Genetic diversity and mating system of the threatened plant Kirengeshoma palmata (Saxifragaceae) in Korea

Abstract

The endangered herb Kirengeshoma palmata, from eastern Asia, has had its population severely reduced in number through habitat loss and fragmentation. All of the individuals within five subgroups at Mt. Baek-un-san, in the southern part of Korea, were genetically surveyed by allozyme analysis. Genetic diversity levels within subgroups were relatively high, and a consistently high outcrossing rate as well as a negligible biparental mating rate were confirmed by this study. Several groups of visibly connected ramets were observed in a clustered distribution which suggested cloning. Absence of mating partner rather than pollinators decreased seed production in small mating groups. The present genetic structure of the five subgroups was probably the result of local extinction of intervening populations. Because K. palmata may be a self-incompatible species, populations with few genets face lowered seed set due to mate scarcity. Thus, this type of population may be at an increased risk of extinction as a result of inbreeding depression, loss of genetic variability, and reduced sexual reproduction. The small, genetically depauperate subgroups may need an input of seeds or plants from other populations in China or Japan in order to regenerate, but the possibility of outcrossing depression leads us to recommend outbreeding among the local subgroups of Mt. Baek-un-san to restore genetic variability.

Genetic diversity in the two endangered endemic species Kirengeshoma koreana (Hydrangeaceae) and Parasenecio pseudotaimingasa (Asteraceae) from Korea: Insights into population history and implications for conservation

“…In addition to this, the high values of multi-population-level F IS (0.347) suggest that inbreeding would have decreased the N e of K. koreana populations, increasing the rate at which genetic diversity is lost due to random genetic drift. Our allozyme data seem to be in contrast with the previous study of Chang et al (2007), in which the authors suggested that K. koreana is a predominant outcrosser. In plants, F IS values of 0.300 or higher are indicative of mixed mating system with nearly equal amounts of selfing and outcrossing; thus, K. koreana is probably a mixedmating species.…”

“…Small effective population size (N e ) has been suggested as the most important reason explaining the low levels of genetic diversity in narrow endemic species (e.g., Barrett and Kohn, 1991;Ellstrand and Elam, 1993;López-Pujol et al, 2013). Although neither recent nor reliable censuses are available for all the few extant populations of K. koreana, these are very small and scatteredly distributed, and are probably declining (Chang et al, 2007;J. M. Chung, pers.…”

“…Individuals grow on moist, nutrient-rich soils under deciduous forests. Its yellow flowers are visited by a variety of insects including Bombus ussuriensis (Apidae), Lasioglossum nipponicola (Halictidae), and Ceratina flavipes (Anthophoridae) (Chang et al, 2007), whereas the small and winged seeds could be dispersed by wind (Zhang et al, 2006). Field observations by Chang et al (2007) suggest that the pollination among close relatives may be prevented by asynchronous flowering.…”

“…Its yellow flowers are visited by a variety of insects including Bombus ussuriensis (Apidae), Lasioglossum nipponicola (Halictidae), and Ceratina flavipes (Anthophoridae) (Chang et al, 2007), whereas the small and winged seeds could be dispersed by wind (Zhang et al, 2006). Field observations by Chang et al (2007) suggest that the pollination among close relatives may be prevented by asynchronous flowering. This species, because of its extremely reduced population size (probably a few hundred individuals) and the few locations in which occur, can be regarded as an 'extremely narrow endemic' species ('ENEs') according to the definition of López-Pujol et al (2013).…”

“…1). K. koreana reproduces both sexually and vegetatively by means of short, stout rhizomes (Chang et al, 2007). Individuals grow on moist, nutrient-rich soils under deciduous forests.…”