Hydrochory as a determinant of genetic distribution of seeds within Hibiscus moscheutos (Malvaceae) populations

Abstract

Seed dispersal is a major determinant of the spatial genetic structure of plant populations. In this study, we evaluated the role of distinct hydrologic regimes in determining the spatial genetic structure of the seed bank of the wetland plant Hibiscus moscheutos. We analyzed seeds in surface soil samples collected in the autumn and the following spring by determining their allozyme genotypes and estimated the pattern in seed movements during flooding. We selected study sites in nontidal and tidal wetlands with different flooding regimes. One nontidal site had no flooding, while the second nontidal site was inundated for most of the year. One tidal wetland site flooded with almost every tide, and a second tidal site was inundated at moderate frequency. Genetic makeup of the seed bank at the nonflooded site changed little between seasons. Secondary seed dispersal altered absolute allele frequencies at the other three sites, with the greatest change occurring at the two tidally influenced sites. This study demonstrates that secondary hydrochory influences the genetic composition of the seed bank and that hydrologic conditions play an important role in determining the local patterns in seed movements.

Urban rivers as dispersal corridors for primarily wind-dispersed invasive tree species

“…In addition to increased transport distances, hydrochory may have further evolutionary and ecological consequences by affecting the spatial distribution of genetic variation (Shimamura et al, 2007;Ruedinger et al, 2008) and species' germination response. Samaras of A. altissima which floated up to 10 days were more likely to germinate and germinated earlier than controls, which may enhance species establishment success in riparian systems (Kowarik and Säumel, 2008).…”

Patterns of seed bank and vegetation diversity along a tidal freshwater river

“…Spatial overlap was greater for the seed bank, suggesting redistribution of seeds via secondary dispersal. The importance of hydrochory for dispersal near creeks but also for infrequent longer‐distance dispersal from infrequently flooded sites has been illustrated for Hibiscus moscheutos L. (Shimamura et al, 2007). While there was overlap in species compositions, seed bank and vegetation communities were distinct.…”

Phenotypic plasticity of invasive Spartina densiflora (Poaceae) along a broad latitudinal gradient on the Pacific Coast of North America

“…After a population of aquatic plants is introduced and established in a new range, hydrologic connectivity and the hydrochorous dispersal of propagules can result in their rapid spread at large spatial scales (Shimamura et al, 2007; Okada et al, 2009). When halophytes grow in salt marshes along a wide latitudinal cline, they face environmental conditions such as air temperature, growing season length, photoperiod, light intensity and quality, and salinity that vary among locations (Pennings et al, 2003; Isacch et al, 2006).…”