The Causes of Evolutionary Radiations in Archipelagoes: Passerine Birds in the Lesser Antilles

To investigate why some lineages undergo evolutionary radiation, we compare the passerine avifaunas of the Hawaiian and Galápagos archipelagoes, which have supported well‐known radiations of birds, with those of the Lesser Antilles, which have not. We focus on four steps required for the buildup of...

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Bibliographic Details
Published in:The American naturalist 2007-03, Vol.169 (3), p.285-297
Main Authors: Ricklefs, Robert E., Bermingham, Eldredge
Format: Article
Language:English
Subjects:
Animal and plant ecology
Animal, plant and microbial ecology
Animals
Archipelagos
Aves
Biodiversity
Biological and medical sciences
Biological taxonomies
Birds
Comparative analysis
Ecological genetics
Ecosystems
Ecuador
Evolution
Evolutionary biology
Evolutionary genetics
Fundamental and applied biological sciences. Psychology
General aspects
Genetic diversity
Genetic Speciation
Geography
Hawaii
Islands
Passeriformes - genetics
Phylogeny
Population ecology
Population genetics
Principal Component Analysis
Radiation
Radiation genetics
Songbirds
Sympatry
Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution
West Indies
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Summary:To investigate why some lineages undergo evolutionary radiation, we compare the passerine avifaunas of the Hawaiian and Galápagos archipelagoes, which have supported well‐known radiations of birds, with those of the Lesser Antilles, which have not. We focus on four steps required for the buildup of diversity through allopatric speciation and secondary sympatry: genetic divergence in isolation, persistence of island populations, recolonization of source islands, and ecological compatibility in secondary sympatry. Analysis of genetic divergence among island populations in the Lesser Antilles reveals evidence of both prolonged independent evolution and re‐expansion of differentiated island populations through the archipelago but little evidence of secondary sympatry of divergent genetic lineages. Archipelagoes with high rates of colonization from continental or nearby large‐island sources might fail to promote evolutionary radiations because colonists fill ecological space and constrain diversification through competition. However, morphological analysis demonstrated similar divergence between allopatric populations in species in Hawaii, Galápagos, and the Lesser Antilles, although the rate of divergence between secondarily sympatric species evidently is more rapid in Hawaii and the Galápagos. Alternatively, endemic buildup of diversity might be facilitated by the relative absence of pathogens in Hawaii and Galápagos that otherwise could prevent the secondary sympatry of populations owing to disease‐mediated competition.
ISSN:0003-0147
1537-5323
DOI:10.1086/510730