Finicky mating behavior appears to be the driving force behind the speedy speciation of the Laupala cricket, the scientists wrote in the Jan. 27 issue of Nature magazine.
Females in the Laupala genus detect tiny differences in the pulse rates of male courtship songs, which differ from one Laupala species to the next. They refuse to mate with males of other species, thus promoting the formation of new species.
The scientists say their findings shed light on the role of individual choices in the evolution of species and the growth of biodiversity.
"Animals with nervous systems and brains have preferences and can make choices," says Tamra Mendelson, an evolutionary biologist at Lehigh. "Changes in these preferences and choices appear to drive speciation.
"That raises the question: Can something seemingly so individual as a choice have macro-evolutionary consequences in terms of increasing biodiversity? If so, this affects how life on the planet looks. The more species you have, the more complex the ecology is going to be."
In down-to-earth terms:
"What turns a female cricket on? Why does she prefer one pulse rate over another? Whatever the reason, it's very important that she exercise this preference in order to keep the species distinct."
Mendelson spent three and one-half years studying the Laupala cricket with Kerry Shaw, an evolutionary biologist at the University of Maryland.
The thumbnail-sized Laupala spawns new species at the rate of 4.17 every 1 million years, or more than 10 times faster than the average speciation rate for invertebrates. This rapid evolution is contributing to an "explosion" of new cricket species, especially on Hawaii, the largest and youngest island in the Hawaiian archipelago, say the two scientists. Some 38 d