Migration Patterns of Epiphyllous Bryophyte Metapopulations in Amazonian Fragmented Landscape Inferred From Census and Genomic Data

Abstract

Habitat fragmentation affects metapopulation dynamics by reducing patch (discrete area occupied by a local population) size and connectivity, but its long-term genetic consequences are confounded by species-specific traits and limitations of sequencing techniques. Studies of terrestrial plants with relatively short generation times, combined with high-throughput sequencing, provide valuable insights into the demographic and genetic effects of land-use change. We integrate long-term censuses and genotyping data from epiphyllous bryophyte metapopulations in experimentally fragmented Amazonian forests. We focused on two bryophyte species with contrasting mating systems across 11 populations in small (1- and 10-ha) and large (100-ha and continuous) habitats. We aim to assess how long-term reductions in colony numbers in small fragments affect population genetic diversity and differentiation compared to larger habitats. We also explore how species' mating systems influence migration patterns across forest sites, with bisexual species expected to exhibit a higher likelihood of sexual reproduction and spore output than their unisexual counterparts. Our results reveal contrasting patterns of genetic structure between the two species, with no consistent effects of forest fragmentation detected across the landscape. The bisexual species showed notably lower genetic diversity and slightly higher differentiation in small fragments, suggesting a non-equilibrium metapopulation driven by limited migration. In contrast, the unisexual species exhibited minimal genetic impact from fragmentation, maintaining symmetrical migration among fragments regardless of size, indicative of patchy metapopulation dynamics. This study highlights how contrasting mating systems in epiphyllous bryophytes influence migration patterns and underscores the species-specific responses to habitat fragmentation.