These Lizards Have Been Playing Rock-Paper-Scissors for 15 Million Years | Deep Look

by Super User, 7 years ago
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Male side-blotched lizards have more than one way to get the girl. Orange males are bullies. Yellows are sneaks. Blues team up with a buddy to protect their territories. Who wins? It depends - on a genetic game of roshambo.

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Every spring, keen-eyed biologists carrying fishing poles search the rolling hills near Los Banos, about two hours south of San Francisco. But they’re not looking for fish. They’re catching rock-paper-scissors lizards.

The research team collects Western side-blotched lizards, which come in different shades of blue, orange and yellow.

Barry Sinervo, a professor of ecology and evolutionary biology at UC Santa Cruz, leads the team. Their intricate mating strategies reminded the the researchers of the rock-paper-scissors game where rock beats scissors, scissors beats paper and paper beats rock.

It’s all about territories. Orange males tend to be the biggest and most aggressive. They hold large territories with several females each and are able to oust the somewhat smaller and less aggressive blues. Blue males typically hold smaller territories and more monogamous, each focusing his interest on a single female. Yellow males tend not to even form exclusive territories Instead they use stealth to find unaccompanied females with whom to mate.

The yellow males are particularly successful with females that live in territories held by their more aggressive orange competitors. Because the orange males spread their attention among several females, they aren’t able to guard each individual female against intruding yellow males. But the more monogamous blues males are more vigilant and chase sneaky yellow males away.

Their different strategies keep each other in check making the system stable. Sinervo believes this game has likely been in play for at least 15 million years.

--- How do side-blotched lizards choose a mate?

The males compete with each other, sometimes violently, for access to females. The females generally prefer males of their own color but also give preference to whichever color male is more rare that mating season.

--- Why do lizards do push up and down?
Male lizards do little pushups as a territorial display meant to tell competitors to back off. It’s best to use a warning instead of fighting right away because there’s always a danger of getting hurt in a fight. Some lizards like side-blotched lizards also use slow push ups to warn their neighbors of an incoming threat.

--- Why do side-blotched lizards fight?
Sometimes aggressive territorial displays are not enough to dissuade invaders so side-blotched lizards will resort to fighting. They have small sharp teeth and will lunge at each other inflicting bites and headbutts.

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The Lab of Dr. Barry Sinervo, LizardLand, University of California, Santa Cruz

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