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Freshwater ostracodes from the Neotropical-Caribbean region are potentially excellent tools for evolutionary and paleoenvironmental studies but their use is limited, because integrated data in taxonomy, environmental, and geographical preferences of the species at large scale remain unknown. A total of 118 species were recorded in the Neotropical-Caribbean region based on existing literature and results from fieldwork. About 74% of the species are restricted to the region and most of them show limited distributional areas as a consequence of environmental heterogeneity. Based on Parsimony Analysis of Endemicity, five areas of endemism were identified:(1) southern Florida, (2) southern Mexico-northern Central America, (3) Cuba, (4) Lesser Antilles, and (5) northern Venezuela-Aruba-Curacao-Trinidad. The conservation status of these areas was revised and lake ecosystems with endemic taxa were proposed to be included in environmental protection initiatives. Biogeographical analysis showed a strong differentiation between the ostracode faunas of the Neotropical-Caribbean region and the Neotropical-Neogen region. Few exchanges of species were attributed to ecological and geographical barriers such as volcanism and irregular orography. Faunal affinities within the Neotropical-Caribbean region indicated closer relationship between southern Mexico, southern Florida and the Antilles suggesting a common biogeographical history. Middle Central America and Chiapas-Guatemala highlands were discriminated as isolated regions.

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<p>Cladocera species composition was analyzed in surface sediments of 29 lakes in Central America (Guatemala, El Salvador and Honduras). The material studied was collected with an Ekman grab in autumn 2013 from lakes located in lowland, highland and mountain regions. The study revealed high variability in qualitative and quantitative composition of subfossil Cladocera. A total of 31 Cladocera species (5 planktonic and 26 littoral) were identified, as well as 4 morphotypes that could not be identified (NRR<em> </em>1-4). Planktonic Bosminidae<em> </em>and<em> </em>Daphniidae were the most abundant families. Daphniidae were restricted to water bodies in mountain regions, whereas Bosminidae were widely distributed in lakes with different abiotic conditions. Moreover, Bosminidae species also occurred in highly mineralized waters (&gt; 900 µS cm^-1). The great majority of the identified Cladocera species belonged to the littoral family Chydoridae. <em>Chydorus </em>cf.<em> sphaericus</em> was the most common species (found in 20 lakes), which probably reflects its tolerance to a wide spectrum of habitat conditions. Cluster analysis discriminated 6 groups of Cladocera species with a high correlation level within groups (≥0.8), which showed different types of correlation with lake characteristics and environmental variables. Canonical correspondence analysis (CCA) showed that altitude and secondly water electrical conductivity were the most important drivers of Cladocera species composition in the region studied. Furthermore, CCA analysis indicated lowland lakes with low water transparency were also characterized by peculiar species assemblages. <strong></strong></p>

The last 85,000 years were characterized by high climate and environmental variability on the Yucatán Peninsula. Heinrich stadials are examples of abrupt climate transitions that involved shifts in regional temperatures and moisture availability. Thus, they serve as natural experiments to evaluate the contrasting responses of aquatic and terrestrial ecosystems. We used ostracodes and pollen preserved in a 75.9-m-long sediment core (PI-6, ~85 ka) recovered from Lake Petén Itzá, Guatemala, to assess the magnitude and velocity of community responses. Ostracodes are sensitive to changes in water temperature and conductivity. Vegetation responds to shifts in temperature and the ratio of evaporation to precipitation. Ostracodes display larger and more rapid community changes than does vegetation. Heinrich Stadial 5-1 (HS5-1) was cold and dry and is associated with lower ostracode and vegetation species richness and diversity. In contrast, the slightly warmer and dry conditions during HS6 and HS5a are reflected in higher ostracode species richness and diversity. Our paleoecological study revealed the greatest ecological turnover for ostracodes occurred from 62.5 to 51.0 ka; for pollen, it was at the Pleistocene/Holocene transition. Future studies should use various climate and environmental indicators from lake and marine sediment records to further explore late glacial paleoclimate causes and effects in the northern neotropics.