Darwin's favorite bird
2001/03/01 Elhuyar Zientzia Iturria: Elhuyar aldizkaria
When Darwin proposed the theory of natural selection, he presented no real evidence that could confirm his theory, evidence that was found later. According to results recently published by a group of biologists from the University of California, it is possible that the Phylloscopus trochiloides bird, which inhabits the temperate forests of Central Asia, provides new evidence of this theory.
In fact, this little singing bird belongs to the species known as "ring species" by experts. But what does that mean? Because in a single group of organisms you can find different levels of variation, with small and large differences between the populations of the neighborhood. This bird is found throughout the territory surrounding Tibet and, according to researchers, the ring breaks in one place, in Central Siberia, where two types of birds coexist that have no genetic relationship. At the ends of the population ring there are therefore two forms that do not relate to each other. These birds are not able to know one song of the other and that capacity is very important for the choice of the couple. It can therefore be said that they act as if they were different species.
Therefore, these results confirm Darwin's beliefs. That is, that small changes in evolution can prevent the proliferation of animals of the same species, that is, they can cause alterations in the species that generate reproductive isolations.