Assortative Pollination in Lythrum

Levin, Donald A.

doi:10.1002/j.1537-2197.1970.tb09784.x

Cited by 29 publications

(7 citation statements)

References 19 publications

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“…In Ontario, however, L. salicaria is mainly pollinated by honeybees (Apis mellifera) and bumble bees (Bombus spp. ), which do not move large distances between foraging bouts (Levin, 1970;C. G. Eckert, personal observation) and are therefore unlikely to mediate random pollen transfer within populations.…”

Section: Discussionmentioning

confidence: 99%

Frequency-dependent selection on morph ratios in tristylous Lythrum salicaria (Lythraceae)

1996

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In the plant sexual polymorphism tristyly, disassortative mating among floral morphs should result in frequency-dependent selection leading to equal frequencies of the three morphs in populations at equilibrium. Direct evidence for frequency-dependent selection in natural populations is, however, lacking. Here we attempt to detect frequency-dependent selection in rapidly expanding populations of the invasive wetland herb Lythrum salicaria. Deterministic computer models were used to assess the expected change in morph ratios. Model results were tested with data from 24 Ontario populations each with an initially low frequency (<0.11) of one morph sampled over a 5-year interval. On average, morph evenness and the frequency of the rare morph increased significantly between samples (mean frequency change = + 0.034; range = -0.045 to + 0.278). As predicted by the theoretical model, changes in both morph evenness and the frequency of the rare morph were positively correlated with initial morph frequencies. However, no evidence was obtained for expected correlations with the magnitude of the 5-year increase in population size. The results provide the first empirical demonstration of frequency-dependent selection on morph ratios in natural populations of a heterostylous plant.

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Section: Discussionmentioning

confidence: 99%

Frequency-dependent selection on morph ratios in tristylous Lythrum salicaria (Lythraceae)

1996

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“…71±0.26, n=47; for L. alatum=2.23±0.16 n=46). In field populations there is nearly complete overlap in the pollinator fauna of these two species -most visits are by bumble bees and honey bees, both of which move freely between the two species (Levin 1970;Brown 1999).…”

Section: Experimental Organismsmentioning

confidence: 99%

Competition for pollination: effects of pollen of an invasive plant on seed set of a native congener

2001

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Competition for pollination can be an important factor in plant reproduction, but little attention has been given to the effect of the growing number of invasive plant species on pollination of native species. As a first step in understanding this threat, we used hand pollination to investigate the effects of pollen from an invasive species (Lythrum salicaria) on seed set in a sympatric and co-flowering native congener (L. alatum). Dispersal of fluorescent dyes in the field confirms that pollinators (bumble bees and honey bees) transfer pollen between species. To determine the potential effect of such interspecific pollen transfer on seed set of the native, we pollinated 773 flowers on 20 plants with one of three treatments: legitimate conspecific pollen, a mixture of conspecific and foreign pollen, and foreign pollen. The mixed-pollen treatment resulted in 28.8% lower seed set relative to conspecific pollination. Foreign crosses resulted in extremely low seed set. Observations of pollen germination indicate that events at the stigmatic surface contribute to the reduction in seed set for mixed pollination. Our results indicate that the impacts of invasive species may extend beyond vegetative competition to include competition for pollination.

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“…Lythrurn alatum Pursh, winged loosestrife, is the most cosmopolitan of the North American species, being widespread throughout the United States and eastern Canada (Cody 1978). Lythrum alatum and L. salicaria can be distinguished by diagnostic, morphological characters (Table 2), While L. alaturn is more mesophytic that L. salicaria, they both occur in overlapping ecotopes (Levin 1970). Lythrurn alarum has been the genetic source of dwarf, interspecific horticultural cultivars because of its short stature (Anderson and Ascher 1993a).…”

Section: Stem Appendages Winged Nonementioning

confidence: 99%

“…Lythrurn alarum has been the genetic source of dwarf, interspecific horticultural cultivars because of its short stature (Anderson and Ascher 1993a). Despite ploidy differences, L salicaria (4x, 6x) and L. alaturn (2x) intercross freely in natural settings (Levin 1970). The presence of 2n gametes in the pollen and eggs allows for the production of fertile, tetraploid (4x) hybrids (Schoch-Bodmer 1938).…”

Section: Stem Appendages Winged Nonementioning

confidence: 99%

Invasiveness in wetland plants in temperate North America

1999

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The spread of invasive taxa, including Lythrum salicaria, Typha X glauca, Myriophyltum spicatum, Phalaris arundinacea, and Phragmites australis, has dramatically changed the vegetation of many wetlands of North America. Three theories have been advanced to explain the nature of plant invasiveness. Aggressive growth during geographic expansion could result because 1) growth is more favorable under new environmental conditions than those of resident locales (environmental constraints hypothesis); 2) herbivores may be absent in the new locale, resulting in selection of genotypes with improved competitive ability and reduced allocation to herbivore defenses (evolution of increased competitive ability hypothesis); and 3) interspecific hybridization occurred between a new taxon and one existing in an area, resulting in novel phenotypes with selective advantages in disturbed sites or phenotypes that can grow under conditions not favorable for either parent (introgression/hybrid speciation hypothesis). A review of published literature found few studies that compare the growth and dynamics of invasive populations in their new range versus those in historic ranges. However, there is evidence that hydrologic alterations could facilitate invasions by Typha × glauca and Phalaris arundinacea and that increased salimty promoted spread of Typha angustifolia (parental taxon) and Phragmites australis, The potential for reduced herbivory causing aggressive growth is greatest for Lythrum salicaria. Introgressive hybridization is potentially a cause of invasiveness for all five species but has been established only for Typha × glauca and Lythrum salicaria.

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Assortative Pollination in Lythrum

Cited by 29 publications

References 19 publications

Frequency-dependent selection on morph ratios in tristylous Lythrum salicaria (Lythraceae)

Frequency-dependent selection on morph ratios in tristylous Lythrum salicaria (Lythraceae)

Competition for pollination: effects of pollen of an invasive plant on seed set of a native congener

Invasiveness in wetland plants in temperate North America

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