Abstract

Birds are known to act as potential vectors for the exogenous dispersal of bryophyte diaspores. Given the totipotency of vegetative tissue of many bryophytes, birds could possibly also contribute to endozoochorous bryophyte dispersal. Fecal samples of Upland Goose (Chloephaga picta) and White-bellied Seedsnipe (Attagis malouinus) contain many bryophyte fragments (Russo et al. 2018). Although one of these generated new growth, the general viability of diaspores following passage through the bird intestinal track remains ambiguous. We tested this hypothesis for bryophytes consumed by these same herbivorous birds in sub-Antarctic Chile. We opportunistically collected droppings of both species from six sites in alpine and lowland habitats of Navarino Island, screened six samples for bryophyte fragments (one from each site), and cultured 343 fragments in containers containing forest, turf, or mixed soil, and in vitro (Gamborg medium). We also sampled three wild populations of local mosses in these habitats (i.e., Conostomum sp., Syntrichia sp., Polytrichum sp.) and tested their totipotency and regeneration ability on the same substrate. Twenty-one conditions containing fragments from feces and fifteen wild moss conditions were placed in a growth chamber. After about 3 months (91 days), four of nine (44%) of White-bellied Seedsnipe samples, eight of 12 (67%) of Upland Goose samples, and 12 of 15 (80%) of the wild moss samples produced new growth based on the occurrence of “light” green shoots. Of these, nine developed on forest soil, five on turf soil, and seven on mixed soil. The three samples of fragmented wild mosses inoculated in solid Gamborg medium showed vegetative growth. On the contrary, by this method no growth was observed on any of the sixsamples tested from both bird species.. The latter results suggest that the three species sampled are totipotent, a necessary condition for effective endozoochory. The former observations reveal that furthermore, moss diaspores may remain viable following the passage through the intestinal track of both birds, and are capable of regeneration. Consequently, sub-Antarctic birds may play a passive and critical role in the dispersal of bryophytes, as birds are more likely to defecate in their feeding grounds, thereby enabling bryophytes to effectively propagate within a generally suitable habitat and where they are likely to be carried by wind or rain.