John Donaldson

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Using data for 25,780 species categorized on the International Union for Conservation of Nature Red List, we present an assessment of the status of the world's vertebrates. One-fifth of species are classified as Threatened, and we show that this figure is increasing: On average, 52 species of mammals, birds, and amphibians move one category closer to(More)
This paper interprets the well-known value effect through the implications of standard Q-theory. An investment growth factor, defined as the difference in returns between lowinvestment stocks and high-investment stocks, contains information similar to the Fama and French (1993) value factor (HML), and can explain the value effect about as well as HML. In(More)
Ongoing expansion of large-scale agriculture critically threatens natural habitats and the pollination services they offer. Creating patches with high plant diversity within farmland is commonly suggested as a measure to benefit pollinators. However, farmers rarely adopt such practice, instead removing naturally occurring plants (weeds). By combining(More)
Complementary field and laboratory tests confirmed and quantified the pollination abilities of Tranes sp. weevils and Cycadothrips chadwicki thrips, specialist insects of their respective cycad hosts, Macrozamia machinii and M. lucida. No agamospermous seeds were produced when both wind and insects were excluded from female cones; and the exclusion of(More)
We examine 1,214 condominium developments in Vancouver, Canada between 1979-1998 to identify the extent to which uncertainty delays investment. We find that increases in both idiosyncratic and systematic risk lead developers to delay new real estate investments. Empirically, a one-standard deviation increase in the return volatility reduces the hazard rate(More)
OBJECTIVE To establish the accuracy of sentinel lymph node (SLN) detection in early cervical cancer. MATERIALS AND METHODS Sentinel lymph node detection was performed prospectively over a 6-year period in 86 women undergoing surgery for cervical carcinoma by the combined method (Tc-99m and methylene blue dye). Further ultrastaging was performed on a(More)
Ce document est publié dans l'intention de rendre accessibles les résultats préliminaires de la recherche effectuée au CIRANO, afin de susciter des échanges et des suggestions. Les idées et les opinions émises sont sous l'unique responsabilité des auteurs, et ne représentent pas nécessairement les positions du CIRANO ou de ses partenaires. This paper(More)
Data from 199 plots in the semi-arid Karoo showed that relationships between soil infiltrability and plant cover/species richness, as depicted by boundary lines, yielded ecological insights not evident if only commonly measured soil properties such as pH, electrical conductivity and the content of clay, silt, sand, nitrogen and carbon were considered. For(More)
Although South African cycads are known to be declining in the wild, there is at present no broad-scale, quantitative analysis to support this view. In this study the fate of 626 individual cycads was assessed from 107 repeat photographs taken at 53 locations over three time-steps (broadly 1940s, mid-1990s and 2014). Of the cycads photographed in the 1940s,(More)