Juliana Braga Silva

Comparative Phylogeography of the Atlantic Forest Endemic Sloth (Bradypus torquatus) and the Widespread Three-toed Sloth (Bradypus variegatus) (Bradypodidae, Xenarthra)

The comparative phylogeographic study of the maned sloth (Bradypus torquatus) and the three-toed sloth (Bradypus variegatus) was performed using a segment of mitochondrial DNA (mtDNA) control region. We examined 19 B. torquatus from two regions and 47 B. variegatus from three distant regions of Atlantic forest. This first characterization of molecular diversity indicates a great diversity (B. torquatus: h = 0.901 ± 0.039 and π = 0.012 ± 0.007; B. variegatus: h = 0.699 ± 0.039 and π = 0.010 ± 0.006) and very divergent mitochondrial lineages within each sloth species. The different sampled regions carry distinct and non-overlapping sets of mtDNA haplotypes and are genetically divergent. This phylogeographic pattern may be characteristic of sloth species. In addition, we infer that two main phylogeographic groups exist in the Atlantic forest representing a north and south distinct divergence.

Morphology, molecular phylogeny, and taxonomic inconsistencies in the study of Bradypus sloths (Pilosa: Bradypodidae)

Abstract This study focuses on morphological and molecular data analyses, misidentifications, and phylogenetic inconsistencies regarding Bradypus variegatus (the brown-throated sloth) and B. tridactylus (the pale-throated sloth). Misidentifications were recorded on 75 of 313 museum specimens of Bradypus. Almost 90% of the misidentified specimens were B. variegatus from north-central Brazil, erroneously attributed to B. tridactylus. These misidentified specimens are reported in taxonomic reviews as the southernmost records of B. tridactylus. A history of confusing nomenclature regarding sloth species exists, and these particular misidentifications could be attributable to the similarity in face and throat color between B. variegatus from north-central Brazil and B. tridactylus. The molecular phylogeny of morphologically confirmed sloth specimens exhibits 2 monophyletic lineages representing B. variegatus and B. tridactylus. The split time between these 2 lineages was estimated at 6 million years ago (mya), contradicting previous studies that estimated this divergence to be 0.4 mya. Taxonomic inconsistencies were detected when comparing the molecular phylogeny to previously published DNA sequences ascribed to B. tridactylus. Misidentification or introgression could underlie such phylogenetic incongruities. Regardless of their causes, these discrepancies lead to misstatements regarding geographic distribution, phylogeny, and taxonomy of B. variegatus and B. tridactylus.

Benthic Foraminifera as Evidence of Paleoenvironmental Changes between 9400 and 8300 cal YBP at the Juréia-Itatins Ecological Station Paleolagoon (SP, Brasil)

ABSTRACT Silva, J.B.; Duleba, W.; Sallun, A.M., and Suguio, K., 2014. Benthic foraminifera as evidence of paleoenvironmental changes between 9400 and 8300 cal YBP at the Juréia-Itatins Ecological Station paleolagoon (SP, Brasil). Many aspects of the Santos Transgression (∼21,227–20,448 to ∼5558–4558 cal YBP) remain controversial, especially before approximately 7800 cal YBP, because of the paucity of data for the Brazilian coast. In this context, benthic foraminiferal assemblages from between 9400 and 8385 cal YBP were analyzed from the S03 core collected at the Juréia-Itatins Ecological Station (JIES) with the aim of clarifying the behavior of the relative sea level along the Brazilian coast during this period. Microfaunal, taphonomical, and morphometric analyses of these microorganisms permitted recognition of eight paleoenvironmental conditions within the lagoon then existing at JIES. There were four phases of conspicuous marine contributions (9400–9338, 9072–8894, 8656–8641, and 8594–8500 cal YBP) with a climax at 8656 cal YBP, when the environment became more favorable to the growth, preservation, or both of benthic foraminifera. They were intercalated with two phases of prominent continental contributions (9338–9072 and 8500–8385 cal YBP), when there was an increase in the local hydrodynamic gradient at the S03 core sampling site. Furthermore, between 8806 and 8672 cal YBP and between 8625 and 8594 cal YBP, the benthic foraminifera are absent, most likely because of the lower pH of the mixohaline/limnetic waters present when the continental contribution was highest. These different phases of marine and continental contributions could be explained by the higher or lower inflow of seawater to the paleolagoon of the JIES and by changes of the regional rainfall. RESUMO Muitos aspectos da Transgressão Santos (∼21.227–20.448 a ∼5558–4558 anos cal AP) são ainda controvertidos, especialmente antes de aproximadamente 7800 anos cal AP, devido à diferença de detalhamento de dados na costa brasileira. Nesse contexto, foram analisadas associações de foraminíferos bentônicos no testemunho S03, coletado na Estação Ecológica Juréia-Itatins (EEJI), entre 9400 e 8385 anos cal AP, para colaborar com o conhecimento acerca do nível relativo do mar na costa brasileira sudeste durante esse período. As análises microfaunísticas, tafonômicas, e morfométricas das testas e associações desses microorganismos permitiram a determinação de oito fases distintas nas condições paleoambientais na laguna então existente na EEJI. Houve quatro fases de contribuição oceânica mais conspícua (9400–9338, 9072–8894, 8656–8641, e 8594–8500 anos cal AP) com clímax há 8656 anos cal AP, quando o ambiente se tornou mais favorável ao crescimento, à preservação, ou ambos dos foraminíferos bentônicos. Elas foram entrecortadas por duas fases de contribuição continental proeminente (9338–9072 e 8500–8385 anos cal AP), quando houve aumento do gradiente hidrodinâmico local no local de coleta do testemunho S03. Além disso, entre 8806 e 8672 anos cal AP e entre 8625 e 8594 anos cal AP, os foraminíferos bentônicos estiveram ausentes, muito provavelmente devido ao menor pH das águas oligohalinas/limnéticas presentes quando a contribuição continental à paleolagoa da EEJI foi maior. Essas diferentes contribuições podem estar vinculadas a modificações da pluviosidade regional e a diferenças no comportamento marinho durante sua fase transgressiva.