Population genetic consequences of the reproductive system in the liverwort Mannia fragrans

Abstract

Ecological factors affecting reproduction and dispersal are particularly important in determining genetic structure of plant populations. Polyoicous reproductive system is not rare in bryophytes; however, to date, nothing is known about its functioning and possible population genetic effects. Using the liverwort Mannia fragrans as a model species, the main aims of this study were to separate the relative importance of the components of the polyoicous reproductive system and to assess its consequences on the genetic structure of populations. High sex expression rates increasing with patch size and strongly female-biased sex ratios were detected. Additional input into clonal growth after production of sex organs was found in males compared to females. Similar clonal traits of the rare bisexual and asexual plants and preference toward newly colonized patches suggest that selection prefers colonizers that first develop organs of both sexes, hence ensuring sexual reproduction when no partner is present. Despite frequent spore production, ISSR markers revealed low genetic diversity, probably resulting from the effective clonal propagation of the species and frequent crossing between genetically identical plants. The presence of numerous rare alleles and unique recombinant haplotypes indicates occasional recombination and mutation. Effective spreading of new haplotypes is probably hampered however by large spore size. Since populations are small and isolated, such haplotypes are probably continuously eliminated by genetic drift. These results suggest that although both sexual and asexual reproductions seem to be effective, asexual components of the reproductive system play a greater role in shaping the genetic composition of the populations.

Spatial genetic structure of aquatic bryophytes in a connected lake system

“…2008) but only 0.010 in a microsatellite study on S. wulfianum on a global scale (Kykjeeide et al. 2012), 0.059 in an ISSR study on Mannia fragrans on a regional scale (Hock et al. 2009), and ISSR diversity ranges of 0.035–0.168 in populations of Leptodon smithii (Spagnuolo et al.…”

“…In previous studies on bryophytes, widely varying levels of genetic diversities have been discovered, e.g. a microsatellite variation range of 0.356-0.744 in six Sphagnum species (Shaw et al 2008) but only 0.010 in a microsatellite study on S. wulfianum on a global scale (Kykjeeide et al 2012), 0.059 in an ISSR study on Mannia fragrans on a regional scale (Hock et al 2009), and ISSR diversity ranges of 0.035-0.168 in populations of Leptodon smithii (Spagnuolo et al 2007a) and 0.098-0.175 in populations of Pleurochaete squarrosa (Spagnuolo et al 2007b). An Nm value of at least 1.0 is considered necessary to prevent divergence due to genetic drift (Wright 1931).…”

Ploidy level, genetic diversity, and differentiation in two closely related mosses,Scorpidium cossoniiandS. revolvens(Calliergonaceae)

“…During field work, only a few gametophytes expressing female gametangia were found (personal observations). These observations may imply a female-biased sex ratio in this species, as is commonly detected in other dioicous bryophytes (Bisang & Hedenäs, 2005;Hock et al, 2009). Owing to the lack of sporophytes and high incidences of multilocus linkage disequilibrium even in clone-corrected data (r d ; Table 1), recent genetic recombination is unlikely.…”

How does reproductive strategy influence demography? A case study in the tropical, unisexual epiphyllous moss Crossomitrium patrisiae

“…Reproductive strategies play an important role in metapopulation ( Johansson et al, 2012 ) and metacommunity ( Lobel et al, 2009 ) dynamics and also in the genetic ( Hock et al, 2009 ) structure of bryophyte populations. However, relatively few studies have attempted to quantify the demographic parameters that trigger shift s between sexual and asexual expression ( McLetchie and Puterbaugh, 2000 ;Zartman et al, 2015 ).…”