Fig 1.
Overview of eukaryotic phylogeny emphasising the supergroup affiliation of organisms discussed here.
Each of five recognised eukaryotic supergroups is shown as a coloured triangle to indicate that it contains a great many lineages, which are under continual diversification; groups not discussed are in gray, whilst Excavata (teal), stramenopiles, alveolates, and Rhizaria (SAR, red), and Opisthokonta (purple) are shown with icons for representative organisms. All of these groups radiated rapidly following the origin of eukaryotes and evolution of the LECA. Relationships are based on recent views of the branching order but should not be considered definitive.
Fig 2.
Conservation and divergence at the nuclear envelope.
The major protein and nucleic acid complexes responsible for control of gene expression, nucleocytoplasmic transport, and regulation of nuclear architecture are shown. The circular nucleus diagram is divided into three colourised sectors that correspond to those of Fig 1. Elements are colourised that are known to deviate from likely LECA components, whilst unknown elements are shown as open symbols. Mixed purple/green is used to designate factors that are shared between Opisthokonts and Apicomplexa. Significantly, the extensively studied Homo sapiens nucleus appears to retain much of the machinery of the LECA, whilst trypanosomes have several clear examples of divergent molecular systems that subtend nuclear functions. In Apicomplexa, the basic nuclear system appears once more to be similar to the LECA, although several aspects (for example, the composition of the nuclear pore complex and the identity of the lamina) remain unknown at this time; evidence suggests that Apicomplexa do not possess a LECA/mammalian type lamina, suggesting the presence of a novel machinery awaiting discovery.