Aim: We investigated the phylogenetic structure of woody Caesalpinioideae species to address whether in situ diversification or habitat shifts from other biomes explain the species diversity in the ...Cerrado. Location: Amazon and Atlantic rain forests, Cerrado and Caatinga in Brazil. Methods: We obtained occurrence data and generated a phylogenetic hypothesis for all woody Caesalpinioideae species occurring in Brazil. We calculated the net relatedness index (NRI) to measure the phylogenetic structure and performed a nodesig analysis to identify which clades contributed to phylogenetic clustering or overdispersion. We also calculated phylogenetic and taxonomic indices of beta diversity to investigate species turnover between Cerrado habitats and neighbouring biomes. Results: Species occurring in savannas and forested savannas were more related than expected by chance, i.e. phylogenetic clustering. Clades that were overabundant in savannas and forested savannas, such as Bauhinia, were poorly represented in neighbouring biomes, providing evidence of in situ diversification in some lineages. Savannas shared clades and showed lower phylogenetic than taxonomic dissimilarity from Caatinga, consistent with habitat shifts, mainly in the Cassia and Caesalpinia clades. Main conclusions: Dry, open habitats (savannas, forested savannas and Caatinga) have lineages that diversified more recently than those in forest habitats. Caesalpinioideae lineages from savannas and Caatinga are closely related, and this dissimilarity was due to both turnover (55.5%) and nestedness (44.5%). Hence, species inhabiting Caatinga and savannas are often resolved as pairs of sister species, indicating habitat shifts (especially in the Cassia and Caesalpinia clades). The higher phylogenetic diversity of species in the Caatinga than in savanna and forested savanna may indicate that lineage shifts may have occurred, mainly from the Caatinga into the savanna habitats. Phylogenetic and taxonomic dissimilarity of savannas with Amazon and Atlantic rain forests was mainly due to the turnover of lineages, with evidence of in situ diversification in some clades, especially Bauhinia.
Environmental and geographical variables are known drivers of community assembly, however their influence on phylogenetic structure and phylogenetic beta diversity of lineages within different ...bioregions is not well-understood. Using Neotropical palms as a model, we investigate how environmental and geographical variables affect the assembly of lineages into bioregions across an evolutionary time scale. We also determine lineage shifts between tropical (TRF) and non-tropical (non-TRF) forests. Our results identify that distance and area explain phylogenetic dissimilarity among bioregions. Lineages in smaller bioregions are a subset of larger bioregions and contribute significantly to the nestedness component of phylogenetic dissimilarity, here interpreted as evidence for a bioregional shift. We found a significant tendency of habitat shifts occurring preferentially between TRF and non-TRF bioregions (31 shifts) than from non-TRF to TRF (24) or from TRF to TRF (11) and non-TRF to non-TRF (9). Our results also present cases where low dissimilarity is found between TRF and non-TRF bioregions. Most bioregions showed phylogenetic clustering and larger bioregions tended to be more clustered than smaller ones, with a higher species turnover component of phylogenetic dissimilarity. However, phylogenetic structure did not differ between TRF and non-TRF bioregions and diversification rates were higher in only two lineages, Attaleinae and Bactridinae, which are widespread and overabundant in both TRF and non-TRF bioregions. Area and distance significantly affected Neotropical palm community assembly and contributed more than environmental variables. Despite palms being emblematic humid forest elements, we found multiple shifts from humid to dry bioregions, showing that palms are also important components of these environments.
Background: Cerrado comprises heterogeneous vegetation types. The flora of the vegetation types has distinct biogeographic origins and thus can be hypothesised to have distinct evolutionary imprints.
...Aims: We hypothesised that the flora of riparian forest was phylogenetically overdispersed, whereas those of more open habitats were phylogenetically clustered.
Methods: We built a species-level phylogeny for 1,663 species of trees, shrubs and palms and analysed the pattern of lineage distribution, alpha and beta phylogenetic diversity among Cerrado vegetation types (riparian forest, rocky savana, savana and seasonally dry forest - SDTF).
Results: We found a gradient of high phylogenetic diversity and overdispersion from riparian forests towards phylogenetic clustering in vegetation in more open and drier habitats. Habitat shifts were common along the evolutionary history of all families analysed and most families showed a high frequency of shifts from SDTF to riparian forest and savanna.
Conclusions: SDTF seems to be a transitional habitat in evolutionary terms, promoting lineage exchanges between stands of riparian forest and savanna. While riparian forest can be seen as a 'museum', that harbours ancient lineages, savanna and rocky savanna are a 'cradle' of derived lineages. Habitat shifts are an important underlying drive of high present-day Cerrado flora diversity.
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