Manaus Agile tourism and culture of the AmazonDiscovery of the genetic mix of species found in the Madeira River region was the subject of an article published in a British magazine.
Studies conducted by researchers from the National Institute for Amazon Research (Inpa/MCTI) in partnership with the Federal University of Amazonas (Ufam)revealed the presence of a population of hybrid red porpoises (animals whose parents have different genetic make-up).
The species was named with the scientific name Inia boliviensis, and was found in the region of the Madeira River, which borders the states of Rondônia and the Amazonas States.
The researchers from the Laboratory of Evolution and Animal Genetics (Legal/Ufam), Waleska Gravena, Izeni Farias and Tomas Hrbek, together with the coordinator of the Laboratory of Aquatic Mammals (LMA/Inpa), Vera M. F. da Silva, and the curator of the Mammal Collection/Inpa, Maria Nazareth F. da Silva, participated in this discovery.
The research had the collaboration of the Associação Amigos do Peixe-boioi (Ampa) and funding from the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and the international funding agencies Scott Neotropical Fund and Society for Marine Mammalogy, as well as support from the Fundação de Amparo à Pesquisa do Estado do Amazonas (Fapeam).
In the opinion of Inpa researcher Vera da Silva, the confirmation of the Bolivian species and its occurrence in Brazilian jurisdictional waters is significant for Brazil. "Today we are the country that harbors the largest number of river dolphin species in the world and these species need to be protected and better studied," says the researcher.
The discovery was part of a previous study, in which the researchers sought to understand the distribution of two species of river dolphins (I. boliviensis and I. geoffrensis) in the region of the Madeira River.
The researchers realized that the Madeira River rapids did not act as a complete barrier between the species. "We first verified that I. boliviensis exceeded the rapids area and occurred until near the municipality of Borba (AM), in the lower Madeira River, almost in the region where it meets the Amazon River," explains Ufam researcher Gravena.
For this finding, the researchers analyzed only mitochondrial DNA markers, which only allows maternal inheritance to be observed. "However, with this type of marker it is not possible to determine the presence of hybrids," says Gravena.
According to the researcher, with the nuclear DNA markers, which define paternal inheritance, it was possible to verify that in the localities, between the rapids, there were animals that were genetically different from those that occurred upstream of the waterfalls, but that nevertheless belonged to the species I. boliviensis.
Gravena explains that these animals were considered differentiated management units, that is, an isolated population with differentiated alleles (small portions that make up the chromosomes and determine characteristics) from the Bolivian dolphin populations.
The researcher considers that these animals, for a long time, were restricted to these locations, crossing only among themselves, and therefore, without the exchange of genetic material with the population of porpoises in Bolivia, thus generating a differentiated genetic material. "This isolated population was unique and with the construction of the dams in the Madeira region and the flooding of the rapids, it will possibly disappear in the future," he said.
These results had already been verified in previous studies, the novelty is that the populations below the Teotônio rapids (5 kilometers from Porto Velho/RO), although they have mitochondrial DNA from the Bolivian porpoise species, have most of their nuclear markers from the other species of porpoise, I. geoffrensis; indicating the presence of hybrids.
The results of this research were recently published in an article entitled "Living between rapids: genetic structure and hybridization in botos (Cetacea: Iniidae: Inia spp.) of the Madeira River, Brazil", in the renowned journal Biological Journal of the Linnean Society, from the United Kingdom.
For researcher Vera da Silva, knowing the Amazon and its rich biodiversity can help science find new conservation strategies for these mammals, symbols of the region.
"Every time a new discovery is made, humanity gets richer and, at the same time, science realizes how much we still have to know, especially with regard to the distribution of species and biodiversity in the Amazon," she said.
