Costs and benefits of the mixed-mating system of Narcissus serotinus (Amaryllidaceae) in the conservation of small fragmented populations

Botany ◽  
2014 ◽  
Vol 92 (2) ◽  
pp. 113-122 ◽  
Author(s):  
Isabel Marques ◽  
David Draper ◽  
José María Iriondo
Keyword(s):  
Inbreeding Depression ◽  
Floral Biology ◽  
Mixed Mating ◽  
Reproductive Assurance ◽  
Evolutionary Potential ◽  
Mixed Mating System ◽  
Fragmented Populations ◽  
Large Populations ◽  
Fruit And Seed Set ◽  
Plant Pollinator

Small fragmented populations often exhibit reduced plant–pollinator interactions and scarce outcrossing opportunities. In this context, mixed-mating systems can be advantageous since selfing can provide reproductive assurance, but they may also carry relevant costs such as those involved in inbreeding depression. This study examines the advantages and costs of selfing in Narcissus serotinus L., a mixed-mating geophyte that currently occurs in several fragmented populations in Portugal, that resulted from the construction of the largest European dam. Observation of pollinators revealed that cross-pollination is less frequent in small than in large populations. Manual self-pollinations significantly increased fruit and seed set in small-size populations, also suggesting limited insect pollination. The existence of selfing may provide reproductive assurance in small-size populations of N. serotinus where outcrossing pollination is reduced. Although floral biology and experimental pollinations showed that N. serotinus is capable of autonomous selfing, four of the six fitness traits studied showed significant inbreeding depression in all populations. The high levels of inbreeding depression found in N. serotinus suggest that the initial reproductive assurance advantage of selfing may be counterbalanced by lower survival of the resulting individuals and a decrease in the evolutionary potential of the populations.

Floral and pollination biology of three sympatric Vaccinium (Ericaceae) species in the Upper Ardennes, Belgium

1996 ◽  
Vol 74 (2) ◽  
pp. 210-221 ◽  
Author(s):  
A. -L. Jacquemart ◽  
J. D. Thompson
Keyword(s):  
Mating System ◽  
Related Species ◽  
Seed Set ◽  
Floral Biology ◽  
Floral Traits ◽  
Mixed Mating ◽  
Mixed Mating System ◽  
Closely Related Species ◽  
Fruit And Seed Set ◽  
Selfing Ability

Comparative studies of the reproductive biology and pollination ecology of closely related species allow us to test several ideas related to the evolution of selfing taxa from outcrossing ancestors. The existence of closely related species in the same habitat provides a particularly useful opportunity to examine this issue. A variety of floral traits likely to be associated with the reproductive system of three sympatric Vaccinium species (V. myrtillus, V. vitis-idaea, and V. uliginosum) were quantified in a heathland in the Upper Ardennes, Belgium. These traits included the length and width of the corolla, the number and size of the anthers, the number of pollen tetrads and ovules, and the length of the style. Pollen to ovule ratios suggest a mixed mating system in the three species. The greater pollen to ovule ratio and stigma–anther separation in V. vitis-idaea suggest that it functions more as an outcrosser than the two congeners. The effects of caging, emasculation, and artificial pollination on fruit and seed set differed among years and among the three species. Supplementary pollination increased fruit set and fruit characteristics (particularly seed number) relative to natural pollination in the three species. The three species showed a varied but poor capacity to self in the absence of pollinators. Seed set per fruit was lower in the spontaneously selfed flowers in comparison with hand-crossed pollinated flowers in V. myrtillus and V. vitis-idaea but not in V. uliginosum. This higher ability to self in V. uliginosum indicates a lower capacity to self in the absence of pollinators. However, all the three species were at least partially self-compatible. Together the floral traits and selfing ability suggest that the polyploid V. uliginosum appears to be more highly selfing than the two diploids, particularly V. vitis-idaea. Keywords: floral biology, mixed mating, mating system, Vaccinium, seed set.

scholarly journals Life cycle expression of inbreeding depression in Eucalyptus regnans and inter-generational stability of its mixed mating system

2019 ◽  
Vol 124 (1) ◽  
pp. 179-187 ◽  
Author(s):  
A Rod Griffin ◽  
Brad M Potts ◽  
René E Vaillancourt ◽  
J Charles Bell
Keyword(s):  
Life Cycle ◽  
Mating System ◽  
Inbreeding Depression ◽  
Field Experiments ◽  
Natural Populations ◽  
Forest Tree ◽  
Mixed Mating ◽  
Mature Trees ◽  
Mixed Mating System ◽  
Eucalyptus Regnans

Abstract Background and Aims Many plants exhibit a mixed mating system. Published models suggest that this might be an evolutionarily stable rather than a transitional state despite the presence of inbreeding depression, but there is little empirical evidence. Through field experimentation, we studied the role of inbreeding depression in eliminating inbred progeny from the reproductive cohort of the forest tree Eucalyptus regnans, and demonstrate a stable mixed primary mating system over two successive generations. Methods Two field experiments were conducted using seed from natural populations. We sowed open-pollinated seeds to simulate a natural regeneration event and determined isozyme genotypes of dominant and suppressed individuals over 10 years. We also planted a mixture of open-pollinated, outcross and selfed families with common maternal parentage; monitored survival of cross types over 29 years; and determined the percentage of outcrosses in open-pollinated seed from a sample of reproductively mature trees using microsatellite analysis. Key Results Both experiments demonstrated progressive competitive elimination of inbred plants. By 29 years, the reproductive cohort in the planted experiment consisted only of outcrosses which produced seed which averaged 66 % outcrosses, similar to the estimate for the parental natural population (74 %). Conclusions Selective elimination of inbred genotypes during the intense intra-specific competition characteristic of the pre-reproductive phase of the life cycle of E. regnans results in a fully outcrossed reproductive population, in which self-fertility is comparable with that of its parental generation. The mixed mating system may be viewed as an unavoidable consequence of the species’ reproductive ecology, which includes the demonstrated effects of inbreeding depression, rather than a strategy which is actively favoured by natural selection.

Mating system of Calluna vulgaris: self-sterility and outcrossing estimations

1998 ◽  
Vol 76 (1) ◽  
pp. 37-42 ◽  
Author(s):  
Grégory Mahy ◽  
Anne-Laure Jacquemart
Keyword(s):  
Mating System ◽  
Inbreeding Depression ◽  
Calluna Vulgaris ◽  
Pollen Tubes ◽  
Outcrossing Rate ◽  
Evolutionary Significance ◽  
Mixed Mating ◽  
Mixed Mating System ◽  
Cross Pollination ◽  
Mating System Evolution

The evolutionary significance of a mixed mating system is currently under debate. Calluna vulgaris (L). Hull, a widespread European shrub, is likely to undergo mixed mating because of geitonogamy. Mating system was investigated in three populations of C. vulgaris by means of greenhouse controlled crosses, pollen tube observations, and outcrossing rate estimations from allozyme markers. The species is highly self-sterile, most probably as a result of early inbreeding depression. Mean fruit set and mean seed number per fruit following hand self-pollination were 48 and 13%, respectively, of those following cross-pollination. Pollen tubes produced by self pollen penetrated the ovary with the same success as those from cross-pollination. Multilocus estimates of the outcrossing rates ranged from 0.71 to 0.90, and two estimates were significantly different from 1.00. Calluna vulgaris could thus be classified as being mixed mating with predominant allogamy. Single-locus estimates did not differ significantly from multilocus estimates suggesting that biparental inbreeding did not contribute to the apparent selfing rate. The maintenance of high early inbreeding depression despite an intermediate level of selfing is discussed with respect to recent theories on mating system evolution. Key words: Calluna vulgaris, mating system, self-sterility, pollen tubes, outcrossing rate, inbreeding depression.

scholarly journals Outbreeding and possibly inbreeding depression in a pollinating fig wasp with a mixed mating system

Heredity ◽  
2009 ◽  
Vol 102 (4) ◽  
pp. 349-356 ◽  
Author(s):  
J M Greeff ◽  
G J Jansen van Vuuren ◽  
P Kryger ◽  
J C Moore
Keyword(s):  
Mating System ◽  
Inbreeding Depression ◽  
Mixed Mating ◽  
Fig Wasp ◽  
Mixed Mating System

scholarly journals Reproductive system of a mixed-mating plant responds to climate perturbation by increased selfing

2013 ◽  
Vol 280 (1766) ◽  
pp. 20131336 ◽  
Author(s):  
N. T. Jones ◽  
B. C. Husband ◽  
A. S. MacDougall
Keyword(s):  
Population Structure ◽  
Environmental Change ◽  
Inbreeding Depression ◽  
Reproductive System ◽  
Fruit Production ◽  
Mixed Mating ◽  
Reproductive Assurance ◽  
Pollinator Visitation ◽  
Chasmogamous Flowers

How plants respond to climatic perturbations, which are forecasted to increase in frequency and intensity, is difficult to predict because of the buffering effects of plasticity. Compensatory adjustments may maintain fecundity and recruitment, or delay negative changes that are inevitable but not immediately evident. We imposed a climate perturbation of warming and drought on a mixed-mating perennial violet, testing for adjustments in growth, reproduction and mortality. We observed several plasticity-based buffering responses, such that the climatic perturbation did not alter population structure. The most substantial reproductive adjustments, however, involved selfing, with a 45% increase in self-pollination by chasmogamous flowers, a 61% increase in the number of cleistogamous flowers that produced at least one fruit and an overall 15% increase in fruit production from selfed cleistogamous flowers. Reproductive assurance thus compensated for environmental change, including low pollinator visitation that occurred independently of our climate treatment. There was also no immediate evidence for inbreeding depression. Our work indicates that plants with vegetative and reproductive flexibility may not be immediately and negatively affected by a climatic perturbation. The stabilizing effects of these reproductive responses in the long term, however, may depend on the implications of significantly elevated levels of selfing.

Seed germination in cleistogamous species: theoretical considerations and a literature survey of experimental results

2017 ◽  
Vol 27 (2) ◽  
pp. 84-98 ◽  
Author(s):  
Jerry M. Baskin ◽  
Carol C. Baskin
Keyword(s):  
Seed Germination ◽  
Reproductive Success ◽  
Inbreeding Depression ◽  
Seedling Emergence ◽  
Sensu Stricto ◽  
Literature Survey ◽  
Mixed Mating ◽  
Mixed Mating System ◽  
Commelina Benghalensis ◽  
Theoretical Considerations

AbstractA cleistogamous species consists of individuals that produce both chasmogamous (open, CH) and cleistogamous (permanently closed, CL) flowers, which facilitates a mixed-mating system. In contrast to what one might expect, CL (obligately selfed) seeds and the plants derived from them can be more fit than CH (potentially outcrossed) seeds and the plants they give rise to. Our aim was to review some theoretical aspects of mixed mating in relation to retention of both CH and CL in cleistogamous species and to determine if data on germination support the notion that CL is advantageous over that of CH. Based on germination (or seedling emergence) of CHvsCL seeds in 29 species in 21 genera and 11 families of monocots and eudicots, CL seeds germinated better in 107 and equally well as in 64 of 252 case studies as CH seeds (67.9%), and the (CH < CL):(CH > CL) ratio was 107/81 (1.32). We conclude that our study lends support to the notion that production of CL seeds by cleistogamous species is advantageous over that of CH seeds. Retention of CH by CL species may be due to the need to prevent complete selfing (s= 1.0) and thus total inbreeding depression (δ), which theory predicts would decrease reproductive success. Some caveats concerning the results of comparative studies on the germination biology of CHvsCL seeds of amphicarpicsensu strictoFabaceae species andCommelina benghalensisand the aerial cleistogamous grassDanthonia spicataare discussed.

scholarly journals The mixed mating system of the sea palm kelp Postelsia palmaeformis : few costs to selfing

2010 ◽  
Vol 278 (1710) ◽  
pp. 1347-1355 ◽  
Author(s):  
Allison K. Barner ◽  
Catherine A. Pfister ◽  
J. Timothy Wootton
Keyword(s):  
Mating System ◽  
First Generation ◽  
Genetic Load ◽  
Mixed Mating ◽  
Reproductive Assurance ◽  
Isolated Populations ◽  
Mixed Mating System ◽  
Fitness Consequences ◽  
Limited Dispersal ◽  
Self Fertilization

Naturally isolated populations have conflicting selection pressures for successful reproduction and inbreeding avoidance. These species with limited seasonal reproductive opportunities may use selfing as a means of reproductive assurance. We quantified the frequency of selfing and the fitness consequences for inbred versus outcrossed progeny of an annual kelp, the sea palm ( Postelsia palmaeformis ). Using experimentally established populations and microsatellite markers to assess the extent of selfing in progeny from six founding parents, we found the frequency of selfing was higher than expected in every population, and few fitness costs were detected in selfed offspring. Despite a decline in heterozygosity of 30 per cent in the first generation of selfing, self-fertilization did not affect individual size or reproduction, and correlated only with a marginally significant decline in survival. Our results suggest both that purging of deleterious recessive alleles may have already occurred and that selfing may be key to reproductive assurance in this species with limited dispersal. Postelsia has an alteration of a free-living diploid and haploid stage, where the haploid stage may provide increased efficiency for purging the genetic load. This life history is shared by many seaweeds and may thus be an important component of mating system evolution in the sea.

scholarly journals A stochastic model of selection on selfing rates in structured populations

1995 ◽  
Vol 65 (3) ◽  
pp. 209-222 ◽  
Author(s):  
J. Ronfort ◽  
D. Couvet
Keyword(s):  
Population Structure ◽  
Stochastic Model ◽  
Mating System ◽  
Inbreeding Depression ◽  
Structured Populations ◽  
Empirical Literature ◽  
Mixed Mating ◽  
Selfing Rate ◽  
Mixed Mating System ◽  
Biparental Inbreeding

SummaryPrevious theoretical studies of the evolution of the selfing rate have shown that mixed mating systems are not evolutionary stable states. Such models have, however, not included the effects of population structure and thus biparental inbreeding together with the evolution of selfing rates and inbreeding depression. In order to examine selection on selfing rates in structured populations, a stochastic model simulating a finite population with partial selfing and restricted pollen and seed dispersal has been developed. Selection on the mating system was followed by introducing modifiers affecting the selfing rate. The major result was that, with density dependent recruitment, a process which maintains the population structure necessary for biparental inbreeding to occur, a mixed mating system could be maintained. This result was associated with an increase of the mutation load with high selfing rates, and the selected selfing rate depended on the degree of population structure rather than on the initial selfing rate. With low dominance of deleterious alleles, complete allogamy can be selected for. Further studies showed that the more general condition of spatial heterogeneity of recruitment can lead to similar results, the most important condition being the maintenance of genetic structure within populations. A brief survey of the empirical literature shows that a positive relationship between the magnitude of inbreeding depression and the inbreeding coefficient within populations has been observed, in support of the present model.

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