Flowers says that orange tails may indicate the quality of a male chuckwalla's territory. The orange color is based on carotenoid pigments absorbed from plants consumed by the individual lizard. Flowers presented his findings during a symposium in Seattle. Response from other researchers was enthusiastic. Examples of male color patterns being influenced by female preferences have been observed in fish and birds, but never before with lizards.
Chuckwallas also have good chemical senses.
Little nuances determine which male a female will select for mating. But I think that his work should contribute to changing the way we think about the causes of differences among populations in male color patterns, as well as the consequences and origins of geographic variations in female mate preferences.