Evidence for spatial clines and mixed geographic modes of speciation for North American cherry-infesting Rhagoletis (Diptera: Tephritidae) flies

• Autores: Meredith, Michael; Saint Jean, Gilbert; Egan, Scott P.; Powell, Thomas H. Q.; Hood, Glen R.; Schuler, Hannes; Bruzzese, Daniel J.; Glover, Mary M.; Smith, James J.; Yee, Wee L.; Goughnour, Robert; Rull Gabayet, Juan Antonio; Aluja, Martin; Feder, Jeffrey L.
• Año de publicación: 2020
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: ALLOPATRY; CLIMATE CHANGE; ISOLATION BY DISTANCE; MICROSATELLITES; MTDNA; RANGE FRAGMENTATION; RHAGOLETIS CINGULATA; RHAGOLETIS INDIFFERENS; WING SPOT
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

An important criterion for understanding speciation is the geographic context of population divergence. Three major modes of allopatric, parapatric, and sympatric speciation define the extent of spatial overlap and gene flow between diverging populations. However, mixed modes of speciation are also possible, whereby populations experience periods of allopatry, parapatry, and/or sympatry at different times as they diverge. Here, we report clinal patterns of variation for 21 nuclear-encoded microsatellites and a wing spot phenotype for cherry-infesting Rhagoletis (Diptera: Tephritidae) across North America consistent with these flies having initially diverged in parapatry followed by a period of allopatric differentiation in the early Holocene. However, mitochondrial DNA (mtDNA) displays a different pattern; cherry flies at the ends of the clines in the eastern USA and Pacific Northwest share identical haplotypes, while centrally located populations in the southwestern USA and Mexico possess a different haplotype. We hypothesize that the mitochondrial difference could be due to lineage sorting but more likely reflects a selective sweep of a favorable mtDNA variant or the spread of an endosymbiont. The estimated divergence time for mtDNA suggests possible past allopatry, secondary contact, and subsequent isolation between USA and Mexican fly populations initiated before the Wisconsin glaciation. Thus, the current genetics of cherry flies may involve different mixed modes of divergence occurring in different portions of the fly's range. We discuss the need for additional DNA sequencing and quantification of prezygotic and postzygotic reproductive isolation to verify the multiple mixed-mode hypothesis for cherry flies and draw parallels from other systems to assess the generality that speciation may commonly involve complex biogeographies of varying combinations of allopatric, parapatric, and sympatric divergence.
Fil: Meredith, Michael. University of Notre Dame-Indiana; Estados Unidos
Fil: Saint Jean, Gilbert. University of Notre Dame-Indiana; Estados Unidos
Fil: Egan, Scott P.. Rice University; Estados Unidos
Fil: Powell, Thomas H. Q.. University of Notre Dame-Indiana; Estados Unidos
Fil: Hood, Glen R.. University of Notre Dame-Indiana; Estados Unidos
Fil: Schuler, Hannes. University of Notre Dame-Indiana; Estados Unidos
Fil: Bruzzese, Daniel J.. University of Notre Dame-Indiana; Estados Unidos
Fil: Glover, Mary M.. University of Notre Dame-Indiana; Estados Unidos
Fil: Smith, James J.. Michigan State University; Estados Unidos
Fil: Yee, Wee L.. Usda-ars; Estados Unidos
Fil: Goughnour, Robert. United States Department of Agriculture. Agricultural Research Service; Argentina
Fil: Rull Gabayet, Juan Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina
Fil: Aluja, Martin. Instituto de Ecología A.c.; México
Fil: Feder, Jeffrey L.. University of Notre Dame-Indiana; Estados Unidos