Where a male is hard to find: consequences of male rarity in the surfgrass Phyllospadix torreyi 

Abstract

Determining whether seed production is limited by pollen availability has been an area of intensive study. Past studies have focused largely on terrestrial species with biotic pollination modes, but precise causes and consequences of pollen limitation remain unknown. Here, sex ratio, seed production, seed recruitment, and viability were examined in intertidal populations of a dioecious, abiotically pollinated marine angiosperm, Phyllospadix torreyi (Torrey's surfgrass). Using field surveys and a common garden experiment, this study was conducted near Santa Barbara, California, USA, from 2007 to 2008. Reproduction and recruitment of P. torreyi primarily occur near the parental source (tens of meters) because female reproductive success ratio (RSR, measured as the ratio of fertilized ovules to total ovules) increased with local pollen production (RSR range: 0.02−0.71), and seed recruitment was predicted by local (site) seed production and elevation zone within the intertidal. Low RSR at sites with extreme male rarity (< 0.3 male flowering shoots m −2 ) suggests that pollen limitation is occurring within this system. Seed recruitment was predicted by local (site) seed production and elevation zone (area of potential seed recruitment within the intertidal). The occurrence of seed production and recruitment at sites with extreme male rarity suggests some dispersal of seeds and pollen extending beyond the immediate vicinity of the site. Pollen or seed dispersal over longer distances, although rare, may reduce habitat fragmentation by facilitating colonization of newly available habitat. Localized pollen availability affected seed quantity but not quality; seed germination and growth were uniform among sites.

Nursery‐propagated plants from seed: a novel tool to improve the effectiveness and sustainability of seagrass restoration

“…Previous studies indicate that sex ratios can become female biased with increasing clone age in some species of the genus Phyllospadix, possibly due to sex differences in growth or survivorship (Williams ; Shelton ; Buckel et al . ). Here, the sex ratio of C. nodosa flowering genets was not biased towards females, and there was no difference in survival between sexes at least during the study period.…”

Variation in reproductive effort, genetic diversity and mating systems across Posidonia australis seagrass meadows in Western Australia

“…Pollen limitation has been reported in several seagrass genera Phyllospadix spp. ( Shelton 2008 ; Buckel et al 2012 ), Thalassia testudinum ( Van Tussenbroek et al 2016b ) and Zostera spp. ( Reusch 2003 ; Van Tussenbroek et al 2016a ), where there is dominance of a few large clones and/or high spatial and temporal heterogeneity in flowering.…”

Coupling and Decoupling of Reproduction and Larval Recruitment

“…Recruitment failure occurred during the strong El Niño in 1998 when fruit was aborted. In a later study conducted on this species at seven sites spanning 50 km of coast in the same area over 9 months, fertilization success and seed production depended on pollen production ≤50 m away, which in turn, determined seed recruitment (F = 64.15 <0.001; Buckel et al 2012). Male abundance also determined fertilization success, seed production and seedling recruitment (Z = 4.02, p < 0.001) in Phyllospadix scouleri at four to seven sites over 3 years across 90 km of the outer coast of the Olympic Peninsula, WA, USA (Shelton 2008).…”