Monoicy (both sexes on same individual) frequently has arisen through hybridization and polyploidy (multiple sets of chromosomes). Barriers to hybridization and to selfing in bryophytes are poorly known. These include external barriers such as spatial/geographic isolation, ecological isolation, and seasonal isolation. Internal barriers include gametic isolation, genetic incompatibility, hybrid sterility, and reduced fitness. Nevertheless, hybridization seems to have played a major role in the evolution of monoicy due to lack of these barriers in many species. Formation of gametangia and especially sporophyte formation incur reproductive costs measurable in reduced future vegetative and reproductive performance. Overall investment in sexual reproduction may vary among species, in some cases being greater in males and in others greater in females, depending on if assessed at the pre- or postfertilization stage.

Tradeoffs occur between dispersal ability of small spores and success of establishment of large spores. Fragments and vegetative diaspores are most successful at colonizing over short distances and are more likely to succeed than spores. Asexual reproduction can keep the species going for many years in the absence of sexual reproduction. Tradeoffs occur also among asexual reproduction, sexual reproduction, and vegetative performance. These tradeoffs vary among species.

The dominant haploid state of bryophytes limits their ability to store recessive alleles, but autopolyploidy, somatic mutations, vegetative reproduction, and independent assortment at meiosis contribute to diversity. Despite their clonal nature, bryophytes still exhibit considerable genetic variation.

The dominant haploid state of bryophytes limits their ability to store recessive alleles, but autopolyploidy, somatic mutations, vegetative reproduction, and independent assortment at meiosis contribute to diversity.  Despite their clonal nature, bryophytes still exhibit considerable genetic variation.  This may be explained in part by the Red Queen hypothesis, a hypothesis that also might explain the persistence of evolution to a dioicous condition despite the difficulty of accomplishing sexual reproduction.  Inbreeding depression may occur in monoicous bryophytes, but very limited data suggest that may be to a limited degree compared to that of tracheophytes.

Bryophytes may lack the morphological diversity expressed by sporophytes in higher plants, but there is evidence that haploid plants and their diaspores can contain as much diversity as tracheophytes, often expressed in their biochemistry as a variety of secondary compounds rather than in morphology.  They have life strategies that have survived since the beginning of land plants.