Ants, the most abundant taxa among canopy-dwelling animals in tropical rainforests, are mostly represented by territorially-dominant arboreal ants (TDAs) whose territories are distributed in a mosaic pattern (arboreal ant mosaics). Large TDA colonies regulate insect herbivores, with implications for forestry and agronomy. What generates these mosaics in vegetal formations, which are dynamic, still needs to be better understood. So, from empirical research based on three Cameroonian tree species (Lophira alata, Ochnaceae; Anthocleista vogelii, Gentianaceae; and Barteria fistulosa, Passifloraceae), we used the Self-Organizing Map (SOM, neural network) to illustrate the succession of TDAs as their host trees grow and age. The SOM separated the trees by species and by size for L. alata, which can reach 60 m in height and live several centuries. An ontogenic succession of TDAs from sapling to mature trees is shown, and some ecological traits are highlighted for certain TDAs. Also, because the SOM permits the analysis of data with many zeroes with no effect of outliers on the overall scatterplot distributions, we obtained ecological information on rare species. Finally, the SOM permitted us to show that functional groups cannot be selected at the genus level as congeneric species can have very different ecological niches, something particularly true for Crematogaster spp. which include a species specifically associated with B. fistulosa, non-dominant species and TDAs. Therefore, the SOM permitted the complex relationships between TDAs and their growing host trees to be analyzed, while also providing new information on the ecological traits of the ant species involved. This article is protected by copyright. All rights reserved.
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Résumé Les Annélides, ou vers segmentés, forment un groupe généralement considéré comme monophylétique, qui est traditionnellement divisé entre les Polychaeta et les Clitellata. Ils sont évolutivement anciens, écologiquement importants et extrêmement diversifiés en terme d’espèces et de plans d’organisation. Pour ces raisons, les Annélides ont toujours constitué l’un des problèmes majeurs dans la résolution de la phylogénie des Métazoaires. La révolution conceptuelle et méthodologique liée à l’analyse cladistique et surtout l’accès, via l’ADN, à une nouvelle classe de caractères ont bouleversé la classification des Annélides au cours des 20 dernières années. Tout récemment, le développement de la phylogénomique a permis, non seulement, de proposer une phylogénie de base stable pour les Annélides mais, également, de résoudre les principaux problèmes liés à ce groupe, tels que la monophylie des Annélides, la composition taxinomique du groupe, le plan d’organisation de l’annélide ancestral, ou la nature mono- ou paraphylétique des Polychètes et des Oligochètes. Ce travail résume les connaissances les plus récentes sur la phylogénie et l’évolution d’un taxon dont l’extraordinaire diversité a peu d’équivalent parmi les Métazoaires. Mots clés : Annélides, phylogénie, évolution Summary Annelida, or segmented worms, constitute a group generally considered as monophyletic, traditionally divided between Polychaeta and Clitellata. They are evolutionary ancient, ecologically important and extremely diversified in terms of species and body plans. For these reasons, Annelida have always represented one of the largest unsolved problems in metazoan phylogeny. The conceptual and methodological revolution related to cladistic analysis and, in particular, access to a fully new category of characters through DNA have drastically changed the classification of Annelida during the last 20 years. Very recently, the development of phylogenomics enabled not only to propose a stable basal phylogeny of Annelida but, also, to resolve the main problems associated to this group, namely the annelid monophyly, the taxonomic composition of the group, the body plan of the ancestral annelid, or the mono- or paraphyletic nature of Polychaeta and Oligochaeta. This work summarizes the most recent knowledge on phylogeny and evolution of a taxon of which the extraordinary diversity has few equivalent amongst the Metazoa. Key words: Annelids, phylogeny, evolution
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