Dispersal and genetic exchange of lichen populations between the Maritime Antarctic and southern South America (with a focus on human impact)

• Main Author: Lagostina, Elisa
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2020
• Subjects: ddc:570; Antarctic; Drake Passage; The Antarctic; Antarc*; Antarctica
• Online Access: http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/57432; https://nbn-resolving.org/urn:nbn:de:hebis:30:3-574327; http://publikationen.ub.uni-frankfurt.de/files/57432/20201211_LagostinaE_thesis.pdf

This manuscript-based thesis is divided into four chapters. Chapter one is an introduction to lichens and the Antarctic. It introduces the goal of the thesis and the problems related with lichen systematics and the lack of knowledge about Antarctic lichens. The Antarctic is one of the last wildernesses, isolated from the other continents by the Antarctic Circumpolar Current, the Subantarctic Front, the Antarctic Polar Front, and the Drake Passage. Terrestrial life in Antarctica is restricted to widely separated and small ice-free areas that cover only 0.3% of the continent. Colonization of the Antarctic is a challenge for many taxa and is related to their ability for long-range dispersal and their adaptation to the harsh climate. Antarctic terrestrial ecosystems are significantly threatened by climate change, invasive species, and their interactions. Glacial retreat caused by higher than average temperatures exposes new habitats that can be easily colonized from local biota, but non-native species can also be favored by the new climatic conditions. In addition, propagule movement mediated by humans can introduce new species or change the population structure of many taxa. The terrestrial biota is comprised almost exclusively by “lower organisms” (invertebrates, bryophytes, algae, lichenized fungi, and microorganisms). Lichens are the dominant component, and the most important primary producers. Lichens are symbiotic associations consisting of a fungus (mycobiont) and one or more photosynthetic (photobiont) partners. They can disperse sexually or vegetatively. There are several problems related to the symbiotic nature of lichens that do not facilitate easy identification; although molecular data offers additional evidence, species delimitation in lichens is still not straightforward. The true number of species is underestimated due to the presence of cryptic species and species pairs. Recommended universal fungal barcode sequences (e. g. ITS) sometimes fail to delimit species pairs. Thus, it is necessary to ...