Publication Search Results

ID: 159180
Type: article
Authors: Abiem, Iveren; Dickie, Ian; Kenfack, David; Chapman, Hazel
Keywords: STRI
Abstract: Questions A leading hypothesis for species coexistence in species-rich, lowland tropical forests is conspecific negative density dependence (CNDD), driven by host-specific pests and pathogens and competition for available resources. The extent to which this applies to Afromontane forests with relatively low diversity, a high frequency of single-species stands, relatively few pests and pathogens and larger edge:core ratios, is unknown. We hoped that the results of our investigation would either confirm the generality of CNDD across these different tropical forest types or offer novel insights into alternative mechanisms leading to the maintenance of Afromontane tree species diversity. Location Ngel Nyaki Forest Reserve, southeastern Nigeria. Methods We monitored the survival of 10,741 seedlings of 93 species over two years in a long-term Forest Global Earth Observatory (ForestGEO) study plot in a montane forest in Nigeria. We assessed the effect of conspecific and heterospecific seedling and adult neighbours on the survival of every seedling and seedling guild (shade vs light-demanding; canopy vs understorey; edge specialists vs generalists; small vs large seedlings). Results We found strong evidence for non-species-specific positive and negative density dependence. CNDD was stronger in canopy species and light-demanding species than in the other growth form and shade tolerance guilds. Conclusions Our study offers some clear predictions about drivers of community coexistence in this environment, which will require further testing using field-based experiments.

ID: 158728
Type: article
Authors: Alfonso‐Rojas, Andrés; Herrera‐Gutierrez, Laura M.; Suárez, Catalina; Ciancio, Martín R.; Pelegrin, Jonathan S.; Cadena, Edwin-Alberto
Keywords: STRI

ID: 158396
Type: article
Authors: Alonso-Garcia, Marta; Grewe, Felix; Payette, Serge; Villarreal, Juan Carlos A.
Keywords: STRI
Abstract: PREMISE Lichens are one of the main structural components of plant communities in the North American boreal biome. They play a pivotal role in lichen woodlands, a large ecosystem situated north of the closed-crown forest zone, and south of the forest-tundra zone. In Eastern Canada (Quebec), there is a remnant LW found 500 km south of its usual distribution range, in the Parc National des Grands-Jardins, originated mainly because of wildfires. We inferred the origin of the lichen Cladonia stellaris from this LW and assessed its genetic diversity in a postfire succession. METHODS We genotyped 122 individuals collected across a latitudinal gradient in Quebec. Using the software Stacks, we compared four different approaches of locus selection and single-nucleotide polymorphism calling. We identified the best fitting approach to investigate population structure and estimate genetic diversity of C. stellaris. RESULTS Populations in southern Quebec are not genetically different from those of northern LWs. The species consists of at least four phylogenetic lineages with elevated levels of genetic diversity and low co-ancestry. In Parc National des Grands-Jardins, we reported high values of genetic diversity not related with time since fire disturbance and low genetic differentiation among populations with different fire histories. CONCLUSIONS This first population genomic study of C. stellaris is an important step forward to understand the origin and biogeographic patterns of lichen woodlands in North America. Our findings also contribute to the understanding of the effect of postfire succession on the genetic structure of the species.

ID: 158420
Type: article
Authors: Amador-Vargas, Sabrina; Orribarra, Vivian Sara; Portugal-Loayza, Ana; Fernandez-Marin, Hermogenes
Keywords: STRI
Abstract: Ants in obligate defense mutualisms with plants protect them against potentially damaging organisms. In the swollen-thorn acacias, organisms linked to the plant inform about the interaction between the tree and the resident ant colony. Some organisms coexist with the aggressive mutualistic ants: specialized herbivores and organisms using the enemy-free space. Conversely, trees inhabited by non-defending ants usually hold a greater load of generalist herbivores and are avoided by organisms looking for the ant protection. We aimed to elucidate the association type between swollen-thorn acacias (Vachellia collinsii) and the almost unstudied Pseudomyrmex simulans ants from Panama. We compared the presence of non-ant organisms on trees inhabited by P. simulans, a well-known mutualist (P. spinicola) and a facultative parasite (non-defending ants; Crematogaster crinosa). We recorded non-ant organisms (e.g., stem galls, acacia true bugs, spiders) that nest, lay eggs, or live on the trees. Except for stem galls, all other non-ant organisms were mostly or exclusively found on trees with the mutualists, which is also the most common resident ant. P. simulans is less able to deter galling midges (Cecidomyiidae) than C. crinosa and even less than P. spinicola, because trees with P. simulans were more likely to have galls and in greater densities than on C. crinosa-trees, and even more than on P. spinicola-inhabited trees. The mechanism by which the Cecidomyiids occur in greater proportion on trees with P. simulans and C. crinosa is still unknown, but the pattern indicates an herbivory specialization or a potentially obligate weaker defender of the swollen-thorn acacias. Abstract in Spanish is available with online material

ID: 158779
Type: article
Authors: Anker, Arthur; Leray, Matthieu; Pachelle, Paulo P. G.
Keywords: STRI
Abstract: Alpheus viserion sp. n. is described based on the material from Bocas del Toro archipelago on the Caribbean coast of Panama. The new species is morphologically closest to three members of the speciose A. armillatus H. Milne-Edwards, 1837 species complex, viz. A. carlae Anker, 2012, A. angulosus McClure, 2002, and A. tenuis Kim & Abele, 1988, differing from them, as well as from all the other species currently included in this complex, by a suite of morphological characters and a diagnostic colour pattern. With the description of yet another new shrimp species from Bocas del Toro, the authors hope to contribute to the awareness that this archipelago represents one of the most biologically diverse places in the Caribbean Sea and to encourage the preservation of the remaining natural habitats of this unique area.

ID: 159181
Type: article
Authors: Arellano, Gabriel; Zuleta, Daniel; Davies, Stuart J.
Keywords: STRI
Abstract: Tree mortality drives changes in forest structure and dynamics, community composition, and carbon and nutrient cycles. Since tropical forests store a large fraction of terrestrial biomass and tree diversity, improved understanding of changing tree mortality and biomass loss rates is critical. Tropical tree mortality rates have been challenging to estimate due to low background rates of tree death, and high spatial and temporal heterogeneity. Furthermore, the causes of mortality remain unclear because many factors may be involved in individual tree death, and the rapid decomposition of wood in the tropics obscures evidence of possible causes of tree mortality. We present a field protocol to assess tree mortality in tropical forests. The protocol focuses on the rapid, repeatable and inexpensive assessment of individual tree death and damage. The protocol has been successfully tested with annual assessments of >62,000 stems in total in several ForestGEO plots in Asia and the Neotropics. Standardized methods for the assessment of tree death and biomass loss will advance understanding of the underlying causes and consequences of tree mortality.

ID: 157996
Type: article
Authors: Avila-Cervantes, Jose; Arias, Carlos; Venegas-Anaya, Miryam; Vargas, Marta; Larsson, Hans C. E.; McMillan, W. Owen
Keywords: STRI
Abstract: The final formation of the Central American Isthmus (CAI) about 3.5 million years ago altered global ocean circulation, connected North and South America terrestrial biotas, and established the Caribbean Sea. The nature of this event creates a natural scenario to test vicariance, divergence, and speciation by allopatry. Studies have shown the effect of the CAI on marine and terrestrial species, but none have examined a large-bodied amphibious taxon. We used RAD sequencing on populations of the American crocodile (Crocodylus acutus) to study the genomic variation of C. acutus on both sides of the CAI, infer its demographic history, and measure the effect of the opening of the Panama Canal. Our results showed three genomic clusters: (1) Caribbean and the Panama Canal, (2) Pacific coast, and (3) Coiba island. The estimated divergence times between the Caribbean and Pacific populations are about 20,000 years ago, which is younger than the formation of the CAI, coinciding with the Last Glacial Maximum. We hypothesize the glacial/interglacial cycles facilitated gene flow between the Caribbean and Pacific crocodile populations after the formation of the CAI, masking any genomic divergence the CAI may have caused. There is no evidence of gene flow associated with the opening of the Panama Canal.

ID: 158627
Type: article
Authors: Baird, Andrew H.; Guest, James R.; Edwards, Alasdair J.; Bauman, Andrew G.; Bouwmeester, Jessica; Mera, Hanaka; Abrego, David; Alvarez-Noriega, Mariana; Babcock, Russel C.; Barbosa, Miguel B.; Bonito, Victor; Burt, John; Cabaitan, Patrick C.; Chang, Ching-Fong; Chavanich, Suchana; Chen, Chaolun A.; Chen, Chieh-Jhen; Chen, Wei-Jen; Chung, Fung-Chen; Connolly, Sean R.; Cumbo, Vivian R.; Dornelas, Maria; Doropoulos, Christopher; Eyal, Gal; Eyal-Shaham, Lee; Fadli, Nur; Figueiredo, Joana; Flot, Jean-Francois; Gan, Sze-Hoon; Gomez, Elizabeth; Graham, Erin M.; Grinblat, Mila; Gutierrez-Isaza, Nataly; Harii, Saki; Harrison, Peter L.; Hatta, Masayuki; Ho, Nina Ann Jin; Hoarau, Gaetan; Hoogenboom, Mia; Howells, Emily J.; Iguchi, Akira; Isomura, Naoko; Jamodiong, Emmeline A.; Jandang, Suppakarn; Keyse, Jude; Kitanobo, Seiya; Kongjandtre, Narinratana; Kuo, Chao-Yang; Ligson, Charlon; Lin, Che-Hung; Low, Jeffrey; Loya, Yossi; Maboloc, Elizaldy A.; Madin, Joshua S.; Mezaki, Takuma; Min, Choo; Morita, Masaya; Moya, Aurelie; Neo, Su-Hwei; Nitschke, Matthew R.; Nojima, Satoshi; Nozawa, Yoko; Piromvaragorn, Srisakul; Plathong, Sakanan; Puill-Stephan, Eneour; Quigley, Kate; Ramirez-Portilla, Catalina; Ricardo, Gerard; Sakai, Kazuhiko; Sampayo, Eugenia; Shlesinger, Tom; Sikim, Leony; Simpson, Chris; Sims, Carrie A.; Sinniger, Frederic; Spiji, Davies A.; Tabalanza, Tracy; Tan, Chung-Hong; Terraneo, Tullia I.; Torda, Gergely; True, James; Tun, Karenne; Vicentuan, Kareen; Viyakarn, Voranop; Waheed, Zarinah; Ward, Selina; Willis, Bette; Woods, Rachael M.; Woolsey, Erika S.; Yamamoto, Hiromi H.; Yusuf, Syafyudin
Keywords: NZP; STRI
Abstract: The discovery of multi-species synchronous spawning of scleractinian corals on the Great Barrier Reef in the 1980s stimulated an extraordinary effort to document spawning times in other parts of the globe. Unfortunately, most of these data remain unpublished which limits our understanding of regional and global reproductive patterns. The Coral Spawning Database (CSD) collates much of these disparate data into a single place. The CSD includes 6178 observations (3085 of which were unpublished) of the time or day of spawning for over 300 scleractinian species in 61 genera from 101 sites in the Indo-Pacific. The goal of the CSD is to provide open access to coral spawning data to accelerate our understanding of coral reproductive biology and to provide a baseline against which to evaluate any future changes in reproductive phenology.

ID: 158908
Type: article
Authors: Banbury Morgan, Rebecca; Herrmann, Valentine; Kunert, Norbert; Bond-Lamberty, Ben; Muller-Landau, Helene C.; Anderson-Teixeira, Kristina J.
Keywords: NZP; STRI
Abstract: Carbon (C) fixation, allocation, and metabolism by trees set the basis for energy and material flows in forest ecosystems and define their interactions with Earth's changing climate. However, while many studies have considered variation in productivity with latitude and climate, we lack a cohesive synthesis on how forest carbon fluxes vary globally with respect to climate and one another. Here, we draw upon 1,319 records from the Global Forest Carbon Database, representing all major forest types and the nine most significant autotrophic carbon fluxes, to comprehensively review how annual C cycling in mature, undisturbed forests varies with latitude and climate on a global scale. Across all flux variables analyzed, rates of C cycling decreased continuously with absolute latitude-a finding that confirms multiple previous studies and contradicts the idea that net primary productivity of temperate forests rivals that of tropical forests. C flux variables generally displayed similar trends across latitude and multiple climate variables, with no differences in allocation detected at this global scale. Temperature variables in general, and mean annual temperature or temperature seasonality in particular, were the best single predictors of C flux, explaining 19%-71% of variation in the C fluxes analyzed. The effects of temperature were modified by moisture availability, with C flux reduced under hot and dry conditions and sometimes under very high precipitation. Annual C fluxes increased with growing season length and were also influenced by growing season climate. These findings clarify how forest C flux varies with latitude and climate on a global scale. In an era when forests will play a critical yet uncertain role in shaping Earth's rapidly changing climate, our synthesis provides a foundation for understanding global patterns in forest C cycling.

ID: 158050
Type: article
Authors: Bayona, Germán; Baquero, Mauricio; Ramírez, Catalina; Tabares, Manuela; Salazar, Ana M.; Nova, Giovanny; Duarte, Edward; Pardo, Andrés; Plata, Angelo; Jaramillo, Carlos; Rodríguez, Guillermo; Caballero, Victor; Cardona, Agustín; Montes, Camilo; Gómez Marulanda, Sebastián; Cárdenas‐Rozo, Andrés L.
Keywords: STRI
Abstract: The onset of deformation in the northern Andes is overprinted by subsequent stages of basin deformation, complicating the examination of competing models illustrating potential location of earliest synorogenic basins and uplifts. To establish the width of the earliest northern Andean orogen, we carried out field mapping, palynological dating, sedimentary, stratigraphic and provenance analyses in Campanian to lower Eocene units exposed in the northern Eastern Cordillera of Colombia (Cocuy region) and compare the results with coeval succession in adjacent basins. The onset of deformation is recorded in earliest Maastrichtian time, as terrigenous detritus arrived into the basin marking the end of chemical precipitation and the onset of clastic deposition produced by the uplift of a western source area dominated by shaly Cretaceous rocks. Disconformable contacts within the upper Maastrichtian to middle Palaeocene succession document increasing supply of quartzose sandy detritus from Cretaceous quartzose rocks exposed in eastern source areas. The continued unroofing of both source areas produced a rapid shift in depositional environments from shallow marine in Maastrichtian to fluvial‐lacustrine systems during the Palaeocene‐early Eocene. Supply of immature Jurassic sandstones from nearby western uplifts, together with localized plutonic and volcanic Cretaceous rocks, caused a shift in Palaeocene sandstones composition from quartzarenites to litharenites. Supply of detrital sandy fragments, unstable heavy minerals and Cretaceous to Ordovician detrital zircons, were derived from nearby uplifted blocks and from SW fluvial systems within the synorogenic basin, instead of distal basement rocks. The presence of volcanic rock fragments and 51–59 Ma volcanic zircons constrain magmatism within the basin. The Maastrichtian–Palaeocene sequence studied here documents crustal deformation that correlates with coeval deformation farther south in Ecuador and Peru. Slab flattening of the subducting Caribbean plate produced a wider orogen (>400 km) with a continental magmatic arc and intra‐basinal deformation and magmatism.

ID: 158679
Type: article
Authors: Beldade, Ricardo; Longo, Gary C.; Clements, Kendall D.; Robertson, D. Ross; Perez-Matus, Alejandro; Itoi, Shiro; Sugita, Haruo; Bernardi, Giacomo
Keywords: STRI
Abstract: Nibblers (family Girellidae) are reef fishes that are mostly distributed in the Indo-Pacific, with one exception: Girella stuebeli, which is found in the Cabo Verde Archipelago, in the Atlantic Ocean. We capitalized on this unusual distribution to study the evolutionary history of the girellids, and determine the relationship between G. stuebeli and the remaining nibbler taxa. Based on thousands of genomic markers (RAD sequences), we identified the closest relatives of G. stuebeli as being a clade of three species endemic to the northwestern Pacific, restricted to the Sea of Japan and vicinity. This clade diverged from G. stuebeli approximately 2.2 Mya. Two alternative potential routes of migration may explain this affinity: a western route, from the Tropical Eastern Pacific and the Tropical Western Atlantic, and an eastern route via the Indian Ocean and Southern Africa. The geological history and oceanography of the regions combined with molecular data presented here, suggest that the eastern route of invasion (via the Indian Ocean and Southern Africa) is a more likely scenario.

ID: 158502
Type: article
Authors: Benites‐Palomino, Aldo; Vélez‐Juarbe, Jorge; Collareta, Alberto; Ochoa, Diana; Altamirano, Ali; Carré, Matthieu; Laime, Manuel J.; Urbina, Mario; Salas‐Gismondi, Rodolfo
Keywords: STRI

ID: 158773
Type: article
Authors: Bennett, Kelly L.; McMillan, W. Owen; Loaiza, Jose R.
Keywords: STRI
Abstract: Local adaptation is important when predicting arthropod-borne disease risk because of its impacts on vector population fitness and persistence. However, the extent that vector populations are adapted to the environment generally remains unknown. Despite low population structure and high gene flow in Aedes aegypti mosquitoes across Panama, excepting the province of Bocas del Toro, we identified 128 candidate SNPs, clustered within 17 genes, which show a strong genomic signal of local environmental adaptation. This putatively adaptive variation occurred across fine geographical scales with the composition and frequency of candidate adaptive loci differing between populations in wet tropical environments along the Caribbean coast and dry tropical conditions typical of the Pacific coast. Temperature and vegetation were important predictors of adaptive genomic variation in Ae. aegypti with several potential areas of local adaptation identified. Our study lays the foundations of future work to understand whether environmental adaptation in Ae. aegypti impacts the arboviral disease landscape and whether this could either aid or hinder efforts of population control.

ID: 158769
Type: article
Authors: Bennett, Kelly L.; Owen McMillan, W.; Enriquez, Vanessa; Barraza, Elia; Diaz, Marcela; Baca, Brenda; Whiteman, Ari; Cerro Medina, Jaime; Ducasa, Madeleine; Gomez Martinez, Carmelo; Almanza, Alejandro; Rovira, Jose R.; Loaiza, Jose R.
Keywords: STRI
Abstract: Monitoring the invasion process of the Asian tiger mosquito Aedes albopictus and its interaction with the contender Aedes aegypti, is critical to prevent and control the arthropod-borne viruses (i.e., Arboviruses) they transmit to humans. Generally, the superior ecological competitor Ae. albopictus displaces Ae. aegypti from most geographic areas, with the combining factors of biology and environment influencing the competitive outcome. Nonetheless, detailed studies asserting displacement come largely from sub-tropical areas, with relatively less effort being made in tropical environments, including no comprehensive research about Aedes biological interactions in Mesoamerica. Here, we examine contemporary and historical mosquito surveillance data to assess the role of shifting abiotic conditions in shaping the spatiotemporal distribution of competing Aedes species in the Republic of Panama. In accordance with prior studies, we show that Ae. albopictus has displaced Ae. aegypti under suboptimal wet tropical climate conditions and more vegetated environments within the southwestern Azuero Peninsula. Conversely, in the eastern Azuero Peninsula, Ae. aegypti persists with Ae. albopictus under optimal niche conditions in a dry and more seasonal tropical climate. While species displacement was stable over the course of two years, the presence of both species generally appears to fluctuate in tandem in areas of coexistence. Aedes albopictus was always more frequently found and abundant regardless of location and climatic season. The heterogenous environmental conditions of Panama shape the competitive outcome and micro-geographic distribution of Aedes mosquitoes, with potential consequences for the transmission dynamics of urban and sylvatic zoonotic diseases.

ID: 159176
Type: article
Authors: Birch, Andrew L.; Stallard, Robert F.; Barnard, Holly R.
Keywords: STRI
Abstract: Mechanisms of runoff generation in the humid tropics are poorly understood, particularly in the context of land-use/land cover change. This study analyzed the results of 124 storm hydrographs from three humid tropical catchments of markedly different vegetation cover and land-use history in central Panama during the 2017 wet season: actively grazed pasture, young secondary succession, and near-mature forest. We used electrical conductivity to separate baseflow (old water) from storm-event water (new-water). In all three land covers, new-water dominated storm runoff generation in 44% of the sampled storm events, indicating the dominance of fast shallow flow paths in the landscape. Activation of these flow paths was found to depend on a combination of maximum rainfall intensity and total storm rainfall, which, in turn, relates to markedly contrasting hydrograph separation results among land covers. Relationships between these rainfall characteristics and storm runoff generation were nonlinear, producing a threshold response with the exceedance of specific rainfall volumes and/or intensities. The pastoral catchment delivered order of magnitude more new-water during storm events than the two forested catchments. Although new-water contributed minimally (<10%) to total wet season runoff in the forested catchments, 43% of runoff generation in the pasture came from five large rainfall events where a threshold response produced substantial increases in total runoff and new-runoff efficiency. Based on our results, we propose a conceptual model of hydrologic flow paths in humid tropical systems that can explain previously observed disparities in seasonal storage and runoff with respect to land use/land cover.

ID: 158170
Type: article
Authors: Boyle, Michael J. W.; Bishop, Tom R.; Luke, Sarah H.; van Breugel, Michiel; Evans, Theodore A.; Pfeifer, Marion; Fayle, Tom M.; Hardwick, Stephen R.; Lane-Shaw, Rachel Isolde; Yusah, Kalsum M.; Ashford, Imogen C. R.; Ashford, Oliver S.; Garnett, Emma; Turner, Edgar C.; Wilkinson, Clare L.; Chung, Arthur Y. C.; Ewers, Robert M.
Keywords: STRI
Abstract: Logging and habitat conversion create hotter microclimates in tropical forest landscapes, representing a powerful form of localised anthropogenic climate change. It is widely believed that these emergent conditions are responsible for driving changes in communities of organisms found in modified tropical forests, although the empirical evidence base for this is lacking. Here we investigated how interactions between the physiological traits of genera and the environmental temperatures they experience lead to functional and compositional changes in communities of ants, a key organism in tropical forest ecosystems. We found that the abundance and activity of ant genera along a gradient of forest disturbance in Sabah, Malaysian Borneo, was defined by an interaction between their thermal tolerance (CTmax) and environmental temperature. In more disturbed, warmer habitats, genera with high CTmax had increased relative abundance and functional activity, and those with low CTmax had decreased relative abundance and functional activity. This interaction determined abundance changes between primary and logged forest that differed in daily maximum temperature by a modest 1.1 degrees C, and strengthened as the change in microclimate increased with disturbance. Between habitats that differed by 5.6 degrees C (primary forest to oil palm) and 4.5 degrees C (logged forest to oil palm), a 1 degrees C difference in CTmax among genera led to a 23% and 16% change in relative abundance, and a 22% and 17% difference in functional activity. CTmax was negatively correlated with body size and trophic position, with ants becoming significantly smaller and less predatory as microclimate temperatures increased. Our results provide evidence to support the widely held, but never directly tested, assumption that physiological tolerances underpin the influence of disturbance-induced microclimate change on the abundance and function of invertebrates in tropical landscapes. A free Plain Language Summary can be found within the Supporting Information of this article.

ID: 157931
Type: article
Authors: Byers, Kelsey J. R. P.; Darragh, Kathy; Fernanda Garza, Sylvia; Abondano Almeida, Diana; Warren, Ian A.; Rastas, Pasi M. A.; Merrill, Richard M.; Schulz, Stefan; McMillan, W. Owen; Jiggins, Chris D.
Keywords: STRI
Abstract: The degree to which loci promoting reproductive isolation cluster in the genome-that is, the genetic architecture of reproductive isolation-can influence the tempo and mode of speciation. Tight linkage between these loci can facilitate speciation in the face of gene flow. Pheromones play a role in reproductive isolation in many Lepidoptera species, and the role of endogenously produced compounds as secondary metabolites decreases the likelihood of pleiotropy associated with many barrier loci. Heliconius butterflies use male sex pheromones to both court females (aphrodisiac wing pheromones) and ward off male courtship (male-transferred antiaphrodisiac genital pheromones), and it is likely that these compounds play a role in reproductive isolation between Heliconius species. Using a set of backcross hybrids between H. melpomene and H. cydno, we investigated the genetic architecture of putative male pheromone compound production. We found a set of 40 significant quantitative trait loci (QTL) representing 33 potential pheromone compounds. QTL clustered significantly on two chromosomes, chromosome 8 for genital compounds and chromosome 20 for wing compounds, and chromosome 20 was enriched for potential pheromone biosynthesis genes. There was minimal overlap between pheromone QTL and known QTL for mate choice and color pattern. Nonetheless, we did detect linkage between a QTL for wing androconial area and optix, a color pattern locus known to play a role in reproductive isolation in these species. This tight clustering of putative pheromone loci might contribute to coincident reproductive isolating barriers, facilitating speciation despite ongoing gene flow.

ID: 159226
Type: article
Authors: Carrillo-Briceño, Jorge D.; Sánchez, Rodolfo; Scheyer, Torsten M.; Carrillo, Juan D.; Delfino, Massimo; Georgalis, Georgios L.; Kerber, Leonardo; Ruiz-Ramoni, Dami; Birindelli, José L. O.; Cadena, Edwin-Alberto; Rincón, Aldo F.; Chavez-Hoffmeister, Martin; Carlini, Alfredo A.; Carvalho, Mónica R.; Trejos-Tamayo, Ra; Vallejo, Felipe; Jaramillo, Carlos; Jones, Douglas S.; Sánchez-Villagra, Marcelo R.
Keywords: STRI
Abstract: The Pliocene–Pleistocene transition in the Neotropics is poorly understood despite the major climatic changes that occurred at the onset of the Quaternary. The San Gregorio Formation, the younger unit of the Urumaco Sequence, preserves a fauna that documents this critical transition. We report stingrays, freshwater bony fishes, amphibians, crocodiles, lizards, snakes, aquatic and terrestrial turtles, and mammals. A total of 49 taxa are reported from the Vergel Member (late Pliocene) and nine taxa from the Cocuiza Member (Early Pleistocene), with 28 and 18 taxa reported for the first time in the Urumaco sequence and Venezuela, respectively. Our findings include the first fossil record of the freshwater fishes Megaleporinus , Schizodon , Amblydoras , Scorpiodoras , and the pipesnake Anilius scytale , all from Pliocene strata. The late Pliocene and Early Pleistocene ages proposed here for the Vergel and Cocuiza members, respectively, are supported by their stratigraphic position, palynology, nannoplankton, and 86 Sr/ 88 Sr dating. Mammals from the Vergel Member are associated with the first major pulse of the Great American Biotic Interchange. In contrast to the dry conditions prevailing today, the San Gregorio Formation documents mixed open grassland/forest areas surrounding permanent freshwater systems, following the isolation of the northern South American basin from western Amazonia. These findings support the hypothesis that range contraction of many taxa to their current distribution in northern South America occurred rapidly during at least the last 1.5 million years.

ID: 159244
Type: article
Authors: Carvalho, Monica R.; Herrera, Fabiany; Gomez, Sebastian; Martinez, Camila; Jaramillo, Carlos
Keywords: STRI
Abstract: Premise of research. Melastomataceae are a diverse and primarily tropical family with a particularly sparse fossil record. Various biogeographic interpretations based on phylogenies, extant distribution, and a limited fossil record have placed the origin of the family in either Laurasia or Gondwana (eastern or western). Methodology. We describe Xystonia simonae M. Carvalho gen. et sp. nov. on the basis of fossil leaves from middle-late Paleocene deposits of the Bogota Formation in central Colombia. These leaves have a characteristic acrodromous venation pattern common among subfamily Melastomatoideae. The leaves are compared with various acrodromously veined fossils and living angiosperms to assess their natural affinities. Pivotal results. The fossil leaves described predate the earliest known occurrence of Melastomatoideae by 5-7 Myr and conflict with previous interpretations that considered Melastomatoideae as Laurasian in origin. In revising the fossil record of Melastomataceae, we reevaluated the age of Melastomaephyllum danielis Huert. to be Miocene (previously Eocene/Oligocene) using pollen obtained from the rock that contained the type specimen. Conclusions. Our findings contribute to the scant early records of Melastomataceae and show that Melastomatoideae was part of a tropical rain forest assemblage by the middle-late Paleocene. Leaf galls and other leaf damage on X. simonae evidence intense and specialized biotic interactions in the early evolution of this lineage.