To what extent are bryophytes efficient dispersers?

Abstract

Bryophytes are typically seen as extremely efficient dispersers. Experimental evidence suggests that efficient short‐distance dispersal coupled with random long‐distance dispersal (LDD) leads to an inverse isolation effect. Under the latter, a higher genetic diversity of colonizing propagules is expected with increasing isolation, counteracting differentiation beyond the range of short‐distance dispersal. This expectation is tested from a review of evidence on spatial genetic structure and analyses of isolation‐by‐distance (IBD) at different scales. A decay of the IBD signal, characterized by non‐significant slopes between kinship coefficients and geographic distance was observed beyond 100 m. A second slope shift was observed at distances larger than 1 km, with a proportion of significant slopes in more than one third of the datasets. The decay of the IBD signal beyond 100 m, which reflects efficient LDD, is consistent with the inverse isolation hypothesis. Persistence of a significant IBD signal at medium ranges in one third of the analysed cases suggests, however, that the inverse isolation effect is not a rule in bryophyte spore dispersal. Furthermore, the higher proportion of significant IBD patterns observed at scales over 100 km likely marks the limits of regional dispersal, beyond which an increasingly smaller proportion of spores travel. Synthesis. We discuss the differences between experimental and genetic estimates of spore dispersal and conclude that geographic distance remains a significant proxy of spore colonization rates, with major consequences for our understanding of actual migration capacities in bryophytes, and hence, our capacity to model range shifts in a changing world.

Effects of Rate of Drying, Life History Phase, and Ecotype on the Ability of the Moss Bryum Argenteum to Survive Desiccation Events and the Influence on Conservation and Selection of Material for Restoration

“…Spores contribute to long distance dispersal across landscapes (Patiño and Vanderpoorten, 2018). Bryophytes are thought to be efficient spore-dispersing organisms, with 100 kilometers suggested as a likely distance a spore could travel (Vanderpoorten et al, 2019). Bryophytes have relatively low rates of endemism compared to seed plants, and species composition patterns match more closely with wind connectivity patterns than geographic proximity (Patiño and Vanderpoorten, 2018).…”

Island biogeography: an avenue for research in bryology

“…this suggests that restrictions to gene flow in insular environments may be sufficient to elevate diversification rates to levels comparable to those observed at much larger continental scales, even in organisms with high long-distance dispersal capacities such as bryophytes. Mounting evidence from fine-scale population genetic studies in bryophytes reveals a significant partitioning of genetic variation among populations structured by short geographical distances (Vanderpoorten et al 2019). We thus propose that the minimum geographical distance required for neutral divergence, and hence speciation, might be much shorter than what bryophytes' capacity for occasional and random long-distance dispersal suggests.…”

Biogeography and integrative taxonomy of Epipterygium (Mniaceae, Bryophyta)

“…This was seen as evidence for in situ diversification within regions (mostly continents), which takes place at a faster rate than the intercontinental migration. The strong phylogeographic signal found in many bryophyte species at the intercontinental scale (Patiño & Vanderpoorten, 2018), along with the strong population genetic structuring observed in a number of continentally disjunct species Vanderpoorten & al., 2019), is in line with the notion that speciation has a spatial scale that depends on both area and levels of gene flow (Kisel & Barraclough, 2010). Our results suggest that in Epipterygium, large geographic areas seem to be required to allow speciation in allopatry.…”