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4,462 results for “South America”
Data from: The early diversification history of didelphid marsupials: a window into South America's "Splendid Isolation"
The geological record of South American mammals is spatially biased because productive fossil sites are concentrated at high latitudes. As a result, the history of mammalian diversification in Amazonia and other tropical biomes is largely unknown. Here we report diversification analyses based on a time-calibrated molecular phylogeny of opossums (Didelphidae), a species-rich clade of mostly tropical marsupials descended from a Late Oligocene common ancestor. Optimizations of habitat and geography on this phylogeny suggest that (1) basal didelphid lineages inhabited South American moist forests; (2) didelphids did not diversify in dry-forest habitats until the Late Miocene; and (3) most didelphid lineages did not enter North America until the Pliocene. We also summarize evidence for an Early- to Middle-Miocene mass extinction event, for which alternative causal explanations are discussed. To the best of our knowledge, this study provides the first published molecular-phylogenetic evidence for mass extinction in any animal clade, and it is the first time that evidence for such an event (in any plant or animal taxon) has been tested for statistical significance. Potentially falsifying observations that could help discriminate between the proposed alternative explanations for didelphid mass extinction may be obtainable from diversification analyses of other sympatric mammalian groups.
A parapithecid stem anthropoid of African origin in the Paleogene of South America
<p>Phylogenetic evidence suggests that platyrrhine (or New World) monkeys and caviomorph rodents of the Western Hemisphere derive from source groups from the Eocene of Afro-Arabia, a landmass that was ~1500 to 2000 kilometers east of South America during the late Paleogene. Here, we report evidence for a third mammalian lineage of African origin in the Paleogene of South America<b>—</b>a newly discovered genus and species of parapithecid anthropoid primate from Santa Rosa in Amazonian Perú. Bayesian clock<b>–</b>based phylogenetic analysis nests this genus (<i>Ucayalipithecus</i>) deep within the otherwise Afro-Arabian clade Parapithecoidea, and indicates that transatlantic rafting of the lineage leading to <i>Ucayalipithecus</i> likely took place between ~35 and ~32 million years ago, a dispersal window that includes the major worldwide drop in sea level that occurred near the Eocene-Oligocene boundary.</p>
Data from: Kooiichthys jono n. gen. n. sp., a primitive catfish (Teleostei, Siluriformes) from the marine Miocene of southern South America
A specimen of a remarkable new catfish genus and species was collected in middle/late Miocene marine beds of the Puerto Madryn Formation at the base of the marine cliff of the sea lion colony area near Puerto Pirámide, southern coast of Península Valdés, northeastern Patagonia, Argentina. Siluriforms (catfishes) constitute a most important monophyletic ostariophysan group of mainly freshwater fishes that occurs in almost all continents but it is especially diverse in South America. Catfishes are presently distributed in tropical to temperate areas and a small number of species are marine or amphibiotic. The new catfish shows many primitive features for catfishes in the maxilla, autopalatine, hyal elements, and Weberian apparatus. The genus is clearly distinguished by four autapomorphies: sand clock—shaped autopalatine, posterior limb of autopalatine widening strongly, post-articular arm of autopalatine longer, and a metapterygoid longer than broad. One tree was obtained both under equal and implied weighting with the following topology: a basal polytomy in the Siluriformes formed by Diplomystidae, Bachmanniidae, Kooiichthys and the Siluroidei. The new species appears to have been a marine or amphibiotic taxon: it was collected in beds considered to represent the Maximum Flooding Horizon of the transgression that deposited the Puerto Madryn Formation. The coast at this moment was at approximately 90 km to the west. According to faunistic evidence, the sea was warm temperate.
Data from: Phylogeny and biogeography of Poecilia (Cyprinodontiformes: Poeciliinae) across Central and South America based on mitochondrial and nuclear DNA markers
Poeciliids are a diverse group of small Neotropical fishes, and despite considerable research attention as models in ecology and evolutionary biology, our understanding of their biogeographic and phylogenetic relationships is still limited. We investigated the phylogenetic relationships of South and Central American Poecilia, by examining 2395 base pairs of mitochondrial DNA (ATPase 8/6, COI) and nuclear DNA (S7) for 18 species across six subgenera. Fifty-eight novel sequences were acquired from newly collected specimens and 20 sequences were obtained from previously published material. Analyses of concatenated and partitioned mitochondrial DNA and nuclear DNA sets resulted in a well-supported phylogeny that resolved several monophyletic groups corresponding to previously hypothesized subgenera and species complexes.
Data from: Color vision varies more among populations than among species of live-bearing fish from South America
Background: Sensory Bias models for the evolution of mate preference place a great emphasis on the role of sensory system variation in mate preferences. However, the extent to which sensory systems vary across- versus within-species remains largely unknown. Here we assessed whether color vision varies in natural locations where guppies (Poecilia reticulata) and their two closest relatives, Poecilia parae and Poecilia picta, occur in extreme sympatry and school together. All three species base mate preferences on male coloration but differ in the colors preferred. Results: Measuring opsin gene expression, we found that within sympatric locations these species have similar color vision and that color vision differed more across populations of conspecifics. In addition, all three species differ across populations in the frequency of the same opsin coding polymorphism that influences visual tuning. Conclusions: Together, this shows sensory systems vary considerably across populations and supports the possibility that sensory system variation is involved in population divergence of mate preference.
Data from: Lake regionalization and diatom metacommunity structuring in tropical South America
Lakes and their topological distribution across Earth's surface impose ecological and evolutionary constraints on aquatic metacommunities. In this study, we group similar lake ecosystems as metacommunity units influencing diatom community structure. We assembled a database of 195 lakes from the tropical Andes and adjacent lowlands (8ºN–30ºS and 58–79ºW) with associated environmental predictors to examine diatom metacommunity patterns at two different levels: taxon and functional (deconstructed species matrix by ecological guilds). We also derived spatial variables that inherently assessed the relative role of dispersal. Using complementary multivariate statistical techniques (Principal Component Analysis, cluster analysis, non-metric multidimensional scaling, Procrustes, variance partitioning), we examined diatom-environment relationships among different lake habitats (sediment surface, periphyton and plankton) and partitioned community variation to evaluate the influence of niche- and dispersal-based assembly processes in diatom metacommunity structure across lake clusters. The results showed a significant association between geographic clusters of lakes based on gradients of climate and landscape configuration and diatom assemblages. Six lake clusters distributed along a latitudinal gradient were identified as functional metacommunity units for diatom communities. Variance partitioning revealed that dispersal mechanisms were a major contributor to diatom metacommunity structure, but in a highly context-dependent fashion across lake clusters. In the Andean Altiplano and adjacent lowlands of Bolivia, diatom metacommunities are niche assembled but constrained by either dispersal limitation or mass effects, resulting from area, environmental heterogeneity, and ecological guild relationships. Topographic heterogeneity played an important role in structuring planktic diatom metacommunities. We emphasize the value of a guild-based metacommunity model linked to dispersal for elucidating mechanisms underlying latitudinal gradients in distribution. Our findings reveal the importance of shifts in ecological drivers across climatic and physiographically distinct lake clusters, providing a basis for comparison of broad-scale community gradients in lake-rich regions elsewhere. This may help guide future research to explore evolutionary constraints on the rich Neotropical benthic diatom species pool.
Data from: New Neogene taxa of the tribe Chlamydini Teppner, 1922 (Pectinidae, Bivalvia) of southern South America
The Chilean species traditionally assigned to the genera Chlamys Röding, 1798 or Zygochlamys Ihering, 1907 are now placed in two new endemic South American taxa: Dietotenhosen n. gen. (middle Miocene–early middle Pliocene) to include the southeastern Pacific Ocean species D. hupeanus (Philippi, 1887) n. comb. and D. remondi (Philippi, 1887) n. comb., and Ckaraosippur n. gen. (earliest middle Miocene–Pliocene) for C. calderensis (Möricke, 1896) n. comb. (Chile) and C. camachoi n. sp. (Argentina). Both genera are the youngest survivors of the tribe Chlamydini in southern South America. None of them are related to the circumpolar genus Psychrochlamys Jonkers, 2003, and the previous proposal of the dispersal through the Antarctic Circumpolar Current for the species included herein in Dietotenhosen is rejected.
Data from: Co-declining mammal-dung beetle faunas throughout the Atlantic Forest biome of South America
The millennial-scale evolutionary relationships between mammals and dung beetles have been eroded due to several drivers of contemporary biodiversity loss. Although some evidence of co-decline has been shown for mammals and dung beetles at some Neotropical sites, a biome-scale analysis for the entire Atlantic Forest of South America would strengthen our understanding of how relictual sets of mammal species can affect dung beetle co-occurrences and co-declines. We therefore collated hundreds of assemblages of both dung beetles and medium- to large-bodied mammals throughout the world's longest tropical forest latitudinal gradient to examine to what extent mammal assemblages may exert a positive influence on dung beetle species composition and functional assembly, and whether this relationship is scale dependent. We also collated several climatic and other environmental variables to examine the degree to which they shape mammal-dung beetle relationships. The relationships between local mammal and dung beetle faunas were examined using regression models, variation partitioning, dissimilarity indices, and ecological networks. We found a clear positive relationship between mammal and dung beetle species richness across this forest biome, indicating an ongoing process of mammal-dung beetle niche-mediated co-decline. We found a strong relationship between the species composition of both taxa, in which dung beetle species dissimilarity apparently track changes in mammalian dissimilarity, typically in 80% of all cases. Co-variables such as phytomass and climatic variables also influenced mammal-dung beetle patterns of co-decline along the Atlantic Forest. We conclude that dung beetle diversity and community assembly are shaped by the remaining co-occurring mammal assemblages and their functional traits, and both groups were governed by environmental features. We emphasize that ecosystem-wide effects of mammal population declines remain poorly understood both quantitatively and qualitatively, and curbing large vertebrate defaunation will ensure the persistence of co-dependent species.
Data from: New DNA data from a Transthyretin nuclear intron suggest an Oligocene to Miocene diversification of living South America opossums (Marsupialia: Didelphidae).
Phylogenetic relationships of 19 species of didelphid marsupials were studied using two nuclear markers, the non-coding transthyretin intron 1 (TTR) and the coding interphotoreceptor retinoid binding protein exon 1 (IRBP), and two mitochondrial genes, the protein-coding cytochrome b (cyt-b) and the structural 12S ribosomal DNA (12S rDNA). Evolutionary dynamics of these four markers were compared to each other, revealing the appropriate properties presented by TTR intron 1 together with its well supported and resolved phylogenetic signal. Nuclear markers supported the monophyly of medium and large-sized opossums Metachirus+(Chironectes, Lutreolina, Didelphis, Philander), and the paraphyly of mouse-sized opossums, with the genera Gracilinanus, Thylamys, and Marmosops as a sister group to medium and large-sized didelphids. Conflicting branching patterns between mitochondrial and nuclear data involved the phylogenetic position of Marmosa-Micoureus-Monodelphis relative to other mouse-sized opossums. Nuclear phylogenetic inferences among genera were confirmed by the presence of synapomorphic indels observed in TTR intron 1. A Bayesian relaxed molecular clock dating of didelphid evolution using nuclear markers estimated their origin in the Middle Eocene (39.8 million years ago), with subsequent diversification during the Oligocene (Deseadan) and Miocene.
Data from: Arrival and diversification of caviomorph rodents and platyrrhine primates in South America.
Platyrrhine primates and caviomorph rodents are clades of mammals that colonized South America during its period of isolation from the other continents, between 100 and 3 million years ago (Mya). Until now, no molecular study investigated the timing of the South American colonization by these two lineages with the same molecular data set. Using sequences from three nuclear genes (ADRA2B, vWF, and IRBP, both separate and combined) from 60 species, and eight fossil calibration constraints, we estimated the times of origin and diversification of platyrrhines and caviomorphs via a Bayesian relaxed molecular clock approach. To account for the possible effect of an accelerated rate of evolution of the IRBP gene along the branch leading to the anthropoids, we performed the datings with and without IRBP (3768 sites and 2469 sites, respectively). The time window for the colonization of South America by primates and by rodents is demarcated by the dates of origin (upper bound) and radiation (lower bound) of platyrrhines and caviomorphs. According to this approach, platyrrhine primates colonized South America between 37.0 +/- 3.0 Mya (or 38.9 +/- 4.0 Mya without IRBP) and 16.8 +/- 2.3 (or 20.1 +/- 3.3) Mya, and caviomorph rodents between 45.4 +/- 4.1 (or 43.7 +/- 4.8) Mya and 36.7 +/- 3.7 (or 35.8 +/- 4.3) Mya. Considering both the fossil record and these molecular datings, the favored scenarios are a trans-Atlantic migration of primates from Africa at the end of the Eocene or beginning of the Oligocene, and a colonization of South America by rodents during the Middle or Late Eocene. Based on our nuclear DNA data, we cannot rule out the possibility of a concomitant arrival of primates and rodents in South America. The caviomorphs radiated soon after their arrival, before the Oligocene glaciations, and these early caviomorph lineages persisted until the present. By contrast, few platyrrhine fossils are known in the Oligocene, and the present-day taxa are the result of a quite recent, Early Miocene diversification.
Data from: Genomic patterns of diversity and divergence of two introduced salmonid species in Patagonia, South America
Invasive species have become widespread in aquatic environments throughout the world, yet there are few studies that have examined genomic variation of multiple introduced species in newly colonized environments. In this study, we contrast genomic variation in two salmonid species (anadromous Chinook Salmon, Oncorhynchus tshawytscha, 11,579 SNPs and resident Brook Charr Salvelinus fontinalis, 13,522 SNPs) with differing invasion success after introduction to new environments in South America relative to populations from their native range in North America. Estimates of genetic diversity were not significantly different between introduced and source populations for either species, indicative of propagule pressure that has been shown to maintain diversity in founding populations relative to their native range. Introduced populations also demonstrated higher connectivity and gene flow than those in their native range. Evidence for candidate loci under divergent selection was observed, but was limited to specific introduced populations and was not widely evident. Patterns of genomic variation were consistent with general dispersal potential of each species and therefore also the notion that life history variation may contribute to both invasion success and subsequent genetic structure of these two salmonids in Patagonia.
FIGURE 2 in A new genus and six new species of the tropical Camptotypus genusgroup (Hymenoptera: Ichneumonidae; Pimplinae) from northern South America
FIGURE 2. Amazopimpla errabunda Sääksjärvi, Gauld & Jussila, sp.n. Mesosoma, anterior part of metasoma and hind leg, showing colour pattern (Holotype female).
FIGURE 6 in A new genus and six new species of the tropical Camptotypus genusgroup (Hymenoptera: Ichneumonidae; Pimplinae) from northern South America
FIGURE 6. Amazopimpla errabunda Sääksjärvi, Gauld & Jussila, sp.n. The tip of the ovipositor (Holotype female).
FIGURE 9 in A new genus and six new species of the tropical Camptotypus genusgroup (Hymenoptera: Ichneumonidae; Pimplinae) from northern South America
FIGURE 9. Amazopimpla lutea Palacio, Sääksjärvi, Gauld & Jussila, sp.n. The tip of the ovipositor (Paratype female).
FIGURE 8 in A new genus and six new species of the tropical Camptotypus genusgroup (Hymenoptera: Ichneumonidae; Pimplinae) from northern South America
FIGURE 8. Amazopimpla guayanaensis Sääksjärvi, Gauld & Jussila, sp.n. The tip of the ovipositor (Holotype female).
FIGURE 3 in A new genus and six new species of the tropical Camptotypus genusgroup (Hymenoptera: Ichneumonidae; Pimplinae) from northern South America
FIGURE 3. Amazopimpla farallonensis Palacio, sp.n. Mesosoma, anterior part of metasoma and hind leg, showing colour pattern (Holotype female).
FIGURES 15–16 in A new species of Metelasmus (Diptera: Streblidae: Streblinae) from southern South America
FIGURES 15–16. Metelasmus sp. (as M. pseudopterus) from Séguy (1926). 15. Habitus; 16. Detail of the head.
FIGURE 17 in A new species of Metelasmus (Diptera: Streblidae: Streblinae) from southern South America
FIGURE 17. Distribution map of Metelasmus species. Wavy lines — M. pseudopterus Coquillett, 1899; Closed boxes — M. wenzeli n. sp.
FIGURES 1–8. Metelasmus wenzeli new species. 1 in A new species of Metelasmus (Diptera: Streblidae: Streblinae) from southern South America
FIGURES 1–8. Metelasmus wenzeli new species. 1. Frontoclypeus, holotype; 2. Postgena, male paratype from Paraná, Brazil; 3. Postvertex and occiputs, male paratype from Paraná; 4. Right wing, male paratype from Paraná; 5. Tergite VII and 6. Epiproct, female paratype from Paraguay; 7. Right gonopod, male paratype from Paraná; 8. Left gonopod, holotype.
FIGURES 9–14. Metelasmus pseudopterus Coquillett. 9 in A new species of Metelasmus (Diptera: Streblidae: Streblinae) from southern South America
FIGURES 9–14. Metelasmus pseudopterus Coquillett. 9. Frontoclypeus, female from Paraná, Brazil; 10. Postgena, female from Paraná; 11. Postvertex and occiputs, female from Paraná; 12. Tergite VII and 13. Epiproct, female from Paraná; 14. Right gonopod, from Rio Grande do Sul, Brazil (from Graciolli & Carvalho, 2001).
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
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The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
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