Name: Renata Pasini Barbosa
Type: PhD thesis
Publication date: 22/06/2022
Advisor:
Name |
Role |
|---|---|
| Sérgio Lucena Mendes | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| Albert David Ditchfield | Internal Examiner * |
| Ana Carolina Loss Rodrigues | Internal Alternate * |
| Flávia Guimarães Chaves | External Alternate * |
| Henrique Batalha Filho | External Examiner * |
| Marina Henriques Lage Duarte | External Examiner * |
| Sérgio Lucena Mendes | Advisor * |
| Yuri Luiz Reis Leite | Internal Examiner * |
Summary: 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 found
in the extent of 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. It is expected that the acoustic structure of the
song varies between the blocks formed by phylogeographic breaks, due to the historical
isolation between these populations; or that the song structure relates to a climatic or
environmental gradient, represented by latitude; or, finally, that the acoustic variation
of the song increases with distance between individuals, due to the isolation time by
distance and considering the entire extent of the species` distribution. 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, when gallery forests
crossed the Cerrado and Caatinga. In the connection between the Amazon and the
Atlantic Forest there would also be two distinct possibilities. If the populations 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
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 relative to the other Amazonian-Andean
subspecies. Therefore, it was observed whether there is a greater acoustic similarity
between the subspecies axillaris and the Atlantic subspecies than between other
Amazonian-Andean subspecies and the subspecies axillaris, and also how the presence
of the Andes among the populations may imply acoustic difference from the other
subspecies. 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
subspecies of Myrmotherula axillaris that occurs in the Atlantic region bears similarity
to the Amazonian subspecies, especially to axillaris. Between the Amazon and Atlantic
blocks, the difference in the analyzed components observed by the PCA, added to the
results observed, inclines us to affirm that the Atlantic populations of the bird, may still
be a subspecies of Myrmotherula axillaris, but show the tendency of speciation by
allopatry. Therefore, the Brazilian nomenclature and subspecies status for the Atlantic
populations should be adopted globally, as is currently done by CBRO.
