Offspring survival
Our results show that incipient colonies may suffer from inbreeding when
facing pathogen pressure. Although cuticular microbial loads did not
differ between inbred and outbred offspring in our study, the increased
susceptibility of inbred offspring is consistent with higher microbial
loads in inbred colonies of Z. angusticollis , potentially
resulting from reduced grooming or a less diverse range of
antimicrobials (Calleri et al. 2006). Notably, our results on
incipient colonies contrast with those uncovered on mature field
colonies of the same species, showing a weak influence of genetic
diversity toward entomopathogens (Aguero et al. 2020; Agueroet al. 2021b). First, this difference may stem from a greater
reduction in heterozygosity in the present study compared to those in
mature colonies, where heterozygosity was only moderately reduced by
neotenic reproduction (Rosengaus & Traniello 2001; Aguero et al.2021b). Similarly, offspring in the present study were probably younger
and thus more susceptible to pathogen exposure []; they were also
reared under lab conditions and did not face the same pathogen exposure
as workers collected from the field, therefore removing the possibility
that immune priming may potentially mask differences between inbred and
outbred groups (Rosengaus et al. 1999; Rosengaus et al.2007). Despite these differences, the better survival of particular
pairings also support the suggestion that the influence of a specific
genetic background may be greater than the overall genetic diversity on
colony survival (Aguero et al. 2020; Aguero et al. 2021b).
Together with previous findings, our results reveal that inbreeding is a
negligible factor in the survival of both founding couples and mature
colonies; but may have an important role in incipient colonies. These
findings indicate that higher inbreeding depression during colony
development, where incipient colonies may be more vulnerable, could
increase the proportion of mature colonies headed by outbred
reproductives (DeHeer & Vargo 2006) (illustrated in Figure 6).