Host race formation in the leaf-mining moth Acrocercops transecta (Lepidoptera: Gracillariidae)

Abstract

Genetic differentiation in ecological traits plays an important role in the reproductive isolation of phytophagous insects. The present study aims to elucidate the genetic changes involved during the process of host shifts, by combining analyses for (1) host adaptations, (2) pre-and postmating isolation, and (3) phylogeney among populations, using a leaf-mining moth, Acrocercops transecta. This species is associated with Juglans ailanthifolia and Lyonia ovalifolia. Transplantation of the larvae demonstrated that the Juglans-associated population completely failed to survive on Lyonia, whereas the Lyonia-associated population survived on Juglans as well as on Lyonia. Females of respective host-associated populations oviposited on their natal host plant only. An mtDNAbased phylogeny clearly separated the Lyonia-associated population from the Juglandaceae-associated population, and indicated that the Lyonia-associated population once evolved from the Juglandaceae-associated population. These results indicate that the processes of host shifting from juglandaceous species to Lyonia involved genetic changes both in larval ability to use host plants and in host preference of females. The derived Lyonia-associated population has retained the potential to assimilate the ancestral host, Juglandaceae. Mating between the two host-associated populations was successful for both directions of crossing, and there were no significant differences in egg hatchability between hybrids and control crosses. No adults emerged when the F1 hybrid larvae were maintained on Lyonia; however, on Juglans the F1 hybrid larvae grew to adulthood as well as in the control, suggesting a lack of genomic incompatibilities between the two host-associated populations. In conclusion, the results showed that the two host-associated populations are host races that are partially reproductively isolated, and that the differences in performance and preference function as strong barriers against gene flow between the host races.

Post-Pleistocene radiation of the pea aphid complex revealed by rapidly evolving endosymbionts

“…Instead, the diversification of pea aphids likely involves the acquisition of novel host plants and divergence from the parental lineages remaining on ancestral plants-that is, host shifts (8,(44)(45)(46). Ancestral host plants may be inferred by a higher polymorphism of associated matrilines and their paraphyly with respect to those associated with derived hosts (47,48). In this regard, the phylogeny (Fig.…”

Host selection in insects: reproductive interference shapes behavior of ovipositing females

“…As a result, it is difficult to distinguish which scenario led to the current situation, especially if the allopatric origin of species in a species complex has not been confirmed maggot fly Rhagoletis pomonella, adults of hawthorn-and apple-infesting races mate exclusively on or near the fruit of their respective host plants (Prokopy et al 1971), and in the same geographical region they seldom move between the two habitats (Feder et al 1994). Even though this hypothesis of sympatric speciation has been extensively tested in various systems, such as pea aphid (Via 1999) and moths (Emelianov et al 2001;Ohshima 2008), compelling evidence that two host races can experience complete genetic divergence in the same geographical region is still lacking (Drès and Mallet 2002;Coyne and Orr 2004). Host fidelity, however, has been shown to be a general phenomenon, especially in phytophagous insects, including in systems of putative host race formation in which sympatric speciation has not been verified (Drès and Mallet 2002;Matsubayashi et al 2010).…”

Analysis of tissue dependent DNA yield for optimal sampling of micro-moths in large-scale biodiversity surveys

“…Over recent decades, molecular methods have complemented traditional comparative morphology and taxonomic classification of micro-moths (Nieukerken et al, in press). Indeed, an increasing number of DNA-based studies on smaller moths have recently been published in the fields of evolutionary biology (Lopez-Vaamonde et al, 2003Kawakita et al, 2004;Bucheli & Wenzel, 2005;Pellmyr et al, 2006;Schmitz et al, 2007;Kawahara et al, 2011), molecular ecology (Mari Mena et al, 2008;Valade et al, 2009), and in clarifications of complicated cases in alphataxonomy such as cryptic differentiation and/or species race formation (Kaila & Ståhls, 2006;Ohshima, 2008;Schmitz et al, 2008).…”