Hybridization of invasive Phragmites australis with a native subspecies in North America

Abstract

Interspecific hybridization can lead to the extinction of native populations and increased aggressiveness in hybrid forms relative to their parental lineages. However, interbreeding among subspecies is less often recognized as a serious threat to native species. Phragmites australis offers an excellent opportunity to investigate intraspecific hybridization since both native and introduced lineages occur in North America. Introduced Phragmites is a highly successful estuarine plant invader throughout North America, but native Phragmites populations are declining in the eastern US. Despite range overlaps, hybridization has not yet been detected between the native and introduced lineages in the wild, suggesting that phenological or physiological barriers preclude cross-pollination. We demonstrate, for the first time, that native and introduced populations of Phragmites can hybridize. There is substantial overlap in flowering period between native and introduced populations from the same geographic locations. We manually cross-pollinated native individuals with pollen from introduced Phragmites and recovered viable offspring. We then used microsatellite markers to prove that alleles unique to the pollen parent were transferred to progeny. Our results imply a mechanism for the further decline of native Phragmites in North America and a potential for the formation of aggressive hybrid offspring.

Management of invasive Phragmites australis in the Adirondacks: a cautionary tale about prospects of eradication

“…The status of the Gulf Coast lineage as native or introduced remains unresolved (Lambertini et al 2012;Colin and Eguiarte 2016). Recently the existence of hybrids between European and North American lineages, long suspected due to common garden evidence (Meyerson et al 2008), has been confirmed in wetlands in New York and Nevada (Saltonstall et al 2014.…”

Increased Methane Emissions by an Introduced Phragmites australis Lineage under Global Change

“…Individual rhizome fragments of native or introduced Phragmites were planted (11-12 June, 2009) into 15-liter pots (24 cm×24 cm×33 cm deep) (n=48 native and n=48 introduced) containing reed-sedge peat (Baccto, Houston, TX) and kept in a greenhouse at the Smithsonian Environmental Research Center until shoot emergence. The native and introduced Phragmites plants used in this study were previously genetically identified and grown in a common environment at the University of Rhode Island since 2006 (Meyerson et al 2010). Each pot was considered an independent experimental unit because there was no hydrologic connectivity between pots.…”

NonnativePhragmites australisInvasion into Utah Wetlands

“…Disturbance also has been shown to disproportionally improve growth of the nonnative P. australis strain in relation to the native strain (Bertness et al 2002, Minchinton and Bertness 2003, Jodoin et al 2008, Park and Blossey 2008; but see Saltonstall and Stevenson 2007). Other potential explanations include allelopathic secretions from the nonnative P. australis (Rudrappa et al 2007) and the potential for native and nonnative strains to hybridize (Meyerson et al 2010). The relative importance of these mechanisms remains unresolved, especially in noncoastal wetlands.…”