When genes go wild: highly variable internal transcibed spacer1 and conserved mitochondrial DNA haplotypes used to examine the genetic diversity and dispersal pathways of invasive Hylotrupes bajulus in Western Australia

Abstract

Abstract Hylotrupes bajulus (Linnaeus) is a cryptic insect pest of seasoned coniferous timber. In 2004, an incursion of Hylotrupes bajulus was discovered in Perth, Western Australia. Two genes, one mitochondrial (cytochrome oxidase subunit I; COI) and one nuclear (internal transcribed spacer 1; ITS1) were used to infer the origin of this incursion, as well as to test the likely dispersal pathways and dispersal distances of H. bajulus. We sequenced and examined 1003 cloned ITS1 fragments and 170 COI fragments from 14 international and 156 domestic specimens. The ITS1 fragment was extremely variable, with 94% of the sites polymorphic. To remove the variability and select only the informative polymorphisms principal component analysis was employed. This resulted in the selection of eight informative single nucleotide polymorphisms and seven microsatellites, which were converted into 119 unique ITS haplotypes. In comparison, COI was highly conserved, yielding only four haplotypes. The data suggest at least three independent incursions, of which two contained the same mitochondrial haplotype but different ITS1 sequences. The datasets were further scrutinized to estimate local dispersal distances. The results suggested that individuals were capable of dispersing > 14 km, which is significantly further than previously reported.