Browsing by Author "Koch, Marcus A."
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- ItemLiving at the dry limits: ecological genetics of Tillandsia landbeckii lomas in the Chilean Atacama Desert(2019) Koch, Marcus A.; Kleinpeter, Dorothea; Auer, Erik; Siegmund, Alexander; Río López, Camilo del; Osses Mc-Intyre, Pablo; García B., Juan Luis; Marzol, Maria V.; Zizka, Georg; Kiefer, ChristianeThe northern Chilean Atacama Desert is among those regions on Earth where life exists at its dry limits. There is almost zero rainfall in its core zone, and the only source of water is a spatio-temporally complex fog system along the Pacifc coast, which is reaching far into the hyperarid mainland. Hardly any vascular plants grow in these areas, and, thus, it is intriguing to be faced with a vegetation-type build-up by one single and highly specialized bromeliad species, Tillandsia landbeckii Phil., forming regular linear structures in a sloped landscape. We studied the genetic make-up of a population system extending an area of approximately 1500 km2 and demonstrated a fne-scale correlation of genetic diversity with spatial population structure and following an elevational gradient of approximately 150 m. Increase in genetic diversity is correlated with increased ftness as measured by fowering frequency, and evidence is provided that outbreeding is linked with a large-distance fying pollinator feeding occasionally as generalist on its fowers, but not using the plant as source for larvae feeding. Our data demonstrate that establishment of linear vegetation structure is in principle a process driven by clonal growth and propagation of ramets over short distances. However, optimal conditions (slope, elevation, fog occurrence) for linear growth pattern formation also increase sexual plant reproductive ftness, thus providing the reservoir for newly combined genetic variation and counteracting genetic uniformity. Our study highlights the Tillandsia vegetation, also called Tillandsia lomas, as unique and genetically diverse system, which is highly threatened by global climate change and disturbance of the coastal fog system.
- ItemSpatial distribution and interannual variability of coastal fog and low clouds cover in the hyperarid Atacama Desert and implications for past and present Tillandsia landbeckii ecosystems(SPRINGER WIEN, 2021) del Rio, Camilo; Lobos Roco, Felipe; Latorre, Claudio; Koch, Marcus A.; Garcia, Juan Luis; Osses, Pablo; Lambert, Fabrice; Alfaro, Fernando; Siegmund, AlexanderThe hyperarid Atacama Desert coast receives scarce moisture inputs mainly from the Pacific Ocean in the form of marine advective fog. The collected moisture supports highly specialized ecosystems, where the bromeliad Tillandsia landbeckii is the dominant species. The fog and low clouds (FLCs) on which these ecosystems depend are affected in their interannual variability and spatial distribution by global phenomena, such as ENSO. Yet, there is a lack of understanding of how ENSO influences recent FLCs spatial changes and their interconnections and how these variations can affect existing Tillandsia stands. In this study, we analyze FLCs occurrence, its trends and the influence of ENSO on the interannual variations of FLCs presence by processing GOES satellite images (1995-2017). Our results show that ENSO exerts a significant influence over FLCs interannual variability in the Atacama at similar to 20 degrees S. Linear regression analyses reveal a relation between ENSO3.4 anomalies and FLCs with opposite seasonal effects depending on the ENSO phase. During summer (winter), the ENSO warm phase is associated with an increase (decrease) of the FLCs occurrence, whereas the opposite occurs during ENSO cool phases. In addition, the ONI Index explains up to similar to 50 and similar to 60% variance of the interannual FLCs presence in the T. landbeckii site during summer and winter, respectively. Finally, weak negative (positive) trends of FLCs presence are observed above (below) 1000 m a. s. l. These results have direct implications for understanding the present and past distribution of Tillandsia ecosystems under the extreme conditions characterizing our study area.