Estimating the timescale of Lobaria diversification

Abstract

Using an ITS mutation rate as calibration reference, a three-locus timetree was generated for the genus Lobaria and its most important clades. The timetree resolved most clades with strong support and gave an estimate of the diversification time for Lobaria during the early Oligocene. A fossil impression from a 12–24 million-year-old Miocene deposit is hypothesized here to belong to an ancestral Lobaria species. Additionally, the age estimate indicates that the paleoclimate and the closing or opening of the Bering Strait played a major role in shaping the current distribution of most Lobaria species. It is hypothesized that the Bering land bridge acted as a major highway during warm-temperate climate periods, but as a barrier during Arctic climate times.

Multiple historical processes obscure phylogenetic relationships in a taxonomically difficult group (Lobariaceae, Ascomycota)

“…36 where a 50 Mya stem age was reported. Furthermore, our crown age estimates agree with other dated phylogenies generated for the genera Sticta 38 and Lobaria 37 , both of which have crown ages around 30 Mya. The timing of the rapid and reticulate Lobariaceae divergence is near the end of the Cretaceous around 70–60 Mya.…”

“…The fossil is an impression that resembles the genus Lobaria . A recent study by Cornejo and Scheidegger 37 , used a molecular clock-calibrated phylogeny of Lobaria , to estimate the age of the fossil impression and found that it fits into the time frame of Lobaria diversification and placed it near the crown of the genus. Based on that, we calibrated the 376 × 96 aa concatenated phylogeny with the impression fossil, by placing it on the branch between L .…”

“…However, another study estimated more recent divergences, with the split from Peltigera around 90 Mya and a stem age of nearly 50 Mya 36 . Furthermore, two additional studies have estimated divergence times in Lobaria and Sticta , both reporting a stem age of nearly 30 Mya for each of the genera 37,38 .…”

Three new species, new combinations and a key to known species ofLobothallia(Megasporaceae)

“…This may be connected with the Cenozoic history of the continent during the Oligocene and middle Miocene epochs, when western Asia was continuously being modified by the rise and subsequent retreat of the Tethys Sea (Popov et al 2004). These geological events, which also appear to correlate with diversification times in some other lichen genera (Leavitt et al 2012;Cornejo & Scheidegger 2018), might have played a role in the lower diversity of Lobothallia in western Asia.…”

“…These geological events, which also appear to correlate with diversification times in some other lichen genera (Leavitt et al . 2012; Cornejo & Scheidegger 2018), might have played a role in the lower diversity of Lobothallia in western Asia.…”