Common Side-Blotched Lizard
Deserts and shrublands
Western United States and northern Mexico
Least Concern (IUCN Red List)
This species is
to the Truckee Meadows.
Common side-blotched lizards are small reptiles around 4 to 6 inches in length. They are one of the most commonly seen and abundant species of lizards in the American West. These lizards are generally a brownish color that can vary slightly in darkness, and they have a noticeable dark blotch on each side of their chest. Unlike some other species of western North American lizards, common side-blotched lizards do not have spiny scales. Due to their small size, these lizards warm up quickly, so this may be one of the first lizards you see out in the morning.
Male common side-blotched lizards have three different genetic morphs, or variations, identified by the color of their throats and their mating behaviors: orange-throated males aggressively defend large territories, blue-throated males guard their mates closely, and yellow-throated males sneak into other males' territories and mate with their females.
The three different morphs' strategies have a "rock, paper, scissors" relationship: orange males beat blue males by stealing their territory, yellow males beat orange males by stealth, and blue males beat yellow males by guarding their mates too closely to let yellow males sneak past.
The "rock, paper, scissor" balance of males has allowed these differences to survive for millions of years, since any strategy that creates the most offspring in one year will be evened out by the dominance of the strategy it "loses" to in subsequent years.
Jill Katz (research & content)
Alex Shahbazi (edits & page design)