Molecular differentiation at nuclear loci in French host races of the European corn borer (Ostrinia nubilalis).
French populations of the European corn borer consist of two sympatric and genetically differentiated host races. As such, they are well suited to study processes that could be involved in sympatric speciation, but the initial conditions of host-race divergence need to be elucidated. Gene genealogies can provide insight into the processes involved in speciation. We used DNA sequences of four nuclear genes to (1) document the genetic structure of the two French host races previously delineated with allozyme markers, (2) find genes directly or indirectly involved in reproductive isolation between host races, and (3) estimate the time since divergence of the two taxa and see whether this estimate is compatible with this divergence being the result of a host shift onto maize after its introduction into Europe approximately 500 years ago. Gene genealogies revealed extensive shared polymorphism, but confirmed the previously observed genetic differentiation between the two host races. Significant departures from the predictions of neutral molecular evolution models were detected at three loci but were apparently unrelated to reproductive isolation between host races. Estimates of time since divergence between French host races varied from approximately 75,000 to approximately 150,000 years, suggesting that the two taxa diverged recently but probably long before the introduction of maize into Europe.
Malausa
Thibaut
T
Laboratoire Dynamique de la Biodiversité, UMR CNRS 5172, Université P. Sabatier-Toulouse III, 118 Route de Narbonne, 31 062 Toulouse Cedex 09, france. thibaut.malausa@sophia.inra.fr
Leniaud
Laurianne
L
Martin
Jean-François
JF
Audiot
Philippe
P
Bourguet
Denis
D
Ponsard
Sergine
S
Lee
Siu-Fai
SF
Harrison
Richard G
RG
Dopman
Erik
E
D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D019143:Evolution, Molecular; D005260:Female; D005602:France; D017344:Genes, Insect; D005828:Genetics, Population; D008297:Male; D008957:Models, Genetic; D009036:Moths / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity; D010802:Phylogeny; D011110:Polymorphism, Genetic; D013997:Time Factors; D003313:Zea mays / Q000469:parasitology
D017931:DNA Primers; D004247:DNA