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.