A team of American biologists has shown thatthe genetic and morphological traits of the speciesare determinedboth by natural selection and by a phenomenon called the founder effect, which occurs when species colonize new territories. The research has been published in the journal ‘Science’.
Scientists randomly collected brown lizards near Great Abaco Island, and left a pair of these lizards on each of the seven nearby islands, whose lizard populations had been depleted by a recent hurricane – the home island is covered of forests, while the other islands have low vegetation. According to previous research, lizards that live in the woods have longer hind limbs than those found in a bush habitat. This is because lizards with longer limbs can run faster, moving between high areas of forests, while those with short limbs tend to move in low vegetation.
The scientists reviewed each of the islands for the next four years to measure the length of the lizards’ limbs, and collect tissue samples for genetic analysis. All new populations survived and grew, in the first two years, before leveling off.
“We observed a founder effect one year after starting the experiment, which resulted indifferences between lizards on the seven islands“explains Kolbe.” On some of the islands there were lizards with longer limbs and, in others, with shorter limbs, but this happened at random, with respect to the vegetation of the new islands, “he points out.
Because the vegetation structure on the islands differs from that on the island of origin, scientists predicted that natural selection would lead lizards to develop shorter limbs. “In the next four years, the lizards on all the islands experienced a decrease in leg length, attributable to natural selection,” adds Kolbe, “but those who started with the longest limbs still had the longest hind limbs. than the rest “.
