To the uninitiated, they are practically identical, and they also have very similar geographic distributions. We refer to two butterflies of the genus Pyrgus that, despite all their similarities, hide very different evolutionary histories.
These two species occupy small nuclei in the Iberian Peninsula that are separated from other populations of their peers by more than a thousand kilometers. How did they get here? A study published in the Journal of Biogeography has used climatic and molecular data to model the distribution of both species and determine the locations that were suitable for them in the past. The models show that while Pyrgus sidae would have diverged from the main nucleus, located in eastern Europe, 270,000 years ago, its relative Pyrgus cinarae would have separated a million years ago coinciding with the first ice ages.
Pyrgus cinarae is a species that needs to live at a certain altitude (between 1200 and 1500 meters) so that during the ice ages it would be isolated in these locations. In the interglacial periods, it would not find other suitable habitats for it, so it would remain confined in these areas without the possibility of expanding. On the contrary, Pyrgus sidae is less demanding in its requirements, and the interglacial periods would have been an opportunity to occupy new territories.
The importance of these types of studies is that they allow us to know the threats under which the species are currently found. For example, although they appear to be very similar, given the prospects of climate change, Pyrgus cinarae is much more threatened than its relative since it has less chance of migration to new territories.
