by Brendan Bane
Children in Tennessee chase fireflies. Kids in California chase lizards. Many young hands across the forests and deserts of the Golden State have clasped to conceal the abundant western side-blotched lizard, Uta stansburiana elegans.
We’ve all seen these guys, flittering through leaf litter and bolting into rock crevices. They may seem commonplace, but these reptiles are one of the most interesting examples of evolutionary strategies at play.
Adults are small, only slightly larger than a pack of gum. Smooth scales are peppered with spots and sometimes stripes. Males come in myriad colors. Although their bodies are mostly black, brown or gray, throat and side colors vary. Those colors serve a special function— three male morphs (distinctly colored strains) correlate with three mating strategies.
Orange males aggressively defend small territories (such as rock outcrops) and breed with many females. Blue males also guard territories, but instead of fighting, they cooperate with other blue males to establish borders, which spares them costly confrontation. Yellow males are female mimics—they disregard territory altogether, look like females and sneak into other males’ territories to secretively breed.
At any given time, one strategy wins more female access than a second, but less than the third strategy. If one strategy becomes more prevalent than another, say sneaker yellow males, the strategy becomes less effective (they’re ousted more often) and becomes less common. UCSC professor Barry Sinervo describes this as a kind of ecological rock paper scissors, where all three strategies coexist in an evolutionarily synced love triangle.
You can usually catch these lizards absorbing mid-morning sun on dirt patches and rock faces. When warm enough, they’ll forage for small invertebrates like ticks, ants and spiders. Males perform pushups to outline territory boundaries. The showy displays of pectoral prowess are easier and cheaper, evolutionarily speaking, than fighting.
The population extends as far north as the Bay Area, east into Utah, and south into San Diego. With such a large distribution, they are well adapted to a variety of habitats, from grasslands to arid regions.
Mating occurs in the spring, with clutches laid between March and August. New lizards emerge between June and September.
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