Biogeographic relationships between Macaronesia and the Americas

Abstract

A vicariance model is presented for the origin of Macaronesian endemics and their allopatric American relatives. Trans-Atlantic relationships are identified for 21 taxa in which an endemicMacaronesian clade either has a sister group in the New World or is part of a larger monophyletic group that includes representatives in the New World. Historical implications of this pattern are discussed in relation to current tectonic and geological models for the Central Atlantic and theMacaronesian Islands. The proposed vicariance model identifies a local origin for theMacaronesian endemics from ancestral distributions that already encompassed ancestralMacaronesia and parts of the New and Old World before formation of the Atlantic. The present-day existence of Macaronesian endemics is attributed to sequential colonisation of newly formed islands within the Atlantic from Mesozoic time.