Evidence for the hybrid origin ofpotamogeton ×cooperi (Potamogetonaceae): Traditional morphology-based taxonomy and molecular techniques in concert

When interspecific prezygotic barriers break down: hybridization between two Potamogeton species (P. wrightii and P. perfoliatus) and comparison of the artificial and natural hybrids

“…However, postzygotic barriers, such as inviable seeds, sterility, and low fitness of hybrids, could still prevent the formation of hybrids. Sterility, which could be attributed to the unreceptive stigmas, sterile ovule, nonviable pollen, etc., has been documented in Potamogeton hybrids many times (Preston 1995a;Kaplan 2001Kaplan , 2007Kaplan and Fehrer 2004;Kaplan and Wolff 2004;Alix and Scribailo 2006).…”

“…The asterisks above the bars indicate significant differences in pollen tube length among the pollination treatments (P \ 0.01). The letters indicate the different crosses based on the maternal parent (a P. wrightii as maternal plant, b P. perfoliatus as maternal plant, c P. 9 intortusifolius as maternal plant, see Table 1) When interspecific prezygotic barriers break down: hybridization between two Potamogeton species 123 anthesis has been described as a typical sterile character in the hybrids of Potamogeton (Preston 1995a; Kaplan and Fehrer 2004;Kaplan and Wolff 2004). However, in this study, the natural and artificial F1 hybrids both flowered normally.…”

“…Wiegleb and Kaplan (1998) made a worldwide revision of the genus and summarized 69 species and 50 well-confirmed hybrids around the world. More recently, with the aid of isozyme and molecular techniques, many putative hybrids have been identified (e.g., Hollingsworth et al 1995;Preston 1995b;Preston et al 1998;Fant et al 2001aFant et al , b, 2003Fant et al , 2005Iida and Kadono 2002;Fant and Preston 2004;Kaplan and Fehrer 2004;Kaplan and Wolff 2004;Whittall et al 2004;Kaplan 2007). Although numerous studies have indicated the origins of many Potamogeton hybrids, the process of the hybridization event has never been studied in this genus.…”

Potamogeton ×jacobsii (Potamogetonaceae) from New South Wales, Australia – the first Potamogeton hybrid from the Southern Hemisphere

“…Although character expression in hybrids is generally unpredictable (Rieseberg & Ellstrand 1993), several previous molecular studies (Hollingsworth et al 1995;Kaplan et al 2002;Fant & Preston 2004;Kaplan & Fehrer 2004Kaplan & Wolff 2004;Kaplan 2007) have demonstrated that for most Potamogeton and Stuckenia hybrids, either the parental species themselves or at least their respective species group can be reliably identified morphologically, as long as adequate expert inspection of a large set of key features is adopted. However, molecular proof of identification of Potamogeton hybrids is always advisable (Kaplan & Fehrer 2007), particularly if a previously unknown hybrid combination is suspected.…”

“…Besides traditional morphological comparisons, stem anatomy (e.g., Raunkiaer 1896Raunkiaer , 1903Fischer 1904Fischer , 1905Fischer , 1907Hagström 1916;Ogden 1943;Symoens et al 1979;Wiegleb 1990aWiegleb , 1990bKaplan 2001Kaplan , 2005aKaplan , 2005bKaplan & Symoens 2004, 2005Zalewska-Gałosz et al 2010), isozyme electrophoresis (e.g., Hollingsworth et al 1995Hollingsworth et al , 1996Preston et al 1998;Fant et al 2001aFant et al , 2001bIida & Kadono 2002;Kaplan et al 2002;Fant & Preston 2004;Kaplan & Wolff 2004;Kaplan 2007) and DNA-based techniques (King et al 2001;Fant et al 2003;Kaplan & Fehrer 2004, 2007Ito et al 2007;Wang et al 2007;Du et al 2009;Zalewska-Gałosz et al 2009, 2010 have all contributed to our understanding of diversity, morphological variation and distribution in Potamogetonaceae hybrids. Although much attention has been paid to the identification of Potamogetonaceae hybrids in taxonomic research, our knowledge is confined to relatively few regions.…”