Natural selection for salt tolerance quantitative trait loci (QTLs) in wild sunflower hybrids: Implications for the origin of<i>Helianthus paradoxus</i>, a diploid hybrid species

Lexer, Christian; Welch, Mark E.; Durphy, Jennifer L.; Rieseberg, Loren H.

doi:10.1046/j.1365-294x.2003.01803.x

Cited by 185 publications

(190 citation statements)

References 63 publications

(80 reference statements)

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“…In contrast, researchers have performed corresponding selection experiments to prove the adaptive benefit of QTLs. For instance, Lexer et al (2003) showed the ecological relevance of QTLs for mineral ion uptake in a hybrid sunflower. Similarly, Martin et al (2006) proved the higher fitness of individuals of Lousiana irises possessing QTLs for flooding tolerance in a selection experiment under field conditions.…”

Section: Proving the Adaptive Relevance Of Gene Variantsmentioning

confidence: 99%

Land ahead: using genome scans to identify molecular markers of adaptive relevance

Holderegger

Herrmann

Poncet

et al. 2008

Plant Ecology & Diversity

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Adaptation is back on the research schedules of evolutionists and ecologists. This renewed interest is driven by global change, to which species, in particular arctic and alpine ones, either react by migration or adaptation. In this overview, we give a brief introduction to the use of genome scans along with environmental data to identify molecular markers of adaptive relevance. This approach encompasses the sampling of many populations along ecological gradients or from different habitat types combined with genome scans using presumably neutral markers such as amplified fragment length polymorphisms or microsatellites. To identify markers linked to genes under selection, two different methods (besides others) are particularly relevant. (1) One searches for markers exhibiting higher genetic differentiation among populations than expected under neutrality. The frequencies of alleles at such outlier loci can then be related to ecological factors. (2) The other method uses logistic regression between allele presence/absence and ecological factors (i.e. an allele distribution model). It thus directly links marker occurrence with environmental data. We illustrate these two methods with examples from the literature. The strength of genome scans used in parallel with environmental data is that they provide distinct clues for selective forces acting on molecular markers of adaptive relevance in real landscapes. We further discuss limitations of genome scans (e.g. sensitivity to phylogeographic structure and bottlenecks) and of other genomic approaches to detect adaptive molecular markers such as candidate genes, quantitative trait loci or transcription profiling. We stress that the selective advantage of particular alleles has to be proven in selection experiments. We conclude that combining studies on adaptive and neutral molecular markers will largely contribute to our understanding of how species react to global change and will allow us to investigate the 'migration of adaptation'.

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Section: Proving the Adaptive Relevance Of Gene Variantsmentioning

confidence: 99%

Land ahead: using genome scans to identify molecular markers of adaptive relevance

Holderegger

Herrmann

Poncet

et al. 2008

Plant Ecology & Diversity

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“…obs. ) The fact that hybrids may have higher fitness than their parents in certain habitats is now well documented (Arnold and Hodges 1995;Arnold 1997;Lexer et al 2003a). Moreover, it was recently demonstrated that transgressive segregation can be very important in generating hybrid genotypes that are adapted to novel habitats Lexer et al 2003b).…”

Section: Hybrid Origin Of Senecio Squalidusmentioning

confidence: 99%

Recent, Allopatric, Homoploid Hybrid Speciation: The Origin of Senecio Squalidus (Asteraceae) in the British Isles From a Hybrid Zone on Mount Etna, Sicily

2005

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Abstract. Homoploid hybrid speciation occurs through stabilization of a hybrid segregate (or segregates) isolated by premating and/or postmating barriers from parent taxa. Theory predicts that ecological and spatial isolation are of critical importance during homoploid hybrid speciation, and all confirmed homoploid hybrid species are ecologically isolated from their parents. Until recently, such species have been identified long after they originated, and consequently it has not been possible to determine the relative importance of spatial and ecological isolation during their origin. Here we present evidence for the recent origin (within the past 300 years) of a new homoploid hybrid species, Senecio squalidus (Asteraceae), in the British Isles, following long-distance dispersal of hybrid material from a hybrid zone between S. aethnensis and S. chrysanthemifolius on Mount Etna, Sicily, Italy. Historical records show that such hybrid material from Sicily was introduced to the Oxford Botanic Garden in Britain in the early part of the 18th century and that S. squalidus began to spread from there after approximately 90 years. A survey of randomly amplified polymorphic DNA/intersimple sequence repeats (RAPD/ISSR) marker variation demonstrated that S. squalidus is a diploid hybrid derivative of S. aethnensis and S. chrysanthemifolius that grow at high and low altitudes, respectively, on Mount Etna and that form a hybrid zone at intermediate altitudes. Senecio squalidus contained 11 of 13 RAPD/ISSR markers that were recorded at high frequency in S. chrysanthemifolius but were absent or occurred at low frequency in S. aethnensis, and 10 of 13 markers for which the reverse was true. Bayesian admixture analysis showed that all individuals of S. squalidus surveyed were of mixed ancestry with relatively high mean proportions of ancestry derived from both S. chrysanthemifolius and S. aethnensis (0.644 and 0.356, respectively). We argue that long-distance isolation of hybrid material from its parents on Mount Etna would have helped favor the origin and establishment of S. squalidus in the British Isles, regardless of whether the initial hybrid material introduced to Britain was preadapted to local conditions.

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“…The positions of the ESTs with putative functions relating to previously analyzed phenotypes were compared to mapped QTLs for more than 70 morphological, physiological, and life history traits across three different mapping populations: wild × domesticated H. annuus (cultivated F 3 ; Burke et al 2002), H. annuus × H. petiolaris raised in the greenhouse (BC 2 -greenhouse; , and H. annuus × H. petiolaris grown in a natural salt marsh habitat (BC 2 -field; Lexer et al 2003). EST positions in the QTL populations were inferred on the basis of shared SSR loci.…”

Section: Genetic Mapping and Comparisons With Qtl Positionsmentioning

confidence: 99%

Identification and mapping of SNPs from ESTs in sunflower

et al. 2005

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More than 67,000 expressed sequence tags (ESTs) have recently been generated for sunflower (Helianthus), including 44,000 from cultivated confectionery (RHA280) and oilseed (RHA801) lines of Helianthus annuus and 23,000 from droughtand salt-tolerant wild sunflowers, H. argophyllus and H. paradoxus, respectively. To create a transcript map for sunflower, we identified 605 ESTs that displayed small insertion-deletion polymorphism (SNP) variation in silico, had apparent tissuespecific expression patterns, and/or were ESTs with candidate functions in traits such as development, cell transport, metabolism, plant defense, and tolerance to abiotic stress. Primer pairs for 535 of the loci were designed from the ESTs and screened for polymorphism in recombinant inbred lines derived from a cross between the same cultivars (RHA280 × RHA801) employed for sequencing. In total, 273 of the loci amplified polymorphic products, of which 243 mapped to the 17 linkage groups previously identified for sunflower. Comparisons with previously mapped QTL revealed some cases where ESTs with putatively related functions mapped near QTLs identified in other crosses for salt tolerance and for domestication traits such as stem diameter, shattering, flowering time, and achene size.

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Natural selection for salt tolerance quantitative trait loci (QTLs) in wild sunflower hybrids: Implications for the origin ofHelianthus paradoxus, a diploid hybrid species

Cited by 185 publications

References 63 publications

Land ahead: using genome scans to identify molecular markers of adaptive relevance

Land ahead: using genome scans to identify molecular markers of adaptive relevance

Recent, Allopatric, Homoploid Hybrid Speciation: The Origin of Senecio Squalidus (Asteraceae) in the British Isles From a Hybrid Zone on Mount Etna, Sicily

Identification and mapping of SNPs from ESTs in sunflower

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