RESUMEN
Our knowledge of the systematics of the papilionoid legume tribe Brongniartieae has greatly benefitted from recent advances in molecular phylogenetics. The tribe was initially described to include species marked by a strongly bilabiate calyx and an embryo with a straight radicle, but recent research has placed taxa from the distantly related core Sophoreae and Millettieae within it. Despite these advances, the most species-rich genera within the Brongniartieae are still not well studied, and their morphological and biogeographical evolution remains poorly understood. Comprising 35 species, Harpalyce is one of these poorly studied genera. In this study, we present a comprehensive, multi-locus molecular phylogeny of the Brongniartieae, with an increased sampling of Harpalyce, to investigate morphological and biogeographical evolution within the group. Our results confirm the monophyly of Harpalyce and indicate that peltate glandular trichomes and a strongly bilabiate calyx with a carinal lip and three fused lobes are synapomorphies for the genus, which is internally divided into three distinct ecologically and geographically divergent lineages, corresponding to the previously recognized sections. Our biogeographical reconstructions demonstrate that Brongniartieae originated in South America during the Eocene, with subsequent pulses of diversification in South America, Mesoamerica, and Australia. Harpalyce also originated in South America during the Miocene at around 20 Ma, with almost synchronous later diversification in South America and Mexico/Mesoamerica beginning 10 Ma, but mostly during the Pliocene. Migration of Harpalyce from South to North America was accompanied by a biome and ecological shift from savanna to seasonally dry forest.
Asunto(s)
Fabaceae , Filogenia , Fabaceae/genética , Pradera , Bosques , Ecosistema , Teorema de Bayes , FilogeografíaRESUMEN
Abstract: This study investigated the current Leguminosae tree species composition in coastal forests over lithosoil soil or sandy plains in the eastern and central portion of Rio de Janeiro state, Brazil. A comparative study between the Atlantic Forest areas of the Southeast Region of Brazil was conducted to evaluate the influence of environmental variables on floristic differentiation. A total of 34 areas of the Southeast Region was selected from the NeoTropTree platform and the Leguminosae species in these areas were the basis for a similarity analysis. The Jaccard Similarity Index and the UPGMA method were applied for grouping analysis. The relationships between the Leguminosae species composition and the environmental variables were investigated via Cannonical Correspondance Analysis (CCA). The cluster analysis showed that the Leguminosae tree species group of this portion of Rio de Janeiro coastline share floristic affinity with seasonal forests, a result confirmed by CCA. This floristic differentiation is sustained by an exclusive group of Leguminosae species established over lithosoils or sandy plains, and signals that the extent of dry forests in Rio de Janeiro state might be larger than currently stated. The results justify distinct conservation actions in view of the floristic singularities of these areas.
Resumo: O presente trabalho investigou a composição de espécies arbóreas de Leguminosae presentes em florestas litorâneas, estabelecidas sobre solos litólicos ou planície arenosa, na porção Central e Leste do estado do Rio de Janeiro, Brasil. Foi realizado um estudo comparativo entre áreas de Floresta Atlântica no Sudeste brasileiro para avaliar a influência de variáveis ambientais nas diferenciações florísticas. Foram elencadas 34 áreas da Região Sudeste na plataforma NeoTropTree e tabuladas as espécies de Leguminosae dessas áreas para análise de similaridade. Foi utilizado o índice de similaridade de Jaccard e o método UPGMA para as análises de agrupamento. As relações entre a composição de espécies de Leguminosae e as variáveis ambientais foram investigadas através da análise de Correspondência Canônica (CCA). A análise de agrupamento mostrou que o conjunto de espécies de Leguminosae arbóreas dessa porção do litoral fluminense possui afinidade florística com as florestas estacionais, resultado igualmente corroborado pela CCA. Essa diferenciação florística é sustentada por um conjunto exclusivo de espécies de Leguminosae, estabelecidas nessas florestas sobre solos litólicos ou planície arenosa e sinaliza que a extensão de matas secas no estado do Rio de Janeiro pode ser maior que o apresentado atualmente. Este resultado justifica ações diferenciadas em termos de conservação, tendo em vista a singularidade florística apresentada por estas áreas.
RESUMEN
This study identified patterns of geographic distribution of 102 Leguminosae taxa within the Park, based on literature data and herbarium specimens. Among the taxa, 38 grow exclusively in Campos Rupestres (rocky fields) and 49 in the Semideciduous Forest. Eleven patterns of geographic distribution were identified, of which the West-East-Central South America pattern was the most representative, with 27 taxa. Of the 102 sampled taxa of Leguminosae, five are endemic to the Espinhaço Range and ten are included in lists of endangered species of the flora of Brazil and Minas Gerais. Information on these taxa is crucial to provide conservation practices for conserving the vegetation formations of the PEIT.
Neste estudo foram identificados os padrões de distribuição geográfica dos 102 táxons de Leguminosae ocorrentes no PEIT, com base nos dados obtidos na literatura e em material de herbário, sendo 38 exclusivos dos Campos Rupestres e 49 das Florestas Estacionais. Foram reconhecidos 11 padrões de distribuição geográfica, dos quais o padrão América do Sul Ocidental-Centro-Oriental foi o mais representativo com 27 táxons. Dos 102 táxons amostrados de Leguminosae, cinco são endêmicos da Cadeia do Espinhaço e 10 constam nas listas de espécies ameaçadas da flora brasileira ou da Flora de Minas Gerais, sendo consideradas importantes para fornecer subsídios na conservação das formações vegetacionais do PEIT.