine. A significant, albeit weak, phylogenetic signal is evident in the medicinal uses of aloes, suggesting that the properties for which they are valued do not occur randomly across the branches of the phylogenetic tree. CONCLUSIONS: Phylogenetic investigation of plant use and leaf succulence among aloes has yielded new explanations for the extraordinary market dominance of Aloe vera. The industry preference for Aloe vera appears to be due to its proximity to important historic trade routes, and early introduction to trade and cultivation. Well-developed succulent leaf mesophyll tissue, an adaptive feature that likely contributed to the ecological success of the genus Aloe, is the main predictor for medicinal use among Aloe species, whereas evolutionary loss of succulence tends to be associated with losses of medicinal use. Phylogenetic analyses of plant use offer potential to understand patterns in the value of global plant diversity.

Literature, museums, and national identity; or, why are there so many writers' house museums in Britain?

Writers’ houses constitute the largest and oldest segment of historic house museums dedicated to famous persons in the United Kingdom. Litterateurs tend to ascribe ‘lit houses’ to the ineffable magic of readers’ connections to writers. By contrast, my analysis deploys the analytic of cultural politics to suggest that writers’ house museums can more fully be understood as assertions of national identity. The elision of language with national distinction is subliminal in everyday life, but can be brought to prominence by historicising the nations of the British Isles, and the practice of writing in English.

Locating the past in its silence: history and marketing theory in India

The paper aims to argue, while examining the history of marketing theory in India, that the discipline is a historical, serves large business interests and is shaped by hegemonic Western knowledge.

Life-history and spatial determinants of somatic growth dynamics in Komodo dragon populations

Somatic growth patterns represent a major component of organismal fitness and may vary among sexes and populations due to genetic and environmental processes leading to profound differences in life-history and demography. This study considered the ontogenic, sex-specific and spatial dynamics of somatic growth patterns in ten populations of the world's largest lizard the Komodo dragon (Varanus komodoensis). The growth of 400 individual Komodo dragons was measured in a capture-mark-recapture study at ten sites on four islands in eastern Indonesia, from 2002 to 2010. Generalized Additive Mixed Models (GAMMs) and information-theoretic methods were used to examine how growth rates varied with size, age and sex, and across and within islands in relation to site-specific prey availability, lizard population density and inbreeding coefficients. Growth trajectories differed significantly with size and between sexes, indicating different energy allocation tactics and overall costs associated with reproduction. This leads to disparities in maximum body sizes and longevity. Spatial variation in growth was strongly supported by a curvilinear density-dependent growth model with highest growth rates occurring at intermediate population densities. Sex-specific trade-offs in growth underpin key differences in Komodo dragon life-history including evidence for high costs of reproduction in females. Further, inverse density-dependent growth may have profound effects on individual and population level processes that influence the demography of this species.

Lynch syndrome: natural history and colonoscopic surveillance

Lynch syndrome is the commonest inherited cause of bowel cancer. This thesis explores the natural history and cancer risk in Lynch syndrome and documents the effect of colorectal cancer on fertility. It also demonstrates that colonoscopic surveillance can prevent colorectal cancers and thus improve survival in these subjects.