Insular and Continental, Amber and Living Diptera: Implications for Historical Biogeography and the Caribbean Region

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The abundant deposits of Oligo-miocene amber from southern Mexico and Hispaniola have yielded a great diversity of exquisitely preserved biological inclusions, the large majority being arthropods and especially Diptera. The amber specimens afford an unparalleled opportunity to address questions on the relationships and origins of the Caribbean fauna, but critical information is lacking on the distributions of most extant Diptera in the caribbean, and the phylogenetic relationships of the amber fossil taxa to living species. This research proposes to examine selected groups represented in the amber collections the AMNH and the NMNH: Asteia (Asteiidae), Aulacigaster (Aulacigastridae), Beckeriella (Ephydridae), Beebeomyia (Richardiidae), Carnus/Meoneura (Carnidae), Lygistorrhina and Proceroplatus (Mycetophilidae), Diathoneura and selected Drosophila groups (Drosophilidae), Odinia (Odiniidae), and a species group within Pholeomyia (Milichiidae). Taxonomic revisions of each will be based on species-level treatments using adult morphology and cladistic methodology to examine phylogenetic relationships. Study will resort to pinned museum specimens but requires extensive sampling using several general and specific collecting techniques in lowland tropical forests, which is proposed for Hispa ola, Cuba, and Costa Rica. Gas chromatography/mass spectroscopy will be done by a collaborator on selected amber specimens to more accurately determine their geological provenance. Aims of the research are the following: define species and their distributions for the above groups in the Netropics; test for repeated, congruent patterns of distributions; and place the fossils among the phylogenetic system of extant species. Implications of these results are that distributions can be examined for correspondence to island origins (vicariance), and the minimum, fossil age of a clade may provide permissive evidence for or refute a particular geological explanation. Also, the role of geographical extinctions in modifying distributions can be assessed, which is directly applicable to vicariance methodology.