The Effectiveness of the Sexual Reproduction in Selected Clonal and Nonclonal Species of the Genus Ranunculus

Abstract

Generative processes have been evaluated in six European buttercup species in order to verify the hypothesis that the reproduction efficiency of clonal species is lower than that of nonclonal ones. The study covered common species (Ficaria verna, Ranunculus auricomus, R. bulbosus, R. cassubicus, R. lanuginosus) and the endangered R. illyricus. The following properties have been assessed: pollen viability (staining method), pollen grain germination and the pollen-tube elongation in pistil tissues (fluorescence microscopy), seed formation efficiency, seed viability (tetrazolium test) and germination ability by introducing factors interrupting dormancy (low temperature and gibberellin application). Additionally, the pistil morphology was documented for R. bulbosus, R. illyricus and R. cassubicus using SEM techniques. It was demonstrated that the reproductive efficiency, expressed as the production of viable seeds able to germinate, was significantly higher in the species reproducing sexually (especially in R. lanuginosus) compared to the clonal ones. However, the complexity observed leads to separation of an additional group (cluster) of apomictic species: R. auricomus and R. cassubicus, distinguished by the lowest pollen viability and a low ability of the seeds to germinate. In the vegetatively reproducing R. illyricus, the seed formation efficiency was just 13.2% despite the having highest number of pistils in its flowers. The developed seeds of this species observed in our experiment were viable, but in general effective methods to stimulate their germination have not been proposed yet. Here, the first comparative study concerning the biology of sexual reproduction of R. illyricus is presented in the context of its decreasing distribution in natural habitats.

Anthropogenic and natural disturbances increase local genetic diversity in an early spring geophyte (Ficaria verna Huds)

“…Despite sampling at a very local scale, we found high levels of allelic and clonal diversity in F. verna, as evidenced by high allele numbers, large ranges of allele lengths, and generally high numbers of MLGs at individual sampling sites (Table 2). Our data thus support previous observations that the species is genetically diverse (Mattingly et al, 2023;Popelka, Sochor, & Duchoslav, 2019;Reisch & Scheitler, 2009) and provide evidence that F. verna is capable of maintaining high levels of genetic diversity despite its predominantly clonal growth (Kocot et al, 2022;Popelka, Tr avníček, et al, 2019;Verheyen & Hermy, 2004). Ficaria verna has several characteristics that are beneficial for maintaining genetic diversity.…”

“…We conclude that short-distance dispersal of both generative (where available) and vegetative propagules is responsible for maintaining clonal diversity and mixing of MLGs at the local scale in F. verna, whereas dispersal of sexually produced pollen and/or seeds, even if infrequently produced (Kocot et al, 2022;Marsden-Jones & Turrill, 1952;Popelka, Tr avníček, et al, 2019), is sufficient to ensure genetic admixture at the regional scale. Due to the generally high levels of local genetic diversity and the presence of unique MLGs at all sites of F. verna, we assume that seedling recruitment is at least occasional at all study sites, although the extent to which sexually produced propagules establish is likely to vary between sites.…”

“…Ficaria verna is capable of both sexual and asexual reproduction. Although the species flowers regularly, few viable seeds are produced (Kocot et al, 2022; Metcalfe, 1939). No evidence for the production of viable seeds by autonomous apomixis has been found in F. verna (Popelka, Trávníček, et al, 2019; but see Metcalfe, 1939).…”

Reproductive Biology of Dry Grassland Specialist Ranunculus illyricus L. and Its Implications for Conservation

“…However, in many countries, this species, associated with xerothermic grasslands, is rare and to various degrees under threat of extinction. So far, however, little is known about its reproductive biology and the available data are only fragmentary [ 30 , 31 , 32 ].…”

“…All three species can be defined as perennial geophytes with monocarpic aboveground stems adapted to seasonal climatic changes. F. verna was also found to exhibit low efficiency of generative reproduction [ 32 ], which does not prevent it from occurring in large numbers thanks to its efficient vegetative reproduction. It is known that in undisturbed communities this mode of reproduction dominates and effectively ensures the survival of plants, e.g., the perennial undergrowth of deciduous forests [ 49 , 50 ] or the steppe perennial in the temperate zone [ 43 ].…”