Genetic studies of the pattern of floral pigmentation in Clarkia gracilis

Gottlieb, L. D.; Ford, V. S.

doi:10.1038/hdy.1988.37

Cited by 33 publications

(36 citation statements)

References 25 publications

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“…Several explanations have been offered to account for the expression of novel or transgressive characters in hybrids, including : an increased mutation rate in hybrids ; the complementary action of new combinations of normal alleles ; the placement of unexpressed (or expressed) alleles in a new genetic background (epistasis), as has been suggested to explain novel floral pigmentation in Clarkia gracilis (Gottlieb & Ford, 1988) ; the fixation of recessive alleles present in the heterozygous form in the parents (dominance) ; reduced developmental stability (Wagner, 1962 ;Levin, 1970 ;Grant, 1975) ; and simple heterosis (overdominance). However, we are aware of only one study that provides a definitive genetic basis for transgressive segregation.…”

Section: Character Expressionmentioning

confidence: 99%

Plant hybridization

1998

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Summary 599 I. Introduction 599 II. Concepts and terminology 600 III. Historical background 600 IV. Studies of experimental hybrids 601 1. Isolating mechanisms 601 2. Prezygotic barriers 602 (a) Gametic barriers to hybridization 602 3. Postzygotic barriers 603 (a) Chromosomal rearrangements 604 (b) Genic sterility or inviability 604 4. Hybrid vigour 605 5. Introgression 606 6. Hybrid speciation 607 V. Experimental manipulations of natural hybrid populations 609 1. Hybrid‐zone formation 610 2. Pollinator‐mediated selection 610 3. Habitat selection 612 VI. The biology of different classes of hybrids 612 1. Character expression 613 (a) Morphological characters 613 (b) Chemical characters 613 (c) Molecular characters 613 2. The fitness of different classes of hybrids 614 (a) The importance of variance 614 (b) Estimating hybrid fitness 615 3. Interactions with parasites and herbivores 616 4. Patterns of mating 617 (a) Outcrossing rate 617 (b) Hybridization frequency 618 (c) Mate choice 618 VII. Conclusions and future research 619 Acknowledgements 620 References 620 Most studies of plant hybridization are concerned with documenting its occurrence in different plant groups. Although these descriptive, historical studies are important, the majority of recent advances in our understanding of the process of hybridization are derived from a growing body of experimental microevolutionary studies. Analyses of artificially synthesized hybrids in the laboratory or glasshouse have demonstrated the importance of gametic selection as a prezygotic isolating barrier; the complex genetic basis of hybrid sterility, inviability and breakdown; and the critical role of fertility selection in hybrid speciation. Experimental manipulations of natural hybrid zones have provided critical information that cannot be obtained in the glasshouse, such as the evolutionary conditions under which hybrid zones are formed and the effects of habitat and pollinator‐mediated selection on hybrid‐zone structure and dynamics. Experimental studies also have contributed to a better understanding of the biology of different classes of hybrids. Analyses of morphological character expression, for example, have revealed transgressive segregation in the majority of later‐generation hybrids. Other studies have documented a high degree of variability in fitness among different hybrid genotypes and the rapid response of such fitness to selection – evidence that hybridization need not be an evolutionary dead end. However, a full accounting of the role of hybridization in adaptive evolution and speciation will probably require the integration of experimental and historical approaches.

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Section: Character Expressionmentioning

confidence: 99%

Plant hybridization

1998

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“…In species with polymorphic petal colouration, it is common that the polymorphism is determined by simple inheritance of one or few genes either with complete or incomplete dominance (Ennos and Clegg 1983;Gottlieb and Ford 1988;Levin and Brack 1995;Sangwan and Lodhi 1998). In the present study, it was not possible to detect a difference between homozygote and heterozygote plants possessing the band.…”

Section: Discussionmentioning

confidence: 98%

Upper petal lip colour polymorphism in Collinsia heterophylla (Plantaginaceae): genetic basis within a population and its use as a genetic marker

Lankinen

2009

J Genet

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Understanding the genetics of a polymorphic trait is important to predict its likely evolution. In Collinsia heterophylla, the upper petal lip colour can be either be white or white with a purple band, while the lower petal lip colour is invariably purple. Because the corolla is only partly polymorphic, the polymorphism can not have evolved due to a mutation where a pigment was lost in the entire plant, which is common in other polymorphic species. In a previous study, high frequency of the purple band was found in populations with darker flowers, indicating possible selection for this trait. In this study, I determined inheritance of the colour polymorphism using two populations (one with only white morph and other with both morphs). I conducted experimental crosses within and between floral morphs to determine whether patterns of segregation in offspring conform to single-gene predictions. Data from F1, F2, F3 and backcross progeny are consistent with a genetic model of one major locus with presence of the band being completely dominant, as indicated in earlier studies using distantly related populations. A novel finding in this study was that the two morphs did not show a difference in seed germination frequency or seedling survival. This trait can thus be valuable as a genetic marker. Even though more thorough ecological data are needed to understand the potential selection pressures on upper petal lip colour in C. heterophylla, its simple inheritance may indicate the possibility of fast evolutionary response to selective forces acting on this trait.

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“…Gottlieb's interests and published work have significant elements in common with the topics of both papers. As pointed out by Hileman [115], Leslie Gottlieb was interested in floral development before the age of genomics and the evolution of development (evo-devo), and this interest is documented in several of his publications [104][105][106][107][108]. Also, he strived to place floral transitions in an evolutionary context [106,107], although some of his early work predated the routine use of DNA sequences for constructing phylogenetic hypotheses.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, often in collaboration with Vera Ford Gottlieb, he studied the genetic/developmental aspects of both floral and vegetative morphology [103][104][105][106][107][108]. One example serves as an illustration of how their work stimulated further research.…”

Section: Introductionmentioning

confidence: 99%

“…One example serves as an illustration of how their work stimulated further research. They were intrigued by the genetic basis and ecological/evolutionary significance of petal spot patterns in the flowers of a species of Clarkia [105], a genus they used as a model system for many and varied studies. Subsequent studies have examined the ecological significance [109,110] and genetics [111] of petal spot patterns.…”

Section: Introductionmentioning

confidence: 99%

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