Few studies explored effects of chemical fertilizers on diversity and abundance of soillitter arthropods in the tropics. To fill this gap, a study focussed on the abundance of soil-litter arthropods and selected soil physicochemical properties in coffee plantations treated with chemical fertilizers and in plantations of coffee and banana treated with organic fertilizers and organic mulches in southern Rwanda. Each land use was replicated three times. Soil-litter arthropods were collected using pitfall traps and hand collection. They were identified to the family level using dichotomous keys. Soil have been collected using auger and taken to the laboratory for the analysis of soil pH, soil organic carbon, total nitrogen, phosphorus, and cation exchange capacity. Findings indicated a total of 12,945 individuals distributed into 3 classes, 16 orders, 50 families and 92 morphospecies, with higher abundance and diversity in coffee plantations treated with organic fertilizers and organic mulches. Collected soil-litter arthropods were mainly classified in the class Insecta, dominated in numbers by ants (Hymenoptera: Formicidae), while Coleoptera and Hemiptera had more families. However, soil under coffee plantations treated with organic fertilizers and organic mulches was acidic compared with the soil under coffee plantations treated with inorganic fertilizers and banana plantations treated with organic fertilizers and organic mulches. The relationships between soil-litter arthropods and soil physicochemical properties suggest that soillitter arthropods respond to the land use independently from soil physicochemical properties. We recommend further studies in coffee and other crop plantations in other regions of Rwanda to verify the findings of this study.
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RBINS Staff Publications 2023
Despite their ecological and evolutionary interests, the phylogeny of Asteroidea (sea stars) is still subject to debate at several taxonomic levels. In the present study, we assemble new mitochondrial genomes for 15 species, including three newly characterized families (Odontasteridae, Poraniidae, and Stichasteridae) and representing an important addition for two orders (Velatida and Spinulosida). By analysing them alongside the 31 previously available mitogenomes, we evaluate mitogenomic variation (mitogenome organization and phylogenetic relationships) within the class. Gene order and sizes were concordant with previous studies. However, an alternative initiation codon (ATT for NAD1) was found in two Pterasteridae species. Evolutionary patterns between orders provided some interesting insights (e.g. Spinulosida as the sister-group to the Valvatida + Paxillosida), but the most novel patterns were observed among families (e.g. close relationships of Stichasteridae and Paulasteriidae; close relationships of Odontasteridae and Poraniidae; Brisingidae and Freyellidae as sister-group to the Asteriidae, Paulasteridae, and Stichasteridae). Finally, we found Pterasteridae to be paraphyletic, which could lead to the incorporation of Myxasteridae within Pterasteridae. Altogether, this study confirms that mitogenomes provide valuable and cost-effective markers to complement evolutionary patterns derived from nuclear data.
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RBINS Staff Publications 2024
