Abstract
Abstract. We evaluated how ranges of four endemic and non-endemic aquatic ostracode species changed in response to long-term (glacial–interglacial cycles) and abrupt climate fluctuations during the last 155 kyr in the northern Neotropical region. We employed two complementary approaches, fossil records and species distribution models (SDMs). Fossil assemblages were obtained from sediment cores PI-1, PI-2, PI-6 and Petén-Itzá 22-VIII-99 from the Petén Itzá Scientific Drilling Project, Lake Petén Itzá, Guatemala. To obtain a spatially resolved pattern of (past) species distribution, a downscaling cascade is employed. SDMs were reconstructed for the last interglacial (∼120 ka), the last glacial maximum (∼22 ka) and the middle Holocene (∼6 ka). During glacial and interglacial cycles and marine isotope stages (MISs), modelled paleo-distributions and paleo-records show the nearly continuous presence of endemic and non-endemic species in the region, suggesting negligible effects of long-term climate variations on aquatic niche stability. During periods of abrupt ecological disruption such as Heinrich Stadial 1 (HS1), endemic species were resilient, remaining within their current areas of distribution. Non-endemic species, however, proved to be more sensitive. Modelled paleo-distributions suggest that the geographic range of non-endemic species changed, moving southward into Central America. Due to the uncertainties involved in the downscaling from the global numerical to the highly resolved regional geospatial statistical modelling, results can be seen as a benchmark for future studies using similar approaches. Given relatively moderate temperature decreases in Lake Petén Itzá waters (∼5 ∘C) and the persistence of some aquatic ecosystems even during periods of severe drying in HS1, our data suggest (1) the existence of micro-refugia and/or (2) continuous interaction between central metapopulations and surrounding populations, enabling aquatic taxa to survive climate fluctuations in the northern Neotropical region.
Highlights
Climate changes are quasi-cyclical natural processes that continuously influence ecosystem dynamics and shape biological diversity worldwide (Blois et al, 2013; Parmesan and Yohe, 2003; Yasuhara et al, 2009, 2017)
In the northern Neotropics, which include southern Mexico, Central America and the Antilles, late Quaternary climate inferences based on climatic simulations with global climate models (GCMs; Hijmans et al, 2005) and reconstructions from marine and lacustrine sedimentary sequences (Hodell et al, 2008; Pérez et al, 2011; Escobar et al, 2012) have revealed climate fluctuations related to temperature and precipitation, especially during transitions between glacial and interglacial episodes and during climate pulses such as the last glacial maximum (LGM) and Heinrich stadials (HSs; Correa-Metrio et al, 2012b)
Our study suggests that the velocity of change in aquatic environments remained low in the northern Neotropical region, enabling local species to adapt and specialize to their environments instead of migrating and/or remaining isolated in refugia, as observed in tropical areas elsewhere
Summary
Climate changes are quasi-cyclical natural processes that continuously influence ecosystem dynamics and shape biological diversity worldwide (Blois et al, 2013; Parmesan and Yohe, 2003; Yasuhara et al, 2009, 2017). In the Neotropics, controls of climate fluctuations are related to orbital forcing and internal component variations, such as the position (north– south) of the intertropical convergence zone (ITCZ), strength of Atlantic meridional overturning circulation (AMOC) and changes in Caribbean surface water temperature (Cohuo et al, 2018). Alterations in these features have produced temperature decreases in a range of 3–5 ◦C, some estimations suggest decreases up to 10 ◦C relative to present and large reductions in precipitation, during HS, when most lakes in the region dried completely (Cohuo et al, 2018). It remains uncertain how aquatic species responded to past climate alterations
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