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J Biogeogr. 2015 Dec;42(12):2289-2301. Epub 2015 Sep 1.

Breaking out of biogeographical modules: range expansion and taxon cycles in the hyperdiverse ant genus Pheidole.

Author information

1
Okinawa Institute of Science and Technology Graduate University1919-1 TanchaOnna-sonOkinawa904-0495Japan; Department of Ecology & Evolutionary BiologyMuseum of ZoologyUniversity of MichiganAnn ArborMIUSA.
2
Department of Entomology University of Illinois at Urbana-Champaign Chicago IL USA.
3
Biology CentreCzech Academy of SciencesČeské BudějoviceCzech Republic; Department of BiologyUniversity of GuanajuatoGuanajuatoMexico.
4
Department of Bioinformatics and Genomics University of North Carolina at Charlotte Charlotte NC USA.
5
Department of Ecology & Evolutionary BiologyMuseum of ZoologyUniversity of MichiganAnn ArborMIUSA; Department of ZoologyTyumen State UniversityTyumenRussia.
6
Okinawa Institute of Science and Technology Graduate University 1919-1 Tancha Onna-son Okinawa 904-0495 Japan.
7
Department of Ecology & Evolutionary BiologyMuseum of ZoologyUniversity of MichiganAnn ArborMIUSA; Committee on Evolutionary BiologyUniversity of ChicagoChicagoILUSA.
8
Department of Ecology & Evolutionary Biology Museum of Zoology University of Michigan Ann Arbor MI USA.
9
CSIRO Land & Water Flagship Darwin NT Australia.
10
Department of Entomology & Nematology University of Florida Gainesville FL USA.
11
Department of Biology University of Rochester Rochester NY USA.
12
Museum of Comparative Zoology Harvard University Cambridge MA USA.

Abstract

AIM:

We sought to reconstruct the biogeographical structure and dynamics of a hyperdiverse ant genus, Pheidole, and to test several predictions of the taxon cycle hypothesis. Using large datasets on Pheidole geographical distributions and phylogeny, we (1) inferred patterns of biogeographical modularity (clusters of areas with similar faunal composition), (2) tested whether species in open habitats are more likely to be expanding their range beyond module boundaries, and (3) tested whether there is a bias of lineage flow from high- to low-diversity areas.

LOCATION:

The Old World.

METHODS:

We compiled and jointly analysed a comprehensive database of Pheidole geographical distributions, the ecological affinities of different species, and a multilocus phylogeny of the Old World radiation. We used network modularity methods to infer biogeographical structure in the genus and comparative methods to evaluate the hypotheses.

RESULTS:

The network analysis identified eight biogeographical modules, and a suite of species with anomalous ranges that are statistically more likely to occur in open habitat, supporting the hypothesis that open habitats promote range expansion. Phylogenetic analysis shows evidence for a cascade pattern of colonization from Asia to New Guinea to the Pacific, but no 'upstream' colonization in the reverse direction.

MAIN CONCLUSIONS:

The distributions of Pheidole lineages in the Old World are highly modular, with modules generally corresponding to biogeographical regions inferred in other groups of organisms. However, some lineages have expanded their ranges across module boundaries, and these species are more likely to be adapted to open habitats rather than interior forest. In addition, there is a cascade pattern of dispersal from higher to lower diversity areas during these range expansions. Our findings are consistent with the taxon cycle hypothesis, although they do not rule out alternative interpretations.

KEYWORDS:

Formicidae; ants; colonization; dispersal; diversification; island biogeography; phylogeny; radiation; range expansion; taxon cycle

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