Scientists discover evolutionary history of the Amazon’s most common group of birds

Researchers from Brazil have almost completed the phylogeny of birds known as antbirds. The findings of the study were presented at an event in England.

By Elton Alisson, in Chicheley, England

Agência FAPESP – The evolutionary history of a highly diverse group of birds comprising more than 230 species and representing approximately 10% of the Brazilian avifauna is close to being released.

Researchers at the Zoology Museum of the University of São Paulo (USP) are completing the phylogeny – the study of evolutionary relationships between species – of birds of the family Thamnophilidae, known popularly in Brazil as antbirds.

Developed within the scope of the research project entitled “Systematics, biogeography and phenotypic evolution of the Thamnophilini (Thamnophilidae birds): a massive parallel DNA sequencing approach,” funded by FAPESP, several of the study’s findings were presented on February 26, 2014; the final day of the UK-Brazil-Chile Frontiers of Science conference.

The United Kingdom’s Royal Society, FAPESP and the Brazilian and Chilean Academies of Sciences organized the event in Chicheley, southern England, to promote scientific and interdisciplinary collaboration among young Brazilian, Chilean and British researchers in fields on the frontiers of knowledge.

“We’re completing the first phylogeny of the family Thamnophilidae. We already have samples from 99% of the species, and now we have a complete hypothesis about the evolutionary history of this group of birds,” Gustavo Adolfo Bravo Mora, a researcher at the USP Zoology Museum, told Agência FAPESP.

According to the researcher, the antbirds represent the most common group of birds in Amazonia. The antbirds also have the greatest species diversity of the family; approximately 45 different antbird species may occur in a single location.

In addition to populating the Amazon rainforest, the group is also present in other Brazilian biomes, such as the Atlantic Forest (which has regions with up to 12 endemic (native) species), the Caatinga and, to a lesser extent, the Cerrado.

One common characteristic of these birds, according to Mora, is their small size: on average, they measure 25-30 centimeters (cm). The smallest antbird species measures 3.5 cm and lives in the tree crowns of the Amazon rainforest. The largest, the Giant Antshrike (Batara cinerea), measures just over 30 cm and occurs most commonly in the Atlantic Forest. “There is quite a large amount of variation between the species,” said Mora.

Another characteristic of these birds is that they feed primarily on insects; thus, they are given the nickname ‘antbird’. In addition, they sing all the time. “When you go into an area of the Amazon rainforest, it’s hard to see them, but you can hear their songs,” said Mora.

Researchers use recordings of the birds’ songs and quantifications of the variations in the songs with the aid of special software to understand patterns of evolution using the group’s phylogeny based on genetic data.

The recorded songs are supplemented by measurements of the beak, plumage, tail and leg of the specimens to provide estimates of the differences between the birds and by sequencing of molecular data obtained from tissue samples of specimens in the collection of the USP Zoology Museum and other museums, primarily in Brazil and the United States.

The researchers are also using geographic information systems to conduct distribution analyses and determine the number of environments in which these birds may be present.

“Based on this set of geographic data, we are able to estimate which species prefer areas with more precipitation or lower temperatures, for example,” Mora explained. “The idea is to combine these various types of data to try to understand how the diversity of bird species has evolved in the family Thamnophilidae.”

Understanding biodiversity

The researchers are currently analyzing the collected data. According to Mora, the results of the analyses will enable them to understand and quantify the biodiversity of this group of birds. It will be possible to examine, for example, whether one particular type of bird morphology evolved more quickly than another, or whether the animals that live in drier areas of the forest evolve more quickly than those that live in wetter areas.

In addition, the collected information can be used in biodiversity conservation studies of this group of birds. “For now, just the number of species in a particular area or those threatened is being used in conservation studies,” Mora said.

“However, there is a whole set of other information about evolution, distribution and morphology, such as that generated for the Thamnophilidae, that could be used to make more objective conservation decisions,” he indicated.

Completion of the phylogeny of the family Thamnophilidae is also expected to facilitate the identification of new species belonging to the group, Mora indicated. During the project, 15 new species of birds of the Amazon region were discovered in early 2013.

The researcher said that four of the 15 species discovered were antbirds, which he described. “There are five more new species that we are describing now within the family Thamnophilidae,” he said.

Importance of data collection

During his presentation in Chicheley, Mora called attention to the importance of natural history museums as sources of information for the evolutionary study of species. In his opinion, despite their clear scientific importance, these institutions are under-utilized by evolutionary studies.

“Natural history museums have enormous species databases and are key players in biodiversity research because they allow us to look at the past while we focus on the future,” he said.

With new DNA sequencing technologies, it is possible to rapidly analyze the genetic characteristics of hundreds of specimens that constitute the collections to build the phylogeny of several groups.

Furthermore, new mobile communication technologies, such as cell phones with cameras and recorders and Internet access, allow ordinary citizens to contribute more actively to studies of biodiversity.

The assessment was made by Nick Isaac, researcher at the Center for Biological Records of the Center for Ecology and Hydrology of the United Kingdom. “Smartphones have become very useful tools for ‘citizen scientists’ to record animal sounds and images, which, in turn, are very useful for populating scientific databases on biodiversity,” said the researcher, who spoke after Mora.

According to Isaac, ordinary citizens in the United Kingdom have been contributing their observations of wildlife for more than 200 years. “This has provided us with a vast amount of data that we can use to try to understand changes in the biodiversity of several groups of species,” he said.

The problem is that many of these records contain “noise”, such as the lack of data regarding the date and site of the collection – important information when studying the way species behave.

“The modeling we are developing can help us recover relevant information that is often ‘erased/deleted’ in the midst of the noise,” he said.