共查询到20条相似文献，搜索用时 31 毫秒
1.
Background and Aims
Variation in mating patterns may be particularly evident in colonizing species because they commonly experience wide variation in plant density. Here, the role of density for the mating system of Ambrosia artemisiifolia (common ragweed), a wind-pollinated annual colonizing species previously reported as self-compatible, is explored.Methods
The effect of population density on the proportion of self- and cross-fertilized seeds was examined using allozyme markers and experimental arrays conducted over two seasons in the field. Also the reproductive success of isolated plants located in diverse habitats was measured. The potential occurrence of a physiological mechanism preventing self-fertilization, i.e. self-incompatibility, following controlled self- and cross-pollinations in the glasshouse was examined.Key Results
Outcrossing rates estimated using allozyme markers were uniformly high, regardless of the spacing between plants. However, when single plants were isolated from congeners they set few seeds. Observations of pollen-tube growth and seed set following controlled pollinations demonstrated that plants of A. artemisiifolia possess a strong self-incompatibility mechanism, contrary to earlier reports and assumptions.Conclusions
The maintenance of high outcrossing rates in colonizing populations of A. artemisiifolia is likely to be facilitated by the prodigious production of wind-borne pollen, high seed production and extended seed dormancy.Key words: Self-incompatibility, outcrossing rate, density dependence, colonization, wind-pollination, Ambrosia artemisiifolia (ragweed), Asteraceae 相似文献2.
Rebecca E. Irwin 《Annals of botany》2009,103(9):1425-1433
Background and Aims
Although the ecological and evolutionary consequences of foliar herbivory are well understood, how plants cope with floral damage is less well explored. Here the concept of tolerance, typically studied within the context of plant defence to foliar herbivores and pathogens, is extended to floral damage. Variation in tolerance to floral damage is examined, together with some of the mechanisms involved.Methods
The study was conducted on Ipomopsis aggregata, which experiences floral damage and nectar removal by nectar-robbing bees. High levels of robbing can reduce seeds sired and produced by up to 50 %, an indirect effect mediated through pollinator avoidance of robbed plants. Using an experimental common garden with groups of I. aggregata, realized tolerance to robbing was measured. Realized tolerance included both genetic and environmental components of tolerance. It was hypothesized that both resource acquisition and storage traits, and traits involved in pollination would mitigate the negative effects of robbers.Key Results
Groups of I. aggregata varied in their ability to tolerate nectar robbing. Realized tolerance was observed only through a component of male plant reproduction (pollen donation) and not through components of female plant reproduction. Some groups fully compensated for robbing while others under- or overcompensated. Evidence was found only for a pollination-related trait, flower production, associated with realized tolerance. Plants that produced more flowers and that had a higher inducibility of flower production following robbing were more able to compensate through male function.Conclusions
Variation in realized tolerance to nectar robbing was found in I. aggregata, but only through an estimate of male reproduction, and traits associated with pollination may confer realized tolerance to robbing. By linking concepts and techniques from studies of plant–pollinator and plant–herbivore interactions, this work provides insight into the role of floral traits in pollinator attraction as well as plant defence.Key words: Compensation, herbivory, indirect effects, Ipomopsis aggregata, male reproductive success, nectar robbing, pollen donation, pollination, resistance, tolerance 相似文献3.
Background and Aims
Because of differences in snowmelt time, the reproductive phenologies of alpine plants are highly variable among local populations, and there is large variation in seed set across populations. Temporal variation in pollinator availability during the season may be a major factor affecting not only seed production but also outcrossing rate of alpine plants.Methods
Among local populations of Phyllodoce aleutica that experience different snowmelt regimes, flowering phenology, pollinator availability, seed-set rate, and outcrossing rate were compared with reference to the mating system (self-compatibility or heterospecific compatibility with a co-occurring congeneric species).Key Results
Flowering occurred sequentially among populations reflecting snowmelt time from mid-July to late August. The visit frequency of bumble-bees increased substantially in late July when workers appeared. Both seed set and outcrossing rate increased as flowering season progressed. Although flowers were self-compatible and heterospecific compatible, the mixed-pollination experiment revealed that fertilization with conspecific, outcrossing pollen took priority over selfing and hybridization, indicating a cryptic self-incompatibility. In early snowmelt populations, seed production was pollen-limited and autogamous selfing was common. However, genetic analyses revealed that selfed progenies did not contribute to the maintenance of populations due to late-acting inbreeding depression.Conclusions
Large variations in seed-set and outcrossing rates among populations were caused by the timing of pollinator availability during the season and the cryptic self-incompatibility of this species. Despite the intensive pollen limitation in part of the early season, reproductive assurance by autogamous selfing was not evident. Under fluctuating conditions of pollinator availability and flowering structures, P. aleutica maintained the genetic composition by conspecific outcrossing.Key words: Alpine snowbed, autogamy, bumble-bee, cryptic self-incompatibility, flowering phenology, mixed pollination, outcrossing rate, Phyllodoce aleutica, pollination success, seasonality, self-pollination 相似文献4.
Jeffrey D. Karron Karsten G. Holmquist Rebecca J. Flanagan Randall J. Mitchell 《Annals of botany》2009,103(9):1379-1383
Background and Aims
Adjacent flowers on Mimulus ringens floral displays often vary markedly in selfing rate. We hypothesized that this fine-scale variation in mating system reflects the tendency of bumble-bee pollinators to probe several flowers consecutively on multiflower displays. When a pollinator approaches a display, the first flower probed is likely to receive substantial outcross pollen. However, since pollen carryover in this species is limited, receipt of self pollen should increase rapidly for later flowers. Here the first direct experimental test of this hypothesis is described.Methods
In order to link floral visitation sequences with selfing rates of individual flowers, replicate linear arrays were established, each composed of plants with unique genetic markers. This facilitated unambiguous assignment of paternity to all sampled progeny. A single wild bumble-bee was permitted to forage on each linear array, recording the order of floral visits on each display. Once fruits had matured, 120 fruits were harvested (four flowers from each of five floral displays in each of six arrays). Twenty-five seedlings from each fruit were genotyped and paternity was unambiguously assigned to all 3000 genotyped progeny.Key Results
The order of pollinator probes on Mimulus floral displays strongly and significantly influenced selfing rates of individual fruits. Mean selfing rates increased from 21 % for initial probes to 78 % for the fourth flower probed on each display.Conclusions
Striking among-flower differences in selfing rate result from increased deposition of geitonogamous (among-flower, within-display) self pollen as bumble-bees probe consecutive flowers on each floral display. The resulting heterogeneity in the genetic composition of sibships may influence seedling competition and the expression of inbreeding depression.Key words: Autogamy, bee, Bombus fervidus, floral display, geitonogamy, mating system, monkeyflower, Mimulus ringens, paternity analysis, pollen carryover, pollinator visitation sequence, self-fertilization 相似文献5.
Background and Aims
The mechanisms of floral nectar production in buckwheat (Fagopyrum esculentum, Polygonaceae), a distylous pseudo-cereal, have received relatively little attention, prompting an investigation of the factors that regulate this process. The aim was to perform a refined study of the structures that secrete nectar and of the internal and external parameters influencing nectar volumes and sugar concentrations.Methods
In order to control environmental parameters, plants were cultivated in growth rooms under controlled conditions. The structure of nectaries was studied based on histological sections from flowers and flower buds. Nectar was extracted using glass micropipettes and the sugar concentration was measured with a hand refractometer. Sugar concentration in the phloem sap was measured using the anthrone method. To test the influence of photosynthesis on nectar production, different light and defoliation treatments were applied.Key Results
Unicellular trichomes were located in the epidermis at the ventral part of eight nectary glands situated on the flower receptacle alternately with stamens. Vascular bundles consisting of both phloem and xylem were identified at the boundary between a multilayered nectary parenchyma and a sub-nectary parenchyma with chloroplasts. A higher volume of nectar in thrum morphs was observed. No other difference was found in morphology or in sugar supply to inflorescences between morphs. Nectar secretion was strongly influenced by plant age and inflorescence position. Nectar volumes were higher in the upper inflorescences and during the flowering peak. Light had a dual role, (1) acting directly on reproductive structures to trigger flower opening, which conditions nectar secretion, and (2) stimulating photosynthetic activity, which regulates nectar accumulation in open flowers.Conclusions
In buckwheat, nectar is secreted by trichomes and probably proceeds, at least in part, from phloem sap. Nectar secretion is strongly influenced by floral morph type, plant age, inflorescence position and light.Key words: Buckwheat, distyly, Fagopyrum esculentum, inflorescence position, morph comparisons, nectary histology, nectar sugar concentration, nectar volume, light intensity, organ biomass, phloem sap, plant age 相似文献6.
Katrien Vandepitte Tim De Meyer Hans Jacquemyn Isabel Roldán-Ruiz Olivier Honnay 《Annals of botany》2013,111(4):623-628
Background and Aims
The combination of clonality and a mating system promoting outcrossing is considered advantageous because outcrossing avoids the fitness costs of selfing within clones (geitonogamy) while clonality assures local persistence and increases floral display. The spatial spread of genetically identical plants (ramets) may, however, also decrease paternal diversity (the number of sires fertilizing a given dam) and fertility, particularly towards the centre of large clumped clones. This study aimed to quantify the impact of extensive clonal growth on fine-scale paternity patterns in a population of the allogamous Convallaria majalis.Methods
A full analysis of paternity was performed by genotyping all flowering individuals and all viable seeds produced during a single season using AFLP. Mating patterns were examined and the spatial position of ramets was related to the extent of multiple paternity, fruiting success and seed production.Key Results
The overall outcrossing rate was high (91 %) and pollen flow into the population was considerable (27 %). Despite extensive clonal growth, multiple paternity was relatively common (the fraction of siblings sharing the same father was 0·53 within ramets). The diversity of offspring collected from reproductive ramets surrounded by genetically identical inflorescences was as high as among offspring collected from ramets surrounded by distinct genets. There was no significant relationship between the similarity of the pollen load received by two ramets and the distance between them. Neither the distance of ramets with respect to distinct genets nor the distance to the genet centre significantly affected fruiting success or seed production.Conclusions
Random mating and considerable pollen inflow most probably implied that pollen dispersal distances were sufficiently high to mitigate local mate scarcity despite extensive clonal spread. The data provide no evidence for the intrusion of clonal growth on fine-scale plant mating patterns. 相似文献7.
Akira S. Hirao 《Annals of botany》2010,105(4):637-646
Background and Aims
A reduction in offspring fitness resulting from mating between neighbours is interpreted as biparental inbreeding depression. However, little is known about the relationship between the parents'' genetic relatedness and biparental inbreeding depression in their progeny in natural populations. This study assesses the effect of kinship between parents on the fitness of their progeny and the extent of spatial genetic structure in a natural population of Rhododendron brachycarpum.Methods
Kinship coefficients between 11 858 pairs of plants among a natural population of 154 R. brachycarpum plants were estimated a priori using six microsatellite markers. Plants were genotyped, and pairs were selected from among 60 plants to vary the kinship from full-sib to unrelated. After a hand-pollination experiment among the 60 plants, offspring fitness was measured at the stages of seed maturation (i.e. ripening) under natural conditions, and seed germination and seedling survival under greenhouse conditions. In addition, spatial autocorrelation was used to assess the population''s genetic structure.Key Results
Offspring fitness decreased significantly with increasing kinship between parents. However, the magnitude and timing of this effect differed among the life-cycle stages. Measures of inbreeding depression were 0·891 at seed maturation, 0·122 (but not significant) at seed germination and 0·506 at seedling survival. The local population spatial structure was significant, and the physical distance between parents mediated the level of inbreeding between them.Conclusions
The level of inbreeding between individuals determines offspring fitness in R. brachycarpum, especially during seed maturation. Genetic relatedness between parents caused inbreeding depression in their progeny. Therefore, biparental inbreeding contributes little to reproduction and instead acts as a selection force that promotes outcrossing, as offspring of more distant (less related) parents survive better. 相似文献8.
Background and Aims
Several models predict that the establishment of polyploids within diploid populations is enhanced by non-random mating (i.e. selfing and assortative mating) of cytotypes and by a higher relative fitness of polyploids. This report assesses the role that antheridiogens (i.e. maleness-inducing pheromones) and intercytotype differences in growth rate have on polyploid performance.Methods
Three buckler-fern species were studied: the allotetraploid Dryopteris corleyi and its diploid parents, D. aemula and D. oreades. In one experiment, gametophytes of these species were cultured under rich growth conditions to compare the timing of gametangia production. The substrata on which these gametophytes had grown were used as antheridiogen sources in a second experiment. The three species were combined as source and target of antheridiogen (i.e. nine species pairs). Timing of antheridia production and gametophyte size were determined after those antheridiogen treatments.Key Results
Under rich growth conditions the allotetraploid produced archegonia earlier than those of diploid parents. Female gametophytes of the three species produced antheridiogens that inhibited growth and favoured maleness both within and among species. Gametophyte size was similar in the three species but antheridia formed earlier in the allotetraploid.Conclusions
Unisexuality, promoted by non-specific antheridiogens, enhances random mating both within and among species. The resulting hybridization can favour the reproductive exclusion of the allopolyploid in sites where it is outnumbered by diploids. However, the earlier production of gametangia in the allotetraploid favours assortative mating and may thus counterbalance reproductive exclusion.Key words: Allopolyploidy, antheridiogen, assortative mating, Dryopteris aemula, Dryopteris corleyi, Dryopteris oreades, gametophytes, gender expression, minority cytotype exclusion 相似文献9.
Introduction
One of the most important trade-offs for many animals is that between survival and reproduction. This is particularly apparent when mating increases the risk of predation, either by increasing conspicuousness, reducing mobility or inhibiting an individual''s ability to detect predators. Individuals may mitigate the risk of predation by altering their reproductive behavior (e.g. increasing anti-predator responses to reduce conspicuousness). The degree to which individuals modulate their reproductive behavior in relation to predation risk is difficult to predict because both the optimal investment in current and future reproduction (due to life-history strategies) and level of predation risk may differ between the sexes and among species. Here, we investigate the effect of increased predation risk on the reproductive behavior of dumpling squid (Euprymna tasmanica).Results
Females, but not males, showed a substantial increase in the number of inks (an anti-predator behavior) before mating commenced in the presence of a predator (sand flathead Platycephalus bassensis). However, predation risk did not affect copulation duration, the likelihood of mating, female anti-predator behavior during or after mating or male anti-predator behavior at any time.Conclusions
Inking is a common anti-predator defense in cephalopods, thought to act like a smokescreen, decoy or distraction. Female dumpling squid are probably using this form of defense in response to the increase in predation risk prior to mating. Conversely, males were undeterred by the increase in predation risk. A lack of change in these variables may occur if the benefit of completing mating outweighs the risk of predation. Prioritizing current reproduction, even under predation risk, can occur when the chance of future reproduction is low, there is substantial energetic investment into mating, or the potential fitness payoffs of mating are high. 相似文献10.
Background and Aims
Gynodioecy is a phylogenetically widespread and important sexual system where females coexist with hermaphrodites. Because dioecy can arise from gynodioecy, characterization of gynodioecy in close relatives of dioecious and sub-dioecious species can provide insight into this transition. Thus, we sought to determine whether Fragaria vesca ssp. bracteata, a close relative to F. chiloensis and F. virginiana, exhibits the functional and population genetic hallmarks of a gynodioecious species.Methods
We compared reproductive allocation of females and hermaphrodites grown in the greenhouse and estimated genetic diversity (allelic diversity, heterozygosity) and inbreeding coefficients for field-collected adults of both sexes using simple sequence repeat (SSR) markers. We estimated mating system and early seed fitness from open-pollinated families of both sex morphs.Key Results
Under greenhouse conditions, females and hermaphrodites allocated similarly to all reproductive traits except flower number, and, as a consequence, females produced 30 % fewer seeds per plant than hermaphrodites. Under natural conditions, hermaphrodites produce seeds by self-fertilization approx. 75 % of the time, and females produced outcrossed seeds with very little biparental inbreeding. Consistent with inbreeding depression, seeds from open-pollinated hermaphrodites were less likely to germinate than those from females, and family-level estimates of hermaphrodite selfing rates were negatively correlated with germination success and speed. Furthermore, estimates of inbreeding depression based on genetic markers and population genetic theory indicate that inbreeding depression in the field could be high.Conclusions
The joint consideration of allocation and mating system suggests that compensation may be sufficient to maintain females given the current understanding of sex determination. Fragaria vesca ssp. bracteata exhibited similar sex morph-dependent patterns of mating system and genetic diversity, but less reproductive trait dimorphism, than its sub-dioecious and dioecious congeners. 相似文献11.
Background and Aims
Variation in fitness depends on corresponding variation in multiple traits which have both genetically controlled and plastic components. These traits are subjected to varying degrees of local adaptation in specific populations and, consequently, are genetically controlled to different extents. In this study it is hypothesized that modulation of different traits would have contrasting relevance for the fitness of populations of diverse origins. Specifically, assuming that environmental pressures vary across a latitudinal gradient, it is suggested that inherited variation in traits differentially determines fitness in annual Lupinus angustifolius populations from contrasting latitudinal origins in western Spain.Methods
Seeds of L. angustifolius from three contrasting origins were grown in a common garden. Traits related to more plastic vegetative growth and more genetically conserved phenology were measured, together with estimates of reproductive success. Fitness was estimated by the number of viable seeds per plant. Structural Equation Models were used to infer causal relationships among multiple traits and fitness, separating the direct and indirect effects of morphological, phenological and reproductive traits.Key Results
Phenological, vegetative and reproductive traits accounted for most of the fitness variation. Fitness was highest in plants of southernmost origin, mainly due to earlier flowering. Fitness within each seed origin was controlled by variation in different traits. Southern origin plants that grew to a larger size achieved higher fitness. However, plant size in plants of northernmost origin was irrelevant, but early flowering promoted higher fitness. Variation in fruit and seed set had a greater effect on the fitness of plants of central origin than phenological and size variation.Conclusions
It is concluded that modulation of a functional trait can be relevant to fitness in a given population (i.e. affecting intensity and direction), but irrelevant in other populations. This points to the need to consider integrated phenotypes when trying to unravel local adaptation effects over single traits.Key words: Lupinus, Structural Equation Models, fitness, phenology, functional traits, reproductive success, SLA, seed size 相似文献12.
Background and Aims
The close relationship between distylic Cordia leucocephala and the bee Ceblurgus longipalpis, both endemic to the Caatinga, north-east Brazil, was investigated, emphasizing reproductive dependence, morphological adaptations of the partners, and pollen flow.Methods
In the municipality of Pedra, in the Caatinga of Pernambuco, the breeding system and reproductive success of C. leucocephala, its interaction with flower visitors and inter- and intramorph pollen flow were determined.Key Results
The bee Ceblurgus longipalpis, the unique flower visitor and effective pollinator of self-incompatible Cordia leucocephala, presents morphological features adapted to exploit hidden pollen and nectar in the long and narrow corolla tubes. Pollen of low-level anthers is collected with hairs on prolonged mouthparts and pollen of high-level anthers with clypeus, mandibles, and labrum, showing pollen removal from both levels with the same effectiveness. In both morphs, this results in similar legitimate, i.e. intermorph cross-pollen flow. Illegitimate pollen flow to stigmas of pin flowers, however, was much higher than to stigmas of thrum flowers. Moreover, more illegitimate pollen was transported to stigmas of pin and less to those of thrum flowers when compared with legitimate pollen flow.Conclusions
The study reveals a one-to-one reproductive inter-dependence between both partners. Data indicate that this relationship between bee species and plant species is one of the rare cases of monolecty among bees. Monotypic Ceblurgus longipalpis, the only rophitine species of Brazil, evolved prolonged mouthparts rare among short-tongued bees that enable them to access pollen from flowers with short-level anthers hidden for bees of other species, and nectar at the base of the flower tube. 相似文献13.
Johanne Brunet 《Annals of botany》2009,103(9):1567-1578
Background and Aims
Pollinators together with other biotic and some abiotic factors can select for floral traits. However, variation in pollinator abundance over time and space can weaken such selection. In the present study, the variation in pollinator abundance over time and space was examined in populations of the Rocky Mountain columbine. The variation in three floral traits is described and correlations between pollinator type, functional pollinator groups or altitude and floral traits are examined.Methods
Pollinator observations took place in six Aquilegia coerulea populations over 1–4 years and spur length, flower colour and sepal length were measured in 12 populations. Pollinator abundance, measured as visits per flower per hour, was compared among populations and years. Pollinators were grouped into two functional groups: pollen or nectar collectors. The following associations were examined: annual presence of hawkmoths and whiter flowers with longer spurs; the presence of Sphinx vashti and longer spurs; and higher altitudes and whiter flowers. The study looked at whether an increase in the proportion of hawkmoths in a population was associated with whiter and larger flowers with longer spurs.Key Results
The abundance of different pollinator groups varied over time and space. Floral traits varied among populations. Higher altitude was correlated with bluer flowers. Whiter flowers were associated with the annual presence of hawkmoths. Populations visited by Sphinx vashti had longer spurs than populations visited only by Hyles lineata. Populations with greater percentage of nectar-collecting pollinators did not have whiter, larger flowers with longer spurs.Conclusions
Despite the large variation in pollinator abundance over time and space, one species of bumble-bee or hawkmoth tended to predominate in each population each year. Future studies of Aquilegia coerulea should examine the specific influences of pollinators and the environment on flower colour and of hawkmoth species on spur length.Key words: Aquilegia coerulea, columbine, pollinator abundance, bumble-bee, hawkmoth, flower colour, spur length, functional pollinator group, altitude, floral trait 相似文献14.
Background and Aims
In Australia, honey-bees have invaded systems that evolved without social insect pollinators, where many plants are adapted to vertebrate pollination. Behavioural differences between pollinators are likely to influence mating patterns, but few studies have examined this empirically in long-lived, woody, perennials. It was shown previously that outcrossing rates in Grevillea macleayana vary among populations. Here tests were conducted to determine whether the behaviour of birds and honey-bees differed between a population previously found to be highly outcrossed and two inbreeding populations.Methods
Visit frequencies and movement patterns of the visitors to inflorescences at three sites over two seasons were compared. A caging experiment was used to test the effects of excluding birds on pollen removal from newly opened flowers and on pollen deposition on stigmas that had been washed clean.Key Results
Honey-bees were the most frequent visitors overall, but honeyeaters were more frequent visitors in the population previously found to have a high outcrossing rate than they were in either of the other populations. More visits by honeyeaters were from distant plants. Pollen removal did not vary greatly among sites, and was not affected by bird exclusion; however, more pollen was deposited on the stigmas of cleaned pollen presenters in the population previously observed to be highly outcrossing than in the other two. This high level of pollen deposition was reduced by experimental bird exclusion.Conclusions
Honey-bees were the most frequent visitors, by an order of magnitude, and excluding vertebrates revealed that bees were removing most of the pollen but deposited fewer pollen grains on stigmas. Birds were more frequent visitors at the site previously found to be outcrossing than the other two sites, and they moved further between plants and visited fewer inflorescences on a plant during a foraging bout than bees did. These characteristics of bird visits to G. macleayana would be sufficient to produce significant variation in outcrossing rates among sites.Key words: Grevillea macleayana, Apis mellifera, honey-bees, honeyeaters, pollinator behaviour, pollen removal, pollen deposition, outcrossing rate 相似文献15.
Gómez JM Bosch J Perfectti F Fernández JD Abdelaziz M Camacho JP 《Annals of botany》2008,101(9):1413-1420
Background and Aims
Floral rewards may be associated with certain morphological floral traits and thus act as underlying factors promoting selection on these traits. This study investigates whether some traits that are under pollinator-mediated selection (flower number, stalk height, corolla diameter, corolla tube length and corolla tube width) in the Mediterranean herb E. mediohispanicum (Brassicaceae) are associated with rewards (pollen and nectar).Methods
During 2005 the phenotypic traits and the visitation rate of the main pollinator functional groups were quantified in 720 plants belonging to eight populations in south-east Spain, and during 2006 the same phenotypic traits and the reward production were quantified in 400 additional plants from the same populations.Key Results
A significant correlation was found between nectar production rate and corolla tube length, and between pollen production and corolla diameter. Visitation rates of large bees and butterflies were significantly higher in plants exhibiting larger flowers with longer corolla tubes.Conclusions
The association between reward production and floral traits may be a factor underlying the pattern of visitation rate displayed by some pollinators.Key words: Erysimum, floral traits, nectar, pollen, pollinator visitation rate, reward 相似文献16.
J Arvid ?gren Wei Wang Daniel Koenig Barbara Neuffer Detlef Weigel Stephen I Wright 《BMC genomics》2014,15(1)
Background
Despite having predominately deleterious fitness effects, transposable elements (TEs) are major constituents of eukaryote genomes in general and of plant genomes in particular. Although the proportion of the genome made up of TEs varies at least four-fold across plants, the relative importance of the evolutionary forces shaping variation in TE abundance and distributions across taxa remains unclear. Under several theoretical models, mating system plays an important role in governing the evolutionary dynamics of TEs. Here, we use the recently sequenced Capsella rubella reference genome and short-read whole genome sequencing of multiple individuals to quantify abundance, genome distributions, and population frequencies of TEs in three recently diverged species of differing mating system, two self-compatible species (C. rubella and C. orientalis) and their self-incompatible outcrossing relative, C. grandiflora.Results
We detect different dynamics of TE evolution in our two self-compatible species; C. rubella shows a small increase in transposon copy number, while C. orientalis shows a substantial decrease relative to C. grandiflora. The direction of this change in copy number is genome wide and consistent across transposon classes. For insertions near genes, however, we detect the highest abundances in C. grandiflora. Finally, we also find differences in the population frequency distributions across the three species.Conclusion
Overall, our results suggest that the evolution of selfing may have different effects on TE evolution on a short and on a long timescale. Moreover, cross-species comparisons of transposon abundance are sensitive to reference genome bias, and efforts to control for this bias are key when making comparisons across species.Electronic supplementary material
The online version of this article (doi:10.1186/1471-2164-15-602) contains supplementary material, which is available to authorized users. 相似文献17.
Ayumi Matsuo Hiroshi Tomimatsu Jun-Ichirou Suzuki Tomoyuki Saitoh Shozo Shibata Akifumi Makita Yoshihisa Suyama 《Annals of botany》2014,114(5):1035-1041
Background and Aims
Although many studies have reported that clonal growth interferes with sexual reproduction as a result of geitonogamous self-pollination and inbreeding depression, the mating costs of clonal growth are expected to be reduced when genets are spatially intermingled with others. This study examined how clonal growth affects both female and male reproductive success by studying a population of a mass-flowering plant, Sasa veitchii var. hirsuta, with a high degree of clonal intermingling.Methods
In a 10 × 10 m plot, genets were discriminated based on the multilocus genotypes of 11 nuclear microsatellite loci. The relationships between genet size and the components of reproductive success were then investigated. Male siring success and female and male selfing rates were assessed using paternity analysis.Key Results
A total of 111 genets were spatially well intermingled with others. In contrast to previous studies with species forming distinct monoclonal patches, seed production linearly increased with genet size. While male siring success was a decelerating function of genet size, selfing rates were relatively low and not related to genet size.Conclusions
The results, in conjunction with previous studies, emphasize the role of the spatial arrangement of genets on both the quantity and quality of offpsring, and suggest that an intermingled distribution of genets can reduce the mating costs of clonal growth and enhance overall fitness, particularly female fitness. 相似文献18.
E. R. Jasper Wubs G. Arjen de Groot Heinjo J. During Johannes C. Vogel Michael Grundmann Piet Bremer Harald Schneider 《Annals of botany》2010,106(4):583-590
Background and Aims
Human-mediated environmental change is increasing selection pressure for the capacity in plants to colonize new areas. Habitat fragmentation combined with climate change, in general, forces species to colonize areas over longer distances. Mating systems and genetic load are important determinants of the establishment and long-term survival of new populations. Here, the mating system of Asplenium scolopendrium, a diploid homosporous fern species, is examined in relation to colonization processes.Methods
A common environment experiment was conducted with 13 pairs of sporophytes, each from a different site. Together they constitute at least nine distinct genotypes, representing an estimated approx. 95 % of the non-private intraspecific genetic variation in Europe. Sporophyte production was recorded for gametophytes derived from each parent sporophyte. Gametophytes were grown in vitro in three different ways: (I) in isolation, (II) with a gametophyte from a different sporophyte within the same site or (III) with a partner from a different site.Key Results
Sporophyte production was highest in among-site crosses (III), intermediate in within-site crosses (II) and was lowest in isolated gametophytes (I), strongly indicating inbreeding depression. However, intragametophytic selfing was observed in most of the genotypes tested (eight out of nine).Conclusions
The results imply a mixed mating system in A. scolopendrium, with outcrossing when possible and occasional selfing when needed. Occasional intragametophytic selfing facilitates the successful colonization of new sites from a single spore. The resulting sporophyte, which will be completely homozygous, will shed large amounts of spores over time. Each year this creates a bed of gametophytes in the vicinity of the parent. Any unrelated spore which arrives is then selectively favoured to reproduce and contribute its genes to the new population. Thus, while selfing facilitates initial colonization success, inbreeding depression promotes genetically diverse populations through outcrossing. The results provide further evidence against the overly simple dichotomous distinction of fern species as either selfing or outcrossing. 相似文献19.
Pedro Adrián Aguilar-Rodríguez M. Cristina MacSwiney G. Thorsten Kr?mer José G. García-Franco Anina Knauer Michael Kessler 《Annals of botany》2014,113(6):1047-1055
Background and Aims
Bromeliaceae is a species-rich neotropical plant family that uses a variety of pollinators, principally vertebrates. Tillandsia is the most diverse genus, and includes more than one-third of all bromeliad species. Within this genus, the majority of species rely on diurnal pollination by hummingbirds; however, the flowers of some Tillandsia species show some characteristics typical for pollination by nocturnal animals, particularly bats and moths. In this study an examination is made of the floral and reproductive biology of the epiphytic bromeliad Tillandsia macropetala in a fragment of humid montane forest in central Veracruz, Mexico.Methods
The reproductive system of the species, duration of anthesis, production of nectar and floral scent, as well as diurnal and nocturnal floral visitors and their effectiveness in pollination were determined.Key Results
Tillandsia macropetala is a self-compatible species that achieves a higher fruit production through outcrossing. Nectar production is restricted to the night, and only nocturnal visits result in the development of fruits. The most frequent visitor (75 % of visits) and the only pollinator of this bromeliad (in 96 % of visits) was the nectarivorous bat Anoura geoffroyi (Phyllostomidae: Glossophaginae).Conclusions
This is the first report of chiropterophily within the genus Tillandsia. The results on the pollination biology of this bromeliad suggest an ongoing evolutionary switch from pollination by birds or moths to bats. 相似文献20.