Rise Above

Complex multicellularity, in which there is cellular differentiation, multiplanar arrangement of cells, and cortical-medullary differentiation, has arisen multiple times within the Eukaryota. There is an extensive diversity of these organisms, and a deep fossil record for them. The fungi represent one of the transitions to complex multicellularity in the Eukaryota. While there are numerous differences in multicellular development across the eukaryotes, it appears that reactive oxygen species signaling is a commonality shared among them. In the process of fungal development, there is an aggregation of filaments, and this aggregation can potentially give rise to genetically heterogeneous individuals, although this is not the case in Neurospora crassa , an ascomycete, as can be shown using CFP and YFP tagged strains of N. crassa.

Within the Fungi, there is a great diversity of complex multicellular development, and a great phylogenetic diversity. The ascomycete genus Neolecta occupies an enigmatic place in fungal evolutionary history; it develops fruit bodies but is phylogenetically distant from the rest of the fruit body forming ascomycetes. It is also developmentally distinct from other fruit body forming ascomycetes; ascal characters and tissue organization also differentiate it from other ascomycetes. This implies that complex multicellularity arose independently in this genus. The genus Neolecta is monophyletic. Neolecta vitellina , found across Europe and western and eastern North America, is virtually uniform at the ITS locus across its range; it grows associated with various species in the Pinaceae; N. irregularis is restricted to spruce fir forests of eastern North America, yet is far more diverse (at the ITS locus) than N. vitellina. Across these two species, increase in genetic diversity does not translate to increase in habitat or geographic range.