Disassortative mating prevails in style-dimorphic Narcissus papyraceus despite low reciprocity and compatibility of morphs

Evolution to reduce inbreeding can favor disassortative (inter-morph) over assortative (intramorph) mating in hermaphroditic sexually polymorphic plant species. Heterostyly enhances disassortative pollination through reciprocal placement of stigmas and anthers of morphs and appropriate pollinators. Stylar dimorphism in which there is not reciprocal anther placement may compromise disassortative mating, particularly when there is not intra-morph incompatibility. Variable rates of disassortative mating along with differential female fecundity or siring success among floral morphs could lead to variation in morph ratio. We investigated mating patterns, female fecundity and siring success of style-length morphs in Narcissus papyraceus, a self-incompatible but morph-compatible species with dimorphic (long- and short-styled) and monomorphic (long-styled) populations in central and north regions of its range respectively. We established experimental populations in both regions and exposed them to ambient pollinators. Using paternity analysis, we found similar siring success of morphs and high disassortative mating in most populations. Female fecundity of morphs was similar in all populations. Although these results could not completely explain the loss of dimorphism in the species’ northern range, they provided evidence for the evolutionary stability of stylar dimorphism in N. papyraceus in at least some populations. Our findings support the hypothesis that prevailing inter-morph mating is key for the maintenance of stylar dimorphism.PostprintPeer reviewe

Range-wide population genetics and variation in morph ratio in style-dimorphic Narcissus papyraceus

• Premise of the study: Theoretical models state that natural selection and mating patterns account for fl oral morph ratio in stylepolymorphic plants. However, the demographic history of populations can also infl uence variation in morph ratios. If so, we hypothesize an association between the morph ratios and the genetic structure across populations. • Methods: We used nuclear microsatellites to assess genetic variation and structure in populations of Narcissus papyraceus, a style-dimorphic plant whose fl oral morph ratios (L-morph to S-morph) gradually vary throughout its distribution range in the southwestern Mediterranean Basin. We implemented analyses to relate the genetic features of populations with their morph ratios. • Key results: We found greater frequencies of the S-morph in central populations and declining frequencies toward the periphery. This geographic pattern was not associated with the genetic structure of populations. Instead, we found two distinct genetic groups, mainly separated by the Strait of Gibraltar, with a mixture of morph ratios within each one. Overall, there was a weak genetic structure. Genetic diversity was greater in central and southern dimorphic populations than in northern L-monomorphic populations. • Conclusions: Altogether, our results do not support the hypothesis that the demographic history of populations can account for the observed geographical pattern of morph ratios in N. papyraceus. We suggest that adaptive processes shown in previous studies in the species are the main determinant of the existing variation in the morph composition of populations.Spanish Ministerio de Ciencia e Innovación. Grant Numbers: CGL-2006-13847-C02-01, CGL-2009-12565 Regional Government of Andalusia. Grant Numbers: P07-RNM-02869, P09-RNM-5280 Ministerio de Ciencia e Innovación of Spain. Grant Number: BES-2008-005014Peer reviewe

Data from: Long-tongued insects promote disassortative pollen transfer in style-dimorphic Narcissus papyraceus (Amaryllidaceae)

1. In hermaphroditic flowers, reciprocal herkogamy e.g. heterostyly enhances pollen transfer between floral morphs (disassortative pollination) while avoiding self-interference between sexual organs. By contrast, disassortative pollination might be compromised in style-dimorphic flowers, which lack perfect reciprocity between the two floral morphs. This sub-optimal functioning has been considered to explain why stylar dimorphism is rare in nature. 2. Some style-polymorphic species receive a wide array of floral visitors, including long-tongued insects that feed on nectar and short-tongued insects that feed on pollen. Differences in the morphology and behaviour of these two insect types could be manifested as different pollination patterns in each floral morph. 3. By observing individual pollinators and pollen deposition and delivery in small field-based experimental arrays with emasculated and intact flowers, we studied pollination patterns mediated by different insect types (long- and short-tongued) in the two floral morphs (long- and short-styled) of the style-dimorphic Narcissus papyraceus. We investigated patterns of pollen transfer between and within style morphs in cross pollinations, as well as self-pollination and pollen-removal rates, for each floral morph mediated by each insect type. 4. Long-tongued insects were efficient pollinators of both floral morphs as they removed little pollen from the anthers but deposited comparatively large amounts on the stigmas. Although disassortative and assortative pollen transfer were equally high to the long-styled morph, the former prevailed in the short-styled morph. Short-tongued insects removed large amounts of pollen from the anthers but deposited only a few pollen grains on the long-styled stigmas and a negligible number of grains on short-styled stigmas regardless of the morph of the donor. 5. In this study we provide empirical support for the hypothesis that, under the action of long-tongued pollinators, pollen transfer patterns in the stylar-dimorphic Narcissus papyraceus resemble in part those of heterostylous species. In addition, we found that short-tongued insects act mostly as pollen thieves, thereby limiting the male fitness of both style morphs, besides depleting the female fitness of S-morph plants. In view of these results, we propose that the differing pollination efficiencies of floral visitors, in addition to their frequency, are key in determining the morph ratio of populations in this Narcissus

Data from: Range-wide population genetics and variation in morph ratio in style-dimorphic Narcissus papyraceus (Amaryllidaceae)

Simón-Porcar_etal_2015_AJB Genetic database of 31 populations of Narcissus papyraceus in the western Mediterranean, genotyped with 8 microsatellite markers. Genotyped individuals are either long-styled (L) or short-styled (S).Premise of the study: Theoretical models state that natural selection and mating patterns account for floral morph ratio in style- polymorphic plants. However, the demographic history of populations can also influence variation in morph ratios. If so, we hypothesize an association between the morph ratios and the genetic structure across populations. Methods: We used nuclear microsatellites to assess genetic variation and structure in populations of Narcissus papyraceus, a style-dimorphic plant whose floral morph ratios (L-morph to S-morph) gradually vary throughout its distribution range in the southwestern SW Mediterranean Basin. We implemented analyses to relate the genetic features of populations with their morph ratios. Key results: We found greater frequencies of the S-morph in central populations and declining frequencies toward the periphery. This geographic pattern was not associated with the genetic structure of populations. Instead, we found two distinct genetic groups, mainly separated by the Strait of Gibraltar, with a mixture of morph ratios within each one. Overall, there was a weak genetic structure. Genetic diversity was greater in central and southern dimorphic populations than in northern L-monomorphic populations. Conclusions: Altogether, our results do not support the hypothesis that the demographic history of populations can account for the observed geographical pattern of morph ratios in N. papyraceus. We suggest that adaptive processes shown in previous studies in the species are the main determinant of the existing variation in the morph composition of populations.Peer reviewe

Rapid local adaptation in both sexual and asexual invasive populations of monkeyflowers (Mimulus spp.)

Background and Aims Traditionally, local adaptation has been seen as the outcome of a long evolutionary history, particularly with regard to sexual lineages. By contrast, phenotypic plasticity has been thought to be most important during the initial stages of population establishment and in asexual species. We evaluated the roles of adaptive evolution and phenotypic plasticity in the invasive success of two closely related species of invasive monkeyflowers (Mimulus) in the UK that have contrasting reproductive strategies: M. guttatus combines sexual (seeds) and asexual (clonal growth) reproduction while M. × robertsii is entirely asexual. Methods We compared the clonality (number of stolons), floral and vegetative phenotype, and phenotypic plasticity of native (M. guttatus) and invasive (M. guttatus and M. × robertsii) populations grown in controlled environment chambers under the environmental conditions at each latitudinal extreme of the UK. The goal was to discern the roles of temperature and photoperiod on the expression of phenotypic traits. Next, we tested the existence of local adaptation in the two species within the invasive range with a reciprocal transplant experiment at two field sites in the latitudinal extremes of the UK, and analysed which phenotypic traits underlie potential local fitness advantages in each species. Key Results Populations of M. guttatus in the UK showed local adaptation through sexual function (fruit production), while M. × robertsii showed local adaptation via asexual function (stolon production). Phenotypic selection analyses revealed that different traits are associated with fitness in each species. Invasive and native populations of M. guttatus had similar phenotypic plasticity and clonality. M. × robertsii presents greater plasticity and clonality than native M. guttatus, but most populations have restricted clonality under the warm conditions of the south of the UK. Conclusions This study provides experimental evidence of local adaptation in a strictly asexual invasive species with high clonality and phenotypic plasticity. This indicates that even asexual taxa can rapidly

Simón-Porcar_etal_2015_AJB

Genetic database of 31 populations of Narcissus papyraceus in the western Mediterranean, genotyped with 8 microsatellite markers. Genotyped individuals are either long-styled (L) or short-styled (S)

Pollen deposited on stigmas in cross and self polllinations and pollen load on anthers

Three tables are provided. Table 1 shows number of pollen grains deposited on stigmas in disassortative and assortative crosses between floral morphs of style-dimorphic Narcissus papyraceus, mediated by insects either with long or short tongue. Table 2 provides number of self-pollen grains deposited on stigmas after a single visit of each insect typpe in each floral morph. Table 3 gives the amount of pollen on anthers of either unvisited flowers and flowers single-visited by each insect type

Recent autopolyploidization in a naturalized population of Mimulus guttatus (Phrymaceae)

Polyploidization can trigger rapid changes in morphology, ecology and genomics even in the absence of associated hybridization. However, disentangling the immediate biological consequences of genome duplication from the evolutionary change that subsequently accumulates in polyploid lineages requires the identification and analysis of recently formed polyploids. We investigated the incidence of polyploidization in introduced populations of Mimulus guttatus in the UK and report the discovery of a new mixed diploid–autopolyploid population in the Shetland Isles. We conducted a genetic analysis of six Shetland populations to investigate whether tetraploid individuals may have originated from local diploid plants and compared the morphology of tetraploids and local diploids to assess the phenotypic consequences of genome duplication. Autotetraploids are genetically close to sympatric diploids, suggesting that they have originated locally. Phenotypically, whole genome duplication has resulted in clear differences between ploidies, with tetraploids showing delayed phenology and larger flowers, leaves and stems than diploids. Our results support the hypothesis that novel evolutionary lineages can rapidly originate via polyploidization. The newly discovered autopolyploidization event in a non-native Mimulus population provides an opportunity to investigate the early causes and consequences of polyploidization in the wild