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
Porphyria cutanea tarda the body. Certain mutations in the "HFE" gene cause hemochromatosis (an iron overload disorder). People who have these mutations are also at an increased risk of developing porphyria cutanea tarda. In the 20% of cases where porphyria cutanea tarda is inherited, it is inherited in an autosomal dominant pattern, which means one copy of the altered gene is sufficient to decrease enzyme activity and cause the signs and symptoms of the disorder. While inherited deficiencies in uroporphyrinogen decarboxylase often lead to the development of PCT, there are a number of risk factors that can both cause and exacerbate the symptoms