RT Journal Article
SR Electronic
T1 The first steps toward a global pandemic: Reconstructing the demographic history of parasite host switches in its native range
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.07.30.228320
DO 10.1101/2020.07.30.228320
A1 Maeva A. Techer
A1 John M. K. Roberts
A1 Reed A. Cartwright
A1 Alexander S. Mikheyev
YR 2020
UL http://biorxiv.org/content/early/2020/07/31/2020.07.30.228320.abstract
AB Host switching allows parasites to expand their niches. However, successful switching may require suites of adaptations and may decrease performance on the old host. As a result, reductions in gene flow accompany many host switches, driving speciation. Because host switches tend to be rapid, it is difficult to study them in real time and their demographic parameters remain poorly understood. As a result, fundamental factors that control subsequent parasite evolution, such as the size of the switching population or the extent of immigration from the original host, remain largely unknown. To shed light on the host switching process, we explored how host switches occur in independent host shifts by two ectoparasitic honey bee mites (Varroa destructor and V. jacobsoni). Both switched to the western honey bee (Apis mellifera) after it was brought into contact with their ancestral host (Apis cerana), ~70 and ~12 years ago, respectively. Varroa destructor subsequently caused worldwide collapses of honey bee populations. Using whole-genome sequencing on 44 mites collected in their native ranges from both the ancestral and novel hosts, we were able to reconstruct the known temporal dynamics of the switch. We further found that hundreds of haploid genomes were involved in the initial host switch, and, despite being greatly reduced, some gene flow remains between mites adapted to different hosts remains. Our findings suggest that while reproductive isolation may facilitate fixation of traits beneficial for exploitation of the new host, ongoing genetic exchange may allow genetic amelioration of inbreeding effects.Competing Interest StatementThe authors have declared no competing interest.