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TRANSCRIPT
08/11/2016
Wolseley, Lichens Autumn, 2016 1
Lichens – life in extreme conditions
British Lichen Society
Pat Wolseley
Rough outline of talk
• Where to find lichens• What is a lichen, mainly about ascomycetes• Fungal reproduction, photobiont and thallus
structure• New insights, molecular and others• Lichen chemistry• New organisms and techniques• Adaptations to a changing environment
A rocky shore – tolerant of salt water, high temperatures and UV, and high nitrogen from sea birds.
Skomer island in Pembrokeshire
The grey lichen below is Ramalina siliquosa and the yellow lichen is Xanthoria parietina – abundant on bird cliffs and also common inland on farm rooves.
Where do we find lichens?
In a desert -
Crustose lichens growing on rocks in the Sierra Nevada
Bright colours produced by fungus as sunscreen to protect algal partner against heat and UV.
High altitudes and polar regions
e.g. Britain at the end of the last ice-age c. 10,000 years ago
Cold and frequently covered in snow and ice. High UV when exposed.
Hot and wet in a Tropical Rainforest in Thailand
Conditions similar to Britain in the tertiary period 70 million years ago.
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A tropical forest or a wet day in a Celtic rain forest?Lichens on rocks as well as trees c.400 species in 36 ha!
In our towns and gardensOn our garden trees where moisture, light and nutrients are plentiful.
On a roof which may be hot and dry or soaking wet!
On pavements – the ‘chewing gum’ lichen prefers the concrete to the brick picture by Alan Silverside
What is a Lichen?
• Fungus (mycobiont) and alga or cyanobacteria (photobiont)
• Symbiotic or Parasitic?• Photobiont: provides food
but does not reproduce sexually in a lichen
• Mycobiont: protection and body shape, sexual reproduction by spores
• Successful relationship: ‘extremophiles’
Schwendener in 1867 looked down a microscope and suggested that lichens are dual organisms with algae and cyanobacteria
a community of two or more organisms
20% of all known fungi lichenized mainly in two orders Ascomycetes and Basidiomycetes
Basidiomycetes
gill and bracket fungi with spores borne on a basidium
Bracket fungi
Tropical basidiomycete
Dictyonema sp.
Gill fungi lichenised
Omphalina umbelliferae
Orange peel cup fungus
Coenogonium luteum - crustose lichen with yellow fruiting bodies
Lobaria pulmonaria tree lungwort with brown fruiting bodies
Ascomycete fruiting bodies
Ascomycetes –spore production
apothecium
hymenium
hypothecium
Lecanorine apothecia –exciple same as thallus
Lecideine apothecia – exciple unlike thallus
Spores produced in an ascus in an apothecium
Lecidella elaeochroma
Physcia aipolia
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Apothecia come in many shapes and sizes
Arthonia radiata –irregular lirellae
Graphis scripta
Star-like fruiting bodies without raised margins
Graphidaceae with raised lip-like margins
Pyrenula macrospora
Pyrenula nitidella
Spores in a carbonised perithecium spores released through a pore-like ostiole
Pyrenulaceae
Lichens – growth form & shape
branched & shrub-like, attached at the base only
leaf-like lobes, closely or loosely attached to the
substrate from the lower surface
with the entire lower surface closely attached
to the substrate
crustosefoliosefruticose
Which photobionts found in lichens?Green single-celled algae Trebouxia rarely found free-living.
Yellowish Trentepohlia filamentous algae -free-living in warm conditions.
Blue-green cyanobacteriaNostoc fixes nitrogen.
Unlike this free-living green alga Desmococcuscommon everywhere.
Photobiont
Trebouxia a green single celled chlorococcoid alga
Lichen orders
Peltigerales
Thallus grey when wet
Lecanorales, Pertusariales
Thallus green when wet
Arthoniales, Graphidales
Thallus yellow when scratched
Nostoc and other cyanobacteria that fix nitrogen
Relationship of phycobionts to lichen orders
Trentepohlia a yellow filamentous chlorococcoid alga (not always appearing filamentous in lichens)
Thallus structure
cortex
medulla
lower cortex
homoiomerousheteromerous
filamentous
Lower cortex
cyphella
pseudocyphella
photobiont
photobiont
Parmotrema perlatum heteromerous with dark lower surface
Leptogium cyanescens –homiomerous with cyanobacterial photobiont
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Molecular insights into Stictis species
Stictis - a genus of saprotrophic fungi growing on decorticated bark of poplar twig
Conotrema –lichenised fungus growing on old bark of poplar
Fruitbody of Conotrema showing lichenised thallus
Molecular cladogram showing that 3 species of Conotrema & Stictis have optional lifestyles
Result – Conotrema spp. included in Stictis (the older name)
Wedin, M. et al. 2004: Saprotrophy and lichenization as options for the same fungal species on different substrata: enzironmental plasticity and fungal lifestyles in the Stictis-Conotrema complex. - New Phytologist164: 459-465.
Is lichenisation optional for a fungus?
Same fungus given two names with different photobionts
James, PW/ Henssen, A 1976: The morphological and taxonomic significance of cephalodia. - In: D. H. Brown, D. L. Hawksworth & R. H. Bailey (eds.): Lichenology: Progress and Problems. Academic Press, London, pp. 27-77.
Sticta dufourii sens lat –cyanobacterial morph
Sticta canariensis - green morph
Adaptation to different photobionts
Two or more photobiontsCephalodia - internal
Or external
Same fungus Lobaria amplissima with cyanobacterial photobiont and thallus changes morphology from foliose to fruticose.
trebouxia
cyanobacteria
Cephalodia in Peltigera sp
How does a symbiotic organism reproduce itself?A germinating fungal spore must find the right algal partner?
The alternative - distribute both partners together as propagules
Granular particles of a mixture of algae and fungus called soredia
Possibilities of a propagule?
Belinchón, R./ Yahr, R./ Ellis, C.J. 2015: Interactions among species with contrasting dispersal modes explain distributions for epiphytic lichens. - Ecography 38(8): 762–768.
Possibilities of a propagule?• Propagules growing into independent lichen thalli• Many propagules from different thalli growing together and producing one
organism• Propagules from one organism raided by another for the photobiont
A Scottish survival story – Nephroma laevigatum and N. parile have the same cyanobacterial photobiont
Nephroma laevigatum with spore producing apothecia and no soredia
Nephroma parile with soredia and no apothecia
Result: co-dependence of the more sensitive N. laevigatum with asexual and more frequent N.parile.
Lichen ChemistrySecondary compounds formed by the mycobiont
situated in cortex or medulla
protection against extreme UV, high moisture and drought, predation, pollution .
Xanthoria parietina – anthraquinones (KOH + purple) in medullaSpot tests for
compoundsFirst used as a taxonomic tool by Nylander in 1850’s
Standard tests:•10% KOH (K)•Thin Bleach (C)• p-phenylenediamine (P)
Parmelinella wallichiana
KOH + red
Salazinic acid
Rikkinen, J 1995: What's behind the pretty colours? A study on the photobiology of lichens. - Bryobrothera 4: 1-239.
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Location of secondary metabolites
SEM Photograph by R. Honegger
As crystals around the hyphae in the medulla and/or the cortexOn the spore bearing tissue
More than 700 compounds identified in lichenssource of pharmaceutically valuable compounds
Detection of secondary compounds Thin layer chromatography (TLC) in 2 different solvents
Control atranorin
norstictic
Usnic acid
Fumarprotocetraric acid
Results of TLC of sterile crust species of Lepraria
Discovery of another organism in lichens in 2015
In the USA two Bryoria species with different chemistry but no other morphological differences were discovered to have live yeast cells in one species C & D and not in the other A & B
http://www.theatlantic.com/science/archive/2016/07/how-a-guy-from-a-montana-trailer-park-upturned-150-years-of-biology/491702/
See Spribille story in:
Fluorescent cell imaging of fungal elements in an SEM of a thallus filament (A) of Bryoria capillarisB - showing yeasts (green), lichen hyphae (blue) and trebouxia photobiont (red)C- detail of yeast cells
Location of components in a Bryoria thallus
Since the first discovery Spribille & team have shown that yeasts are widespread in most lichens!
morphology
ascus structure
thallus structure
chemistry
DNA structure
Barcoding a community?
naked eye and hand lens
microscope
Molecular analysis
microscope, SEM
TLC, HPTLC, HPLC
Taxonomic tools
Acharius 1790’s
Culberson 1960’s - Elix
Hale – 1970s Vobis
Hafellner 1984
Blum 1986 -present
Adaptations to a changing environment
• Disappearing landscapes: veteran trees and woodpasture along with their indicator species.
• Climate change - are Mediterranean species coming in and sensitive species disappearing?
• Urban and agricultural pollution; switch from acid rain to Nitrogen. Look at our cities lichens everywhere but which ones?
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Lobaria pulmonaria – tree lungwort
• air pollution sensitive
• Large foliose indicator of bryo-lichen community
Indicators of ecological continuity
Lichens as indicators of environmental continuity in Somerset
Aerial view of Horner woods NNR. 358 lichens recorded including 45/70 indicators of environmental continuity.
Lungwort - Lobaria pulmonaria the classic indicator of ancient woodlands.
Lobaria pulmonaria in Horner 1970 to 2012Francis Rose surveys in 1974 to 1984 stated Lobaria seen on c. 300 trees
Lobaria pulmonaria in upper Horner valleys in 2012 – 44 trees with Lobaria recorded (Sanderson 2012)
Lobaria pulmonaria in Horner valleys in 1988 on 166 trees – on 62 trees in blue square (Wolseley & O’Dare Exmoor woodland survey
Lobaria in a changing Somerset landscape
1886 ordnance survey of woodlands and parkland at Nettlecombe
Lobaria pulmonaria in 2005 on veteran trees several hundred years old grown in very different conditions
Disjunct distributions – UK and tropics?
Pseudocyphellaria crocata – gold spot lichen rare on ash trees in Barle valley
Kinabalu mountain in BorneoThe same lichen is abundant on trees at c. 4,000 m in Borneo
Usnea florida recorded as common on trunks and branches of trees in 1930 (Watson)
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Climate change - increasing average temp and longer dry periods
Mediterranean species increasing
Flavoparmelia soredians
1960-1999 2000 onwards
Nephroma arcticum in Norway is a conspicuous leafy species with large brown fruits.
Cool temperate species disappearing
N. arcticum now a scruffy infertile species rare in alpine heaths in the Cairngorms
Conservation project to protect it from grazers with wire baskets.
The urban landscape
• Decreasing SO2, increasing Nitrogen mainly as NO2• Increasing dust and particulates - increased bark pH• Increasing warmth from different sources
The rural landscape
• Increasing N as ammonia NH3• Increasing arable and dust
N-tolerant (nitrophytes)N-sensitive ( nitrophobes)
• Involve public in England in collecting data on common easy to ID species that can be used as indicators of air quality.
• Select 3 N-tolerant and 3-N sensitive, & 3 intermediate taxa.
• Produce fold out and workbook
• Survey data entered onlinehttp://www.opalexplorenature.org/
• Pollution index using total N sensitive species minus total N tolerant species using cover value of 1-3
Usnea spp.
Evernia prunastri
Hypogymnia spp.
Xanthoria parietina
Xanthoria polycarpa
Physcia tenella /P.adscendens
Lottery funded OPAL methodology
N pollution score across England
-23 to -54 N-tolerant species dominant – mainly in rural areas with intensive agriculture
0 to-22 N-tolerant species frequent – in urban areas throughout
1 to 22 N-sensitive lichens present N-tolerant spp. may be present –widely distributed in rural and urban areas
23 to54 N-sensitive lichens dominant – only found in unpolluted sites or where ID mistaken!
Note very few surveys undertaken in nature reserves.
abundance x diversity weighted indicator spp. score - data from all trees