Adaptive Radiation of the Hawaiian Silversword Alliance (Compositae- Madiinae): Ecological, Morphological, and Physiological Diversity

Robichaux, Robert H.; Carr, Gerald D.; Liebman, Matt; Pearcy, Robert W.

doi:10.2307/2399626

Cited by 113 publications

(91 citation statements)

References 11 publications

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“…Some of the richest examples of evolution in morphological and ecophysiological traits with recognized adaptive function (Robichaux et al 1990;Kim et al 1996) are in wild nonmodel plant lineages, which will need to be studied directly if the genetic basis for their trait differences is to be understood. Fortunately, the wealth of genetic resources and data generated from model plants should greatly facilitate evolutionary studies in other plant lineages.…”

Section: Into the Wildmentioning

confidence: 99%

“…Genetic studies in plant lineages that have undergone recent adaptive radiation in ecophysiological and morphological traits, such as the Hawaiian silversword alliance (Robichaux et al 1990) and the Macaronesian Sonchus alliance (Kim et al 1996), would be especially valuable for gaining a greater understanding of trait evolution. Appropriate study systems would have to consist of species in which fertile hybrids can be generated, in order to allow the use of genetic approaches.…”

Section: Data and Technical Gapsmentioning

confidence: 99%

“…Ideal study systems would involve plants with shoot growth in vegetative as well as reproductive stages, so effects of selection primarily based on flowering time could be factored out. The Hawaiian silversword alliance, for example, includes pairs of interfertile sister taxa with large differences in size, vegetative growth rates, and habitat requirements that might be especially useful for mapping studies (Robichaux et al 1990; D. L. Remington, unpublished data), although study designs that accommodate their woody perennial life history will be required. Such mapping studies would be the first step in identifying the actual genes, and therefore the genetic mechanisms, involved in growth and ecophysiological variation in wild populations.…”

Section: Data and Technical Gapsmentioning

confidence: 99%

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Candidate Genes, Quantitative Trait Loci, and Functional Trait Evolution in Plants

Remington

Purugganan

2003

International Journal of Plant Sciences

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Two key characteristics of the neo-Darwinian synthesis in evolutionary biology have been its emphasis on the importance of mutations of small effect (micromutationism) and the view that studies of individual gene function shed relatively little light on evolutionary processes. Recent advances in molecular biology, however, have broken down many of the barriers between functional and evolutionary inquiry, opening the door to detailed studies of the genetic basis of functional trait evolution in plants. In this article, we review the insights into plant evolution that have been provided by molecular methods and address future research needs. Quantitative trait locus (QTL) mapping in crop and model plants has shown that individual loci often have large effects on trait variation, at variance with the micromutationist perspective. Evidence so far indicates that QTLs with large effects are also important in wild populations, underlying interspecific differences as well as intraspecific variation. Isolation of some of these QTLs, in particular for flowering time variation, has revealed a prominent role for regulatory genes known to function in regulation of flowering and exposed the complexity of regulatory processes. Preliminary evidence indicates that plant growth variation may be directly regulated rather than primarily the indirect result of selection on constituent processes. Future research should expand the number of traits that are intensively studied and make greater use of QTL mapping in wild plant taxa, especially those undergoing adaptive radiations, while continuing to draw on insights from model plants. Promising techniques include testing of candidate gene-trait associations in wild populations, genetic mapping in hybrid zones, and microarray analyses of gene expression.

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Section: Into the Wildmentioning

confidence: 99%

Section: Data and Technical Gapsmentioning

confidence: 99%

Section: Data and Technical Gapsmentioning

confidence: 99%

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Candidate Genes, Quantitative Trait Loci, and Functional Trait Evolution in Plants

Remington

Purugganan

2003

International Journal of Plant Sciences

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“…With reference to the evolutionary diversification of Hawaiian tarweeds, there may have been important founder effects associated with each of the estimated 14 major dispersal and colonization events (Robichaux, Carr, Liebman, and Pearcy 1990).…”

Section: Introductionmentioning

confidence: 99%

“…The morphology may have been influenced by the environment. For example, the diverse leaf length (5-500 mm; Robichaux et al 1990) of the Hawaiian tarweeds can be related to the diverse ecology of these plants. Alternatively, the morphology of the trichomes of the Hawaiian tarweeds may result from founder effect.…”

Section: Introductionmentioning

confidence: 99%

Nonglandular Trichomes of Californian and Hawaiian Tarweeds

Maclachlan¹,

Carlquist²

1992

aliso

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The purpose of this paper was to demonstrate the diversity in nonglandular trichome morphology of tarweeds at the ultrastructural level, and to propose categories for the morphologies reported for such trichomes. Using light and scanning electron microscopy (SEM), the authors surveyed 31 species of II genera of tarweeds from California and three genera of tarweeds from Hawaii. Trichome cell wall thickness in the Californian species ranged from I to 6 ~tm, whereas in the Hawaiian species trichome cell wall thickness ranged from I to 14 ~tm. Based on their surface appearance using SEM, trichomes were grouped into four categories: grooved; smooth + grooved; smooth; and verrucose.The verrucose surface of trichomes is an innate feature of the cell wall and is not due to resinlike deposits. The ecology and growth form of the plants in each group were compared to the trichome surface structure. Ecologically, members of the grooved group were alike in experiencing prolonged exposure to solar irradiation; eight of the nine plants in this group are perennial. The smooth + grooved group of trichomes was found on tarweeds that inhabit various types of habitats. This is likely a transitional group. The smooth trichome group is composed of mostly low-elevation Californian annuals. No Hawaiian tarweed surveyed had completely smooth trichomes. Tarweeds having verrucose-surfaced trichomes were mostly found in regions of moderate moisture. The trichomes observed in Dubautia platyphy/la were unique and could not be placed into any of the four groups; the surface of these trichomes was a combination of verrucose and smooth.

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Exploring evolutionary adaptations of leaf heteroblasty in subspecific taxa of Hawaiian Chenopodium oahuense

Bullock

Cantley

2022

American J of Botany

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Premise: Chenopodium oahuense is a polymorphic Hawaiian endemic plant inhabiting several xeric habitats. Considerable variability in leaf morphology has made comprehensively describing its diversity difficult. Chenopodium oahuense subsp. ilioense is differentiated from C. oahuense subsp. oahuense by smaller, less-lobed, succulent leaves, smaller seeds, and prostrate to scandent habit. The lacking quantification of leaf shape, succulence, and previously unknown heteroblastic leaf transition in C. oahuense subsp. ilioense complicates the morphological boundaries separating subspecies. Methods: This study used landmark analyses, elliptical Fourier descriptors (EFDs), and traditional shape descriptors measured from 1585 greenhouse-grown plant leaves collected over 18 weeks. Principal component analyses visualized correlations in leaf shape, and linear discriminant analyses predicted classifications, either subspecific or heteroblastic.Results: Identity determination and heteroblastic change visualization were limited in landmark analyses. On the basis of EFDs and shape descriptors, C. oahuense subsp. ilioense was determined to be morphologically differentiated from C. oahuense subsp. oahuense with the Pu'u Ka Pele population as intermediate. The EFDs depicted heteroblastic change, predominantly in lobing. All analyses were restricted in correctly attributing a leaf to the week collected. Shape descriptors generally represented significant heteroblastic change over the growth period. Conclusions: These analyses support significant differentiation between the subspecies, particularly from shape descriptors. Furthermore, we quantified the morphological intermediacy of the Pu'u Ka Pele population. Results suggest this population could be the result of incomplete lineage sorting or a recent hybridization of the two subspecies. Hawaiian Chenopodium is a polymorphic lineage notable for future research in adaptive radiations, phenotypic plasticity, and heteroblasty.

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Adaptive Radiation of the Hawaiian Silversword Alliance (Compositae- Madiinae): Ecological, Morphological, and Physiological Diversity

Cited by 113 publications

References 11 publications

Candidate Genes, Quantitative Trait Loci, and Functional Trait Evolution in Plants

Candidate Genes, Quantitative Trait Loci, and Functional Trait Evolution in Plants

Nonglandular Trichomes of Californian and Hawaiian Tarweeds

Exploring evolutionary adaptations of leaf heteroblasty in subspecific taxa of Hawaiian Chenopodium oahuense

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