Factors influencing reproductive success in the clonal moss, Hylocomium splendens

Abstract

Female reproductive success in the unisexual perennial clonal moss Hylocomium splendens was examined by recording, if the segment was reproductive [produced sporophyte(s)] or not, together with several distance-to-male and male density variables, and segment size. This was done for every female segment in a population over a 5 year study period. A high fraction of the population could be sexed because we monitored the population in situ for 5 years, and thereafter harvested the population for electrophoretic analysis from which the clonal identity and expressed sex could be deduced. Fertilization distances in H. splendens were short, indicated by the fact that as many as 85% of the female segments with sporophytes were situated within a distance of 5.0 cm from the nearest male. The longest distance measured between a sporophytic female and the closest male was 11.6 cm. However, analysed within a generalized linear modelling (GLM) framework, the year was the best single predictor for the presence of H. splendens sporophyte although female-segment size and distance to the closest situated male were also strongly significant. The two latter factors explained larger fractions of variation in sporophyte presence in a GLM model with three predictors than in single-predictor models. This is because (i) the large variation in sporophyte production among years partly obscures the strong general increase in sporophyte production with increasing female-segment size and vitality, and (ii) the between-year variation and the size obscure the effect of the distance to the most proximate male. To our knowledge, this study is the first to incorporate into one model the relative importance of several factors for bryophyte reproductive success. Our results demonstrate the value of multiple-predictor approaches in studies of reproductive success.

Reproductive output of mosses under experimental warming on Fildes Peninsula, King George Island, maritime Antarctica

“…Sexual reproduction and the production of sporophytes in mosses may be reduced by sperm-limitation [43,46], resource limitation [24,56,58,59], and abiotic stress ( [8]; Eppley et al [25]). Our experimental warming treatments increased sporophyte production in two moss species, P. alpinum and B. patens, compared with controls (Tables 2a and 3), and this warming potentially altered many steps in the process of sporophyte formation, from sperm and egg production, to gamete dispersal, to fertilization success, to sporophyte maturation.…”

Dispersal potential of spores and asexual propagules in the epixylic hepatic Anastrophyllum hellerianum

“…Furthermore, sexual reproduction requires specific demands for substrate quality (Laaka-Lindberg 2000), colony structure (e.g. Bowker et al 2000;Laaka-Lindberg 2003, 2004;Rydgren et al 2006) and climatic conditions (LaakaLindberg 2005). Consequently, the success of sexual reproduction, which forms a significant part of the life history, encompasses high temporal and spatial variability (Rydgren Table 6 The deposition percentage of the produced progules by the source and the cumulative numbers of propagules that were daily deposited from the source colony up to 10 m. As in Table 3, spore production is measured per day, but gemma production refers to the entire production in the standing gemma population 3.6 (1900) 2.4 (2600) 1.5 (6000) 0.009 (2600) 0.16 (294 · 10 3 ) 0.02 (73 · 10 3 ) 250 9.7 (5000) 6.5 (7000) 3.9 (16 · 10 3 ) 0.02 (5800) 0.6 (1.1 · 10 6 ) 0.08 (280 · 10 3 ) 500 20.4 (11 · 10 3 ) 13.8 (15 · 10 3 ) 8.3 (34 · 10 3 ) 0.04 (11 · 10 3 ) 1.7 (3.1 · 10 6 ) 0.23 (775 · 10 3 ) 1000 43.1 (23 · 10 3 ) 29.2 (31 · 10 3 ) 17.5 (72 · 10 3 ) 0.07 (19 · 10 3 ) 4.8 (8.7 · 10 6 ) 0.64 (2.1 · 10 6 ) and Økland 2002; Rydgren et al 2006).…”

Increased diversification rates follow shifts to bisexuality in liverworts

“…However, fertilization ranges are generally much shorter. Rydgren et al (2006) found, for example, that 85% of the female shoots with sporophytes were situated within a distance of 5 cm from the nearest male and the longest distance was 11.6 cm. Sexual reproduction in unisexual species may be further challenged by: the strongly biased sex ratio of their populations (Bisang et al, 2014); the spatial segregation of the sexes due to differences in niche preference between males and females (Stark & McLetchie, 2006;Brzyski et al, 2014; but see Bisang et al, 2015); and the potential incompatibility between certain male and female genotypes in unisexual species (McLetchie, 1996).…”