Tropical freshwater fishes have the most diversified genetic, morphological, behavioral, and ecological traits of any continental vertebrate fauna. My research focuses on the systematics, biogeography, and evolution of teleost fishes. I reconstruct phylogenies using molecular data, estimate diversification timing with fossil calibrations, and test biogeographic hypotheses in teleost clades. My research also involves sampling, discovering, characterizing, and describing fish species.
Phylogenomics of Teleost Fishes
Colleagues and I study the evolution of teleost fish groups by utilizing ultraconserved elements (UCEs) to resolve species, genera, and family relationships.
We've used this strategy in several subgroups, including the phylogeny of the fish order Characiformes (right figure), which shows three families with significant speciation rates (Melo et al. 2022).
We assembled a UCE probeset for superorder Ostariophysi, which includes carps, tetras, catfishes and knifefishes (Faircloth et al. 2020).
Phylogenies employ fossil calibrations to estimate the timing of evolution and test macroevolutionary theories such as the origins of tropical diversity, paedomorphosis, migration, and major innovations. Why do some clades have more species? Which changes promoted speciation?
Project 1: Phylogenomics and evolution of the African fish family Alestidae (Teleostei, Characiformes). The phylogenomics and systematics of African tetras belonging to the family Alestidae are the main topics of this project. How paedomorphosis affects the diversification of alestids is one of the key issues we wish to examine. AMNH Axelrod Research Curatorship; CNPq 200159/2020-8. Col: M. Stiassny.
Project 2: Phylogenomics of Neotropical tetras of the family Characidae (Teleostei, Characiformes). The goal of this project is to reconstruct a phylogeny at the species level for the family Characidae (>1300 spp.) and to examine the subclades' biogeographic history. Col. C. Oliveira and R. Benine (UNESP), R. Ota (UFGD), F. Lima (UNICAMP), F. Carvalho (UFMS), G. Mattox (UFSCar), and others (FAPESP grant #14/26508-3).
Biogeography of Freshwater Fishes
Molecular phylogenies and parametric biogeographic approaches have lately been used to better the study of historical biogeography (ex. timetrees and BioGeoBEARs). We use these approaches to test hypotheses.
1: How did the final uplift of the Andes and the rise of the Eastern Cordillera (12–8 Ma) affect the diversification of freshwater fish during the Miocene?
2: How did the formation of the transcontinental Amazon River (10-5 Ma) facilitate gene transfer between lowland floodplain and highland shield fishes?
3: Were recent cladogenetic events in genera caused by Plio-Pleistocene river captures in the watersheds of the Brazilian Shield?
Three of our latest studies answer some of these questions (Melo et al. 2021; Santos et al. 2021; Frable et al. 2022).
Systematics and Comparative Morphology
We also investigate the systematics of Characiformes, particularly clades within Alestidae, Characidae, and Curimatidae. We have been undertaking species delimitation investigations over the past years in order to elucidate species boundaries in complicated genera such as Cyphocharax, Pygocentrus, and Characidium. We also developed projects and published findings on Curimatopsis, Gymnocorymbus, Potamorhina, Prochilodus, and Tetragonopterus.
Using genus-level CT-scan images, this research line also maps the development of characteristics and assesses systematic problems in otophysan fishes. The goal is to comprehend the ontogenetic development of juvenile and adult characters, define diagnostic features, and discover derived morphological features.
More about our fish science can be found in our peer-reviewed publications.
Phylogenomics and macroevolution of the order Characiformes
Melo et al. 2022 – Syst Biol
Biogeographic reconstruction of Curimatidae showing multiple transitions from lowlands to uplands of South America
Melo et al. 2021 – Ecol Evol
Biogeographic history of Prochilodontidae
Frable et al. 2022 – Zool Scr
Endemism areas for Curimatidae
Melo et al. 2021 – Ecol Evol
©2019 by Bruno Melo