Variations in habitat, season, flower traits and pollinators in dimorphic <i>Narcissus tazetta</i> L. (Amaryllidaceae) in Israel

2010

Phil. Trans. R. Soc. B

119

Charles Darwin studied floral biology for over 40 years and wrote three major books on plant reproduction. These works have provided the conceptual foundation for understanding floral adaptations that promote cross-fertilization and the mechanisms responsible for evolutionary transitions in reproductive systems. Many of Darwin's insights, gained from careful observations and experiments on diverse angiosperm species, remain remarkably durable today and have stimulated much current research on floral function and the evolution of mating systems. Here I review Darwin's seminal contributions to reproductive biology and provide an overview of the current status of research on several of the main topics to which he devoted considerable effort, including the consequences to fitness of cross-versus self-fertilization, the evolution and function of stylar polymorphisms, the adaptive significance of heteranthery, the origins of dioecy and related gender polymorphisms, and the transition from animal pollination to wind pollination. Post-Darwinian perspectives on floral function now recognize the importance of pollen dispersal and male outcrossed siring success in shaping floral adaptation. This has helped to link work on pollination biology and mating systems, two subfields of reproductive biology that remained largely isolated during much of the twentieth century despite Darwin's efforts towards integration.

Section: Darwin and The Foundations Of Plant Reproductive Biology (A)mentioning

confidence: 99%

Darwin's legacy: the forms, function and sexual diversity of flowers

2010

Phil. Trans. R. Soc. B

119

“…These factors include differences in the pollinator fauna among populations, particularly the presence of short-vs long-tongued pollinators (Arroyo & Dafni, 1995), and the role of the inheritance of style length on morph representation in monomorphic populations following founder effects (Baker et al, 2000b;Arroyo et al, 2002). Interestingly, in several species (N. assoanus in France, Baker et al, 2000c;N.…”

Section: Mating Patterns and The Evolution Of Morph Ratiosmentioning

confidence: 99%

“…Additionally, equilibrium morph ratios could vary considerably among populations, because of the influence of local environmental conditions on both floral phenotypes and insect visitors, with corresponding effects on mating patterns. Indeed, extensive surveys of morph ratios in five Narcissus species with stigmaheight dimorphism have revealed striking variation among populations (Arroyo & Dafni, 1995;Barrett et al, 1996;Baker et al, 2000b;Arroyo et al, 2002;Arroyo, 2002).…”

Section: Mating Patterns and The Evolution Of Morph Ratiosmentioning

confidence: 99%

“…These species are not distylous, because both morphs have anthers in similar positions, and so lack reciprocal herkogamy. Both monomorphic and dimorphic species with the paperwhite morphology are pollinated primarily by Lepidoptera (Sphingidae, Pieridae, Nymphalidae: Vogel & Müller-Doblies, 1975;Arroyo & Dafni, 1995;Arroyo et al ., 2002;Thompson et al ., 2003), which transport pollen on their proboscides or faces. Long-tongued bees also visit these species; however, their tongues are too short to reach the nectar at the base of the tube, so they collect only pollen.…”

Section: Floral Morphology and Pollinationmentioning

confidence: 99%

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The evolution of polymorphic sexual systems in daffodils (Narcissus)

Harder

2004

New Phytologist

SummaryNarcissus , the daffodil genus, exhibits an unusual diversity of sexual systems, with populations that are monomorphic, dimorphic or trimorphic for style length. Associated with this variation are striking differences among species in floral morphology and pollination biology. This diversity provides an opportunity to investigate the evolution of mating polymorphisms, and to determine how floral morphology promotes transitions among sexual systems. Because of the absence of heteromorphic incompatibility in Narcissus , floral morphology plays a key role in governing patterns of outcrossed mating. Phylogenetic evidence indicates that stylar monomorphism is ancestral in the genus, with multiple origins of stylar polymorphism, including independent origins of stigma-height dimorphism, distyly and tristyly. Sexual polymorphisms have evolved only in lineages with narrow floral tubes that are pollinated by Lepidoptera and/or long-tongued bees. Populations of polymorphic Narcissus species are typically dominated by the long-styled morph and display imperfect reciprocity in the positions of sexual organs. These features are consequences of the unusual association between stylar polymorphism and a self-incompatibility system that permits intramorph mating.New Phytologist (2005) 165 : 45-53 © New Phytologist (2004

“…For example, in stigma dimorphic Narcissus assoanus , both L-morph biased and isoplethic populations are reported in southern France and these differ in size and the quantity and quality of pollinator service ( Baker et al, 2000a , c ). Diff erences in the types of pollinators visiting populations of other stigma-height dimorphic Narcissus species have also been implicated in causing variation in morph ratios ( Arroyo and Dafni, 1995 ;Simón-Porcar et al, 2014 ). A theoretical model of pollination and mating in stigma-height dimorphic populations, based on empirical data on the fl oral biology of Narcissus species, demonstrated that greater assortative mating in the L-morph, because of the reduced herkogamy of this morph compared to the S-morph, could explain the L-biased populations that are most commonly encountered in this genus ( Baker et al, 2000a ).…”

Section: Discussionmentioning

confidence: 99%

Associations between sex‐organ deployment and morph bias in related heterostylous taxa with different stylar polymorphisms

Ferrero

Rojas

et al. 2016

American J of Botany

Self Cite

Heterostyly is a genetic polymorphism in which populations are composed of two (distyly) or three (tristyly) fl oral morphs that differ in the reciprocal placement of stigmas and anthers within fl owers ( Darwin, 1877 ;Barrett, 1992 ). Th e genetic control of the polymorphism in distylous plants usually involves a single Mendelian diallelic locus in which the long-styled morph is of genotype ss and the short-styled morph is of genotype Ss , although in several species the dominance relations at the S -locus are reversed ( Lewis and Jones, 1992 ). Th e fl oral morphs are maintained in populations by negative frequency-dependent selection resulting from intermorph (disassortative) mating. With this genetic system and disassortative mating, a 1:1 morph ratio (isoplethy; Finney, 1953 ) is expected in equilibrium populations.Th e classic textbook depiction of heterostyly as a balanced polymorphism (e.g., Roughgarden, 1979 ;Silvertown and Charlesworth, 2009 ;Charlesworth and Charlesworth, 2010 ) is largely based on knowledge of distyly in Primula and emphasizes how the reciprocal positioning of sex organs (reciprocal herkogamy) associated with a self and intramorph incompatibility system (heteromorphic incompatibility) promotes outcrossing in populations. PREMISE OF THE STUDY:Populations of heterostylous species are characterized by two or three fl oral morphs with reciprocal positioning of stigmas and anthers. Theoretical models predict equal morph frequencies (isoplethy) when disassortative mating is prevalent in populations, but biased morph ratios may occur when variation in the expression of heterostyly causes deviations from intermorph mating. METHODS:We explore the role of sex-organ deployment in governing morph ratios in two closely related genera of Boraginaceae, exhibiting striking variation in fl oral traits associated with the heterostylous syndrome. We sampled 66 populations of six species of Glandora and 39 populations of three species of Lithodora across their distributional range in the Mediterranean. In each population we estimated morph ratios and measured several fl oral traits. We used phylogenetically corrected and noncorrected regressions to test the hypothesis that diff erences in sex-organ reciprocity and herkogamy are associated with deviations from isoplethy.KEY RESULTS: Biased morph ratios occurred in 24% of populations, particularly in Lithodora . Populations biased for the long-styled morph (L-morph) were more frequent than the short-styled morph (S-morph). Distylous species were less likely to exhibit biased ratios than species with stigma-height dimorphism. In Lithodora fruticosa , a species lacking reciprocity, decreased herkogamy in the S-morph was associated with increasing L-morph bias, perhaps resulting from self-interference. CONCLUSION:Striking variation in the expression of heterostyly in Glandora and Lithodora is associated with biased morph ratios, which probably result from pollinator-mediated mating asymmetries within populations.