The gene rx3 is required for eye development in Astyanax mexicanus surface fish. Further, cis-regulatory variation in rx3 may play a role in evolution of reduced eye size in cavefish of this species.

The pattern of body size response to temperature corresponds to the pattern of fitness, showing the evolutionary limits of phenotypic plasticity. Body size plastically decreases with increasing temperature within a certain optimal thermal range, while no plasticity is observed outside this range.

Main life-history events and traits of the hippopotamus (Hippopotamus amphibius) and its skeletal and craniomandibular developmental processes. The major skull changes in infancy (0–3 years) and puberty (10–15 years) and the late stabilization (20–25 years) of the mandibular shape with respect to the cranial shape stand out. This last and unique process suggests ongoing dietary adaptations.

Individuals of Asellus infernus, a sulfidic subterranean population of the Asellus aquaticus species complex from southeastern Romania (left) and surface individuals of A. aquaticus (right). Extreme differences in phenotype are seen comparing the subterranean and surface individuals as adults (top panels) and as embryonic samples (bottom panels).