Association between temporal patterns in helminth assemblages and successful range expansion of exotic Mus musculus domesticus in Senegal

Relationships between parasitism and invasion success are increasingly evidenced in the literature. However, the dynamic nature of the major parasite-related processes has been rarely taken into account until now, while the residence time of invaders in colonized regions was shown to be associated to crucial changes in parasite communities. Here, we strive to bridge this gap using a temporal survey of rodent populations along one invasion route of the exotic house mouse Mus musculus domesticus that currently invades North Senegal. In this study, we investigated whether gastrointestinal helminth (GIH) assemblages changed over time in native (Mastomys erythroleucus) and/or invasive (M. m. domesticus) rodent populations sampled at an invasion front, and whether these potential changes may be associated to the invasion success of the exotic mouse. Four years separated two rodent sampling campaigns (2013 and 2016/17) in six localities. Despite being relatively short, the timeframe considered here allowed to evidence significant patterns in rodent communities and their GIH assemblages. At the host community level, we showed that the exotic mouse was now established at all sites, becoming the dominant species in sites where it was not recorded before. At the GIH community level, increased infection of the single shared cestode (Mathevotaenia symmetrica) in both rodent species brought support to the “spill-back” hypothesis. Infection levels of GIH that remained low at the invasion front in invading mice over time also supported the “enemy release” hypothesis. Both hypotheses should deserve further experimental work to demonstrate their role in the invasion success of the house mouse in Senegal.