FRACTAL STRUCTURES AND FRACTAL FUNCTIONS AS DISEASE INDICATORS

Developmental instability is an early indicator of stress, and has bee n used to monitor the impacts of human disturbance on natural ecosyste ms. Here we investigate the use of different measures of developmental instability on two species, green peppers (Capsicum annuum), a plant, and Spanish ibex (Capra pyrenaica), an animal. For green peppers we c ompared the variance in allometric relationship between control plants , and a treatment group infected with the tomato spotted wilt virus. T he results show that infected plants have a greater variance about the allometric regression line than the control plants. We also observed a reduction in complexity of branch structure in green pepper with a v iral infection. Box-counting fractal dimension of branch architecture declined under stress infection. We also tested the reduction in compl exity of behavioral patterns under stress situations in Spanish ibex ( Capra pyrenaica). Fractal dimension of head-lift frequency distributio n measures predator detection efficiency. This dimension decreased und er stressful conditions, such as advanced pregnancy and parasitic infe ction. Feeding distribution activities reflect food searching efficien cy. Power spectral analysis proves to be the most powerful tool for ch aracterizing fractal behavior, revealing a reduction in complexity of time distribution activity under parasitic infection.