Parallel Miocene‐dominated diversification of the lichen‐forming fungal genus Oropogon (Ascomycota: Parmeliaceae) in different continents

Abstract

Lineages with broad, intercontinental distributions can provide insight into factors that influence diversity across both temporal and geographic scales. Lichens are well known for distinct biogeographic distribution patterns, including a high number of lineages with intercontinental distributions. The lichen‐forming fungal genus Oropogon, from one of the largest families of lichen‐forming ascomycetes, Parmeliaceae, occurs in both Asia and the Neotropics. How this genus obtained this disjunct distribution is not currently known. To better understand factors shaping diversity in Oropogon, we (i) estimated the timing of diversification of major clades within this genus; (ii) inferred the historical biogeography of Oropogon; and (iii) identified factors that potentially affected the distribution and evolution of this genus. Our results suggest that the genus originally radiated during the early Miocene, with subsequent diversification events occurring during the middle Miocene. Ancestral area reconstructions for Oropogon suggest that the genus was either widespread with subsequent separate diversification in Asia and America or originated in the New World (America), with subsequent migration to Asia. We hypothesize that the Mi‐1 glaciation impacted diversification of Oropogon species in Asia, and that the rise of major mountain ranges, such as the Himalayas, helped promote diversification in Oropogon in the Old World.

New insights into the earlier evolutionary history of epiphytic macrolichens

“…Extant lichenized clades that are largely epiphytic have been dated back to as far as the early Jurassic, such as microlichens in the Graphidaceae, Pyrenulaceae, and Trypetheliaceae ( Lücking et al, 2013; Beimforde et al, 2014; Kraichak et al, 2018; Nelsen et al, 2019, 2020 ). However, the oldest extant macrolichen clade, Umbilicaria , is almost exclusively rock-dwelling (saxicolous), and while extant macrolichen vary greatly in substrate choice ( Belnap et al, 2001; Brodo et al, 2001; Nash, 2008 ), extant epiphytic macrolichen clades are consistently younger than the K–Pg boundary and only since then have evolved to form the conspicuous elements of terrestrial woody ecosystems they are today ( Ahti et al, 1993; Esslinger,1985; Goward and McCune, 2007; McCune et al, 2000; Spribille and Muggia, 2013; Wei et al, 2017 ). The fossil record and molecular clock studies indicate that gymnosperms diverged around 315 Mya ( Crisp and Cook, 2011 ; Nie et al, 2020 ), while conifers originated approximately 300 Mya and diversified between 190–160 Mya in the Early to Middle Jurassic ( Leslie et al, 2018 ) into the various families recognized today.…”

“…greatly in substrate choice (Belnap et al, 2001;Brodo et al, 2001;Nash, 2008), extant epiphytic macrolichen clades are consistently younger than the K-Pg boundary and only since then have evolved to form the conspicuous elements of terrestrial woody ecosystems they are today (Ahti et al, 1993;Esslinger,1985;Goward and McCune, 2007;McCune et al, 2000;Spribille and Muggia, 2013;Wei et al, 2017). The fossil record and molecular clock studies indicate that gymnosperms diverged around 315 Mya (Crisp and Cook, 2011;Nie et al, 2020), while conifers originated approximately 300 Mya and diversified between 190-160 Mya in the Early to Middle Jurassic (Leslie et al, 2018) into the various families recognized today.…”

Parallel Miocene dispersal events explain the cosmopolitan distribution of the Hypogymnioid lichens

“…The fossil record of Hypogymnioid lichens is relatively poor (Kaasalainen, Schmidt, & Rikkinen, ; Taylor, Krings, & Taylor, ). Therefore, we used molecular sequence data from extant taxa to infer the historical biogeography of the Hypogymnioid clade, which have been widely used to better understand biogeographic patterns in other clades of Parmeliaceae (Divakar et al., ; Leavitt et al., ; Wei et al., ).…”

“…Analyses were performed using four independent MCMC runs of 50 million generations, with a sampling tree every 1,000 generations followed Wei et al. () and are detailed in Appendix S2.…”

“…More and more biogeographical studies attempting to understand factors influencing the widely disparate distributional patterns of lichen‐forming fungi have occurred in recent years (see e.g. Leavitt, Esslinger, Divakar, & Lumbsch, ; Núñez‐Zapata et al., ; Wei et al., ).…”