Home-field advantage is a sports phenomenon where the home team tends to have an advantage over the visiting team. The causes of home-field advantage are debated, but range from physiological adaptions of players to the home-field climate, to psychological and behavioral effects of supportive fans, to greater familiarity with features of the home field. According to a recent study led by Nathalie Feiner, a postdoctoral fellow at Lund University in Sweden, lizard athletes also have a home-field advantage. The study investigated why lizards of the same species have different shapes in different environments and whether this affects their athletic performance in their environments. In a process known as phenotypic plasticity, individuals of the same animal species frequently develop different shapes and physiology when exposed to different environments or experiences, which includes why people who frequently lift weights get bigger muscles. Feiner sought to find out whether phenotypic plasticity is completely responsible for the lizards’ home-field advantage.
Feiner and colleagues raised two species of anole lizard hatchlings (green and brown anoles), from the same sets of parents, in two different environments: one with narrow platforms that mimic thin branches and one with broad platforms that simulate the ground. After 5 months of growing up in their different homes, the lizards were tested to see how well they ran on narrow and wide platforms.
It turned out that the anoles that had been raised scampering along broad boards were better runners when tested on these than the anoles that had been raised in an environment where the boards were thin. The lizards that had a home-field advantage performed better in situations where they had significant prior experience. What caused this advantage, though?
After measuring the anoles’ performance, Feiner and colleagues used CT scanners to create 3D X-ray images of the lizards to study their build and compare how they differed between the two environments. Both species had different shoulder and hip shapes depending on which environment they had grown up in, suggesting that they had adapted to their homes. The green anoles raised on the broad boards also had longer limbs, which may make running more efficient on wide surfaces. But, do these differences in the lizards’ build explain the differences in their performance?
Not really. Using mathematical models, Feiner and colleagues found that the shape differences only helped a tiny bit. Something else was causing the anoles raised on wide platforms to perform better on their familiar surface, but what could that be? It turns out to be the same thing that allows trapeze artists to walk across tightropes, while the rest of us would fall after the first step; behavioral changes. By practicing for years, trapeze artists have learned the best methods for moving across tightropes, which most of us will never master. Similarly, Feiner suggests that the lizards that grew up on the wider platforms have developed better patterns of movement for confidently negotiating broad platforms through experience. Lizards that grew up on narrow platforms, however, have not learned the best methods, so they do not perform as well.
The home-field advantage is a real phenomenon. In lizards, Feiner and colleagues have shown that it is caused by changes in behavior rather than any physical changes. Anoles, like people, perform better when they feel comfortable and at home. So, next time you are at your favorite stadium, remember that when you cheer on the home team, you are actually helping them win!