Divergence and evolution of reproductive barriers among three allopatric populations of Rhagoletis cingulata across eastern North America and Mexico

Abstract

Geography is often a key factor facilitating population divergence and speciation. In this regard, the geographic distributions of flies in the genus Rhagoletis (Diptera: Tephritidae) in temperate North America have been affected by cycles of Pleistocene glaciation and interglacial periods. Fluctuations in climatic conditions may have had their most dramatic effects on geographically isolating Rhagoletis flies in the central highland region of Mexico. During past periods of allopatry, a degree of post‐zygotic reproductive isolation appears to have evolved between hawthorn‐infesting populations of Rhagoletis pomonella (Walsh) in the central Eje Volcanico Trans Mexicano (EVTM) and those from the Sierra Madre Oriental Mountains (SMO) of Mexico, as well as hawthorn flies from the eastern USA. Here, we investigate the generality of this finding in the genus Rhagoletis by testing for reproductive isolation among populations of Rhagoletis cingulata (Loew) (Diptera: Tephritidae) collected from infested domesticated sweet cherry (Prunus avium L.) in the USA and black cherry [Prunus serotina Ehrh. (both Rosaceae)] from the SMO and EVTM. We report evidence for marked post‐mating reproductive isolation among certain R. cingulata populations. The high levels of reproductive isolation were observed between R. cingulata flies from populations in the USA and SMO differed from the pattern seen for R. pomonella, primarily involving the EVTM. In addition, egg hatch was significantly reduced for crosses between SMO males and EVTM females, but not greatly in the opposite direction. We discuss potential causes for the different patterns of post‐mating reproductive isolation among Rhagoletis flies.

The effect of winter length on duration of dormancy and survival of specialized herbivorous Rhagoletis fruit flies from high elevation environments with acyclic climatic variability

“…Average (±SE) duration (days) corrected for artificial winter length (by substracting the total number of days held at 5°C according to treatment) from pupation to adult eclosion of three species of Rhagoletis fruit flies and their parasitoids. These 'populations' exhibited significant differences in the time from fruit collection to adult eclosion under uncontrolled environmental conditions in central Mexico (Xalapa), and were found to be reproductively isolated (Tadeo et al, 2015). Here we found that under similar environmental conditions, two of these populations (central and norteastern Mexico) differ in duration of dormancy.…”

Geographic and Ecological Dimensions of Host Plant-Associated Genetic Differentiation and Speciation in the Rhagoletis cingulata (Diptera: Tephritidae) Sibling Species Group

“…New microsatellite and mtDNA sequencing data in the current study were generated from three non-cherry-infesting populations of R. cingulata group flies: R. chionanthi (site 18, collected from fringe-tree at Perry, Georgia), R. osmanthi (site 19, collected from tea-olive at Lake Lizzie, Florida), and R. turpiniae (site 20, collected from muttonwood at Xalapa, Veracruz, Mexico). Flies were reared to adulthood in the laboratory using standard Rhagoletis husbandry methods [41], as described in Feder et al [42] and Tadeo et al [43]. Specimens were frozen and stored at −80 °C prior to genetic analysis.…”

“…Crosses testing for intrinsic postzygotic RI were performed as described in Tadeo et al [43]. Rhagoletis cingulata collected as larvae infesting black cherry fruit from South Bend, IN and R. indifferens infesting sweet cherries in Vancouver, WA in 2015 were transported to the University of Notre Dame, Notre Dame, IN, where they were reared to adulthood following a five-month overwintering period as pupae.…”

Experimental hybridization and reproductive isolation between two sympatric species of tephritid fruit flies in the Anastrepha fraterculus species group

“…With the advent of molecular techniques, research on fruit flies advanced our understanding of mixed models of speciation, in particular those involving speciation with gene flow (Feder et al, 2003). Experimental hybridization studies and molecular data revealed that several Rhagoletis species in the pomonella, suavis, and cingulata species groups potentially interbreed, leading in some cases to speciation and adaptive introgression (Schwarz & McPheron, 2007;Rull et al, 2010;Arcella et al, 2015;Tadeo et al, 2015). In general, many more animal species are likely exchanging genes than has been previously appreciated, with some groups exhibiting greater frequency of introgression than others (Mallet et al, 2016).…”