Amazonian avian biogeography: Broadscale patterns, microevolutionary processes, and habitat-specific models revealed by multidisciplinary approaches

Our understanding of Amazonian biogeography is quickly increasing, catalyzed by the growing use of genomic datasets, improved knowledge of species distributions, and the accumulation of new data on the geological and climatic history of the region. The high number of species in Amazonia and their intricate patterns of geographic distribution triggered the development of many diversification hypotheses that shaped historical biogeography as a discipline. Here, we present a historical overview of avian biogeographic studies in Amazonia, their recent advances, outstanding questions, and future directions. We focus on how new approaches have led to novel understandings of the distribution patterns and diversification processes that underpin avian diversity. We show how genomic tools are being used to establish new hypotheses about the drivers of diversification and highlight the importance of recent studies of birds in previously overlooked environments, such as floodplains and open vegetation enclaves. We emphasize the importance of gene flow, species traits, and habitat affinities in studying diversification processes to fully acknowledge the complexity of Amazonian ecosystems and their history. We then discuss the current gaps in Amazonian taxonomic and biogeographic knowledge, with a focus on the issues that we believe hinder our understanding of the field. Amazonia has been facing increasing levels of forest loss due to agricultural expansion, infrastructure development, mining, climate change, and illegal activities catalyzed by weak governance. To halt biodiversity loss, it is crucial to increase our knowledge of the natural history and biogeography of Amazonian species. We suggest increasing incentives for research and training at institutions based in the region, as well as the establishment of partnerships with governments, local communities, NGOs, and international institutions to bring diverse communities together to address crucial questions. center dot Amazonia is a natural laboratory for ornithological research and has played a central role in our understanding of how species originate.center dot Biogeographic studies have been vital in efforts to describe patterns of species richness.center dot Recent studies have greatly expanded our knowledge of the effects of landscape dynamics on speciation processes.center dot Genomic datasets improved knowledge of species evolution, and the accumulation of new information on the geological and climatic history of the region is considerably changing our view on how Amazonian biodiversity was formed.center dot In this review, we present a historical overview of avian biogeographic studies in Amazonia, describe recent advances, address outstanding questions, and explore exciting new directions and future approaches. Nosso entendimento sobre biogeografia amazonica tem crescido rapidamente, catalisado pelo aumento no uso de dados genomicos, melhor conhecimento sobre a distribuicao das especies e acumulacao de novos dados sobre a historia climatica e geologica da regiao. O elevado numero de especies na Amazonia e os intricados padroes de distribuicao geografica estimularam o desenvolvimento de varias hipoteses de diversificacao que moldaram a biogeografia historica como disciplina. Neste trabalho, nos apresentamos uma visao geral dos estudos sobre a biogeografia de aves na Amazonia, seus avancos recentes, questoes pendentes e direcionamentos futuros. Nos focamos em como novas abordagens melhoraram o entendimento sobre os padroes de distribuicao e os processos de diversificacao que ancoram a diversidade de aves. Mostramos como ferramentas genomicas estao sendo utilizadas para desenvolver novas hipoteses sobre as origens da diversidade e destacamos a importancia de estudos recentes sobre aves em ambientes antes negligenciados, como as planicies alagaveis e enclaves de vegetacao aberta. Nos enfatizamos a importancia do fluxo genico, tracos especificos e afinidades com habitats no estudo de processos de diversificacao para reconhecer a complexidade dos ecossistemas amazonicos e sua historia. Discutimos entao as lacunas no conhecimento taxonomico e biogeografico na Amazonia, com foco nos problemas que acreditamos serem relevantes para disciplina. A Amazonia tem sofrido constante perda de sua cobertura florestal devido a expansao da agricultura, desenvolvimento de infraestrutura, mineracao, alteracoes climaticas e atividades ilegais. Para frear a perda de biodiversidade e crucial melhorar nosso conhecimento sobre a historia natural e biogeografia de especies amazonicas. Nos sugerimos mais incentivos para pesquisa e treinamento nas instituicoes baseadas na regiao amazonica, assim como a construcao de parcerias entre governos, comunidades locais, ONGs e instituicoes internacionais para unir estas comunidades diversas no enfrentamento de questoes cruciais.