Lek mating females away from the hotshot. A manipulative experiment using the little bustard, "Tetrax tetrax", was done to test the various lek evolution models. The experiment involved varying the size and sex ratio of leks using decoys. To test whether or not the presence of a hotshot determined lek formation, a hotshot little bustard decoy was placed within a lek. After the fake hotshot was added to the lek, both male and female visitation to the lek increased. The hotspot model considers the female density to be the catalyst for the clustering of males. This model predicts that leks will form
Xylota tarda Russia and the Caucasus then through Russia to Siberia and the Pacific coast (Kuril islands). Old woodland species running on the foliage of bushes and shrubs and on tree stumps and nearby bare ground. The larva has been found in sap runs at the base of the trunk of "Populus tremula" and in rotting wood of "Fagus". Xylota tarda Xylota tarda is a Palearctic species of hoverfly. External images For terms see Morphology of Diptera<br> Wing length 5·5-8·5 mm. Large red areas on black abdomen. Wing membrane not infuscated. Dorso-apical white bristle on metatarsus 1. Antero-dorsal pale hairs on the