Mayr, Dobzhansky, and Bush and the complexities of sympatric speciation in Rhagoletis
- Jeffrey L. Feder†,‡,
- Xianfa Xie†,
- Juan Rull§,
- Sebastian Velez†,
- Andrew Forbes†,
- Brian Leung†,¶,
- Hattie Dambroski†,∥,
- Kenneth E. Filchak†, and
- Martin Aluja§
- †Department of Biological Sciences, University of Notre Dame, Galvin Life Science Center, P.O. Box 369, Notre Dame, IN 46556-0369; §Instituto de Ecología, Asociación Civil, Kilometro 2.5 Antigua Carretera a Coatepec 351, 91070 Xalapa, Veracruz, Mexico; ¶Department of Biology, McGill School of Environment, McGill University, Montreal, QB, Canada H3A 1B1; and ∥Cereal Disease Laboratory, United States Department of Agriculture, Agricultural Research Service, Midwest Area Office, University of Minnesota, 1551 Lindig Avenue, St. Paul, MN 55104
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Fig. 1.The current range of R. pomonella in North America. Estimated distributions for the hawthorn-infesting U.S. (light gray) and Mexican Altiplano (dark gray) populations of flies, as well as the recently discovered Sierra Madre Oriental population (black; see text for discussion of “Sierra” flies), are shown. The fly is also distributed patchily in the western United States. Further work is needed to clarify the distribution and origins of these western populations, because they may represent recent introductions. Numbers indicate sampling sites in study (see the Fig. 2 legend for site descriptions).
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Fig. 2.MP gene trees for P220 (A), mtDNA (B), P661 (C), P309 (D), P3060 (E), and P2620 (F). Trees are scaled so that the longest distance from an allele to the outgroup R. electromorpha (R. elect.) are relatively the same across loci. Chromosome position for loci, bootstrap support for nodes (10,000 replicates), sequence lengths (in bp), and branch lengths (no. of steps) are given. Exact location for P3060 is not known, but the locus does not map to chromosomes 1-3. For locus 220 in A, haplotypes are abbreviated as follows: N, North United States; SN, South/North United States; and M, Mexican (gray). For the other four nuclear loci and mtDNA, U.S. haplotypes are black and Mexican haplotypes are gray. Open circles indicate the contrast between deep and shallow RNDs shown for chromosome 1-3 loci and mtDNA (A and B) vs. genes that do not reside in rearrangements (C-F). Taxa, hosts, location, and collecting dates (month/day/year) are as follows: MI, R. pomonella [apple (M. pumila) and hawthorn (C. mollis)], Grant, MI, 8/15/95; NY, R. pomonella [hawthorn (C. mollis)], Geneva, NY, 9/16/00; TX, R. pomonella [hawthorn (C. mollis)], Brazos Bend, TX, 10/6/89; CJ, R. pomonella n.s. [hawthorn (C. mexicana)], Coajomulco, Morelos, Mexico, 11/12/02; MC, R. pomonella n.s. [hawthorn (C. mexicana and C. rosei rosei)], Tancitaro, Michoacan, Mexico, 11/15/02; and R. electromorpha [gray dogwood (Cornus racemosa)], Dowagiac, MI, 9/12/99. Gene trees do not include all of the sequenced alleles for each locus, but subsets that encapsulate the general topological structure for trees. Also, networks incorporating recombinant alleles are not shown for P661 and P3060. Additional alleles and networks are given in supporting information.
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Fig. 3.Distribution of RNDs for nuclear loci not residing on chromosomes 1-3 (black bars), for genes located on chromosomes 1-3 (white bars), and for mtDNA (gray bar). The list on the left gives the number of loci displaying shallow RNDs (<0.16) for the six sequenced genes not mapping to chromosomes 1-3 vs. the nine genes that do. The list on the right gives the number of loci displaying deep RNDs (>0.63). RND values for each locus are given in Table 1. P values were determined by two-tailed Fisher's exact tests.
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Fig. 4.Biogeographic model depicting two cycles of isolation and differential introgression between Mexican Altiplano and Northern (United States) populations of R. pomonella.
Footnotes
- Copyright © 2005, The National Academy of Sciences
