La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	[Contact zones between tropical birds and their biogeographical significance]
Auteurs :	Juergen Haffer, Auteur
Type de document :	Article
Dans :	Ornithologischer Anzeiger (39(1) Feb., 2000)
Article en page(s) :	43-62
Résumé :	As in the bird faunas of the Temperate Zones, numerous contact zones exist between species and subspecies of birds in the tropics where the representatives (1) hybridize, (2) exclude each other geographically without hybridization or (3) overlap their ranges narrowly. Examples are given for Amazonia, tropical Africa and New Guinea. It is largely unknown which processes of ecological competition maintain the replacement zones between taxa which do not hybridize. Contact zones represent regions of major biogeographic discontinuity in ecologically rather uniform environments. Geoscientific data have become known from all tropical regions of the world suggesting that strong climatic- vegetational fluctuations occurred there in the lowlands and mountains during the last 60 million years (Tertiary and Quaternary) leading to the repeated separation and differentiation of bird and other animal populations in ecological "refugia" during unfavorable climatic phases and their subsequent range expansion and secondary contact when favorable climatic conditions had returned. Reproductively and ecologically isolated taxa were then able to overlap their ranges over extensive areas, where they now occur sympatrically.

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