Ai. Cognato et al., Incomplete barriers to mitochondrial gene flow between pheromone races of the North American pine engraver, Ips pini (Say) (Coleoptera : Scolytidae), P ROY SOC B, 266(1431), 1999, pp. 1843-1850
Citations number
47
Categorie Soggetti
Experimental Biology
Journal title
PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON SERIES B-BIOLOGICAL SCIENCES
The pine engraver Ips pini (Say) is known to include three pheromone races,
but gene flow between these races has not been investigated. We used mater
nally inherited mitochondrial DNA (mtDNA) variation to infer gene flow betw
een 22 widely distributed North American populations of I. pini for a total
of 217 individuals, based on 354 bp of the cytochrome oxidase I gene. Gene
how was estimated cladistically as migrants per generation (Nm) and as hap
lotype variation between populations (N-st). Three distinct mtDNA haplotype
lineages, generally corresponding to eastern (I), Rocky Mountain (II) and
western (III) regions of North America, were resolved with a total of 34 di
stinct I. pini haplotypes. The distributions of these lineages were largely
congruent with the geographical ranges of the 'New York', 'California' and
'Idaho-Montana' pheromone races. Only individuals with lineage I mtDNA wer
e observed among eastern populations, whereas individuals with lineage II o
r III mtDNA predominated among western populations. Gene flow (Nm and N-st)
was generally moderate between all populations. However, the presence of l
ineage I mtDNA on the eastern side of western North America and the absence
of lineage II and III mtDNA in eastern North America suggest directional g
ene flow from cast to west. These results indicate that female-controlled a
ssortative mating among pheromone races may disrupt gene flow between consp
ecifics, reflecting incomplete pre-mating barriers.