Partitioning and diversity of nuclear and organelle markers in native and introduced populations ofEpipactis helleborine(Orchidaceae)

Abstract

Variability of allozymes (1170 individuals, 47 populations) and chloroplast DNA (692 individuals, 29 populations) was examined in native European and introduced North American populations of Epipactis helleborine (Orchidaceae). At the species level, the percentage of allozyme loci that were polymorphic (P(99)) was 67%, with a mean of 2.11 alleles (A) per locus, and an expected heterozygosity (H(exp)) of 0.294. At the population level, mean P(99) = 56%, mean A = 1.81, and mean H(exp) = 0.231. Although field observations suggest that self-pollination occurs frequently, populations had a genetic structure consistent with Hardy-Weinberg expectations and random mating (mean F(IS) = 0.002). There was significant deviation from panmixia associated with population differentiation (mean F(ST) = 0.206). The distribution of two chloroplast haplotypes showed that 15 of the 29 populations were polymorphic. Using both nuclear and organelle F(ST) estimates, a pollen to seed flow ratio of 1.43 : 1 was calculated. This is very low compared with published estimates for other plant groups, consistent with the high dispersability of orchid seeds. Finally, there was no evidence for a genetic bottleneck associated with the introduction of E. helleborine to North America.

Interaction Between Fournder Effect and Selection During Biological Invasion in an Aquatic Plant

“…Although long-distance colonization associated with biological invasion creates opportunities for founder effect, extreme reductions in genetic diversity seem the exception rather than the rule. Somewhat reduced diversity has been detected for some invasive plants (Barrett and Richardson 1986;Novak and Mack 1993;Neuffer and Hurka 1999;Meekins et al 2001), but not others (Brown and Marshall 1981;Warwick et al 1987;Consaul et al 1991;Squirrell et al 2001;Maron et al 2004). Severe reductions, as we observed for B. umbellatus, appear unusual.…”

Patterns of genetic diversity reveal multiple introductions and recurrent founder effects during range expansion in invasive populations of Geranium carolinianum (Geraniaceae)

“…If a high proportion of the total diversity in the native range is contained within individual populations (that is, low F ST ), founder effects will be mitigated even with a low number of colonizing individuals (for example, Epipactis helleborine, Squirrell et al, 2001). In its native range, G. carolinianum has higher allozyme genetic diversity and less genetic structure than expected when compared with similar species, with 80% of the total genetic variation residing within populations (Tables 1a and 3a).…”

Changing partners in the dark: isotopic and molecular evidence of ectomycorrhizal liaisons between forest orchids and trees

“…We did not generate mass-spectroscopy data for these plants. The species were: E. dunensis (T. & T. A. Stephenson) Godfery (seven plants), an endemic inhabitant of Pinus-forested dunes in northwest England and Wales; E. gigantea Douglas ex Hooker (18 plants and one underground seedling), a native inhabitant of unshaded riparian areas, where it often grows adjacent to Alnus or Salix, in California and Oregon; and E. helleborine (29 plants, including one nonphotosynthetic individual), a native European forest species that is an introduced invasive in urban and native North American ectomycorrhizal forests (Squirrell et al 2001).…”