Consistent phenological shifts in the making of a biodiversity hotspot: the Cape flora

Background The best documented survival responses of organisms to past climate change on short (glacial-interglacial) timescales are distributional shifts. Despite ample evidence on such timescales for local adaptations of populations at specific sites, the long-term impacts of such changes on evolutionary significant units in response to past climatic change have been little documented. Here we use phylogenies to reconstruct changes in distribution and flowering ecology of the Cape flora - South Africa's biodiversity hotspot - through a period of past (Neogene and Quaternary) changes in the seasonality of rainfall over a timescale of several million years. Results Forty-three distributional and phenological shifts consistent with past climatic change occur across the flora, and a comparable number of clades underwent adaptive changes in their flowering phenology (9 clades; half of the clades investigated) as underwent distributional shifts (12 clades; two thirds of the clades investigated). Of extant Cape angiosperm species, 14-41% have been contributed by lineages that show distributional shifts consistent with past climate change, yet a similar proportion (14-55%) arose from lineages that shifted flowering phenology. Conclusions Adaptive changes in ecology at the scale we uncover in the Cape and consistent with past climatic change have not been documented for other floras. Shifts in climate tolerance appear to have been more important in this flora than is currently appreciated, and lineages that underwent such shifts went on to contribute a high proportion of the flora's extant species diversity. That shifts in phenology, on an evolutionary timescale and on such a scale, have not yet been detected for other floras is likely a result of the method used; shifts in flowering phenology cannot be detected in the fossil record

Deconstructing Each Item's Category Contribution

Retailers and manufacturers believe that the mere presence of certain items in a retail assortment increases the sales volume of the whole assortment. This paper provides an empirical study of the role of every item in an assortment. Our results show that many items affect category sales over and above their own sales volume. After deconstructing the role of a stockout of individual items into three effects—lost own sales, substitution to other items, and the category sales impact—we find that the category impact has the largest magnitude. Interestingly, the disproportionate impact of individual items on category sales is not restricted to top-selling items, for almost every single individual item affects category sales. It seems that variety is indeed the price of entry in retailing. Our results support recent findings that more frequently purchased categories are less adversely affected by reductions in assortment. We also find that the assortment appears to gain attractiveness when certain items are out of stock, a result that is consistent with the discussion in the literature concerning category clutter.apparel retailing, retail assortment, category management, out-of-stocks, substitution, key items, hierarchical Bayes, COM-Poisson