SANTA CRUZ, Calif., Oct. 6 (UPI) -- Researchers say a species of lizard in California deserts lives in family groups, showing patterns of social behavior more commonly seen in mammals and birds.
Scientists at the University of California, Santa Cruz, say their research into the formation and stability of family groups in desert night lizards (Xantusia vigilis) in the Mojave desert provides new insights into the evolution of cooperative behavior, a university release said.
Alison Davis, who led the study as a graduate student at UC Santa Cruz, said one of the unusual characteristics of desert night lizards is that they are viviparous, giving birth to live young instead of laying eggs.
But even more unusual, she said, was that both young and old lizards could be found huddling together every winter beneath fallen Joshua trees and other desert plant debris.
"This is remarkable, given the fact that in most species of lizards, individuals actively avoid each other," Davis said.
The researchers found that young desert night lizards stay with their mother, father, and siblings for several years after birth, and some groups aggregated under the same fallen log year after year, forming what the researchers termed dynasties.
The fact the young are born live, rather than hatching from eggs, is crucial for the evolution of cooperative behaviors, Davis said.
It "provides the opportunity for prolonged interaction between the mother and offspring, which predisposes the animal to form a family group," Davis said. "The importance of parent-offspring interaction fits with what is currently understood about evolution of family groups and cooperative behaviors in birds and mammals."
