Dispersal potential of spores and asexual propagules in the epixylic hepatic Anastrophyllum hellerianum

Abstract

Dispersal ability is of great importance for plants, which commonly occupy spatially and temporally limited substrate patches. Mixed reproductive strategies with abundant diaspore production are favoured in a heterogeneous landscape to ensure successful colonisation at different distances. In bryophytes, long-distance dispersal has been thought to take place primarily by spores, while asexual propagules are important in local dispersal and in the maintenance of colonies. In the present study, we investigated the dispersal potential of two equally sized propagules, sexually formed spores and asexually produced gemmae in the dioecious, epixylic hepatic, Anastrophyllum hellerianum, which inhabits spatially and temporally limited substrate patches. We trapped propagules at different distances (0-10 m) and directions from the source colonies in two experiments: one in a natural habitat within a forest and another involving an artificial set-up in an open habitat. Spore dispersal showed only slight distance dependence both in the open and the forest habitats, presumably as a consequence of wind affecting the dispersal pattern. Gemma dispersal was more strongly distance-dependent in the open habitat than in the forest sites. Considerably more gemmae were deposited during rainy than dry periods, possibly because of the effect of rain drops on gemma release. However, weather conditions had no effect on the dispersal patterns of spores or gemmae. In A. hellerianum, the combination of occasional spore production and practically continuous, massive gemma production facilitates dispersal both on local scale and over long distances. Unlike previously assumed, not only spores but also the asexual propagules may contribute to longdistance dispersal, thus allowing considerable gene flow at the landscape level.

Distribution, ecology, and reproduction of bryophytes in a humid enclave in the semiarid region of northeastern Brazil

“…Sexual reproduction strategies (predominate among monoicous plants) result in the production of spores -creating the possibility of dispersal over much larger distances than are possible with asexual propagules (Longton 1997;Pohjamo et al 2006). Spores are also more resistant to desiccation and can remain dormant in spore banks (Leck & Simpson 1987;Maciel-Silva et al 2012a).…”

Baker's law and the island syndromes in bryophytes

“…Therefore, wind has long been identified as the main vector for LDD in bryophytes (Muñoz et al 2004;Sundberg 2013). The wind-dispersed units in bryophytes are the spores, which are on average smaller than asexual diaspores (Longton 1997; but see Pohjamo et al 2006). A small diaspore size has in fact been identified as a critical condition for efficient wind LDD, with diaspores bigger than 20 lm in diameter becoming increasingly unlikely to be wind-dispersed (Wilkinson et al 2012).…”

Plant biotechnology for deeper understanding, wider use and further development of agricultural and horticultural crops

“…Molecular and population genetics studies are carried out at DAB on several plant groups, including also algae and non-vascular plants such as mosses which are photosynthesizing organisms important to the ecosystems affected by or interacting with the agricultural and forest environments. For example, mosses are used as model organisms to study gene flow, population genetic structures and adaptation (Korpelainen et al 2005, Pohjamo et al 2006) and also evolution of pathogen resistance in plants (Akita and Valkonen 2002, Andersson et al 2005, Lehtonen et al 2006. Dispersal, colonization and gene flow are important to species in order to avoid population decline and extinction.…”