Diversity of Hoplias malabaricus (Bloch, 1794) in South America: an evolutionary and ecological approach

• Ano de defesa: 2019
• Autor(a) principal: Escobar, Nicole Estefania Ibagon
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Erithrinidae; Characiformes; Peixes de água doce; Genética Animal
• Link de acesso: https://locus.ufv.br//handle/123456789/28489

The erythrinid Hoplias malabaricus (Bloch, 1794) is a freshwater fish species widely distributed from Panama to northern Argentina, occupying most of the cis and trans-Andean hydrographic basins. This species complex includes seven karyomorphs, with 40 or 42 chromosomes, with different chromosome morphology, and sex chromosome systems. H. malabaricus also includes several molecular independent lineages. The low vagility of this species facilitates the fixation of chromosomal rearrangements and genetic differentiation in independent molecular lineages. The lack of an extensive taxonomic revision for H. malabaricus and the existence of several nominal species considered junior synonyms, make this group one of the most complex taxonomic problems of Neotropical fishes. The three papers that compose this thesis are the result of extensive sampling and three methodological approaches. We used geometric morphometric (1,942 samples), cytogenetics (32 samples), and phylogeography (74 samples) to explore the current diversity and historical biogeography of H. malabaricus in both regional and continental scales. Our geometric morphometrics analyses from the Brazilian Continental Margin and South America, comprising 1,942 samples, aimed to explore the head shape of H. malabaricus. We tested the effect of allometry, long-term evolutionary isolation, adaptation to different aquatic systems and latitude in the shape of the head of H. malabaricus. We found that all the variables have a significant response. However, the effect of allometry is the only one that shows a clear pattern of correlation. Thus, we suggested that environmental adaptation constraints morphometric differentiation between independent molecular clades that maintain distinct morphological shapes, hampering the identification of new species within the H. malabaricus complex. We also used samples from Lower Central America and Northern South America to trace the influence of the uplift of the Northern Andes in H. malabaricus diversity using cytogenetics, geometric morphometrics, and molecular phylogeny. We found a clear Miocene/Pliocenevicariance between the cis and trans-Andean and a sharp discontinuity along the Magdalena River. Upper/Middle and Lower Magdalena samples exhibit different karyomorphs with a contrasting fluorescence pattern. Lower Magdalena karyomorph is similar to the other cis-Andean populations. The shape of the head of those groups also differs significantly. Finally, the molecular data show two principal clades separating Upper/Middle Magdalena from Lower Magdalena. While Upper/Middle Magdalena groups with other trans-Andean specimens, Lower Magdalena groups with cis-Andean samples. We hypothesized that the emergence of the Eastern Cordillera of the Andes worked as a vicariant event that initially separated the two principal clades, but posterior colonization of the Lower Magdalena generated a discontinuity along the Magdalena River.