RESUMEN

In a recent paper in Current Biology, Fennessy and colleagues [1] conclude that there are four species of giraffe and that their numbers are declining in Africa. Giraffes (Giraffa camelopardalis) are presently classified as one species, with nine subspecies, which are considered 'Vulnerable' on the IUCN Red List [2]. The present consensus of one species divided into nine subspecies has previously been questioned (Supplemental information), and Fennessy and colleagues [1] provide another viewpoint on giraffe taxonomy. The fundamental reason for different taxonomic interpretations is that they are based upon different datasets that adopt different statistical techniques and follow different criteria for nomenclature.

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RESUMEN

We report a series of experiments with three competing species and a novel graphical analysis that explores the dynamics of this simple multi-species system. The three competing species (Drosophila hydei, D. immigrans and D. virilis) were maintained in five very large cages, on a natural fruit resource. The analytic method involved constructing a "dynamic surface", by interpolation, from the population trajectories. Within the dynamic surface constructed from the five experiments a small "equilibrium area" (an area of point vectors) could be identified. The implications of both the method and the results are discussed.

RESUMEN

We present some data on drosophilid oviposition and analyse the distribution of egg numbers over patches using an 'iterated' negative binomial. This suggests that there are three different reasons for empty patches; patches are not found, patches are not suitable, or females are not able to lay eggs. This leads to five categories of site which can be disentangled using the 'iterated' negative binomial. Since empty patches have important consequences for population dynamics and coexistence, this analysis will highlight how microscopic processes influence macroscopic behaviour in population biology.