Genetic differentiation of the large turkey louse (Chelopistes meleagridis) populations reveals limited movement of turkeys across the Mississippi River

Molecular genetic data from parasites can reveal information about parasite dispersal abilities as well as movement patterns of their hosts. In this study, mitochondrial cytochrome oxidase I DNA sequences of the large turkey louse (Chelopistes meleagridis) are investigated to determine louse dispersal abilities and wild turkey (Meleagris gallopavo ) movement within the Midwest. DNA was extracted from 190 lice found on 26 turkeys sampled from 4 states across the Midwest. A 356 base pair sequence was amplified via PCR, aligned with Clustal W, and analyzed with DnaSP v4.20 and GenAlEx v6.1 software. Eighteen haplotypes were found with 35 polymorphic sites. Two distinct genetic groups, designated the “West” and “East” clades, were revealed by a neighbor-joining tree and a haplotype network. These clades were nonrandomly distributed with respect to the Mississippi River, indicating a population split along the river. AMOVA analysis supported the West and East clade split along the Mississippi River with 34% of variation apportioned between “regions” west and east of the Mississippi (ΦPT=0.342, p=0.001). A Mantel test revealed no correlation between genetic distance and geographic distance. My data suggest that there is little gene flow between C. meleagridis populations on opposite sides of the river, indicating that M. gallopavo movement across the river is either limited or absent. Given current estimates for substitution rates of mitochondrial cytochrome genes in lice, it is possible that the patterns seen in C. meleagridis populations reflect patterns that evolved 300,000 years ago. While the actual mechanisms of haplotype evolution and the maintenance of the W-E distribution are still unclear, these data hint at a more complicated host-parasite history than expected.