Allopatric genetic origins for sympatric host-plant shifts and race formation in Rhagoletis

Jeffrey L. Feder, Stewart H. Berlocher, Joseph B. Roethele, Hattie Dambroski, James J. Smith, William L. Perry, Vesna Gavrilovic, Kenneth E. Filchak, Juan Rull, Martin Aluja

Research output: Contribution to journalArticlepeer-review

Abstract

Tephritid fruit flies belonging to the Rhagoletis pomonella sibling species complex are controversial because they have been proposed to diverge in sympatry (in the absence of geographic isolation) by shifting and adapting to new host plants. Here, we report evidence suggesting a surprising source of genetic variation contributing to sympatric host shifts for these flies. From DNA sequence data for three nuclear loci and mtDNA, we infer that an ancestral, hawthorn-infesting R. pomonella population became geographically subdivided into Mexican and North American isolates ≈1.57 million years ago. Episodes of gene flow from Mexico subsequently infused the North American population with inversion polymorphism affecting key diapause traits, forming adaptive clines. Sometime later (perhaps ±1 million years), diapause variation in the latitudinal clines appears to have aided North American flies in adapting to a variety of plants with differing fruiting times, helping to spawn several new taxa. Thus, important raw genetic material facilitating the adaptive radiation of R. pomonella originated in a different time and place than the proximate ecological host shifts triggering sympatric divergence.

Original languageEnglish (US)
Pages (from-to)10314-10319
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume100
Issue number18
DOIs
StatePublished - Sep 2 2003

ASJC Scopus subject areas

  • General

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