Sex ratio, sex-specific pattern in vegetative growth and gemma production in an aquatic liverwort,Scapania undulata(Marchantiophyta: Scapaniaceae)

Abstract

Scapania undulata is an aquatic dioicous liverwort growing in shallow streams in boreal to subtropical zones. We studied the expressed sex ratio, sex-specific differences in shoot architecture and possible trade-off between sexual and asexual reproduction in ten populations of S. undulata by surveying 100 plots in ten streams in southern Finland. The expressed sex ratio was male biased, in contrast with the sex ratio in most dioicous bryophytes. It was also highly variable between the streams, but individual plots frequently comprised shoots from only one sex. The overproduction of males might be a strategy to overcome sperm dilution and ensure fertilization over longer distances in water. No size differences between females and males were detected, but they differed in branching patterns. Evidence for a higher cost of sexual reproduction in females than males can be seen from the following: the male-biased sex ratio; low number of sex-expressing female shoots in female-only plots; no co-occurrence of gemmae and female sex organs on a single branch, and no more than one sexual branch per female shoot. In contrast, high gemma production of male and female sex-expressing shoots indicates a minimal trade-off between sexual and asexual reproduction.

Reproductive biology of Syzygiella rubricaulis (Nees) Steph. (Adelanthaceae, Marchantiophyta), a liverwort disjunctly distributed in high‐altitude Neotropical mountains

“…from streams in Finland (71%; Holá et al . ). Non‐sex‐expression in bryophytes may be associated with factors such as size threshold of colonies (McLetchie & Puterbaugh ), shoot length (Stark et al .…”

“…Conversely, male‐skewed expressed sex ratios have been recorded in the liverwort Lophozia silvicola growing on decaying wood (Laaka‐Lindberg ); in the aquatic liverwort Scapania undulata (Holá et al . ); and in the epiphyllous (growing on leaves) moss Crossomitrium patrisiae (Brid.) Müll.…”

Reproductive traits as predictors of assembly chronosequence patterns in epiphyllous bryophyte metacommunities

“…In theory, species composition of stable patches with high connectivity is molded by biotic interactions, whereas those of spatially isolated ephemeral patches are governed by dispersal limitation (Figure ). The latter example, the patch‐tracker model (sensu Snäll, Ribeiro, & Rydin, ), is globally represented by phylogenetically disparate groups adapted to ephemeral substrates of terrestrial and aquatic environments alike (Altermatt, IlmariPajunen, & Ebert, ; Göthe, Angeler, & Sandin, ; Hanski, ; Holá, Vesalainen, Tesitel, & Laaka‐Lindberg, ; Miller & terHorst, ; Mungia, ; Snäll et al, ; Yawata et al, ; Zartman, Nascimento, Cagani, Alvarenga, & Snäll, ). Demographic evidence from patch‐tracking metacommunities such as invertebrates in manipulated micro‐landscapes (Gonzalez, Lawton, Gilbert, Blackburn, & Evans, ), inquilines of water columns (Kneitel & Miller, ), and tropical forest epiphylls (Zartman & Shaw, ) all point to the importance of regional dispersal for their metacommunity maintenance.…”

Prezygotic resource‐allocation dynamics and reproductive trade‐offs in Calymperaceae (Bryophyta)

“…Expressed SRs are variable in angiosperms (Barrett et al, 2010) and bryophytes alike (Wyatt and Anderson, 1984), but they are more heavily skewed toward females in populations of the latter (Bowker et al, 2000; Bisang and Hedenäs, 2005; Stark et al, 2010). Nearly one‐fifth of bryophyte taxa exhibit either a balanced or a male‐biased SR, including rare cases of male‐skewed populations, which typically inhabit ecologically extreme substrates such as leaves (e.g., epiphylls; Alvarenga et al, 2013) and rocks in fast‐flowing streams (Hola et al, 2014). Nonetheless, reproductive‐allocation studies in bryophytes have been principally focused on mechanisms that promote female‐bias.…”

“…In bryophytes, investigations have been focused on postzygotic reproductive investment and asexual reproduction (reviewed in Stark et al, 2009), with few demonstrations of trade‐offs between prezygotic rates of sexual expression and investment in production of asexual propagules (Fuselier and McLetchie, 2002). Dioicous bryophyte populations range from no sex‐specific differences in gemma frequency (Hóla et al, 2014) to sharp ones (Laaka‐Lindberg, 2001), suggesting that gender‐biased investment in asexual reproduction is not consistent in bryophytes.…”