Browsing by Author "Gonzalez-Pinilla, Francisco J."

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    High- and low-latitude forcings drive Atacama Desert rainfall variations over the past 16,000 years
    (2021) Gonzalez-Pinilla, Francisco J.; Latorre, Claudio; Rojas, Maisa; Houston, John; Ignacia Rocuant, M.; Maldonado, Antonio; Santoro, Calogero M.; Quade, Jay; Betancourt, Julio L.
    Late Quaternary precipitation dynamics in the central Andes have been linked to both high- and low-latitude atmospheric teleconnections. We use present-day relationships between fecal pellet diameters from ashy chinchilla rats (Abrocoma cinerea) and mean annual rainfall to reconstruct the timing and magnitude of pluvials (wet episodes) spanning the past 16,000 years in the Atacama Desert based on 81 C-14-dated A. cinerea paleomiddens. A transient climate simulation shows that pluvials identified at 15.9 to 14.8, 13.0 to 8.6, and 8.1 to 7.6 ka B.P. can be linked to North Atlantic (high-latitude) forcing (e. g., Heinrich Stadial 1, Younger Dryas, and Bond cold events). Holocene pluvials at 5.0 to 4.6, 3.2 to 2.1, and 1.4 to 0.7 ka B.P. are not simulated, implying low-latitude internal variability forcing (i.e., ENSO regime shifts). These results help constrain future central Andean hydroclimatic variability and hold promise for reconstructing past climates from rodent middens in desert ecosystems worldwide.
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    Molecular systematics of chinchilla rats and taxonomic assessment of the Abrocoma cinerea species complex
    (2024) Gonzalez-Pinilla, Francisco J.; Latorre, Claudio; Palma, R. Eduardo
    Chinchilla rats (family Abrocomidae) are hystricomorph rodents primarily inhabiting the central Andes in South America with 8 species in the genus Abrocoma and 2 in Cuscomys. The systematics of this family-relying only on morphological differences-has faced several controversies, particularly in arid-adapted species of Abrocoma (the A. cinerea species complex, or ACC). By using partial DNA sequences of 1 mitochondrial (Cytochrome b) and 2 nuclear genes (GHR and RAG1), we: (i) inferred phylogenetic relationships between 5 species of Abrocoma and 1 of Cuscomys; (ii) performed molecular species-delimitation analyses in 4 species of the ACC (A. cinerea, A. famatina, A. schistacea, and A. uspallata); and (iii) estimated divergence times using stratigraphic ages of extinct taxa. Our phylogenetic analyses recovered 3 main clades: A. bennettii (basal); C. ashaninka; and the ACC. Striking differences in habitat use, morphology, and genetics suggest that each of these main clades might represent a distinct genus. In species-delimitation analyses in the ACC, only 2 species were recognized, and we thus suggest the synonymy of A. famatina with A. cinerea and of A. uspallata with A. schistacea. The origin of extant abrocomids was estimated at the late Miocene (similar to 5.6 million years ago, Ma) with the subsequent origin of arboreal species during the early Pliocene (similar to 4.3 Ma) and the ACC during the late Pliocene (similar to 3.3 Ma). We hypothesize that topographic uplift of the central Andes and associated climatic and ecological changes were the main drivers of diversification in this family.