Malimbus

Abstract: ummary Interspecific tree sharing and niche overlap was studied in six weaver bird species. The three species pairs which shared nest trees were P. cucullatus (35 colonies) and P. nigerrimus (34 colonies), M. rubricollis (71 colonies) and P. tricolor (8 colonies), M. scutatus (22 colonies) and M. nitens (12 colonies). In the first species pair high niche overlap values along all four dimensions (habitat, nest height, nest materials and diet) contradicted Pianka's (1974) niche overlap hypothesis that high overlap is the result of reduced competition. At an inter-generic level his theory appeared applicable because high overlap values along one dimension followed low values along others. May & MacArthur (1972) predicted an inverse relationship between niche overlap and intensity of competition. Low alpha (a) values of nest materials (M. rubricollis-P. tricolor) and nest height (M. scutatus-M. nitens) fitted their explanation because competition must have caused complete distinctness in the two axes. Population assessment provided evidence that under shared colony conditions, only one species numerically dominated. Hence competition risk was reduced even though overlapping of certain niche dimensions allowed for the possibility of competition. The beaks of all six species are not specialized for diet although Ploceus spp. is granivorous and Malimbus spp. and P. tricolor are insectivorous. Within the malimbes segregation along this axis was incomplete while only partial niche segregation was evident between the two groups. Ecological separation of P. tricolor nests was considered to be the result of competition from P. cucullatus and P. nigerrimus. Resume Le partage des ressources et le recouvrement des niches ecologiques de certains tisserins des genres Ploceus et Malimbusa Ife, Nigeria. On a etudie le partage des arbres et le recouvrement des niches ecologiques de six especes de tisserins. Les trois paires d'especes qui construisent leur nid dans les memes arbres sont P. cucullatus (35 colonies) et P. nigerrimus (34 colonies), M. rubricollis (71 colonies) et P. tricolor (8 colonies), ot M. scutatus (22 colonies) et M. nitens (12 colonies). Dans la premiere paire, un recouvrement important de la niche ecologique a quatre points de vue (habitat, hauteur et materiau du nid, et regime alimentaire) contredit I'hypothese de Pianka (1974) selon laquelle un recouvrement important est le resultat d'une competition restreinte. Au niveau intergenerique, sa theorie semble applicable parce que de hautes valeurs de recouvrement dans un domaine coincident avec de basses valeurs dans d'autres. May et MacArthur (1972) predisaient une relation inverse entre le recouvrement de la niche ecologique et l'intensite de la competition. Des valeurs alpha (a) basses pour le materiau du nid (M. rubricollis-P. tricolor) et pour sa hauteur (M. scutatus-M. nitens) s'accordent parfaitement a leurs explications parce que la competition doit avoir cause une distinction complete dans ces deux domaines. L'evaluation de la population montre a l'evidence que, dans les conditions d'une colonie mixte, une seule espece domine numerique-ment. D'ou le risque reduit de competition meme lorsque le recouvrement de certains aspects de la niche ecologique aurait pu creer une situation de competition. Les becs des six especes ne sont pas specialises; cependant, Ploceus spp. est grani-vore et Malimbus spp. plus P. tricolor sont insectivores. Entre les malimbes, la segregation alimentaire est incomplete, et I'on ne constate qu'une segregation partielle de la niche ecologique entre les deux groupes. La separation ecologique des nids de P. tricolor semble etre le resultat de la competition entre P. cucullurus et P. nigerrimus.

Abstract: The diverse Old World avian family Ploceidae (weaverbirds) presently comprises 117 species in 17 genera. Despite being a well-known bird group, the family has received incomplete attention in terms of molecular systematics; systematists have often focused on subclades, with the most extensive study to date covering <66% of recognized species. As a consequence, weaverbird taxonomy remains outdated, and phylogenetic relationships, particularly of the African Malimbus (previously Ploceus and Malimbus) clade, remains largely unresolved. Here, we sampled 109 weaver species (and numerous nominal subspecies), including 99 of the 103 recognized “typical weaverbird” taxa for an 8-gene dataset. Antique DNA techniques were used to extract DNA from study skins of 27 rare taxa not available in global tissue collections. The study included 32 species and 4 genera of ploceids previously unstudied phylogenetically. Our analyses supported monophyly of the family and identified 8 distinct clades. Our results conflict extensively with current taxonomy. We suggest that plumage traits and morphology exhibit high plasticity, such that phenotype does not always reflect phylogenetic relationships in weaverbirds. We recommend (1) uniting African-Ploceus, Malimbus, Anaplectes, and Notiospiza in Malimbus; (2) retaining the monotypic genus Pachyphantes; and (3) placing Brachycope with Euplectes. This study, the first near-species-level phylogeny for the family, lays a firm foundation for downstream studies of biogeography and character evolution.