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Agrawal, Anurag A. ; Boroczky, Katalin ; Haribal, Meena ; Hastings, Amy P. ; White, Ronald, A. ; Jiang, Ren-Wang ; Duplais, Christophe |
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Cardenolides, toxicity, and the costs of sequestration in the coevolutionary interaction between monarchs and milkweeds |
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Journal Article |
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2021 |
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PNAS |
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118 |
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16 |
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e2024463118 |
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For highly specialized insect herbivores, plant chemical defenses are often co-opted as cues for oviposition and sequestration. In such interactions, can plants evolve novel defenses, pushing herbivores to trade off benefits of specialization with costs of coping with toxins? We tested how variation in milkweed toxins (cardenolides) impacted monarch butterfly ( Danaus plexippus ) growth, sequestration, and oviposition when consuming tropical milkweed ( Asclepias curassavica ), one of two critical host plants worldwide. The most abundant leaf toxin, highly apolar and thiazolidine ring–containing voruscharin, accounted for 40% of leaf cardenolides, negatively predicted caterpillar growth, and was not sequestered. Using whole plants and purified voruscharin, we show that monarch caterpillars convert voruscharin to calotropin and calactin in vivo, imposing a burden on growth. As shown by in vitro experiments, this conversion is facilitated by temperature and alkaline pH. We next employed toxin-target site experiments with isolated cardenolides and the monarch’s neural Na + /K + -ATPase, revealing that voruscharin is highly inhibitory compared with several standards and sequestered cardenolides. The monarch’s typical >50-fold enhanced resistance to cardenolides compared with sensitive animals was absent for voruscharin, suggesting highly specific plant defense. Finally, oviposition was greatest on intermediate cardenolide plants, supporting the notion of a trade-off between benefits and costs of sequestration for this highly specialized herbivore. There is apparently ample opportunity for continued coevolution between monarchs and milkweeds, although the diffuse nature of the interaction, due to migration and interaction with multiple milkweeds, may limit the ability of monarchs to counteradapt. |
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National Academy of Sciences |
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EcoFoG @ webmaster @ |
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1014 |
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Poorter, Laurens ; Craven, Dylan ; Jakovac, Catarina C. ; van der Sande, Masha T. ; Amissah, Lucy ; Bongers, Frans ; Chazdon, Robin ; Farrioir, Caroline E. ; Kambach, Stephan ; Meave, Jorge A. ; Munoz, Rodrigo ; Norden, Natalia ; Ruger, Nadja ; van Breugel, Michiel ; et all ...... |
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Multidimensional tropical forest recovery |
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Journal Article |
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2021 |
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Science |
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374 |
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6573 |
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1370-1376 |
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Tropical forests disappear rapidly because of deforestation, yet they have the potential to regrow naturally on abandoned lands. We analyze how 12 forest attributes recover during secondary succession and how their recovery is interrelated using 77 sites across the tropics. Tropical forests are highly resilient to low-intensity land use; after 20 years, forest attributes attain 78% (33 to 100%) of their old-growth values. Recovery to 90% of old-growth values is fastest for soil (<1 decade) and plant functioning (<2.5 decades), intermediate for structure and species diversity (2.5 to 6 decades), and slowest for biomass and species composition (>12 decades). Network analysis shows three independent clusters of attribute recovery, related to structure, species diversity, and species composition. Secondary forests should be embraced as a low-cost, natural solution for ecosystem restoration, climate change mitigation, and biodiversity conservation. |
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American association for the advancement of science |
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EcoFoG @ webmaster @ |
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1039 |
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Llusia, Joan ; Asensio, Dolores ; Sardans, Jordi ; Filella, Iolanda ; Peguero, Guille ; Grau, Oriol ; Ogaya, Roma ; Gargallo-Garriga, Albert ; Verryckt, Lore T. ; Van Langenhove, Leandro ; Brechet, Laëtitia M. ; Courtois, Elodie A. ; Stahl, Clément ; Janssens, Ivan A. ; Penuelas, Josep |
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Contrasting nitrogen and phosphorus fertilization effects on soil terpene exchanges in a tropical forest |
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Journal Article |
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2021 |
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Science of the Total Environment |
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802 |
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149769 |
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Production, emission, and absorption of biogenic volatile organic compounds (BVOCs) in ecosystem soils and associated impacts of nutrient availability are unclear; thus, predictions of effects of global change on source-sink dynamic under increased atmospheric N deposition and nutrition imbalances are limited. Here, we report the dynamics of soil BVOCs under field conditions from two undisturbed tropical rainforests from French Guiana. We analyzed effects of experimental soil applications of nitrogen (N), phosphorus (P), and N + P on soil BVOC exchanges (in particular of total terpenes, monoterpenes, and sesquiterpenes), to determine source and sink dynamics between seasons (dry and wet) and elevations (upper and lower elevations corresponding to top of the hills (30 m high) and bottom of the valley). We identified 45 soil terpenoids compounds emitted to the atmosphere, comprising 26 monoterpenes and 19 sesquiterpenes; of these, it was possible to identify 13 and 7 compounds, respectively. Under ambient conditions, soils acted as sinks of these BVOCs, with greatest soil uptake recorded for sesquiterpenes at upper elevations during the wet season (-282 μg m-2 h-1). Fertilization shifted soils from a sink to source, with greatest levels of terpene emissions recorded at upper elevations during the wet season, following the addition of N (monoterpenes: 406 μg m-2 h-1) and P (sesquiterpenes: 210 μg m-2 h-1). Total soil terpene emission rates were negatively correlated with total atmospheric terpene concentrations. These results indicate likely shifts in tropical soils from sink to source of atmospheric terpenes under projected increases in N deposition under global change, with potential impacts on regional-scale atmospheric chemistry balance and ecosystem function. |
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Elsevier |
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EcoFoG @ webmaster @ |
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1033 |
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Van Langenhove, Leandro ; Depaepe, Thomas ; Verryckt, Lore T. ; Fuchslueger, Lucia ; Donald, Julian ; Celine, Leroy ; Krishna Moorthy, Sruthi M. ; Gargallo-Garriga, Albert ; Farnon Ellwood, M. D.; Verbeeck, Hans ; Van Der Straeten, Dominique ; Penuelas, Josep ; Janssens, Ivan A. |
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Comparable canapy and soil free living nitrogen fixation rates in e lowland tropical forest |
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Journal Article |
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2021 |
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Science of the total environment |
Abbreviated Journal |
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754 |
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Biodiversité ; Systématique ; phylogénie ; taxonomie ; Ecologie, Environnement ; Ecosystèmes ; Biologie végétale ; Botanique ; Biodiversité |
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Biological nitrogen fixation (BNF) is a fundamental part of nitrogen cycling in tropical forests, yet little is known about the contribution made by free-living nitrogen fixers inhabiting the often-extensive forest canopy. We used the acetylene reduction assay, calibrated with 15N2, to measure free-living BNF on forest canopy leaves, vascular epiphytes, bryophytes and canopy soil, as well as on the forest floor in leaf litter and soil. We used a combination of calculated and published component densities to upscale free-living BNF rates to the forest level. We found that bryophytes and leaves situated in the canopy in particular displayed high mass-based rates of free-living BNF. Additionally, we calculated that nearly 2 kg of nitrogen enters the forest ecosystem through free-living BNF every year, 40% of which was fixed by the various canopy components. Our results reveal that in the studied tropical lowland forest a large part of the nitrogen input through free-living BNF stems from the canopy, but also that the total nitrogen inputs by free-living BNF are lower than previously thought and comparable to the inputs of reactive nitrogen by atmospheric deposition. |
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Elsevier |
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Anglais |
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EcoFoG @ webmaster @ |
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1006 |
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Van Langenhove, Leandro ; Verryckt, Lore T. ; Stahl, Clement ; Courtois, Elodie A. ; Urbina, Ifigenia ; Grau, Oriol ; Asensio, Dolores ; Peguero, Guille ; Margalef, Olga ; Freycon, Vincent ; Penuelas, Josep ; Janssens, Ivan A. |
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Soil nutrient variation along a shallow catena in Paracou, French Guiana |
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Journal Article |
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2021 |
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Soil Research |
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59 |
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2 |
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130 |
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French Guiana, lowland tropical forest, Paracou, phosphorus, topography, water drainage. |
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Tropical forests are generally considered to stand upon nutrient-poor soils, but soil nutrient concentrations and availabilities can vary greatly at local scale due to topographic effects on erosion and water drainage. In this study we physically and chemically characterised the soils of 12 study plots situated along a catena with a shallow slope in a tropical rainforest in French Guiana both during the wet and the dry season to evaluate seasonal differences. Soils along the catena were all Acrisols, but differed strongly in their water drainage flux. Over time, this differential drainage has led to differences in soil texture and mineral composition, affecting the adsorption of various nutrients, most importantly phosphorus. The more clayey soils situated on the slope of the catena had higher total concentrations of carbon, nitrogen, phosphorus and several micronutrients, while extractable nutrient concentrations were highest in the sandiest soils situated at the bottom of the catena. We found that carbon, nitrogen and extractable nutrients all varied seasonally, especially in the surface soil layer. These results are interesting because they show that, even at the local scale, small differences in topography can lead to large heterogeneity in nutrient concentrations, which can have large impacts on plant and microbial community organisation at the landscape level. |
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CSIRO Publishing |
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EcoFoG @ webmaster @ |
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1042 |
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Barr, Cheryl B. ; Cerdan, Axel ; Clavier, Simon ; Murienne, Jérôme |
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Amazonopsis cerdani (Coleoptera: Elmidae: Elminae), a New Species of RiffleBeetle from French Guiana with Habitat Observations |
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Journal Article |
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2021 |
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The Coleopterists Bulletin |
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75 |
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2 |
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427-439 |
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A third species of Amazonopsis , Amazonopsis cerdani Barr and Cerdan, new species (Coleoptera: Elmidae), is herein described from French Guiana. One female paratype of Amazonopsis theranyi Barr from Peru is tentatively reassigned to A. cerdani as a non-paratype. Photographic images of the male and female habitus, and the male genitalia, are provided, as is a distribution map and a key to the species. Amazonopsis cerdani differs from A. theranyi from Peru and Amazonopsis camachoi Barr from Venezuela by the presence of prominent spines on protarsomeres 1–4 of males, among other characters. The habitat of this species is small, shallow, lowland streams with sandy-silty substrates and low flow. Specimens were collected from unconsolidated leaf litter in depositional areas, and from stick and leaf packs lodged in the current. Genetic analysis conducted on three specimens from two localities, a male and two females, showed that they are conspecific. |
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BioOne |
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EcoFoG @ webmaster @ |
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1035 |
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Gonzalès-Melo, Andrès ; Posada, Juan Manuel ; Beauchêne, Jacques ; Lehnebach, Romain ; Leviennois, Sébastien ; Rivera, Katherine ; Clair, Bruno |
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Radial variations in wood functional traits in a rain forest from eastern Amazonia |
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Journal Article |
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2021 |
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Trees |
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36 |
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569–581 |
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Trees can modify their wood structure in response to changes in mechanical, hydraulic and storage demands during their life-cycles. Thus, examining radial variations in wood traits is important to expand our knowledge of tree functioning and species ecological strategies. Yet, several aspects of radial changes in wood functional traits are still poorly understood, especially in angiosperm trees from tropical humid forests. Here, we examined radial shifts in wood traits in trunks of tropical forest species and explored their potential ecological implications. We first examined radial variations in wood specific gravity (WSG). Then, we asked what anatomical traits drove radial variations in WSG, and whether WSG, vessel fraction and specific hydraulic conductivity vary independently from each other along the radius gradients. We measured WSG and eight wood anatomical traits, at different radial positions along the trunks, in 19 tree species with contrasting shade-tolerance from a lowland tropical forest in eastern Amazonia. Most species had significant radials shifts in WSG. Positive radial gradients in WSG (i.e., increments from pith to bark) were common among shade-intolerant species and were explained by different combinations of fiber and parenchyma traits, while negative radial shifts in WSG (e.g., decreases towards the bark) were present in shade-tolerants, but were generally weakly related to anatomical traits. We also found that, in general, WSG was unrelated to vessel fraction and specific hydraulic conductivity in any radial position. This study illustrates the contrasting radial variations in wood functional traits that occur in tree species from a humid lowland tropical forest. In particular, our results provide valuable insights into the anatomical traits driving WSG variations during tree development. These insights are important to expand our knowledge on tree ecological strategies by providing evidence on how wood allocation varies as trees grow, which in turn can be useful in studying trait-demography associations, and in estimating tree above-ground biomass. |
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Springer Link |
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EcoFoG @ webmaster @ |
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1037 |
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Lormée, Hervé ; Berzins, Rachel ; Rocheteau, Vincent ; De Coster, Fran ; Denis, Thomas ; Richard-Hanssen, Cécile |
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Seasonal Variation in the Home Ranges of Black Curassow, Crax alector, in French Guiana |
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2021 |
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Tropical Conservation Science |
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14 |
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1 |
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1-10 |
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spatial ecology, Cracids, tracking, Kernel method, Home range, movement pattern |
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Cracidae is the most threatened avian family in the Neotropics, mainly because of habitat destruction, heavy hunting pressure and poaching. In French Guiana, Black Curassows are heavily hunted, although basic knowledge of the ecological and demographical traits of the species remains limited. Such a gap prevents any attempt to assess the impact of hunting and to help stakeholders to develop proposals ensuring hunting sustainability. The spatial relationship between animals and their habitat is important for conservation management, being related to population densities through complex patterns. Here, we report on a radio-tracking study of Black Curassows in tropical primary rainforest, in Nouragues National Reserve, French Guiana. The aims of the study were to estimate home range size and its variation across seasons, and to quantify movement patterns of the birds. We captured and fitted VHF tags to four adults, and tracked them for 10 to 21.5 months. Daily movements were recorded, and home ranges estimated using the Kernel Density method, for two consecutive wet seasons and one dry season. Using 95% and 50% Kernel densities, the average annual home range and core area were 96.3± 32.6 ha (SE) and 22.8 ± 2.8 ha respectively. Home ranges appeared spatially stable over the two years, and overlapped between neighbouring groups. During the dry season, Black Curassows did not migrate but tended to enlarge their home range, with greater daily movements and higher home range overlap. Although additional data are still needed, our results can help to improve the knowledge and management of this poorly studied species |
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SAGE |
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EcoFoG @ webmaster @ |
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1036 |
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Campos Barros, Luisa Antonia ; Chaul, Julio Cezar Mario ; Orivel, Jérome ; Cardoso de Aguiar, Hilton Jeferson Alves |
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Cytogenetics of Strumigenys louisianae Roger, 1863 (Formicidae: Myrmicinae) from North-eastern Amazonia shed light on a difficult species complex |
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2021 |
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Zoologischer Anzeiger |
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294 |
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100-105 |
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Cytogenetic techniques provide powerful insights on species-rich taxa–such as ants–allowing better understanding of their biodiversity. Some hints on evolutionary paths can be observed through comparative populational cytogenetics among different ant groups. In this study, the karyotype of Strumigenys louisianae Roger from the Amazon rainforest is described and showed diploid chromosome number of 26 chromosomes. This configuration intriguingly contrasts with the already described karyotype for this species from the Atlantic rainforest with only 2n = 4 chromosomes. 18S rDNA site were detected on the pericentromeric region of the long arm of a metacentric pair and co-localizing with GC-rich chromatin. Recurrent synonymizations of S. louisianae may not reflect the species status of this taxon. The karyotypic differences and the observable morphological variation between the populations of both localities corroborates the idea of a species complex within S. louisianae. The morphology of S. louisianae from the Amazonian region is similar to that from the United States, the type locality. On the other hand, specimens from the Atlantic rainforest are more similar to the junior synonym Strumigenys unidentata Mayr. This study reinforces the need of taxonomical revision in S. louisianae by means of integrative taxonomy approaches. |
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Elsevier |
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EcoFoG @ webmaster @ |
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1028 |
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