Biogeografia e bioacústica aplicadas à Myrmotherula axillaris (Aves: Thamnophilidae)
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Data
2022-06-22
Autores
Barbosa, Renata Pasini
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Universidade Federal do Espírito Santo
Resumo
Myrmotherula axillaris luctuosa, popularly known as white-flanked-antwren, is a Thamnophilidae bird that lives in forested areas of the Atlantic Forest, being found in diverse forested environments. In the Amazon we find the subspecies albigula, axillaris, melaena, fresnayana and heterozyga. Although well documented and very easy to find birds, the distribution measurements of Myrmotherula species are usually wrong or incomplete, and each record repository ends up formulating its own distribution, resulting in different maps. There are no modelings done with Myrmotherula axillaris luctuosa. Modeling with ModleR was innovative in this study. The modeled distribution was close to what was already conceived for the subspecies, adding, however, locations in the Northeast that were not previously assumed, but that invite local surveys.
Due to the latitudinal variation and phylogeographic breaks in the Atlantic Forest, we could find noticeable phenotypic differences between populations within the same subspecies. Therefore, to investigate geographic variation in the song of Myrmotherula axillaris luctuosa in the Atlantic Forest, three possible patterns of geographic variation in the subspecies' song were tested: discrete, gradual and clinal variation patterns. The results of the analyses suggest that the song rhythm is more distinct among individuals that are more geographically distant throughout the subspecies' distribution in the Atlantic Forest and in the central part of the biome. The songs retain much acoustic similarity among themselves, leading us to believe that similarity is greater than dissimilarity between them. Even though there are no large population differences in the distribution area of Myrmotherula axillaris luctuosa, the variation probably occurs due to the adaptation of the vocalizations to the environmental conditions.
Migration of biota between the Amazon and Atlantic Forest would have occurred several times in wetter climatic periods, such as during the late Pleistocene. In the connection between the Amazon and the Atlantic Forest there would also be two distinct possibilities: the populations may form a disjunction having little acoustic variation between them, or they could be considered distinct species, because of the great acoustic distinction. In addition, the subspecies M. a. axillaris is distributed further east in the Amazon than the other Amazonian-Andean subspecies. This subspecies may have had a greater chance of interaction with the Atlantic population in the geological past. Therefore, analysis of acoustic variation of Myrmotherula axillaris in the Amazon and between the Amazon and Atlantic Forest was performed to observe the acoustic dissimilarity between the subspecies and to appreciate ambiguity about the taxonomic status for the subspecies resident in the Atlantic Forest. The vocalization of the Atlantic subspecies bears similarity to the Amazonian subspecies, especially to axillaris. The Atlantic populations may still be a subspecies of Myrmotherula axillaris, but show the tendency of speciation by allopatry.
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Suboscines , Modelagem de distribuição , Variação acústica