4.4 Plasmid lifestyle
The concept of generalists (the capability of adapting to diverse habitats) and specialists (adapting to specific habitats) (Sriswasdi et al., 2017; Van Tienderen, 1991) have been extended to microbial ecology (Sriswasdi et al., 2017; Székely & Langenheder, 2014). We propose this theory can be further extended to plasmids, the habitats of which are their host cell. Our analysis indicates that R27 is a specialist, transferring withinEnterobacteriaceae . This is supported by both the low host divergence (figure 3b), lower similarity to the sewage community than pB10 transconjugants (figure 3c and d), and the lack of correlation between the ASV abundance in the recipient sewage community and the R27 transconjugant community (figure 5a). Contrarily, the transfer dynamics of pB10 resemble that of a generalist, with a high host divergence (figure 3b) higher similarity to the sewage community than R27 transconjugants (figure 3c and d) and a high correlation between ASV abundance in the recipient sewage community and the pB10 transconjugant community (figure 5a).
The specialization‐disturbance hypothesis imposes that generalists are more resilient to disturbances altering niches than specialists (Vázquez & Simberloff, 2002). Thus a generalist plasmid lifestyle could ensure a higher resilience to change in the composition of available hosts. We argue that having a broad host range does not in theory have to be accompanied by being a generalist, yet being a generalist will likely be accompanied by also having a broad host range. The high transfer of the generalist pB10 could be considered as an adaptation to a low level of events that eventually are evolutionarily stable. Conversely, a specialist like R27, in which the majority of transfers are to very similar hosts, might have a high level of stable events due to low negative influence by host defence systems. Likewise this could result in a higher tendency of carrying more and/or diverse anti-defense systems for the generalist, than the specialist, as a co-evolutionary response to the encounter with diverse host defense systems. Further investigation on the long term persistence of plasmids in the host cell, derived from these two distinct competitive strategies in multispecies communities could be of interest to the field and our understanding of HGT mediated dissemination of ARGs.