How far is 3 Km for a butterfly?
A study of the Department of Biology on the environment and biodiversity
The question asked by the researchers of the Department of Biology allows us to shed light on biodiversity and evolutionary history of Sicilian butterflies, separated from the mainland by a short stretch of sea but genetically very different from the populations of the peninsula.
The international team coordinated by Leonardo Dapporto, researcher of the Department of Biology, has studied thousands of mitochondrial DNA sequences of 84 of the 90 butterfly species documented in Sicily to explain what are the forces and mechanisms that generate the genetic diversity of the specimens of the Mediterranean islands and, more importantly, how biodiversity is generated, maintained and lost. The study was published in the Journal of Animal Ecology.
“Although butterflies have great flight capabilities and are considered among the best migrants together with birds,” says Dapporto, “in Sicily — the largest and least isolated of the Mediterranean islands, just 3 kilometres from Calabria — almost half of the butterfly populations is genetically different from those living on the Italian peninsula and many of the genetic lineages analysed are endemic to the island. The first factor determining this phenomenon is the strong tangential wind blowing along the sea strait, the others being the characteristics of the individual species, such as the wing dimensions related to flight capacity.”
By comparing the Sicilian genetic lineages with those of the entire Palearctic region, the researchers also observed that many of the Sicilian populations do not derive directly from the butterflies living in Calabria but are closer relatives to those now occurring in very distant Palearctic regions.
According to the researchers, many populations of butterflies that currently populate Italy have replaced over time the ancestral ones that lived in distant times in our country and in other areas of the Palearctic. “Once they arrived at the strait, however, they were unable to invade Sicily,” concludes Dapporto, “and the original populations were saved as relicts, which by further differentiated and developed the amazing diversity now present on the island.”
The study is authored — in addition to the Unifi researchers of the Numerical and Experimental Zoology Lab — ZenLab — by colleagues from the Forestry and Wood Research Centre of the Council for Research in Agriculture and Economic Analysis, the Center for Biodiversity and Environment Research — University College London, the University of Turin, the Polskiej Akademii Nauk in Warsaw, the University of Oulu in Finland and the Barcelona Institute of Evolutionary Biology.