"The females are responding to cues that predict something about the future environment, but we're not sure yet exactly what that is," Lancaster said. "Orange-throated neighbors may indicate a trend in the frequency of orange-throated lizards within the population or in the overall population density."
According to Sinervo, the density of the lizard population is probably a critical factor. At high densities, the aggressive orange-throated males are so busy fighting with other lizards that they are especially vulnerable to predators. As a result, the predators are likely to focus on them, giving a survival advantage to lizards with different patterns.
After Lancaster released the lizards from her breeding experiments into the wild, she found that the ones whose mothers had tweaked their back patterns had a clear survival advantage. The highest survival rates were seen in the induced progeny types--yellow-throated lizards of both sexes with barred backs, orange-throated males with striped backs, and blue-throated females with striped backs.
"The frequencies of yellow and orange were both increasing in the wild that year, so the females exposed to orange neighbors and yellow sires in the experiments had the most fit progeny," Lancaster said. "But under different environments, maybe the progeny that weren't tweaked would have the highest fitness. If these same estradiol-induced types had the highest survival rates in all years, there would be no need for the females to respond to their social environment--they would just always give their eggs estradiol."
To understand these complex interactions more fully, the researchers plan to study the hormones and their effects in the field over several generations of lizards.
Source:University of California - Santa Cruz