RESUMO
Bees are the most significant pollinators of flowering plants. This partnership began ca. 120 million years ago, but the uncertainty of how and when bees spread across the planet has greatly obscured investigations of this key mutualism. We present a novel analysis of bee biogeography using extensive new genomic and fossil data to demonstrate that bees originated in Western Gondwana (Africa and South America). Bees likely originated in the Early Cretaceous, shortly before the breakup of Western Gondwana, and the early evolution of any major bee lineage is associated with either the South American or African land masses. Subsequently, bees colonized northern continents via a complex history of vicariance and dispersal. The notable early absences from large landmasses, particularly in Australia and India, have important implications for understanding the assembly of local floras and diverse modes of pollination. How bees spread around the world from their hypothesized Southern Hemisphere origin parallels the histories of numerous flowering plant clades, providing an essential step to studying the evolution of angiosperm pollination syndromes in space and time.
Assuntos
Fósseis , Magnoliopsida , Abelhas/genética , Animais , Filogenia , Genômica , Magnoliopsida/genética , América do SulRESUMO
It is widely recognized that different regions of a genome often have different evolutionary histories and that ignoring this variation when estimating phylogenies can be misleading. However, the extent to which this is also true for morphological data is still largely unknown. Discordance among morphological traits might plausibly arise due to either variable convergent selection pressures or else phenomena such as hemiplasy. Here, we investigate patterns of discordance among 282 morphological characters, which we scored for 50 bee species particularly targeting corbiculate bees, a group that includes the well-known eusocial honeybees and bumblebees. As a starting point for selecting the most meaningful partitions in the data, we grouped characters as morphological modules, highly integrated trait complexes that as a result of developmental constraints or coordinated selection we expect to share an evolutionary history and trajectory. In order to assess conflict and coherence across and within these morphological modules, we used recently developed approaches for computing Bayesian phylogenetic information allied with model comparisons using Bayes factors. We found that despite considerable conflict among morphological complexes, accounting for among-character and among-partition rate variation with individual gamma distributions, rate multipliers, and linked branch lengths can lead to coherent phylogenetic inference using morphological data. We suggest that evaluating information content and dissonance among partitions is a useful step in estimating phylogenies from morphological data, just as it is with molecular data. Furthermore, we argue that adopting emerging approaches for investigating dissonance in genomic datasets may provide new insights into the integration and evolution of anatomical complexes. [Apidae; entropy; morphological modules; phenotypic integration; phylogenetic information.].
Assuntos
Filogenia , Animais , Teorema de Bayes , Abelhas/genéticaRESUMO
The pharyngeal plate is a morphological complex with extensive anatomical variation among bees and, therefore, potential as a source of phylogenetic information. The pharyngeal plate of bees is divided into four morphologically distinct regions: sitophore, hypopharyngeal lobe, pharyngeal rods, and median oral plate. In this work we illustrate and document in detail for the first time the pharyngeal plate of 43 bee species, providing descriptions of the morphological variation and contrasting these findings with representatives of apoid wasps (Crabronidae and Sphecidae). We evaluate and discuss the potential of this structure as a rich source of morphological information in the context of bee phylogeny and any research potentially impacted by comparative morphological data. The shape of the hypopharyngeal lobe is highly variable among suprageneric taxa of bees and can be readily employed to characterise taxa at various levels. We argue that the global patterns in the variation of the pharyngeal plate can provide information for phylogenetic inference within bees and constructed and coded 10 characters that encompass the most noticeable morphological differences discussed herein.