Dataset Information

Variation in the mating system of Vincetoxicum hirundinaria (Asclepiadaceae) in peripherial island populations.

ABSTRACT: BACKGROUND AND AIMS:Self-fertility may be selected for in small and isolated plant populations of normally outcrossing species. In addition, adaptations for self-fertility are likely to arise in island populations and in populations that are located at the border of the species range. The mating system of Vincetoxicum hirundinaria (Asclepiadaceae) is examined in island populations that are located at the northern border of the species range. METHODS:Pollination experiments were conducted under glasshouse conditions with plants from four populations. KEY RESULTS:The frequencies of self-fertile individuals were relatively high and did not differ among populations. Cross-pollination resulted in higher fruit set than self-pollination. However, fruit-set from self-pollination and cross-pollination did not differ in the self-fertile individuals. Interestingly, the proportion of aborted fruits was on average higher following cross-pollination than following self-pollination. No differences were observed in seed number or seed mass between self- and cross-pollinated fruits. Pollen tube growth following self- and cross-pollinations was indistinguishable. CONCLUSIONS:The results of this study revealed that V. hirundinaria possess a mixed-mating system in the studied island populations. Evidence was also provided for a late-acting self-incompatibility system commonly observed in Asclepiadaceae. No clear signs of inbreeding depression were observed in the early stages of development.

SUBMITTER: Leimu R

PROVIDER: S-EPMC4242266 | biostudies-literature | 2004 Jan

REPOSITORIES: biostudies-literature

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Variation in the mating system of Vincetoxicum hirundinaria (Asclepiadaceae) in peripherial island populations.

Leimu Roosa R

Annals of botany 20040101 1

<h4>Background and aims</h4>Self-fertility may be selected for in small and isolated plant populations of normally outcrossing species. In addition, adaptations for self-fertility are likely to arise in island populations and in populations that are located at the border of the species range. The mating system of Vincetoxicum hirundinaria (Asclepiadaceae) is examined in island populations that are located at the northern border of the species range.<h4>Methods</h4>Pollination experiments were co ...[more]

PMID: 14678943

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Project description:Background and aimsSporophytic self-incompatibility (SI) prevents inbreeding in many members of the Brassicaceae, and has been well documented in a variety of high-profile species. Arabis alpina is currently being developed as a model system for studying the ecological genetics of arctic-alpine environments, and is the focus of numerous studies on population structure and alpine phylogeography. Although it is highly inbreeding throughout most of its range, populations in central Italy have been identified that show inbreeding coefficients (F(IS)) more typical of self-incompatible relatives. The purpose of this study was to establish whether this variation is due to a functioning SI system.MethodsOutcrossing rate estimates were calculated based on 16 allozyme loci and self-compatibility assessed based on controlled pollinations for six Italian populations that have previously been shown to vary in F(IS) values. Putative SRK alleles (the gene controlling the female component of SI in other Brassicaceae) amplified from A. alpina were compared with those published for other species. Linkage of putative SRK alleles and SI phenotypes was assessed using a diallel cross.Key resultsFunctional avoidance of inbreeding is demonstrated in three populations of A. alpina, corresponding with previous F(IS) values. The presence is described of 15 putative SRK-like alleles, which show high sequence identity to known alleles from Brassica and Arabidopsis and the high levels of synonymous and nonsynonymous variation typical of genes under balancing selection. Also, orthologues of two other members of the S-receptor kinase gene family, Aly8 (ARK3) and Aly9 (AtS1) are identified. Further to this, co-segregation between some of the putative S-alleles and compatibility phenotypes was demonstrated using a full-sibling cross design.ConclusionsThe results strongly suggest that, as with other species in the Brassicaceae, A. alpina has a sporophytic SI system but shows variation in the strength of SI within and between populations.

Project description:Background and aimsFlowering plants display considerable variation in mating system, specifically the relative frequency of cross- and self-fertilization. The majority of estimates of outcrossing rate do not account for temporal variation, particularly during the flowering season. Here, we investigated seasonal variation in mating and fertility in Incarvillea sinensis (Bignoniaceae), an annual with showy, insect-pollinated, 'one-day' flowers capable of delayed selfing. We examined the influence of several biotic and abiotic environmental factors on day-to-day variation in fruit set, seed set and patterns of mating.MethodsWe recorded daily flower number and pollinator abundance in nine 3?×?3-m patches in a population at Mu Us Sand land, Inner Mongolia, China. From marked flowers we collected data on daily fruit and seed set and estimated outcrossing rate and biparental inbreeding using six microsatellite loci and 172 open-pollinated families throughout the flowering period.Key resultsFlower density increased significantly over most of the 50-d flowering season, but was associated with a decline in levels of pollinator service by bees, particularly on windy days. Fruit and seed set declined over time, especially during the latter third of the flowering period. Multilocus estimates of outcrossing rate were obtained using two methods (the programs MLTR and BORICE) and both indicated high selfing rates of ?80 %. There was evidence for a significant increase in levels of selfing as the flowering season progressed and pollinator visitation declined. Biparental inbreeding also declined significantly as the flowering season progressed.ConclusionsTemporal variation in outcrossing rates may be a common feature of the mating biology of annual, insect-pollinated plants of harsh environments but our study is the first to examine seasonal mating-system dynamics in this context. Despite having large flowers and showy floral displays, I. sinensis attracted relatively few pollinators. Delayed selfing by corolla dragging largely explains the occurrence of mixed mating in I. sinensis, and this mode of self-fertilization probably functions to promote reproductive assurance when pollinator service is limited by windy environmental conditions and competition from co-occurring flowering plants.

Dataset Information

Variation in the mating system of Vincetoxicum hirundinaria (Asclepiadaceae) in peripherial island populations.

Publications

Variation in the mating system of Vincetoxicum hirundinaria (Asclepiadaceae) in peripherial island populations.

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