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Lichen

About: Lichen is a research topic. Over the lifetime, 7015 publications have been published within this topic receiving 158026 citations. The topic is also known as: lichens.


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Journal ArticleDOI
09 Jun 1995-Science
TL;DR: A highly resolved parsimony analysis of small subunit ribosomal DNA (SSU rDNA) sequences suggests at least five independent origins of the lichen habit in disparate groups of Ascomycete and Basidiomycetes.
Abstract: Phylogenetic hypotheses provide a context for examining the evolution of heterotrophic lifestyles. The lichen lifestyle, which is the symbiotic association of fungi with algae, is found in various representatives of Dicaryomycotina, both Ascomycetes and Basidiomycetes. A highly resolved parsimony analysis of small subunit ribosomal DNA (SSU rDNA) sequences suggests at least five independent origins of the lichen habit in disparate groups of Ascomycetes and Basidiomycetes. Because lichen associations arose from parasitic, mycorrhizal, or free-living saprobic fungi, neither mutualism nor parasitism should be construed as endpoints in symbiont evolution.

334 citations

Journal ArticleDOI
TL;DR: The single most important action promoting the accumulation of old-growth-associated epiphytes will be the retention of propagule sources in and near all cutting units.
Abstract: Epiphytic lichen biomass accumulates slowly in forest canopies. We eval- uated three alternative hypotheses for the slow accumulation of epiphytic lichens, using two experiments in tree crowns from 15 Douglas-fir forest stands representing three age classes: old growth, young, and recent clearcuts. The first experiment evaluated whether forest age, bark roughness, or dispersal rate limits the establishment of the dominant old- growth-associated lichen, Lobaria oregana. Surface-sterilized branches with either rough or smooth bark were repeatedly inoculated with propagules and compared 1 yr after the last inoculation. Dispersal affected rates of establishment: inoculated branches had 27X more newly established thalli than controls. Establishment on smooth bark was highest in clearcuts, intermediate in young forests, and lowest in old growth. There was as much or more establishment of sown propagules on smooth-barked branches as on rough-barked branches in all age classes. In the second, transplant-performance experiment, Lobaria oregana grew as rapidly in young forests as in old growth but lost biomass and suffered more injuries in clearcuts. In contrast, L. pulmonaria performed at least as well in clearcuts as in young forests and old growth. Poor dispersal and establishment limit the development of L. oregana populations in Douglas-fir forests. Particular substrates and microenviron- ments found only in old growth are not essential for Lobaria establishment and growth. Maximizing the number and dispersion of remnant trees in cutting units should maximize the rate of accumulation of L. oregana biomass in the regenerating forest. The single most important action promoting the accumulation of old-growth-associated epiphytes will be the retention of propagule sources in and near all cutting units.

324 citations

Journal ArticleDOI
TL;DR: Use of phylogenetic analyses that incorporate these newly recovered fungi and ancestral state reconstructions that take into account phylogenetic uncertainty provide the basis for estimating trophic transition networks in the Ascomycota and provide a first set of hypotheses regarding the evolution of symbiotrophy and saprotrophy in the most species-rich fungal phylum.
Abstract: Fungi associated with photosynthetic organisms are major determinants of terrestrial biomass, nutrient cycling, and ecosystem productivity from the poles to the equator. Whereas most fungi are known because of their fruit bodies (e.g., saprotrophs), symptoms (e.g., pathogens), or emergent properties as symbionts (e.g., lichens), the majority of fungal diversity is thought to occur among species that rarely manifest their presence with visual cues on their substrate (e.g., the apparently hyperdiverse fungal endophytes associated with foliage of plants). Fungal endophytes are ubiquitous among all lineages of land plants and live within overtly healthy tissues without causing disease, but the evolutionary origins of these highly diverse symbionts have not been explored. Here, we show that a key to understanding both the evolution of endophytism and the diversification of the most species-rich phylum of Fungi (Ascomycota) lies in endophyte-like fungi that can be isolated from the interior of apparently healthy lichens. These "endolichenic" fungi are distinct from lichen my- cobionts or any other previously recognized fungal associates of lichens, represent the same major lineages of Ascomycota as do endophytes, largely parallel the high diversity of endophytes from the arctic to the tropics, and preferentially associate with green algal photobionts in lichen thalli. Using phylogenetic analyses that incorporate these newly recovered fungi and ancestral state reconstructions that take into account phylogenetic uncertainty, we show that endolichenism is an incubator for the evolution of endophytism. In turn, endophytism is evolutionarily transient, with endophytic lineages frequently transitioning to and from pathogenicity. Although symbiotrophic lineages frequently give rise to free-living saprotrophs, reversions to symbiosis are rare. Together, these results provide the basis for estimating trophic transition networks in the Ascomycota and provide a first set of hypotheses regarding the evolution of symbiotrophy and saprotrophy in the most species-rich fungal phylum. (Ancestral state reconstruction; Ascomycota; Bayesian analysis; endolichenic fungi; fungal endophytes; lichens; pathogens; phylogeny; saprotrophy; symbiotrophy; trophic transition network.)

320 citations

Book
01 Jun 1975

316 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023369
2022815
2021188
2020231
2019227
2018231