Influence of late Quaternary climate on the biogeography of Neotropical aquatic species as reflected by non-marine ostracodes

Abstract

<p><strong>Abstract.</strong> 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 ka in the northern Neotropical region. We employed two complementary approaches, fossil records and species distribution modeling (SDM). Fossil assemblages were obtained from sediment cores PI-1, PI-2, PI-6 and Petén-Itzá 22-VIII-99 from Petén Itzá Scientific Drilling Project, Lake Petén Itzá, Guatemala. To obtain a spatially resolved pattern of (past) species distribution, a downscaling cascade is employed. SDM's were reconstructed for the Last Interglacial (~ 120 ka BP), the Last Glacial Maximum (~ 22 ka BP) and the middle Holocene (~ 6 ka BP). During glacial/interglacial cycles and Marine Isotope Stages, modeled paleo-distributions and paleo-records show 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. Modeled 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 benchmark for future studies using similar approaches. Given relatively moderate temperature decreases in Lake Petén Itzá waters (~ 5 ºC) and persistence of some aquatic ecosystems even during periods of severe drying in HS1, our data suggest 1) 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.</p>

Ecological turnover in neotropical freshwater and terrestrial communities during episodes of abrupt climate change

“…Moreover, the endemic ostracodes C. petenensis and P. opesta dominated the species assemblage of the past 85 ka. This suggests that such species were resilient, in agreement with the findings of Cohuo et al (2020). Other species that displayed lower abundances include H. putei , P. antilliana , and S. intrepida .…”

“…Because freshwater and terrestrial ecosystems in Guatemala and elsewhere in Central America provided a corridor for the exchange of aquatic and terrestrial taxa between North and South America, we would expect ostracode species richness to be high, but surprisingly this was not the case in this study or in previous investigations (Cohuo et al, 2018, 2020). This highlights the role of abrupt climate and environmental changes in shaping biotic communities in the northern neotropics and the different strategies used by species (adaptation, dispersal, reproduction, etc.)…”

“…Nevertheless, ostracode abundance was low during this period, suggesting that inferences should be accepted with caution. Cohuo et al (2020) found shells of C. ilosvayi at 87–85 and 53 ka in drill site PI-2, confirming its early presence in the lake and reinforcing evidence for slightly warmer glacial conditions.…”

“…Their communities respond rapidly, in part because individuals have short life cycles (Pérez et al, 2010a). Ostracodes in lake sediment cores have been used to infer past shifts in lake stage and water-column conductivity, temperature, pH, trophic state, and ionic composition (Pérez et al, 2013a(Pérez et al, , 2013bCohuo et al, 2020). Their use in climate and environmental inferences is maximized by combining molecular, morphological, and ecological approaches (Macario-González et al, 2018).…”

Geodiversity influences limnological conditions and freshwater ostracode species distributions across broad spatial scales in the northern Neotropics

“…Freshwater ostracodes are a well-suited group to evaluate past and present drivers of species distribution in the northern Neotropics. Ostracodes are bivalved microcrustaceans that are abundant, diverse, and widely distributed in aquatic ecosystems (Pérez et al, 2011b(Pérez et al, , 2013Cohuo et al, 2016Cohuo et al, , 2020Macario-González et al, 2018;Echeverria-Galindo et al, 2019). This taxonomic group shows levels of endemism (restricted distribution) as high as 74 %, sometimes confined to a single lake, or found in surface waters throughout the region (Cohuo et al, 2016).…”