Past, present, and future research in bipolar lichen‐forming fungi and their photobionts

Abstract

Compared to other organisms, such as vascular plants or mosses, lichen-forming fungi have a high number of species occurring in both northern and southern hemispheres but are largely absent from intermediate, tropical latitudes. For instance, ca. 160 Antarctic species also occur in polar areas or mountainous temperate regions of the northern hemisphere. Early interpretations of this particular distribution pattern were made in terms of vicariance or long-distance dispersal. However, it was not until the emergence of phylogenetics and the possibility of dating past diversifi cation and colonization events that these initial hypotheses started to be evaluated. The premise of a relatively recent colonization of the southern hemisphere by boreal lichens through long-distance dispersal has gained support in recent studies based on either the comparison of genetic affi nities (i.e., tree topology) or more robust, statistical migratory models. Still, the scarcity of such studies and a concern that taxonomic concepts for bipolar lichens are often too broad preclude the generation of sound explanations on the mechanisms and origin of such fascinating disjunct distributions.This review provides an up-to-date overview of bipolar distributions in lichen-forming fungi and their photobionts. Evidence provided by recent, molecular-based studies as well as data on the type of lichen reproduction, dispersal ability, photobiont identity and availability, and habitat preferences are brought together to discuss how and when these distributions originated and their genetic footprints. Ideas for future prospects and research are also discussed.

High levels of endemism and local differentiation in the fungal and algal symbionts of saxicolous lecideoid lichens along a latitudinal gradient in southern South America

“…The diverging patterns of dispersal in the cosmopolitan lecideoid lichen group are still under-researched. Acquiring larger datasets along the assumed distribution routes of the highest mountain ranges (Garrido-Benavent & Pérez-Ortega 2017; Hale et al . 2019), and a consequent sampling for better global coverage, will help to understand colonization events and specialization in this, so far, quite overlooked group of crustose lichens.…”

American amphitropical disjuncts: Perspectives from vascular plant analyses and prospects for future research

“…For the Special Issue: Patterns and Processes of American Amphitropical Plant Disjunctions: New Insights American amphitropical disjuncts: Perspectives from vascular plant analyses and prospects for future research 1 Michael G. Simpson 2,7 , Leigh A. Johnson 3 , Tamara Villaverde 4,5 , and C. Matt Guilliams 6 lichens ( Lewis et al, 2014a ), we only consider vascular plants in this study. See the articles by Lewis et al (2017) and Garrido-Benavent and Pérez-Ortega (2017) in this issue for updated studies on bryophytes and lichens, respectively.…”

Effects of dispersal strategy and migration history on genetic diversity and population structure of Antarctic lichens

“…Distribution patterns of bryophytes and lichens on sub‐Antarctic islands are indeed correlated with the prevailing wind patterns indicating directional long‐distance colonisation (Muñoz et al, 2004). For some lichens and bryophytes with bipolar distribution, long‐distance dispersal mediated by migratory birds has also been demonstrated (Garrido‐Benavent & Pérez‐Ortega, 2017; Lewis, Behling, et al, 2014; Lewis et al, 2014). The wide geographical ranges of many lichens and genetic similarities amongst widely separated populations have sometimes been interpreted as evidence for ongoing long‐range dispersal, even between continents (Geml et al, 2010).…”

“…Of the more than 400 reported species, 34% are endemics, indicating isolation of lichen biotas over geological timescales. The other species are mostly cosmopolitan or bipolar (Garrido‐Benavent & Pérez‐Ortega, 2017); many are found in southern South America. Global distribution patterns and molecular phylogenetic analyses suggest that some of the more widespread species evolved in the Antarctic and colonised South America and the Arctic from there (Søchting & Castello, 2012), whilst others migrated from the Northern Hemisphere southwards into Patagonia and Antarctica (Fernández‐Mendoza & Printzen, 2013).…”