A new study suggests that if we would reset everything and go back in the past, we’d still see the same species making evolution predictable.
Luke Mahler, lead author of the study and a postdoctoral researcher at the University of California, Davis, and his colleagues took the measurements of 100 out of 119 Anole Lizards from the wild and museum specimens and compared them with those that live on four neighboring islands – Puerto Rico, Jamaica, Hispaniola (the countries of Haiti and the Dominican Republic), and Cuba.
They established a remarkable degree of convergence. On each island, evolution had fashioned a set of very similar-looking lizards dwelling in similar environmental niches.
“The predictability of evolution over timescales of million years has long been debated by biologists. Predictions of the late Stephen Jay Gould like you would get an entirely different result, if you would “rewound the tape”, disagreeing on the small events like a storm that wiped out a pond or a poor period for insects could have a lopsided effect,” Mahler wrote in the press release.
Alternatively, such as the cichlid fishes of African lakes, there are still number of species in similar environment that evolve autonomously into similar-looking forms.
"It's a big question in evolutionary biology, but very hard to test. The adaptive radiations match on all four islands – with few exceptions, each species on an island has a match on the other islands," Mahler said.
Mahler and colleagues were able to create an "adaptive landscape" for the lizards by merging the body-form data with a family tree of the anoles. An adaptive landscape is an essential concept in evolutionary biology but hard to show in practice. Peaks on an adaptive landscape correspond to various combinations of features that will be supported by natural selection, whereas valleys are just the opposite. Genus with similar practice will tend to huddle on the same peak.
Each Anole lizard have diverse adaptations and forms different adaptive peak. They might be living on tree-trunks, or among twigs up in a tree, or in the grasses on the ground.
But the researchers discovered that the adaptive landscapes of all those islands mentioned are very alike and it drives convergence. Glancing back at the lizards' evolutionary record, they were able to determine when a particular peak was populated, or when a species jumped from one peak to another.
"The cool part is that we now have a way of modeling the adaptive landscape that explains this convergence," Mahler said.
The study was published in the July 19 issue of Science.
