Scientists find that the highest speciation rates – species formation – of birds occurred in regions with less diversity

For more than 40 years of collection are needed, many expeditions to the most remote tropical regions of the globe, carried out by scientists from 21 museums from different countries, and genome analyzes of 1,300 bird species to unveil one of the greatest paradoxes about the origin of species in the tropics. In the Neotropical region, which extends from Mexico to Argentina, the rate of formation of new species is more accelerated in unstable environments and with more extreme climates, such as in the tropical Andes, than in more stable areas, such as the Amazon basin.

“It was believed that regions rich in bird species, such as the Amazon, were also those that had the highest speciation rates, and we saw that this is not true”, says the ornithologist and scientific director of the Zoology Museum (MZ) of USP, Luís Fábio Silveira, one of the authors of the study that has just been published in the journal Science .

According to the scientist, climatic conditions have an important influence on species diversification. “Extreme environments seem to limit wealth and diversity, but at the same time they offer opportunities for speciation, while more stable or moderate environments reduce these opportunities, but they have low extinction rates and allow the accumulation of diversity, which is why they are so rich in species ”, analyzes Silveira.

Robust phylogenies such as the one presented in this article prove that the vast majority of species in this group originated recently, between the end of the Pliocene period and the Pleistocene

The work opens up a number of other issues and suggests that conservation efforts to save tropical landscapes need to focus not only on areas such as the Amazon, which is rich in species, but also in areas with less diversity, such as the cold puna and suction cup of the Andes.

Studying genes
For 40 years, samples of 1,300 bird species were collected and deposited in natural history museums. Based on this material, scientists sequenced a total of 2,400 genes from each of these species. Robust computational analyzes allowed the team to unveil the differentiation and speciation patterns of the largest group of tropical birds, known as Passeriformes Suboscines . “Robust phylogenies such as the one presented in this article prove that the vast majority of species in this group originated recently, between the end of the Pliocene period and the Pleistocene.”

For the researcher, this article, in addition to solving an important question about neotropical biogeography, is also important for many other areas, such as taxonomy, ecology and conservation.

As a researcher and scientific director at the Zoology Museum (MZ) at USP, Silveira points out that for the past 20 years MZ has been collecting specimens that were part of the present work. “The collection of Brazilian birds in our museum is the largest and most complete in the world, with a collection that has around 118 thousand specimens”, he says. According to the scientist, the MZ teams carry out about six to seven annual expeditions to different regions of the country. “Many of these expeditions were essential for this article to have such a complete sample”, he evaluates.

In addition to researchers from MZ, the work recently published in the journal Science has collaborations by scientists linked to dozens of other natural history museums, such as the Museu Paraense Emílio Goeldi, in Belém, Pará. Many of the researchers involved in the study are from Latin America (Colombia, Brazil, Uruguay and Venezuela).

“It would be impossible to produce this work if it weren’t for the network of scientists from all over the world, and collaborative science is capable of producing results of great impact, which would never be obtained by just one or a few isolated researchers”, says Silveira.