Browsing by Author "Jara-Arancio, Paola"

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    Extreme Drought Affects Visitation and Seed Set in a Plant Species in the Central Chilean Andes Heavily Dependent on Hummingbird Pollination
    (2020) Arroyo, Mary T. K.; Robles, Valeria; Tamburrino, Italo; Martinez-Harms, Jaime; Garreaud, Rene D.; Jara-Arancio, Paola; Pliscoff, Patricio; Copier, Ana; Arenas, Jonas; Keymer, Joaquin; Castro, Kiara
    Rising temperatures and increasing drought in Mediterranean-type climate areas are expected to affect plant-pollinator interactions, especially in plant species with specialised pollination. Central Chile experienced a mega drought between 2010 and 2020 which reached an extreme in the austral summer of 2019-2020. Based on intensive pollinator sampling and floral studies we show that the subalpine form of Mutisia subulata (Asteraceae) is a specialised hummingbird-pollinated species. In a two-year study which included the severest drought year, we quantified visitation frequency, flower-head density, flower-head visitation rates, two measures of floral longevity, nectar characteristics and seed set and monitored climatic variables to detect direct and indirect climate-related effects on pollinator visitation. Flower-head density, nectar standing crop and seed set were significantly reduced in the severest drought year while nectar concentration increased. The best model to explain visitation frequency included flower-head density, relative humidity, temperature, and nectar standing crop with highly significant effects of the first three variables. Results for flower-head density suggest hummingbirds were able to associate visual signals with reduced resource availability and/or were less abundant. The negative effect of lower relative humidity suggests the birds were able to perceive differences in nectar concentration. Reduced seed set per flower-head together with the availability of far fewer ovules in the 2019-2020 austral summer would have resulted in a major reduction in seed set. Longer and more intense droughts in this century could threaten local population persistence in M. subulata.
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    Genetic Diversity and Population Structure of Jubaea chilensis, an Endemic and Monotype Gender from Chile, Based on SNP Markers
    (2022) Jara-Arancio, Paola; da Silva Carvalho, Carolina; Carmona-Ortiz, Martin R.; Bustamante, Ramiro O.; Schmidt Villela, Priscilla M.; da Silva Andrade, Sonia C.; Pena-Gomez, Francisco T.; Gonzalez, Luis A.; Fleury, Marina
    Jubaea chilensis (Molina) Baill., also named Chilean palm, is an endemic species found in the coastal area of Mediterranean sclerophyllous forest in Chile. It has a highly restricted and fragmented distribution along the coast, being under intense exploitation and anthropogenic impact. Based on 1038 SNP markers, we evaluated the genetic diversity and population structure among six J. chilensis natural groups encompassing 96% of the species distribution. We observed low levels of genetic diversity, a deficit of heterozygotes (mean H-E = 0.024; H-O = 0.014), and high levels of inbreeding (mean F-IS = 0.424). The fixation index (F-ST) and Nei's genetic distance pairwise comparisons indicated low to moderate structuring among populations. There was no evidence of isolation by distance (r = -0.214, p = 0.799). In the cluster analysis, we observed a closer relationship among Culimo, Cocalan, and Candelaria populations. Migration rates among populations were low, except for some populations with moderate values. The K value that best represented the spatial distribution of genetic diversity was Delta K = 3. Habitat fragmentation, deterioration of the sclerophyllous forest, lack of long-distance dispersers, and a natural regeneration deficit may have driven inbreeding and low levels of genetic diversity in the palm groves of J. chilensis. Although extant populations are not at imminent risk of extinction, the rate of inbreeding could increase and migration could decrease if the effects of climate change and human impact become more acute.
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    Ovule bet-hedging at high elevation in the South American Andes : evidence from a phylogenetically controlled multispecies study
    (2019) Arroyo, Mary T.K.; Pérez Trautmann, María Fernanda; Jara-Arancio, Paola; Pacheco, Diego; Vidal, Paula
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    Vegetation, disturbance, and climate history since the onset of ice-free conditions in the Lago Rosselot sector of Chiloe continental (44°S), northwestern Patagonia
    (2021) Moreno, Patricio I.; Videla, Javiera; Kaffman, Maria Jose; Henriquez, Carla A.; Sagredo, Esteban A.; Jara-Arancio, Paola; Alloway, Brent V.
    We present results from Lago Negro, a small closed-basin lake adjacent to Lago Rosselot, to examine the vegetation and environmental history of an insufficiently studied sector of Chiloe Continental (41 degrees 30'-44 degrees S) in northwestern Patagonia. Lake sediment cores from Lago Negro reveal 27 tephra deposited since similar to 12.7 ka, including two prominent rhyodacite tephra marker beds erupted from Volcan Melimoyu, and a stratified basal clastic unit we attribute to meltwater discharge from an ice tongue that originated from Monte Queulat and covered Lago Rosselot during its expanded position, presumably Antarctic Cold Reversal in age. The pollen record shows closed-canopy North Patagonian rainforests since similar to 12.7 ka, with variations in species composition and structure that suggest dynamic responses of the vegetation to past environmental changes. Vegetation responses to climate in the Lago Negro record were modulated, sometimes interrupted, by high magnitude and frequent disturbance regimes, most notably during maxima in explosive volcanic activity (similar to 9.5-7.2 ka and similar to 3.6-1.6 ka) and heightened fire activity.