Nonlinear growth dynamics and the origin of fluctuating asymmetry

Fluctuating asymmetry and fractal dimension of the sagittal suture as indicators of inbreeding depression in dama and dorcas gazelles

The effects of inbreeding on the developmental instability of skulls of dorcas (Gazella dorcas) and dama (G. dama) gazelles were investigated. In total, 132 dorcas gazelle skulls and 74 dama gazelle skulls from the Estación Experimental de Zonas Aridas in Almera, Spain, were measured. The fluctuating asymmetry of 9 meristic characters, consisting of the numbers of foramina on the two sides of the skull and mandible, was calculated. Although only the foramen infraorbitalis showed a significant increase in asymmetry with inbreeding in dorcas gazelles, the sum of the foramina in 5 of the skull regions clearly indicates an increase in asymmetry with inbreeding in both dorcas and dama gazelles. The fractal dimension of the sagittal suture was calculated by means of the coastline method. A greater effect of inbreeding on the sagittal suture in dama than in dorcas gazelle was observed, in concordance with the more evident deleterious effects of inbreeding depression in dama than in dorcas gazelles.

Fluctuating asymmetry in the skeleton of the American kestrel, Falco sparverius: a test of the consequences of sexual size dimorphism

Fluctuating asymmetry, i.e., random, subtle departures from perfect bilateral symmetry, is believed to be a measure of developmental noise. The more physical stress an organism has undergone, the greater the asymmetry. We investigated the degree of fluctuating asymmetry in bones of the American kestrel (Falco sparverius) as a test of the developmental consequences of sexual dimorphism in size. The "cost of rearing" hypothesis predicts that females, because of their larger size, will suffer food shortages more often than males and hence show greater asymmetry. In contrast, the "female dominance" hypothesis predicts that females will be under less developmental stress because their size gives them an advantage when they compete with their brothers for limited food while in the nest. Significant fluctuating asymmetry was detected for all characters of both sexes; however, differences between males and females only approached statistical significance. We suggest that the degree of among-broods variation is so great that the role of gender in influencing developmental stability may be relatively small.