The orientation of walking honeybees in odour fields with small concentration gradients

The behaviour of walking honeybees in small gradient odour fields was investigated by means of a simulation technique. The bee was kept in one place by a locomotion compensator (‘running sphere’). This compensator allowed for a precise reconstruction of the bee's actual locomotion on the sphere, and presented the bee with a stimulating odour whose concentration was controlled by feedback from the reconstructed locomotion. This rendered possible the application of well-defined odour fields and revealed that: (1) honeybees are capable of finding odour sources in the absence of optical cues and with concentration gradients too small to allow tropotactic or klinotactic orientation; (2) bees are capable of memorizing odour concentrations with a high degree of accuracy; (3) this orientation system is based on a switching over from negative to positive anemotaxis at a ‘reference’ concentration; (4) this reference is a function of the odour concentration at which a sugar reward is given. The results do not support any hypothesis for an orientation system based on the detection and comparison of successive values of odour concentration. A hypothesis on the nature of the ‘reference value’ is discussed and supported by experiments.     

Polymorphic microsatellite markers for the Florida scrub lizard (Sceloporus woodi)

The Florida scrub lizard (Sceloporus woodi) is one of a suite of species restricted to Florida scrub, a threatened ecosystem. We characterized eight microsatellite loci from scrub lizards based on screening of 75–91 individuals per locus. Polymorphism was high (8–20 alleles per locus). Observed and expected heterozygosities ranged from 0.32–0.83 and 0.77–0.91, respectively. These markers will be useful for population‐level analyses and can contribute to a genetic foundation for conservation strategies for this endemic species.     

The biological meaning of species*

The two medieval species concepts, the essentialist and the nominalist, have been replaced by the biological species concept, denned in terms of the relation (i.e. ‘reproductively isolated’) between populations. The species represents an important level in the hierarchy of biological entities from the molecule to the community. Six major areas are discussed, on which much of the research on species is now focused.     

Cryptostomid Bryozoans From The Sassito Formation,Upper Ordovician Cool‐Water Carbonates of the Argentinean Precordillera

Abstract: Two new bryozoan species are described from the Upper Ordovician Sassito Formation of the Argentinean Precordillera: Moyerella  spinata sp. nov. and Phylloporina  sassitoensis sp. nov. The bryozoans are found in cool‐water carbonates. The Silurian genus Moyerella is reported the first time in the Ordovician, showing palaeobiogeographic connections with Estonia and Siberia.