Studying this ontogenetic change may shed some light on the general questions related to ontogenetic color change that are not directly related to mate choice or social hierarchy. In most diurnal lizard species, only the juvenile's tail is brightly colored-the contrasting color fades and becomes similar to the cryptic body colors when the lizard approaches the minimal size for sexual maturity ( Arnold 1984 Vitt and Cooper 1986). In most diurnal lizards, the conspicuous tail is colorful (e.g., blue, green, or red) in nocturnal species, contrasting colors (light and dark bands) make the tail noticeable.

Typical examples of conspicuous tail colors that contrast with cryptic body coloration can be found in a variety of lizard species belonging to different families ( Arnold 1984 Cooper and Vitt 1985 Vitt and Cooper 1986). Other studies suggested that colored tails may serve as a visual signal for social behavior, as a lure to approaching prey, or as a signal to a predator that it has been spotted or that the prey is unpalatable ( Clark and Hall 1970 Arnold 1984 Hasson et al. In the few studies that have addressed the adaptive value of conspicuous tail colors, the most common suggestion was that conspicuous tails deflect predator attacks to expendable or relatively invulnerable body parts in reptiles ( Cooper and Vitt 1985 Cooper 1998), amphibians ( Caldwell 1982 McCollum and Leimberger 1997), and fish ( MacPhail 1977). Such a cost, on top of the energetic cost of the ontogenetic color alteration, should be offset by the advantages that the individual gains from having a conspicuous tail. Brightly colored tails may expose cryptic individuals to increased risk of predation. Although the phenomenon is very common, especially in reptiles, the adaptive significance of color change that is not directly related to reproduction has received very little attention ( Booth 1990).Ĭonspicuous colors in juvenile tails that fade during maturation are widespread and are a clear example of ontogenetic color change among amphibians, reptiles, and fish ( Caldwell 1982 Cooper 1998 Kynard, Henyey, and Horgan 2002). For example, Hoffman and Blouin (2000), who reviewed the coloration in 225 polymorphic anuran species, found that 46 of the assessed species went through an ontogenetic color or pattern change. Many vertebrate species belonging to different taxa show age-related (ontogenetic), directional changes in coloring or pattern. The persistence of both striped body pattern and blue tail fits the active foraging period of neonates and hence may be appropriate for other species that display a conspicuous tail accompanied by a striped pattern. Conspicuous colors and deflection displays may shift attacks to the expendable tail, increasing the prey's overall probability of surviving attacks. Active lizards that forage in open habitats increase their probability of attack by ambush predators. The results suggest that activity alteration may be a major factor affecting the ontogenetic color and pattern change. In comparison, 2 other lacertids that do not undergo ontogenetic change did not switch to safer foraging when growing up. Striped blue-tailed hatchlings foraged more actively than 3-week-old juveniles, spent a longer time in open microhabitats, and performed deflective tail displays. In addition, we explored whether tail displays, often assumed to direct a predator's attention to the tail, disappear with the color change. We observed blue-tailed, newly hatched lizards ( Acanthodactylus beershebensis) in the field and compared 5 behavioral parameters with those of older individuals that had already lost their neonate coloration. We suggest a novel hypothesis: conspicuous tail colors that appear only in juveniles compensate for an increased activity level, deflecting imminent attacks to the tail. One example is conspicuous colors in the tails of fish, amphibians, and reptiles that fade out later in life. Ontogenetic changes in color and pattern that are not directly related to reproduction are very common yet remain a poorly understood phenomenon.

Bluetail skinks