Waleska Barbosa is a PhD student at the National Institute of Amazonian Research in Manaus, Brazil. She is an ecologist interested in the evolutionary history of Amazonian birds. Here, Waleska shares her recent work on species historical demography and habitat associations along Amazonian floodplains.
Waleska Barbosa on the observation tower at the Amazonian Museum (Museu da Amazônia – MUSA)
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Institute. National Institute of Amazonian Research (INPA)
Academic life stage. PhD student
Major research themes. Biogeography; Evolutionary history of birds; Climate change
Current study system. Bird species with different habitat associations are interesting systems to investigate the history of landscapes and their environments. Life habits make some birds intrinsically related to specific vegetation types; through the study of species’ evolutionary history, we can infer the past dynamics of these natural communities. In our recent paper, we study Synallaxis albigularis and Mazaria propinqua, a sympatric and closely related pair of ovenbirds; S. albigularis occurs mostly along the floodplains on the river banks, using more diverse habitat types, while M. propinqua is specialized on early succession vegetation of river islands.
Recent JBI paper. Barbosa, W. E. S., Ferreira, M., Schultz, E. D., Luna, L. W., Laranjeiras, T. O., Aleixo, A., & Ribas, C. C. (2022). Habitat association constrains population history in two sympatric ovenbirds along Amazonian floodplains. Journal of Biogeography, 49, 1683– 1695. https://doi.org/10.1111/jbi.14266
Motivation behind this paper. This paper emerged from a larger project, in which one of the main objectives was to improve our knowledge about birds associated with flooded Amazonian environments and their biogeographic history. Wetlands represent almost 15% of the total area of Amazonia. They include permanently and seasonally flooded areas and many distinct habitat types, which are quite dynamic, controlled by the continuous processes of sedimentation and erosion driven by precipitation patterns, river discharges and local topography. During sedimentation processes, channel changes may occur, modifying existing habitats and creating new ones, resulting in isolation or contact among populations. Some bird species prefer specific habitat types within the floodplains, as it is the case of M. propinqua and S. albigularis. Thus, in our recent paper we wanted to understand how did these species (which are co-distributed in the floodplains, but exhibit environmental differences) respond to the evolution of these environments, taking into account spatial/ecological heterogeneity.
Flooded forest in Juruá River; the dark line in the trees shows the inundation height (Credits: Marina Maximiano).
Key methodologies. We started by compiling occurrence records from online databases and scientific collections to corroborate the previously described distribution patterns and habitat affinities of our study species, building a new and more complete dataset that improves our knowledge on their entire distribution areas. Then, we used genomic data (UCE- Ultraconserved Elements, SNPs, mitogenome) to understand the evolutionary history of the two species. For this, we analysed their genetic structure, phylogenetic relationships, divergence times and demographic history.
Unexpected challenges. The biggest challenge that I experienced was becoming a mother during my Master’s degree, and to have another baby during the process of reviewing this paper. Luckily, I had a lot of support from my family and the BioGeoAm study group team, as well as from my supervisor Camila Ribas and colleagues, who helped me during all stages of research and publication of this paper. They also helped me to overcome all obstacles and inspired me to continue investigating the evolution of Amazonian birds. Another challenge was learning how to process genomic data, but this is part of the learning process, and nothing is more difficult than raising a baby.
Major results. We found differences in population histories related to distinct habitat associations along Amazonian floodplains. More resilient habitats, which are inhabited by S. albigularis, may sustain local populations, generating and maintaining diversity. In contrast, M. propinqua’spreference for more ephemeral island habitats may favour local extinctions, leading to demographic change, low genetic variability, no population structure, and smaller effective population size. Our results suggest that climatic variations during the late Pleistocene and Holocene caused changes in distribution and connectivity of the different habitats types along the Amazonian floodplains, affecting gene flow and population sizes of associated bird populations.
Synallaxis albigularis in a river bank vegetation (Credits: Tomaz de Melo).
Next steps for this research. We are currently investigating the effects of historical climate changes on bird populations associated with different environments across the Amazonian sub-basins of Negro River and Xingu River. Paleoclimate studies have shown that climate variations along the Amazon basin were not homogeneous; for instance, the climate history of the western Amazon seems to be more stable than the eastern part. At present, the Amazon landscape is made up of a mosaic of different types of environments. Climate variations during the Quaternary may have affected bird populations associated with these different environments distinctly, and it is here that our current research goals lie.
If you could study any organism on Earth, what would it be? It could be any organism that helps me understand how the Amazon was in the past and how it evolved. The Amazon is a magical place. Unfortunately, it is extremely vulnerable and terribly endangered. But I love birds and I am very happy to study them. When I was a child, like any child, I loved dinosaurs and now I study their living descendants! This is so cool! And I could study anything about birds, like their plumage, vocalizations, behaviour, and so on. Birds are incredibly interesting!
Anything else to add? I am wishful to go on an expedition into the Amazon. Even though I was born and currently live there, I feel that I know too little about this incredible biome. When I read about the expeditions of the first naturalists that visited the region, like Wallace and Bates, I start to think about how much I crave this experience.