Abstract:The geographical distribution, ecological characteristics, flowering and fruiting times, and pollinating agents of Passiflora alata are considered and related to molecular genetic data gathered simultaneously. The first report on this species in Rio Grande do Sul was made in 1934, only in cultivated gardens. Approximately 20 years later, however, the species was already classified as efferata (wild) in Porto Alegre's suburbs. The data presented here, together with the DNA investigations, indicate that P. alata… Show more
“…Similar levels of nucleotide diversity were observed in Solanum pimpinellifolium (p = 0.0064; Caicedo and Schaal 2004), Abies kawakamii (p = 0.00648; Shih et al 2007) and Citrullus colocynthis (p = 0.0049; Dane et al 2007), when they were analyzed using the GapC gene. However, nucleotide diversity was high for the GapC region in Manihot esculenta (p = 0.49; Olsen 2002) and Passiflora alata (p = 0.01051; Koehler-Santos et al 2006).…”
To characterize the genetic diversity of present populations of Symplocos laurina, which grow in the montane forests in India, we analyzed the DNA sequences of a nuclear gene. Using the 881 bp sequence of cytosolic Glyceraldehyde-3-phosphate dehydrogenase gene, we detected 24 haplotypes among 195 individuals sampled from 14 populations. Two dominant haplotypes were distributed over the entire range of this species in India and several private haplotypes were found. Low genetic diversity within population, high differentiation, number of population specific haplotypes and deviation from neutral evolution characterized the present populations of S. laurina. An analysis of molecular variance indicated the presence of geographic structure within the haplotype distribution. The occurrence of S. laurina preglaciation in India is the most parsimonious explanation for the current geographic structure observed. The populations are presumably ancient and might have spread across its extant distribution range in India through a recent range expansion event.
“…Similar levels of nucleotide diversity were observed in Solanum pimpinellifolium (p = 0.0064; Caicedo and Schaal 2004), Abies kawakamii (p = 0.00648; Shih et al 2007) and Citrullus colocynthis (p = 0.0049; Dane et al 2007), when they were analyzed using the GapC gene. However, nucleotide diversity was high for the GapC region in Manihot esculenta (p = 0.49; Olsen 2002) and Passiflora alata (p = 0.01051; Koehler-Santos et al 2006).…”
To characterize the genetic diversity of present populations of Symplocos laurina, which grow in the montane forests in India, we analyzed the DNA sequences of a nuclear gene. Using the 881 bp sequence of cytosolic Glyceraldehyde-3-phosphate dehydrogenase gene, we detected 24 haplotypes among 195 individuals sampled from 14 populations. Two dominant haplotypes were distributed over the entire range of this species in India and several private haplotypes were found. Low genetic diversity within population, high differentiation, number of population specific haplotypes and deviation from neutral evolution characterized the present populations of S. laurina. An analysis of molecular variance indicated the presence of geographic structure within the haplotype distribution. The occurrence of S. laurina preglaciation in India is the most parsimonious explanation for the current geographic structure observed. The populations are presumably ancient and might have spread across its extant distribution range in India through a recent range expansion event.
“…(Durka et al 2005), Avena barbata(Latta et al 2007), Centaurea diffusa (A. Blair, personal communication), Cirsium arvense(Slotta et al 2006), Passiflora alata(Koehler-Santos et al 2006), and Phragmites australis (L. Meyerson, personal commuincation).…”
Less than a decade ago, we proposed that hybridization could serve as a stimulus for the evolution of invasiveness in plants (Ellstrand and Schierenbeck Proc Nat Acad Sci USA 97:7043-7050, 2000). A substantial amount of research has taken place on that topic since the publication of that paper, stimulating the symposium that makes up this special issue. Here we present an update of this emergent field, based both on the papers in this volume and on the relevant literature. We reevaluate the lists that we presented in our earlier paper of reports in which hybridization has preceded the evolution of invasiveness. We discard a few cases that were found to be in error, published only as abstracts, or based on personal communication. Then we augment the list from examples in this volume and a supplementary literature search. Despite the omissions, the total number of cases has increased. Many have been strengthened. We add a list of cases in which there has been evidence that intra-taxon hybridization has preceded the evolution of invasiveness. We also provide a number of examples from organisms other than plants. We consider how our examples suggest mechanisms whereby hybridization may act to stimulate the evolution of invasiveness. Hybridization does not represent the only evolutionary pathway to invasiveness, but it is one that can explain why the appearance of invasiveness often involves a long lag time and/or multiple introductions of exotics.
“…The general conclusion that can be inferred from the nuclear molecular variability, as well as by field and historical observations (Koehler‐Santos et al ., 2006), is that P. alata maintained high indices of intrapopulation genetic diversity probably due to the many introductions that should have taken place in southern Brazil over the last 50 years. These events could have occurred due to human influence, which facilitated the transfer of plants from one place to another, as well as by an intense intra‐ and interpopulation gene flow, coupled with adaptive genetic plasticity.…”
Section: Discussionmentioning
confidence: 94%
“…The inference that P. alata is an invasive species in Rio Grande do Sul is derived from different sources, both historical (bibliographic search, herbaria survey) and our field studies, as described in detail elsewhere (Koehler‐Santos et al ., 2006). The genetic data, as discussed below, point in the same direction.…”
Section: Discussionmentioning
confidence: 99%
“…This species was introduced into this region in 1934 (first historical registration), which represents the extreme southern distribution, mainly through human cultivation. However, starting in the 1960s, there were indications that P. alata was invading open territories, leading to its classification as a subspontaneous species (Koehler‐Santos et al ., 2006).…”
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