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Introduction history and genetic diversity of the invasive ant Solenopsis geminata in the Gala´pagos Islands
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The Gala´pagos Islands constitute one of the most pristine tropical systems on Earth. However, the complex and fragile equilibrium of native species is threatened by invasive species, among which is one of the most successful ants in the world, the tropical fire ant, Solenopsis geminata. We characterized the genetic structure and diversity of populations of S. geminata in the Galapagos Islands and unravelled the archipelago colonization by combining Bayesian clustering methods and coalescent-based scenario testing. Using 12 microsatellite markers and one mitochondrial DNA fragment (COI), we analysed individuals collected in all main invaded islands of the archipelago and from the native areas in Costa Rica and mainland Ecuador. We also used mitochondrial DNA to infer evolutionary relationships of samples collected in Galapagos Islands, Ecuador, Costa Rica and other Latin American countries. Our results showed that genetic diversity was significantly lower in Galapagos Islands and mainland Ecuador populations when compared to Costa Rican populations, and that samples from Galapagos Islands and mainland Ecuador (Guayaquil) clustered in a single group and all share a single mtDNA haplotype. Approximate Bayesian Computation favoured a scenario assuming that populations from Galapagos Islands diverged from mainland Ecuador. The city of Guyaquil, an obligatory hub for tourism and trade, could act as a bridgehead.
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RBINS Staff Publications 2018
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Impact of Laying Date and Fire Ants on Hatchlings of Chelonoidis porteri on Santa Cruz Island, Galápagos, Ecuador
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Chelonoidis land tortoises are iconic species endemic to the Galápagos Islands of Ecuador. Their populations have been dramatically reduced by human activities in the last three centuries, including indirect effects such as the introduction of invasive species. We investigated the mortality of eggs and hatchlings in 48 nests of Chelonoidis porteri on Santa Cruz Island with regard to various mortality causes such as the occurrence of fire ants and the date of laying. The average mortality rate was 0.56. Tropical Fire Ants (Solenopsis geminata) were present within 1 m of 75% of the C. porteri nests, and we encountered fire ants in 12.5% of excavated nests. We found no relationship between Tropical Fire Ant abundance and C. porteri egg and hatchling survivorship. We observed no signs of mold inside the nests. We determined that early deposition dates were associated with lower clutch survival and identified egg development as the critical life stage. Finally, we discuss the potential impacts of fire ants and climate change on tortoise survival and reproduction and stress the importance of taking these factors into account for the conservation of the endemic land tortoises of the Galápagos
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RBINS Staff Publications 2018
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Espaces verts comme une alternative de conservation de la biodiversité en villes : le cas des fourmis (Hyménoptère : Formicidae) dans le district d’Abidjan (Côte d’Ivoire)
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Objectif: Cette étude vise à évaluer le rôle des espaces verts dans la préservation de la biodiversité dans le district d’Abidjan (Côte d’Ivoire). Les fourmis ont été utilisées comme des indicateurs biologiques afin d’examiner l’influence des activités anthropiques sur la biodiversité de ces habitats localisés dans la matrice urbaine. Méthodologie et résultats : Les fourmis ont été collectées à l’aide d’appât de thon et du protocole ALL (pièges fosses et Winkler) dans trois types d’espaces verts (espaces verts publics, jardins botaniques et le Parc National du Banco). Les résultats indiquent que les espaces verts sont pollués (pourcentage de nuisance compris entre 1,7 % et 28,8 %) et illégalement occupés (pourcentage d’occupation compris entre 1,08 % à 52,3 %) par les activités humaines. Ces milieux abritent toutefois une faune de fourmis riche avec 176 espèces collectées. De plus, les jardins botaniques et les espaces verts publics partagent 8,51 % et 42,55 % des espèces de fourmis avec le Parc National du Banco, malgré leur faible connectivité à cet habitat naturel. Conclusion et application : Cette étude suggère que les espaces verts du district d’Abidjan présentent des atouts de conservation de la biodiversité, en particulier les fourmis. Toutefois, l’occupation de ces milieux par les activités commerciales conduit à leur dégradation progressive et à la disparition des communautés animales et végétales. Les résultats de cette étude devraient interpeller les décideurs à définir une politique de gestion des espaces verts et parcs urbains afin de rehausser leur valeur de conservation de la biodiversité en ville.
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RBINS Staff Publications 2018
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Use of Soil and Litter Ants (Hymenoptera: Formicidae) as Biological Indicators of Soil Quality Under Different Land Uses in Southern Rwanda
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The use of soil and litter arthropods as biological indicators is a way to assess environmental changes, where ant species in particular may serve as important indicators of soil quality. This study aimed at relating the abundance of soil and litter ant species to soil parameters under different tree species, both native and exotic, and varieties of coffee and banana plantations. Variations were found in soil physicochemical parameters. A total of 30 species belonging to 14 genera, and four subfamilies, the Formicinae, Dorylinae, Myrmicinae, and Ponerinae were identified. Higher abundance was found in coffee plantations compared to banana plantations, exotic and native tree species. Species of Camponotus cinctellus and Odontomachus troglodytes occurred in all land uses which is a sign of tolerance to a wide range of soil properties. In addition, these species, together with Myrmicaria SP02, Phrynoponera gabonensis, Camponotus SP06, Myrmicaria opaciventris, Pheidole SP03, Tetramorium simillimum, Pheidole SP01, and Tetramorium laevithorax were not strongly correlated with soil physicochemical parameters. Species of Pheidole SP02 and Camponotus SP05 were restricted to specific soil physicochemical properties, while species of Tetramorium zonacaciae and Bothroponera talpa discriminated between native tree species, coffee plantations, soil organic carbon, sandy soil texture, and aggregate stability. We concluded that these ant species can differently indicate the soil quality depending on the land use. We recommended further studies in order to generalize these findings
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RBINS Staff Publications 2018
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Short-term changes in the structure of ant assemblages in a Guinean savanna under differing fire regimes at Lamto Scientific Reserve, Côte d’Ivoire
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To maintain savanna vegetation, mid-seasonal fire has been applied since 1961 in the Lamto Savanna (Côte d’Ivoire). However, this prescribed fire has not impeded tree encroachment during recent years, nor have its effects on insect assemblages been documented. Also the impact of tree intrusion on insect assemblages is poorly studied in savanna. To prevent tree density increasing, a change in fire regime might be a solution. In this study, we examined the effect of different fire regimes (early, mid-seasonal and late fires) on leaf-litter ant assemblages in order to suggest appropriate measures for preventing tree invasion without having an effect on insect communities. Sampling was implemented by combining pitfall trapping and leaf-litter sampling before and after three different fire regimes, early, mid-seasonal and late fires. While the ant species richness declined after the passage of early and mid-seasonal fires, significantly more species were found in the burnt savanna after the late fire. However, the losses or gains of species due to different fire regimes did not cause severe changes in the ant species composition. Of the functional groups identified, only the generalists and specialist predators were respectively strongly affected by the early and mid-seasonal fires, certainly due to micro-habitat modification. Based on the trends observed in the present study, we suggest sampling other invertebrate fauna in similar savanna plots to find out if other insect groups have similar reactions to the applied fire regimes.
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RBINS Staff Publications 2018
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FROM THEORY TO PRACTICE: A PHOTOGRAPHIC INVENTORY OF MUSEUM COLLECTIONS TO OPTIMIZE COLLECTION MANAGEMENT
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The digitization of museum specimens is a key priority in the Digital Era. Digital databases help to avoid unnecessary manipulation hazards to delicate collections, increase their accessibility to third party researchers, and contribute to the ongoing documentation of global biodiversity. Time, workforce and the need of specialized infrastructures limit the processing of the vast number of specimens in natural history collections. Cheaper, easy-to-use methods and volunteer programs are developing quickly to help bridge the gap. We present the results of combining citizen science for the digitization of an entomological collection in conjunction with the cooperation of a taxonomic expert for the remote identification of samples. In addition, we provide an assessment of the avoided monetary costs and the time needed for each step of the process. A photographic inventory of specimens belonging to the leaf beetle genus Calligrapha was compiled by volunteers using a low-cost compact camera and the species were identified using these images. Using digital photographs allowed for a rapid screening of specimens in the collection and resulted in an updated taxonomic identification of the Calligrapha collection at the Royal Belgian Institute of Natural Sciences. The pictures of the specimens and their original labels, as well as the new information from this endeavor were placed in an online public catalogue. This study demonstrates a worked example of how digitization has led to a practical, useful outcome through cooperation with an end user and highlights the value of museum collection digitization projects
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RBINS Staff Publications 2018
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IMPACT OF ANTS ON THE GROWTH AND PRODUCTIVITY OF LAMTO SAVANNA PERENNIAL GRASSES (COTE D’IVOIRE)
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Lamto savanna soil known to have low agronomic value paradoxically has one of the highest grasses biomass productions in the world. During recent surveys, ant nest were encountered under some grass tufts and it as suggested that ants are able to influence the availability of resources for these grasses and also other organisms. An interaction is suspected between these savanna grass tufts and their associated ants. Three grasses species Andropogon schirensis, Hyparrhenia diplandra and Loudetia simplex were chosen to inventory ant communities associated with grass tufts and to assess the influence of ant communities on growth and productivity of perennial grasses. Three study sites were chosen and each was subdivided in two experimental plots of 2500 m². By systematic digging out method we were collected 38 ant species under grass tufts. They belong to 19 genera and 7 sub-families. Lamto herbaceous stratum was dominated by Camponotus acvapinensis. Diameter measures of grass tufts base at ground level, have allowed establishing the link between the size of ant nest and grass tufts size. Pearson coefficient r ranged no correlation between the size of ants nest and grass tufts size. The association rate with ants of one of the grasses Hyparrhenia diplandra was greater than for two other grasses studied Andropogon schirensis and Loudetia simplex (54.208 % versus 49.433 %, and 38.496 % respectively). Parameters such as grasses height, diameter (at ground level, and 10 cm above), dry biomass and seeds production were assessed. The results showed that Hyparrhenia diplandra with ant nest recorded the best results of growth and productivity. Association with ants nest is beneficial for the growth and productivity of Lamto perennial grasses.
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RBINS Staff Publications 2018
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Investigating urban ant community (Hymenoptera: Formicidae) in port cities and in major towns along the border in Côte d’Ivoire: a rapid assessment to detect potential introduced invasive ant species
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Objective: This study aimed at examining ant communities of port and border cities in order to identify introduced and potential invasive ant species and microhabitats likely to contribute to the spread of these ant species. Therefore, the sampling design are linear transects of 200 metres on which ants were collected using tuna baits at 15, 30, 45 and 60 minutes in the two port cities of Abidjan and San Pedro, and seven cities that are Man, Touba, Odienne, Ferkéssedougou, Bouna, Bondoukou and Abengourou located near the borders of Côte d’Ivoire. The results showed 83 ant species including 9 potential introduced or invasive ant species. These invasive ants contributed importantly to the ant assemblage in port cities (23.95±2.7 % of total richness and 37±6.1 % of total abundance) and border cities (20.17±4.7 % / 30.6±7 %). In addition two notorious invaders, Solenopsis geminata (Fabricius, 1804) (Tropical fire ant) and Pheidole megacephala (Fabricius, 1793) (Big-headed ant) were detected during this study. The results also indicated that potential introduced or invasive ant species were mostly detected in microhabitats where human activities are uninterrupted such port zones, markets, domestic streets and residential. Conclusion: In the end, this study has shown that ant communities in port and border cities harbour invasive potential ant species, particularly microhabitats characterized by high human activities such as port areas, markets, domestic streets and residential areas.
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RBINS Staff Publications 2018
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Do private coffee standards ‘walk the talk’ in improving socio-economic and environmental sustainability?
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Private sustainability standards cover an increasingly large production area and involve an increasing number of farmers worldwide. They raise expectations among consumers about the economic, ethical and environmental implications of food production and trade; and attract donor funding to certification schemes. The sustainability impact of standards remains unclear as research focuses on either economic or environmental implications. We analyze both the socio-economic and environmental impacts of coffee standards in Uganda and show that these are not in line with expectations created towards consumers. We find that standards improve either productivity and farm incomes or biodiversity and carbon storage but fail to eliminate trade-offs between socioeconomic and environmental outcomes, even when combined in multiple certification. Our analysis is based on a unique combination of economic survey data and ecological field inventory data from a sample of certified and noncertified coffee farms. Our findings are relevant for farmers, food companies, policy-makers, donors and consumers. They imply that combining different standards in multiple certification is counterproductive; that the design of standards could improve to mitigate observed trade-offs between economic and environmental outcomes; and that this requires increased productivity within ecological boundaries, rather than a price premium and added control mechanisms through multiple certification
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Locomotor behavior of Paleocene mammals: Insights from the semicircular canals of the inner ear
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The end-Cretaceous mass extinction triggered the collapse of ecosystems and a drastic turnover in mammalian communities leading to the demise of many ecologically specialized species. While Mesozoic mammals were ecomorphologically diverse, recognizable ecological richness was only truly established in the Eocene. Questions remain about the ecology of the first wave of mammals radiating after the extinction. Here, we use the semicircular canals of the inner ear as a proxy for locomotor behavior. Thirty new inner ear virtual endocasts were generated using high-resolution computed tomography scanning. This sample was supplemented by data from the literature to construct a dataset of 79 fossils spanning the Jurassic to the Eocene alongside 262 extant mammals. Vestibular sensitivity was measured using the radius of curvature against body mass and the residuals of this relationship were analyzed. The petrosal lobule size relative to body mass were compared with the inner ear data as they have a role in maintaining gaze stabilization during motion. Paleocene mammals exhibited smaller canal radius of curvature, compared to Mesozoic, Eocene, and extant taxa. In the early Paleocene, canal radius and associated petrosal lobules were relatively smaller on average compared to other temporal groups, suggesting less ability for fast movements. Our results support previous work on tarsal morphology and locomotor behavioral ancestral state reconstructions suggesting that ground dwelling mammalian species were more common than arboreal taxa during the Paleocene. Ultimately, this may indicate that the collapse of forested environments immediately after extinction led to the preferential survivorship of more terrestrially adapted mammals.
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RBINS Staff Publications 2023
