Marine invasions and parasite escape: updates and new perspectives

Marine invasions have risen over time with enhanced globalization, and so has the introduction of non-native hosts and their parasites. An important and well-supported paradigm of invasion biology is the significant loss of parasites that hosts enjoy in introduced regions compared to native regions (i.e. parasite escape), yet less is known about the factors that influence parasite escape in marine systems. Here, we compile an up-to-date review of marine parasite invasions and test several hypotheses related to host invasion pathway that we suspected could influence parasite escape across the 31 host-parasite systems included in our investigation. In general, we continued to show significant support for parasite escape; however, escape varied among parasite taxa, with most taxa demonstrating moderate levels of escape and a few showing complete or no escape. Moreover, we revealed several important factors related to host taxa, geography, time, and vector of introduction that influenced parasite escape, and in some cases demonstrated significant interactions, revealing the complexity of the invasion pathway in filtering parasites from native to introduced regions. In some (but not all) cases, there was also evidence of invasive host advantages due to parasite escape, but more evidence is required to demonstrate clear support for the enemy release hypothesis. In general, our study revealed the need for further research across systems, especially in understudied regions of the world.