Insights into the ecology and genetics of lichens with a cyanobacterial photobiont

Katja Fedrowitz

Insights into the ecology and genetics of lichens with a cyanobacterial photobiont

Katja Fedrowitz

Institutionen för ekologi

Publikation: Avhandling › Doktorsavhandling

3 Nedladdningar

Sammanfattning

Djupgående kunskap om de ekologiska processer som inverkar på en arts olika levnadsstadier är viktig inom naturvården. Hos lavar omfattar dessa levnadsstadier spridning, etablering och tillväxt. Syftet med denna avhandling var att öka kunskapen om epifytiska cyanolavar genom att studera olika aspekter kopplade till dessa levnadsstadier - processer som artkolonisering och artutdöende, överlevnad och vitalitet hos transplanterade lavar, samt den genetiska mångfalden av symbionter inom släktet Nephroma. Artikel I visar att lokal kolonisering samt lokala stokastiska och deterministiska utdöenden förekommer hos flera epifytiska lavar. Denna så kallade "habitatföljande" metapopulationsdynamik kunde delvis förklaras av kvaliteten och storleken på habitat, men också av rumslig konnektivitet samt förmodad samverkan mellan arter som använder samma fotobiont. Simuleringar av de undersökta arternas framtida fortlevnad visade på en utrotningsrisk på beståndsnivå för vissa ovanliga och sexuellt spridda arter, särskilt när låga trädantal och observerad trädfallsfrekvens beaktades. Skogsbruk påverkar den naturliga förekomsten av arter, och en åtgärd för att bevara den biologiska mångfalden är att lämna träd vid avverkning. Åtgärdens långsiktiga nytta för mångfalden diskuteras dock fortfarande. Resultaten från en 14 år lång transplantationsstudie med epifyten lunglav (Lobaria pulmonaria; artikel IV) ger stöd för att naturvårdsträden kan hjälpa arter att överleva, särskilt om lavarna växer på nordsidan av stammen. Eftersom lavar är symbiotiska organismer måste både mykobiont och fotobiont spridas, vilket ofta sker separat. Nybildning av lavar och selektion av ny symbiont är därför viktiga processer för lavars fortlevnad. Genom analys med genetiska markörer, visar resultaten från två artiklar (II & III) på att "valet" av symbiotiskt partner inom släktet Nephroma inte sker slumpmässigt och att selektionsmönstret varierar mellan olika träd, och mellan lokal och global nivå. Vissa symbiontföreningar är knutna till specifika geografiska områden, medan flera lavbildande svampar i Nephroma delar sekvensidentiska tRNALeu (UAA)-fotobionter på en global skala. Relativt sett högre selektivitet på lokal än global nivå visar på livsmiljöpreferenser hos vissa symbiontkombinationer, men också på en möjlig grundareffekt. Även om det återstår att förklara hur och var lavar får sina symbiotiska partners, stödjer artikel II och III idén att arter bildar fotobiontdelande grupper, vilket skulle kunna gynna deras kolonisationsförmåga.

Originalspråk	Engelska
Kvalifikation	Doktor i filosofi
Förlag	Swedish University of Agricultural Sciences
Tryckta ISBN	978-91-576-7640-5
Status	Publicerad - 2011

Nyckelord

biodiversity
boreal forests
epiphytes
finland
genotypes
habitats
lichenes
population dynamics
populus
sweden
symbionts

SLU-serie

Acta Universitatis Agriculturae Sueciae

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title = "Insights into the ecology and genetics of lichens with a cyanobacterial photobiont",

abstract = "Nature conservation requires an in-depth understanding of the ecological processes that influence species persistence in the different phases of a species life. In lichens, these phases comprise dispersal, establishment, and growth. This thesis aimed at increasing the knowledge on epiphytic cyanolichens by studying different aspects linked to these life stages, including species colonization extinction dynamics, survival and vitality of lichen transplants, and the genetic symbiont diversity in the genus Nephroma. Paper I reveals that local colonizations, stochastic, and deterministic extinctions occur in several epiphytic macrolichens. Species habitat-tracking metapopulation dynamics could partly be explained by habitat quality and size, spatial connectivity, and possibly facilitation by photobiont sharing. Simulations of species future persistence suggest stand-level extinction risk for some infrequent sexually dispersed species, especially when assuming low tree numbers and observed tree fall rates. Forestry practices influence the natural occurrence of species, and retention of trees at logging is one measure to maintain biodiversity. However, their long-term benefit for biodiversity is still discussed. The results of a 14-year transplantation study with the epiphytic Lobaria pulmonaria (paper IV) support the suitability of retention trees for species survival, especially if lichen thalli occur on north-facing sides. Lichens symbiotic nature requires the dispersal of both mycobiont and photobiont, which often occurs separately. Re-lichenization and symbiont selectivity are hence essential parts for lichen persistence. Using genetic markers, two papers (II \& III) indicate that the 'choice' of the symbiotic partners in the genus Nephroma is not random, and that selectivity patterns vary between tree, local, and global scales. Particular symbiont associations are linked to geographical areas, and several lichen-forming fungi in Nephroma share tRNALeu (UAA) sequence-identical photobionts over a global scale. Relatively higher selectivity locally compared to globally indicated habitat preferences of particular symbiont combinations, but also a possible founder effect. While it still needs to be identified how and where lichen symbionts acquire their symbiotic partners, papers II and III support the idea that species form photobiont-sharing guilds, which possibly benefits their colonization success.",

keywords = "biodiversity, boreal forests, epiphytes, finland, genotypes, habitats, lichenes, population dynamics, populus, sweden, symbionts, biodiversity, boreal forests, epiphytes, finland, genotypes, habitats, lichenes, population dynamics, populus, sweden, symbionts",

author = "Katja Fedrowitz",

year = "2011",

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N2 - Nature conservation requires an in-depth understanding of the ecological processes that influence species persistence in the different phases of a species life. In lichens, these phases comprise dispersal, establishment, and growth. This thesis aimed at increasing the knowledge on epiphytic cyanolichens by studying different aspects linked to these life stages, including species colonization extinction dynamics, survival and vitality of lichen transplants, and the genetic symbiont diversity in the genus Nephroma. Paper I reveals that local colonizations, stochastic, and deterministic extinctions occur in several epiphytic macrolichens. Species habitat-tracking metapopulation dynamics could partly be explained by habitat quality and size, spatial connectivity, and possibly facilitation by photobiont sharing. Simulations of species future persistence suggest stand-level extinction risk for some infrequent sexually dispersed species, especially when assuming low tree numbers and observed tree fall rates. Forestry practices influence the natural occurrence of species, and retention of trees at logging is one measure to maintain biodiversity. However, their long-term benefit for biodiversity is still discussed. The results of a 14-year transplantation study with the epiphytic Lobaria pulmonaria (paper IV) support the suitability of retention trees for species survival, especially if lichen thalli occur on north-facing sides. Lichens symbiotic nature requires the dispersal of both mycobiont and photobiont, which often occurs separately. Re-lichenization and symbiont selectivity are hence essential parts for lichen persistence. Using genetic markers, two papers (II & III) indicate that the 'choice' of the symbiotic partners in the genus Nephroma is not random, and that selectivity patterns vary between tree, local, and global scales. Particular symbiont associations are linked to geographical areas, and several lichen-forming fungi in Nephroma share tRNALeu (UAA) sequence-identical photobionts over a global scale. Relatively higher selectivity locally compared to globally indicated habitat preferences of particular symbiont combinations, but also a possible founder effect. While it still needs to be identified how and where lichen symbionts acquire their symbiotic partners, papers II and III support the idea that species form photobiont-sharing guilds, which possibly benefits their colonization success.

AB - Nature conservation requires an in-depth understanding of the ecological processes that influence species persistence in the different phases of a species life. In lichens, these phases comprise dispersal, establishment, and growth. This thesis aimed at increasing the knowledge on epiphytic cyanolichens by studying different aspects linked to these life stages, including species colonization extinction dynamics, survival and vitality of lichen transplants, and the genetic symbiont diversity in the genus Nephroma. Paper I reveals that local colonizations, stochastic, and deterministic extinctions occur in several epiphytic macrolichens. Species habitat-tracking metapopulation dynamics could partly be explained by habitat quality and size, spatial connectivity, and possibly facilitation by photobiont sharing. Simulations of species future persistence suggest stand-level extinction risk for some infrequent sexually dispersed species, especially when assuming low tree numbers and observed tree fall rates. Forestry practices influence the natural occurrence of species, and retention of trees at logging is one measure to maintain biodiversity. However, their long-term benefit for biodiversity is still discussed. The results of a 14-year transplantation study with the epiphytic Lobaria pulmonaria (paper IV) support the suitability of retention trees for species survival, especially if lichen thalli occur on north-facing sides. Lichens symbiotic nature requires the dispersal of both mycobiont and photobiont, which often occurs separately. Re-lichenization and symbiont selectivity are hence essential parts for lichen persistence. Using genetic markers, two papers (II & III) indicate that the 'choice' of the symbiotic partners in the genus Nephroma is not random, and that selectivity patterns vary between tree, local, and global scales. Particular symbiont associations are linked to geographical areas, and several lichen-forming fungi in Nephroma share tRNALeu (UAA) sequence-identical photobionts over a global scale. Relatively higher selectivity locally compared to globally indicated habitat preferences of particular symbiont combinations, but also a possible founder effect. While it still needs to be identified how and where lichen symbionts acquire their symbiotic partners, papers II and III support the idea that species form photobiont-sharing guilds, which possibly benefits their colonization success.

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KW - genotypes

KW - habitats

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KW - sweden

KW - symbionts

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KW - boreal forests

KW - epiphytes

KW - finland

KW - genotypes

KW - habitats

KW - lichenes

KW - population dynamics

KW - populus

KW - sweden

KW - symbionts

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