Progressive cross- and self-sterility associated with aging in fern clones and perhaps other plants

Abstract

Plant reproductive cells differentiate from cell lineages derived ultimately from apical meristem initials, cells that are mitotically active throughout the life span of the plant. Because of the chemostat-like properties of these initial-cell populations, the frequency of mutant initials (or apical meristems) will increase as the plant ages. These properties led to three predictions when comparing long-lived species in which the frequency of sexual reproduction varies. The most asexual species should have the highest mean frequency of mutant ramets per chimeric genet, the highest genetic load, and the highest level of genetic load with dominant effects in embryonic and juvenile growth phases. These predictions were confirmed in a study of two fern species.

Genetic variation and ecotypic differentiation in the wild rice species Oryza rufipogon. I. Population differentiation in life-history traits and isozymic loci.

“…In other plant species, evidence exists that long-lived plants may bear an appreciable genetic load (Klekowski, 1988): this may also be the case in perennial wild ricer .…”

Genetic diversity of a clonal angiosperm near its range limit: the case of Cymodocea nodosa at the Canary Islands

“…Sexual allocation in clonal plants may become reduced due to environmental (Kanno & Seiwa 2004, Honnay & Bossuyt 2005 and genetic factors (Klekowski 1988, Barret et al 1993, Eckert 2002, which leaves asexual reproduction as the only means of population growth and colonization and may even set the stage for genetic sterility (Eckert 2002). Several clonal plant species show reduced sexual capacity at the margins of their distribution (Erikson 1996, Reusch et al 1999, Eckert 2002, Billingham et al 2003.…”

Evolutionary vestigialization of sex in a clonal plant: selection versus neutral mutation in geographically peripheral populations

“…Under some conditions, therefore, sex may contribute very little to population recruitment and hence to fitness. At the extreme, traits involved in sex may cease to be maintained by selection, and might, as a result, become lost or dysfunctional (Klekowski 1988). Sexual reproduction by flowering plants involves an intricate series of developmental and morphological traits, from the formation of flowers and gametophytes to the production of fruits and seeds.…”