Genetic diversity and geneflow between Arctic and Antarctic populations of the lichen Cetraria aculeata along the Andes and the Rocky Mountains
Lichens are present in most land ecosystems, frequently occupying habitats where few other organisms are able to survive. Their contribution to the ecosystems in terms of biomass and ground cover increases with latitude and altitude, being, together with bryophytes, the most conspicuous component of...
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| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
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2014
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| Online Access: | http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/32989 https://nbn-resolving.org/urn:nbn:de:hebis:30:3-329897 http://publikationen.ub.uni-frankfurt.de/files/32989/Fernando_Fernandez_Mendoza.pdf |
| Summary: | Lichens are present in most land ecosystems, frequently occupying habitats where few other organisms are able to survive. Their contribution to the ecosystems in terms of biomass and ground cover increases with latitude and altitude, being, together with bryophytes, the most conspicuous component of alpine and polar landscapes. Whereas some polar lichens have reduced distributions and are restricted to high latitudes, most of them have very wide distributional ranges, which oven extend over several climatic regions. Many of them are common to Polar Regions of both hemispheres, a distributional pattern that has been denominated as bipolar, antitropical or amphitropical. Bipolar distributions are not exclusive to lichens, but common to many groups of organisms. The bipolar element in lichens is exceptional as it includes a large number of species, while in most other land organisms it includes genera or families but very seldom species. In this dissertation I use the bipolar lichen Cetraria aculeata to give a first insight into the phylogeography of this biogeographic element in lichens. I discuss how and when the disjunct distribution of C. aculeata came to be, and try to partial out the roles that historical and ecological processes played in shaping its distribution. Sampling was designed to cover a wide geographic extension. The main e"ort was made to collect in boreal, temperate and tropical mountain ranges in North and South America, as well to include Mediterranean populations in which specimens with deviant morphologies are observed. I found that Cetraria aculeata forms a genetically congruent taxon. Although whether it should include C. muricata remains unsolved, I excluded all specimens identified as the latter from our analyses. Thee populations of both algal and fungal symbionts have a strong geographic structure. The study of the lichen fungus suggested that the species originated in the Eurasian continent and later expanded to acquire its current distribution during the Pleistocene. The results ... |
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