Evolution of complex symbiotic relationships in a morphologically derived family of lichen‐forming fungi

Abstract

SummaryWe studied the evolutionary history of the Parmeliaceae (Lecanoromycetes, Ascomycota), one of the largest families of lichen-forming fungi with complex and variable morphologies, also including several lichenicolous fungi. We assembled a six-locus data set including nuclear, mitochondrial and low-copy proteincoding genes from 293 operational taxonomic units (OTUs).The lichenicolous lifestyle originated independently three times in lichenized ancestors within Parmeliaceae, and a new generic name is introduced for one of these fungi. In all cases, the independent origins occurred c. 24 million yr ago. Further, we show that the Paleocene, Eocene and Oligocene were key periods when diversification of major lineages within Parmeliaceae occurred, with subsequent radiations occurring primarily during the Oligocene and Miocene.Our phylogenetic hypothesis supports the independent origin of lichenicolous fungi associated with climatic shifts at the Oligocene-Miocene boundary. Moreover, diversification bursts at different times may be crucial factors driving the diversification of Parmeliaceae. Additionally, our study provides novel insight into evolutionary relationships in this large and diverse family of lichen-forming ascomycetes.

Shackletonia cryodesertorum (Teloschistaceae, Ascomycota), a new species from the McMurdo Dry Valleys (Antarctica) with notes on the biogeography of the genus Shackletonia

“…Other genera in our phylogeny, including the more or less geographically restricted Gondwania, Pachypeltis, and Xanthocarpia, the widely disjunct Amundsenia, Austroplaca, Cerothallia, and Xanthomendoza and the cosmopolitan Squamulea, largely diversified throughout the late Paleogene and Neogene (<34 Ma), when the global paleoclimate was characterized by changing conditions (Zachos et al 2001). These times further concur with inferred ages for the radiation of many Parmelioid genera (Amo de Paz et al 2011;Divakar et al 2015). Finally, the S. cryodesertorum-sauronii split is dated back at some point during the Oligocene and Miocene, and this timing partially overlaps with age estimates for the initial exposure of the Dry Valleys (Sudgen et al 2006).…”

Phylogeny, taxonomy and diversification events in the Caliciaceae

“…In our dating analysis based on a secondary calibration the split between the Caliciales sensu Gaya et al 2012 (the CaliciaceaePhysciaceae clade) and the Teloschistales took place in the Middle Jurassic, around 171 Mya. The age for the Physciaceae crown group in A9 is estimated at 102 Mya, and the Caliciaceae crown group at 126 Mya, thus comparable to the estimate in and estimates produced by independent studies in other lichen families (Amo de Paz et al, 2011;Beimforde et al 2014;Divakar et al 2015;Gaya et al 2015). The age of the A + B clade (main mazaediate clade) is estimated at 103 Mya (95 % HPD =80-131 Mya) with two diversification events within the group; a first event at 85 Mya giving rise to clade B, and a second event at 60 Mya giving rise to clade A.…”

“…The main diversification events of mazaediate taxa took place during the Paleocene, Eocene and Oligocene as it has been reported for taxa within the lichen family Parmeliaceae (Divakar et al 2015). The parallel, independent gains of the mazaedium in the history of the Ascomycota have already been demonstrated .…”

“…Divergence time estimation has become increasingly prominent in evolutionary biology, including in the study of several groups of Ascomycota (Amo de Paz et al, 2011;Gueidan et al 2011;Beimforde et al 2014;Divakar et al 2015;Gaya et al 2015). Information used to calibrate a phylogenetic tree is obtained from three principal sources: (1) geological events; (2) estimates from independent molecular dating studies; and (3) the fossil record, which normally is the major source of calibration points (Forest 2009).…”

Phylogenetic studies uncover a predominantly African lineage in a widely distributed lichen-forming fungal species

“…1). This is inconsistent with currently hypothesized species boundaries based on phenotypical features (Divakar and Upreti 2015;Benatti 2014). Species-level polyphylies are commonly found in Parmeliaceae and other groups of lichen-forming fungi (see reviews by Crespo and Lumbsch 2010;Lumbsch and Leavitt 2011).…”