Chloroplast Dna Introgression in Southern California Sunflowers

Dorado, Óscar; Rieseberg, Loren H.; Arias, Dulce M.

doi:10.1111/j.1558-5646.1992.tb02061.x

Cited by 62 publications

(23 citation statements)

References 49 publications

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“…Although some studies have been mentioned that DNA satellites might be useful for hybridization and introgression studies (PadhiBhaja, Ghosth & Mandal, 1998; Nijman et al, 1999), no repetition unit of the pBuM-2 satellite DNA characteristic of D. antonietae was observed in the population of Analaˆndia/SP locality. This could be related to the observations that mitochondrial genes tend to introgress more easily than the nuclear genes (Dorado, Rieseberg & Arias, 1992;Arnold, 1993). The most cited explanations for this observation are related to cytonuclear disequilibria processes (Arnold, 1993) and sterility of hybrid males (Aubert & Solignac, 1990).…”

Section: Resultsmentioning

confidence: 75%

Conservation of pBuM–2 satellite DNA sequences among geographically isolated Drosophila gouveai populations from Brazil

et al. 2006

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In this study, we have compared 34 repetition units of pBuM-2 satellite DNA of individuals from six isolated populations of Drosophila gouveai, a cactophilic member of Drosophila buzzatii cluster (repleta group). In contrast to the results of previous morphological and molecular data, which suggest differentiation among the D. gouveai populations, the sequences and the cluster analysis of pBuM-2 monomers showed that this repetitive element is highly conserved among the six D. gouveai populations (97.8% similarity), indicating a slow rate of evolution of pBuM-2 sequences at the population level. Probably, some homogenization mechanisms of tandem sequences, such as unequal crossing or gene conversion, have maintained the sequence similarity of pBuM-2 among D. gouveai populations. Alternatively, such a result may be associated with a functional role of pBuM-2 sequences, although it is not understood at present.

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Section: Resultsmentioning

confidence: 75%

Conservation of pBuM–2 satellite DNA sequences among geographically isolated Drosophila gouveai populations from Brazil

et al. 2006

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“…More recently, Rieseberg and colleagues re-examined these hypotheses using a combination of molecular marker surveys and molecular phylogenetic analyses (Dorado et al 1992;Rieseberg et al 1988Rieseberg et al , 1990aRieseberg et al , b, 1991aRieseberg, 1991). These studies verified much of Heiser's work, including the occurrence of natural hybridization between H. annuus and each of the species listed above, as well as the introgressive origin of H. a. texanus.…”

Section: Hybridization In Sunflowersmentioning

confidence: 71%

Hybridization and the colonization of novel habitats by annual sunflowers

et al. 2006

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Although invasive plant species often have a hybrid ancestry, unambiguous evidence that hybridization has stimulated the evolution of invasive behaviors has been difficult to come by. Here, we briefly review how hybridization might contribute to the colonization of novel habitats, range expansions, and invasiveness and then describe work on hybrid sunflowers that forges a direct link between hybridization and ecological divergence. We first discuss the invasion of Texas by the common sunflower and show that the introgression of chromosomal segments from a locally adapted species may have facilitated range expansion. We then present evidence that the colonization of sand dune, desert floor, and salt marsh habitats by three hybrid sunflower species was made possible by selection on extreme or "transgressive" phenotypes generated by hybridization. This body of work corroborates earlier claims regarding the role of hybridization in adaptive evolution and provides an experimental and conceptual framework for ongoing studies in this area.

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“…If Helianthus annuus arrived in California within only the past few thousand years as hypothesized by Heiser and others (Heiser 1954;Heiser and Smith 1969;Dorado et al 1992), then this woody perennial ecotype is very recently evolved. Indeed, although it can be genetically distinguished with sufficient sampling of its genome, the ecotype is closely related to nearby H. annuus populations on the valley floor (F p ST ) and shows reduced heterozygosity consistent with a 0.034 possible founder event or population bottleneck (B. T. Moyers and L. H. Rieseberg, unpublished data).…”

Section: Discussionmentioning

confidence: 91%

“…Heiser and others have hypothesized that the ancestral range of H. annuus was originally restricted to the Great Plains and expanded in conjunction with human disturbance (Heiser and Smith 1969;Dorado et al 1992), inferring this on the basis of the plant's increased affinity for marginal or disturbed habitats and frequent hybridizations with congeners outside of the region. If this hypothesis is correct, it is likely that H. annuus arrived in California via the Sierra Nevada Mountains sometime in the past few thousand years, likely with the aid of indigenous traders or European settlers.…”

Section: Study System and Collectionsmentioning

confidence: 98%

Divergence in Gene Expression Is Uncoupled from Divergence in Coding Sequence in a Secondarily Woody Sunflower

Moyers

Rieseberg

2013

International Journal of Plant Sciences

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Premise of research. The transition from herbaceous annual to woody perennial has occurred numerous times during angiosperm evolution, but the suite of genetic changes that accompanies this life history shift remains poorly understood. Here we analyze genetic sequence and gene expression divergence between the annual Helianthus annuus and a recently diverged woody perennial ecotype from California.Methodology. We grew plants from populations of typical H. annuus and the woody perennial ecotype in a common garden and measured days to flower, mature height, and basal stem density. We looked for evidence of genome size evolution in the woody ecotype using flow cytometry and conducted anatomical observations of stem development in seedlings. We sequenced the aboveground seedling transcriptomes of six individuals of each ecotype and identified genes with high fixation index (F ST ) and significant divergence in gene expression. Finally, we examined the gene ontology annotation of differentiated genes and assessed the extent of overlap between genes with divergent sequence and those with divergent expression.Pivotal results. Plants from the novel woody ecotype flowered later and were taller at maturity than typical H. annuus plants. Despite differences in the initiation and extent of secondary growth, the two sunflowers were similar in basal stem density at 6 mo. The ecotypes do not differ in genome size. We discovered 575 genes (3.5%) with significantly different expression between the ecotypes and identified seven biological processes associated with divergent gene expression. Surprisingly, only five of the differentially expressed genes were also present among genes with the most coding sequence divergence (top 3.5% of F ST distribution).Conclusions. The recent transition in H. annuus from annual to woody perennial has been accompanied by numerous genomic changes, including divergence in gene expression and in coding sequence. These two mechanisms may represent alternative pathways toward the same adaptive optimum, or genes may be constrained to evolve via one mechanism or the other over short timescales.

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Chloroplast Dna Introgression in Southern California Sunflowers

Cited by 62 publications

References 49 publications

Conservation of pBuM–2 satellite DNA sequences among geographically isolated Drosophila gouveai populations from Brazil

Conservation of pBuM–2 satellite DNA sequences among geographically isolated Drosophila gouveai populations from Brazil

Hybridization and the colonization of novel habitats by annual sunflowers

Divergence in Gene Expression Is Uncoupled from Divergence in Coding Sequence in a Secondarily Woody Sunflower

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