Browsing by Author "Betancourt, Julio L."

Now showing 1 - 5 of 5
  • No Thumbnail Available
    Item
    Ecological fidelity and spatiotemporal resolution of arthropod death assemblages from rodent middens in the central Atacama Desert (northern Chile)
    (2019) Dezerald, Olivier; Latorre, Claudio; Betancourt, Julio L.; Brito Vera, Gabriel A.; Gonzalez, Angelica L.
    Evaluating the magnitude and direction of biases affecting the ecological information captured by death assemblages is an important prerequisite for understanding past, present, and future community-environment relationships. Here, we establish the ecological fidelity andspatiotemporal resolution of an overlooked source of fossil remains: the soil arthropod assemblages found in rodent middens (that span from the present to >44,420 cal yr BP) collected in the central Atacama Desert of northern Chile. We evaluated the "live-dead agreement" across four sources of soil arthropod data; two contemporary surveys of live communities (i.e., live), and two sources of death assemblages (i.e., dead). Although live-dead agreements and diversity indices are highly variable among samples (live and dead assemblages), our results consistently demonstrate that an average fossil midden (i) better captures the structure and composition of living communities than species richness per se; (ii) offers a spatially-resolved picture of those communities at local scales; and (iii) is only weakly affected by time-averaging. The fine spatio-temporal resolution of fossil midden records in the Atacama, and most likely other areas of the world where rodent middens occur offers ecological information on the structure and composition of fossil arthropod assemblages potentially over many thousands of years. This information is reliable enough to establish historical baselines before past and ongoing anthropogenic impacts. (C) 2019 Elsevier Ltd. All rights reserved.
  • No Thumbnail Available
    Item
    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.
  • No Thumbnail Available
    Item
    New uses for ancient middens: bridging ecological and evolutionary perspectives
    (2024) Becklin, Katie M.; Betancourt, Julio L.; Braasch, Joseph; Dezerald, Olivier; Diaz, Francisca P.; Gonzalez, Angelica L.; Harbert, Robert; Holmgren, Camille A.; Hornsby, Angela D.; Latorre, Claudio; Matocq, Marjorie D.; Smith, Felisa A.
    Rodent middens provide a fine-scale spatiotemporal record of plant and animal communities over the late Quaternary. In the Americas, middens have offered insight into biotic responses to past environmental changes and historical factors influencing the distribution and diversity of species. However, few studies have used middens to investigate genetic or ecosystem level responses. Integrating midden studies with neoecology and experimental evolution can help address these gaps and test mechanisms underlying eco-evolutionary patterns across biological and spatiotemporal scales. Fully realizing the potential of middens to answer cross -cutting ecological and evolutionary questions and inform conservation goals in the Anthropocene will require a collaborative research community to exploit existing midden archives and mount new campaigns to leverage midden records globally.
  • Thumbnail Image
    Item
    Past and future global transformation of terrestrial ecosystems under climate change
    (2018) Nolan, Connor; Overpeck, Jonathan T.; Allen, Judy R.M.; Anderson, Patricia M.; Betancourt, Julio L.; Binney, Heather A.; Brewer, Simon; Bush, Mark B.; Chase, Brian M.; Latorre H., Claudio
  • Thumbnail Image
    Item
    The Neotoma Paleoecology Database, a multiproxy, international, community-curated data resource
    (2018) Williams, John W.; Grimm, Eric C.; Blois, Jessica L.; Charles, Donald F.; Davis, Edward B.; Goring, Simon J.; Graham, Russell W.; Smith, Alison J.; Anderson, Michael; Arroyo-Cabrales, Joaquin; Ashworth, Allan C.; Betancourt, Julio L.; Bills, Brian W.; Booth, Robert K.; Buckland, Philip I.; Curry, B. Brandon; Giesecke, Thomas; Jackson, Stephen T.; Latorre H., Claudio; Nichols, Jonathan; Purdum, Timshel; Roth, Robert E.; Stryker, Michael; Takahara, Hikaru