Floral Development of Agalinis neoscotica, Agalinis paupercula var. Borealis, and Agalinis purpurea (Scrophulariaceae): Implications for Taxonomy and Mating System

Stewart, Heather M.; Canne-Hilliker, Judith M.

doi:10.1086/297561

Cited by 12 publications

(13 citation statements)

References 44 publications

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“…The evolutionary shift from outcrossing to high levels of selfing in angiosperms is usually accompanied by major changes in flower morphology, which include reductions in flower size, flower organ size, pollen production and anther-stigma distance (Ornduff 1969;Wyatt 1988; Barrett and Harder 1992;Sherry and Lord 2000). These shifts also involve changes in the timing of flower developmental processes (Guerrant 1989;Hill and Lord 1990;Diggle 1992;Hill et al 1992;Stewart and Canne-Hilliker 1998;Runions and Geber 2000;Armbruster et al 2002;Georgiady and Lord 2002). With few exceptions (e.g., Georgiady and Lord 2002), these conclusions about heterochronic changes are based on late or even mature developmental stages.…”

Section: Introductionmentioning

confidence: 99%

“…For these, it is necessary to study a larger portion of the developmental process. Furthermore, most published flower ontogenetic studies used the length of the corolla or pistil as indicators of developmental age (e.g., Stewart and Canne-Hilliker 1998;Sherry and Lord 2000), a method that does not necessarily provide true developmental time or age information. Such approaches are thus actually studies of allometry rather than heterochrony (McKinney 1988a;Klingenberg and Spence 1993;Li and Johnston 2000), and the two methods can give different results whenever growth rate of the reference structure differs among taxa.…”

Section: Introductionmentioning

confidence: 99%

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Flower Development and the Evolution of Self-fertilization in Amsinckia: The Role of Heterochrony

Johnston

2010

Evol Biol

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We studied the development of 26 flower traits under natural conditions in three clades of the genus Amsinckia (Boraginaceae). Each clade contained both a derived highly self-fertilizing taxon and an ancestral more highly outcrossing taxon. The more outcrossing taxa contained two flower morphs-pins and thrums-with opposite positioning of the sex organs (heterostyly). The highly selfing taxa had smaller flowers with sex organs in close proximity (homostyly). Growth trajectories were quantified over the entire or nearly the entire period from primordium initiation to flower opening. These trajectories were compared in the heterochronic framework and, in contrast with previous studies, character size was tracked over time rather than relative to another character. We focused on three hypotheses: (1) The distinct developmental trajectories leading to pins and thrums should be similar in all clades, while the trajectories leading to homostylous flowers might differ among clades. This was supported. Specifically, contrasting growth rates of stamen and pistil heights in heterostylous flowers caused pin and thrum flowers to have the reciprocal arrangement of anther and stigma heights. From the viewpoint of heterochrony, the decreased size (paedomorphosis) of the homostylous morph, compared to pins and thrums, resulted from decreased growth rate (neoteny) and earlier offset (progenesis) in all clades. Nevertheless, multiple heterochronic processes were involved in the mosaic development and evolution of homostylous flowers. (2) We tested the hypothesis that small, self-fertilizing flowers have reduced development times, one of the proposed selective advantages of increased self-fertilization rates. We found in contrast that developmental duration of homostylous flowers was either the same (two clades) or longer (one clade) compared to duration of pins and thrums. (3) Finally, we tested von Baer's Law, which proposes that developmental differences among closely related taxa should arise later in development than differences among more distantly related taxa. Von Baer's Law was supported strongly among homostyles, moderately among thrums and weakly among pins.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Flower Development and the Evolution of Self-fertilization in Amsinckia: The Role of Heterochrony

Johnston

2010

Evol Biol

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“…Associated with transition from cross-pollination to self-pollination are changes in various other floral traits, including loss of selfincompatibility and heterostyly, reduction in flower size (Grant, 1958;Jain, 1976) and pollen-ovule ratio (Cruden, 1977(Cruden, , 2000, and developmental adjustments affecting the spatial separation of pollen and stigma (herkogamy) and the timing of self-pollination (Ritland and Ritland, 1989;Fenster et al, 1995;Barrett, Harder, and Worley, 1996;Schoen, Morgan, and Bataillon, 1996;Fishman and Wyatt, 1999;Motten and Stone, 2000). However, little is known about the developmental processes that underlie differences in morphology, herkogamy, and timing of self-pollination (but see Fenster et al, 1995;Stewart, Stewart, and Canne-Hilliker, 1996;Stewart and Canne-Hilliker, 1998) or how various morphological and developmental traits are functionally and evolutionarily interrelated (Fenster et al, 1995).…”

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confidence: 99%

Comparative analysis of late floral development and mating‐system evolution in tribe Collinsieae (Scrophulariaceae s.l.)

Armbruster

Mulder

Baldwin

et al. 2002

American J of Botany

158

231

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Species of Collinsia and Tonella, the two sister genera of self-compatible annuals that constitute tribe Collinsieae, show extensive variation in floral size and morphology and in patterns of stamen and style elongation during the life of the flower (anthesis). We used a nuclear ribosomal ITS phylogeny, independent contrasts, and phylogenetically corrected path analysis to explore the patterns of covariance of the developmental and morphological traits potentially influencing mating system. Large-flowered taxa maintain herkogamy (spatial separation of anthers and stigmas) early in anthesis by differential elongation of staminal filaments, which positions each of the four anthers at the tip of the "keel" upon dehiscence. Small-flowered taxa do not show this pattern of filament elongation. The styles of large-flowered taxa elongate late in the 2-5 d of anthesis, resulting in late anther-stigma contact and delayed self-pollination. Anther-stigma contact and self-pollination occur early in anthesis in small-flowered species/populations. Thus, we found complex covariation of morphological and developmental traits that can be interpreted as the result of multitrait adaptation for early selfing and high levels of autogamy, delayed selfing and higher levels of outcrossing, or intermediate levels of outcrossing. Continuous variation in these traits suggests the operation of continuous variation in selective optima or the combined effects of divergent selection and phylogenetic inertia.

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“…In Orobanchaceae, floral organogenesis reveals that initiation processes in Pedicularis are more similar to those of Agalinis (Kampny & Canne‐Hilliker, ) than to those of Rhinanthus (Armstrong & Douglas, ; Endress, ). Initiations of sepals and stamens in Rhinanthus are unidirectional from the abaxial to the adaxial side of floral apex (Armstrong & Douglas, ; Endress, ; Tucker, ), however, in Pedicularis and Agalinis they occur almost simultaneously, in particular, the two adaxial sepal primordia in both genera being prior to the two abaxial sepal primordia (Canne‐Hilliker, ; Kampny & Canne‐Hilliker, ; Stewart & Canne‐Hilliker, ; Cai et al, ). Some specific differences between Pedicularis and Agalinis are also found (Canne‐Hilliker, ; Kampny & Canne‐Hilliker, ; Stewart & Canne‐Hilliker, ; Cai et al, ; also this study).…”

Section: Discussionmentioning

confidence: 99%

Floral ontogeny ofPedicularis(Orobanchaceae), with an emphasis on the corolla upper lip

Cai

et al. 2013

J of Sytematics Evolution

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Pedicularis shows high diversity in its corolla form, however, its floral ontogeny has been rarely investigated. In particular, the development of the highly variable upper lip (galea), three broad morphological types of which (beakless and toothless, beakless and toothed, beaked) can be discriminated, remains unknown. We used scanning electron microscopy to investigate the early stages of floral ontogeny in two beaked species, Pedicularis gruina and P. siphonantha. To compare the developmental processes of the three galea types, three species for each type were investigated. Initiations of floral organs in Pedicularis are consistent. Sepal initiations are successive from the lateral-adaxial primordia, followed by the lateral-abaxial ones (these sometimes missing), then the mid-adaxial one (again sometimes missing). The stamens are initiated prior to the petals, or development of petal primordia may be retarded at the early stages in comparison with that of stamen primordia. Four stamen primordia are initiated simultaneously. The five petal primordia are initiated almost simultaneously. Development processes of the upper lip among the three galea types differ in the expansion rates and directions of the cells of the two lobes and these differences govern whether or not a beak and/or teeth are formed on the upper lip. The floral ontogeny of Pedicularis is close to that of Agalinis, which supports the molecular assignment. Floral monosymmetry of Pedicularis is established at the beginning of sepal initiation and is maintained until flowering. The development of the upper lip provides some clues to the evolution of beaked and/or toothed galeas in Pedicularis.

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Floral Development of Agalinis neoscotica, Agalinis paupercula var. Borealis, and Agalinis purpurea (Scrophulariaceae): Implications for Taxonomy and Mating System

Cited by 12 publications

References 44 publications

Flower Development and the Evolution of Self-fertilization in Amsinckia: The Role of Heterochrony

Flower Development and the Evolution of Self-fertilization in Amsinckia: The Role of Heterochrony

Comparative analysis of late floral development and mating‐system evolution in tribe Collinsieae (Scrophulariaceae s.l.)

Floral ontogeny ofPedicularis(Orobanchaceae), with an emphasis on the corolla upper lip

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