Welcome to IMC 2018 International Mycological Congress
Conference Calendar

 

Displaying One Session

Symposia
Location
201 2nd Floor
Date
07/21/2018
Time
02:00 PM - 04:00 PM
Symposia

An integrative taxonomic approach to elucidate the diversity of the lichen genus Sticta (Ascomycota: Lobariaceae) in Puerto Rico

Session Number
S45
Location
201 2nd Floor, Puerto Rico Convention Center, San Juan, Puerto Rico
Date
07/21/2018
Time
02:00 PM - 04:00 PM
Presentation Number
S45-1
Authors
  • J. Mercado-Díaz
  • R. Lücking
  • B. Moncada
  • T. Widhelm
  • T. Lumbsch

Abstract

Abstract

Tropical islands harbor the highest diversity and the largest proportion of endemics per unit area in many biological groups. In understudied organisms such as lichens, however, these patterns remain poorly understood. In this work, we use integrative taxonomic approaches to elucidate the diversity and degree of endemism of the macrolichen genus Sticta in Puerto Rico. A combination of existing multi-locus sequence data from different regions and newly generated data from 64 specimens from the island was used to evaluate if current morphology-based taxonomy agree with evidence from phylogenies. Results from several molecular-based species delimitation analyses (i.e. bPTP, GMYC, BP&P) were also used for assessing species boundaries. We obtained evidence for at least 11 species of Sticta occurring in Puerto Rico. Of these, eight are potentially endemic to the island. All endemic species are nested within larger South American clades, suggesting frequent colonization from the continent. Lastly, the number of species recovered from our phylogenetic analysis broadly agree with previous morphology-based estimates, suggesting that morphology could be a good predictor of lichen species diversity in tropical islands. We discuss how factors such as constraints on diaspore dispersal in tropical forests might explain observed trends. We also suggest that the patterns observed might be generalizable and that further studies will likely reveal more cases of lichen endemism in other island systems.

Collapse
Symposia

Tasmania: an island lichen biota at the edge of the world

Session Number
S45
Location
201 2nd Floor, Puerto Rico Convention Center, San Juan, Puerto Rico
Date
07/21/2018
Time
02:00 PM - 04:00 PM
Presentation Number
S45-2
Authors
  • G. Kantvilas

Abstract

Abstract

The island of Tasmania lies in the Southern Ocean and displays strong biogeographical relationships with other former components of Gondwanaland. At the same time, it is the southern extremity of the Australian landmass, from which it is separated only occasionally in geological time. That Tasmania is isolated, serves as a refugium, especially for species of cool, moist habitats, presents a wide diversity of lichen habitats in close juxtaposition within a small area, and retains more than half of its land area in a more or less natural state, are discussed. At the same time, although supporting a rich lichen biota of c. 1300 taxa, the level of lichen endemism is relatively low (approximately 10%). The unusual or unique components of the lichen biota are attributed chiefly to the presence of certain equally unusual habitats: the island’s geology is dominated by Jurassic dolerite and Precambrian metamorphosed sediments; and the extensive expanses of natural forest may contain very large (e.g. Eucalyptus), very old (e.g. conifers) or unusual trees (e.g. Richea). In combination with a mild, oceanic climate, these factors create diverse and noteworthy microhabitats for lichens, as illustrated by the endemic genera Cameronia, Meridianelia and Siphulella, as well as by genera such as Menegazzia, Siphula s. lat., Bactrospora and Rimularia, all of which have achieved high levels of speciation in Tasmania in cool, moist habitats. However, somewhat surprisingly, more than a quarter of Tasmania’s endemic lichens occur in coastal and dry, open woodland habitats, where direct physical and ecological links to mainland Australia are strongest and most recent.

Collapse
Symposia

Lichens, molecular barcoding, and island biogeography

Session Number
S45
Location
201 2nd Floor, Puerto Rico Convention Center, San Juan, Puerto Rico
Date
07/21/2018
Time
02:00 PM - 04:00 PM
Presentation Number
S45-3
Authors
  • R. Lücking
  • B. Moncada

Abstract

Abstract

Islands are laboratories of evolution, having defined limits for dispersal and gene exchange and well-traceable geological histories. In the 19th century, Darwin and Wallace conceived the theory of evolution through natural selection, both inspired by travels including island archipelagos, such as the Galápagos Islands and the Malay Archipelago. The Galápagos Islands and particularly the Hawaiian Archipelago have become prime examples for evolutionary studies, documenting high levels of endemism and striking radiations particularly in vascular plants and animals. Notably, Darwin wrote to Hooker in 1850: "Of all places in the world I would like to see a good flora of the Sandwich Islands [Hawaii]. I would subscribe 50 pounds to any collector to go there and work at these islands." A century after Darwin's book On the Origin of Species, MacArthur and Wilson developed the theory of island biogeography, predicting species richness on islands through estimations of immigration and extinction based on island size and distance from a dispersal source. This model is complicated by factors such as island geology, climate, and topography, as well as origin, whether oceanic or continental; whereas oceanic islands go through de novo colonization from various sources, continental island start out with a fully developed ecosystem, further evolving through isolation. Lichens were traditionally considered to include widespread taxa, many cosmopolitan or pantropical; as such, the level of endemism among lichens in island ecosystems has been estimated to be low, usually not exceeding 20%, compared to around 80% for vascular plants. With the advent of molecular phylogeny and DNA barcoding, mounting evidence suggests that presumed widespread taxa in reality consist of various, often unrelated species. Here, we reassessed levels of endemism in island ecosystems using Lobariaceae, a family of conspicuous macrolichens, often confined to well-preserved habitats and including well-known examples of presumably widespread species. We focused on four taxa: the genus Lobariella, the Crocodia aurata complex, the Pseudocyphellaria crocata complex, and the Sticta filix complex. We tested the theory of island biogeography on three model systems: New Zealand (continental), Galápagos (oceanic, close to source), and Hawaii (oceanic, far from source), using species richness estimates for Lobariaceae before and after assessment with DNA barcoding. We found levels of endemism in lichens in island biota to be remarkably high, comparable to those of vascular plants, at 70–80%, with examples of local microradiations in Lobariella and the P. crocata complex. Diversification correlates with niche preferences, with tropical species, such as C. aurata, showing reduced levels compared to montane-temperate taxa, such as in the P. crocata complex. The Crocodia aurata complex exhibits an inverse effect of endemism relative to distance between Galápagos and Hawaii, explained by dispersal stochasticity. Galápagos exhibits a reduced richness of Lobariaceae relative to predictions based on the theory of island biogeography, explained by its predominantly dry climate. The example of the S. filix complex in New Zealand highlights the importance of accurate species concepts in the use of lichens as bioindicators of forest health in highly threatened island biota.

Collapse
Symposia

The Galapagos Lichen Inventory – challenging taxonomic bias to address conservation ecology for a highly diverse group of organisms

Session Number
S45
Location
201 2nd Floor, Puerto Rico Convention Center, San Juan, Puerto Rico
Date
07/21/2018
Time
02:00 PM - 04:00 PM
Presentation Number
S45-4
Authors
  • F. Bungartz

Abstract

Abstract

Ecuador is one of seventeen countries characterized by the highest species diversity world-wide. With this mega-diversity comes the obligation to preserve this heritage for humanity. One of Ecuador's most emblematic natural heritage sites are the Galapagos Islands. Known for their unique and iconic species as much as for their most famous visitor, Charles Darwin. Much isolated, the number of species in this insular province is significantly lower than on the Ecuadorian mainland. Therefore, the archipelago represents a simplified ecosystem, a 'natural laboratory of evolution', well suited to study biodiversity. A substantial part of species in the Galapagos occur nowhere else on earth, some even restricted to particular islands only. Many species are attractive, famous icons of conservation biology. Yet, despite being in the limelight of global attention, the majority of species in the archipelago remains ignored. Taxonomic bias is a significant obstacle towards developing objective conservation strategies. The biodiversity of lichenized fungi in the Galapagos is one example of a long neglected group. In 1985, Bill Weber from the University of Colorado published the first checklist with 229 species, suggesting that less than 8% were endemic. Today, results from more than ten years inventory research (2005-2018) suggest that at least 960 lichen species occur in this archipelago. Though a significant amount of new reports remains unpublished and more than 100 species still have to be described, the data suggest that at least 20% of Galapagos lichens may be endemic. Today lichenized fungi represent the most species-diverse of all groups of organisms reported from the terrestrial parts of this archipelago – a result immediately relevant to conservation. Although we better understand general diversity in this group, assessing abundance and species rarity, and characterizing habitat requirements becomes important to objectively assess, which species are threatened. Detailed habitat data collected as part of the inventory can be extremely useful for this task. Characterizing the Galapagos landscape, identifying refugia and biodiversity hot spots is also part of this challenge. A preliminary IUCN red-list assessment of endemic species indicates that many lost their original habitat and only managed to survive colonizing alternative sites within ecosystems that have drastically changed. Conservation management of these systems is typically aimed at restoring an 'original aspect' of the landscape, an objective that potentially conflicts with protecting some endemic lichen species. An example is Acantholichen galapagoensis, a basidiolichen that on Santa Cruz Island survives only on an introduced, invasive tree: Cinchona pubescens. Restoration strategies that include mechanical and chemical control of this tree need to be balanced against potential population loss of Acantholichen. Preserving population refugia of rare lichens becomes even more urgent, if climate change further amplifies environmental stress. A phenomenon most recently observed in situ was the 2016-17 El Niño, causing an exceptional drought in the Galapagos humid highlands, resulting in massive population collapse of Acantholichen. This is just one example that illustrates how restoration ecology can no longer afford to focus on iconic species only. Conservation strategies must be designed to address and eliminate taxonomic bias.

Collapse
Symposia

Islands as promoters of lichen diversity: case studies from the Peltigerales

Session Number
S45
Location
201 2nd Floor, Puerto Rico Convention Center, San Juan, Puerto Rico
Date
07/21/2018
Time
02:00 PM - 04:00 PM
Presentation Number
S45-5
Authors
  • A. Simon
  • B. Goffinet
  • E. Sérusiaux

Abstract

Abstract

Biologists have long been fascinated by island biogeography, and their understanding of the evolutionary processes associated with insular regions naturally increases over time. Because rates of speciation are generally higher on islands than on their continental counterparts, due to adaptive radiations following initial colonization, islands are usually seen as hotspots of biodiversity. Insular radiations within fungal taxa, including lichenized fungi, are poorly explored, and hence the hypothesis that symbiotic fungal species can radiate on islands or even evolve in unique, endemic, lineages remains basically untested. Here we review three studies from the Peltigerales (Lecanoromycetes, Ascomycota), that highlight how islands can act as important promoters of biodiversity of lichenized fungi. Using multilocus sequence data and model-based phylogenetic methods, along with molecular-clock dating, we wish to establish the biogeographical history of each fungal lineage considered here: Dendriscosticta (Lobariaceae) on Taiwan, Nephroma (Nephromataceae) in Macaronesia, and Sticta (Lobariaceae) on Madagascar and the Mascarenes. Our results reveal remarkable cases of insular endemism and radiation within the Peltigerales, and emphasize the importance of insular regions in fungal biogeography. We show here that these diversification events, although often substantial, may appear concealed by our inability to distinguish closely related species based on morphology.

Collapse
Symposia

How did the endemic fruticose lichens on St Helena evolve?

Session Number
S45
Location
201 2nd Floor, Puerto Rico Convention Center, San Juan, Puerto Rico
Date
07/21/2018
Time
02:00 PM - 04:00 PM
Presentation Number
S45-6
Authors
  • A. Aptroot

Abstract

Abstract

St Helena is the most isolated island on earth. It is situated halfway Africa and America, with no other islands within a radius of 1300 km. The island is very stony and home to many lichens. Almost all rock surfaces are covered with Ramalina and Roccella species. Despite the fact that St Helena was always visited by exploring expeditions, and people like Darwin, Cook and Wallace collected there, the lichens remained largely unstudied until the first lichenologist (me) visited there in 2006. The dominant fruticose lichens, and many crustose ones, turned out to be mostly endemic species. They are mostly not considered threatened, as they are locally abundant, even though the whole of St Helena is a scanty 122 km2. There are no less than four endemic species of Ramalina, one of which can attain a length of 80 cm and (probably) a considerable age. One of the Roccella species is endemic, and there furthermore is an enigmatic Roccellaceae that is described in the genus Dolichocarpus (otherwise only known from the type from Chile) and represents a fruticose Enterographa s. lat. Sequencing allowed to reconstruct the history of these enigmatic species. The four endemic Ramalina species are closely related (though very different in morphology) and have originated on St Helena, evolving from a common ancestor that arrived there from the North from Macaronesia. The endemic Roccella is a non-sorediate species that is usually represented by isolated, gnarled, and probably long-lived specimens that occurs among the abundant sorediate species that is shared with W. Africa. Here the story is slightly different: Although in many other cases sorediate species are secondary to non-sorediate ones, here the situation is the other way around. One lineage of the sorediate Roccella species lost its ability to form soralia and hence became stuck on St Helena. Just because it is stuck there, it is a separate species, as its evolutionary fate differs from the sorediate parent species. The history of the Dolichocarpus is still mysterious. It is known from two small overhanging rock faces and one of the rarest lichens on earth. In addition to the endemic fruticose lichens, there is a whole range of wider distributed fruticose species on St Helena, including e.g. Macronesian Ramalina species like R. maderensis, and palaeotropical Ramalina, Usnea and Roccella species. Now that an airport recently opened on the island, conservation measures for the endemic species are becoming urgent as tourism is rocketing.

Collapse