Conclusions
We confirmed the hypothesis that fragmented bryophyte gametophytes
retrieved from the feces of herbivorous birds could regenerate in
laboratory conditions. Consequently, our research shows that it is
plausible for fragments to be dispersed through endozoochory by these
herbivorous birds in the sub-Antarctic, possibly further aiding
bryophytes in this region to disperse beyond wind or rain, and
increasing their capability to reach specific habitat types (Figure 2).
As both bird species are robust fliers, altitudinal migrants for short
distances and latitudinal migrants for long distances, their role as
dispersers might not only occur locally, but also at a broader scale.
This is especially important as with warming conditions, organisms such
as mosses would have to move to higher altitudes or latitudes to
maintain viable populations. By serving as dispersal vectors, birds
would be able to aid in this process in short time scales in the
vertical and horizontal axes of the landscape. This process is
especially critical in maintaining the viability of bryophytes in
Navarino Island, which contains an “ecosystem of highest ecological
importance” (Goffinet et al., 2012) and holds many endemic species
(Méndez et al., 2013), and just as critical globally where
bryophytes are also being affected by changes to their ecosystems.
Sub-Antarctic birds may play a passive, but likely critical role in the
dispersal of bryophytes, as birds are more likely to defecate in like
habitat conditions where they graze (J. Jiménez, 2019, pers. comm.).
Thus, potentially enabling bryophytes to effectively propagate within a
generally suitable habitat and in locations where they are unlikely to
be established by wind or rain, but are accessible to birds. However,
further research needs to be done to test bryophyte dispersal through
endozoochory and the role of birds in this process. To progress along
this line of research, we suggest a larger sample size and replication,
more substrate treatments, as bryophyte fragments might respond variably
to distinct types of soil, and conducting DNA sequencing of the
bryophyte fragments found in the fecal samples to identify the bryophyte
species before culturing them. Finally, there is the need to reproduce
these results under field conditions, so we can understand the relevance
of this type of zoochory in bryophyte dispersal at these high-latitude
landscapes.