An experimental demonstration of the cost of sex and a potential resource limitation on reproduction in the moss Pterygoneurum (Pottiaceae)

Abstract

The cost of sexual reproduction is incurred when the current reproductive episode contributes to a a decline in future plant performance. To test the hypotheses that a trade-off exists between current sexual reproduction and subsequent clonal regeneration and that resources limit reproduction and regeneration, plants of the widespread moss Pterygoneurum ovatum were subjected to induced sporophytic abortion, upper leaf removal, and nutrient amendment treatments. Sexually reproducing plants were slower or less likely to produce regenerative structures (protonemata or shoots) and produced fewer regenerative tissue areas or structures. The ability and the timeline to reproduce sexually and regenerate clonally were unaffected by an inorganic nutrient amendment. However, when leaves subtending the sporophyte were removed, the sporophytes were less likely to mature, tended to take a longer time to mature, and were smaller compared to sporophytes from shoots with a full complement of upper leaves. Our findings indicate that plants investing in sexual reproduction suffer a cost of decreased clonal regeneration and indicate that sporophyte maturation is resource-limited, with upper leaves contributing to the nutrition of the sporophyte. This study represents only the second explicit experimental demonstration of a trade-off between sexual and asexual reproduction in bryophytes.

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.…”

Effects of salinity and clonal integration on growth and sexual reproduction of the invasive grass Spartina alterniflora

“…Since resources for metabolism and biomass gain are limited, increasing resource allocation to one function may reduce that to other functions (Bai et al, 2009;Liu et al, 2009). Reduced growth in response to increased sexual production has been known for many species (Snow and Whigham, 1989;Stark et al, 2009;Thiele et al, 2009). On the other hand, sometimes such a trade-off is not obvious (Liu et al, 2009;Thompson and Eckert, 2004).…”

Passive warming reduces stress and shifts reproductive effort in the Antarctic moss,Polytrichastrum alpinum

“…Indeed several studies have since demonstrated greater sperm dispersal distances (for a review, see Glime, 2007), as well as stresstolerant sperm (Rosenstiel and Eppley, 2009;Shortlidge et al, 2012) and microarthropod-mediated sexual reproduction (Cronberg et al, 2006;Cronberg, 2012;Rosenstiel et al, 2012). Other factors can limit sexual reproduction in mosses, including: inadequate resources (Stark et al, 2000) growth trade-offs (Ehrlén et al, 2000) and investment in environmental stress defence (Convey and Smith, 1993;Stark et al, 2009;Eppley et al, 2011). In Antarctic mosses, sporophyte formation appears to be restricted to all but the most favourable microsites (Seppelt et al, 1992), with most species relying primarily on vegetative (asexual) reproduction for dispersal and colonization.…”