Pollen-mediated introgression and hybrid speciation in Louisiana irises.

Arnold, Michael L.; Buckner, Cindy M.; Robinson, J. J.

doi:10.1073/pnas.88.4.1398

Cited by 290 publications

(190 citation statements)

References 12 publications

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“…The rbcL-ORF106 region was difficult to amplify for many species using the primers described in Arnold et al (1991), and was not successfully amplified for 27 species. Amplification problems were apparently due to the ORF106 primer, which appears to be part of variable spacer region, rather than a coding region as originally thought.…”

Section: Methodsmentioning

confidence: 99%

“…Five regions of the chloroplast genome located within the large single copy region were amplified via PCR: trnT-trnF (Taberlet et al 1991), rbcL-ORF106 (Arnold et al 1991), trnH-trnK (Demesure et al 1995), trnF-trnV, andtrnV-rbcL (Dumoulin-Lapègue et al 1997). The approximate length of each region in Poa is as follows: trnT-trnF, ϳ1800-1850 base pairs (bp); trnF-trnV, ϳ3100-3280 bp; trnV-rbcL, ϳ3900-4000 bp; rbcL-ORF106, ϳ2250-2550 bp; and trnH-trnK, ϳ1950-2000 bp.…”

Section: Methodsmentioning

confidence: 99%

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A Phylogenetic Analysis of the Bluegrass Genus Poa Based on cpDNA Restriction Site Data

Gillespie¹,

Soreng²

2005

Systematic Botany

113

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ABSTRACT. Poa, with about 575 species, is the largest genus of grasses, and has diversified throughout temperate, boreal, and arctic regions, and similar habitats through the tropics. This new phylogenetic study of Poa based on analysis of restriction site data from PCR amplified regions of chloroplast DNA expands previous sampling in the genus to where 1/5 to 1/6 of the species have been characterized for chloroplast DNA types. A broad phylogenetic structure detected in a previous study using restriction site mapping of Poa chloroplast DNA gained additional and robust support. Accounting for extended intra-and extrageneric sampling, Poa remains monophyletic if Austrofestuca and Parodiochloa are included as sections within P. Poa L. is the largest genus of grasses. Independent assessments by Clayton and Renvoize (1986) and RJS indicate there are about 500 or 575 species, respectively (Table 1). The genus has diversified throughout temperate, boreal, and arctic regions, and islands of similar habitats through the tropics, at all latitudes habitable by vascular plants. Poa exhibits both high species diversity and a high degree of endemism in many regions. For example, there are 34 endemic species in Malesia (Veldkamp 1994), 36 species in Australia (Sharp and Simon 2002), and 34 in New Zealand (Edgar 1986), with only two or three native species shared between Australia and New Zealand, and none shared between these areas and the rest of the world. Extensive polyploidy, hybridization, and few useful morphological characters combine to make Poa a taxonomically challenging genus.In contrast to other large grass genera (notably Festuca L. and Panicum L.), the monophyly of Poa has not been disproved, and no modern taxonomist nor data have seriously challenged its circumscription except by the removal of a few small, isolated groups of uncertain affinity. Modern revisions for several regions of the world have left Poa whole, or only removed one or a few species. In the opinion of RJS, there are few species that might be removed from the genus, but also a few small genera might be subsumed.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

A Phylogenetic Analysis of the Bluegrass Genus Poa Based on cpDNA Restriction Site Data

Gillespie¹,

Soreng²

2005

Systematic Botany

113

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“…The area of geograph-ical overlap between these three species occurs in southern Louisiana and numerous cases of natural hybridization have been reported from this region (Viosca, 1935;Riley, 1938;Anderson, 1949;Randolph eta!. 1967;Bennett & Grace, 1989;Arnold et a!., 1 990a, b;1991). Recent studies of this species complex have determined the distribution of nuclear, genetic markers and have led to the inference of both sympatric and allopatric introgression (Arnold et a!., 1 990a, b;1991).…”

mentioning

confidence: 99%

“…1967;Bennett & Grace, 1989;Arnold et a!., 1 990a, b;1991). Recent studies of this species complex have determined the distribution of nuclear, genetic markers and have led to the inference of both sympatric and allopatric introgression (Arnold et a!., 1 990a, b;1991). An initial study of chloroplast DNA (cpDNA) markers for I. fu!va and I. hexagona suggested that introgression between these two species was a result of pollen being transferred between allopatric populations of the taxa rather than seed dispersal followed by pollen transfer (Arnold et a!., 1991).…”

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Pollen dispersal and interspecific gene flow in louisiana irises

et al. 1992

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An analysis of chloroplast DNA (cpDNA) variation was carried out for 106 individual plants from three natural populations of Louisiana irises. Two of the samples (59 individuals) represented I. brevicaulis populations. The third sample was from a population defined by allozyme markers as an area of contact between I. fidva, I. hexagona and I. brevicaulis. The cpDNA acts as a seed-specific genetic marker because it is inherited from the maternal parent. cpDNA markers were thus used to discriminate between (i) introgressive hybridization due to seed movement followed by pollen transfer and, (ii) introgression resulting from direct transfer of pollen between allopatric populations of the hybridizing taxa. Furthermore, the concurrent analysis of biparental and maternal markers for the same individuals allowed a test for any directionality in the introgression. A comparison of cpDNA results with data from previous nuclear analyses led to the conclusion that pollen flow occurred from allopatric populations of I. hexagona into an area of sympatry involving I. fulva and I. brevicaulis. In addition, the genotypes detected in the hybrid population indicate that 1. fulva and I. brevicaulis have acted as both pollen and seed parents to produce introgressant individuals. The results of the present study and those of previous nuclear and cpDNA analyses suggest that pollen dispersal is the most important avenue for gene flow between these Iris species.

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Genetic structure in Louisiana Iris species reveals patterns of recent and historical admixture

Zalmat

Sotola

Nice

et al. 2021

American J of Botany

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Premise When divergent lineages come into secondary contact, reproductive isolation may be incomplete, thus providing an opportunity to investigate how speciation is manifested in the genome. The Louisiana Irises (Iris, series Hexagonae) comprise a group of three or more ecologically and reproductively divergent lineages that can produce hybrids where they come into contact. We estimated standing genetic variation to understand the current distribution of population structure in the Louisiana Irises. Methods We used genotyping‐by‐sequencing techniques to sample the genomes of Louisiana Iris species across their ranges. We sampled 20 populations (n = 632 individuals) across 11,249 loci and used Entropy and PCA models to assess population genetic data. Results We discovered evidence for interspecific gene flow in parts of the range. Our analysis revealed patterns of population structure at odds with widely accepted nominal taxonomy. We discovered undescribed hybrid populations, designated as belonging to the I. brevicaulis lineage. Iris nelsonii shared significant ancestry with only one of the purported parent species, I. fulva, evidence inconsistent with a hybrid origin. Conclusions This study provides several key findings important to the investigation of standing genetic variation in the Louisiana Iris species complex. Compared to the other nominal species, I. brevicaulis contains a large amount of genetic diversity. In addition, we discovered a previously unknown hybrid zone between I. brevicaulis and I. hexagona along the Texas coast. Finally, our results do not support the long‐standing hypothesis that I. nelsonii has mixed ancestry from three parental taxa.

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Pollen-mediated introgression and hybrid speciation in Louisiana irises.

Cited by 290 publications

References 12 publications

A Phylogenetic Analysis of the Bluegrass Genus Poa Based on cpDNA Restriction Site Data

A Phylogenetic Analysis of the Bluegrass Genus Poa Based on cpDNA Restriction Site Data

Pollen dispersal and interspecific gene flow in louisiana irises

Genetic structure in Louisiana Iris species reveals patterns of recent and historical admixture

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