Movement herkogamy in Kosteletzkya virginica: Effect on reproductive success and contribution to pollen receipt and reproductive assurance

Herkogamy may act as a mechanism to reduce interference between the reproductive functions of female and male organs, but too great a distance between stigmas and anthers may also decrease the outcross pollen transfer and male and female fitness. Our goal was to quantify the effect of movement herkogamy in Kosteletzkya virginica on reproductive success and its contribution to pollen receipt and reproductive assurance. Field investigations and hand-pollination experiments were performed to test: (1) the relationship between herkogamy before curvature of un-pollinated lobes and reproductive success under pollinator exclusion; (2) the contribution of movement herkogamy to pollen receipt; and (3) the relationship between pollen load and seed set. We noted that variation in herkogamy before curvature of un-pollinated lobes did not affect the outcome of autogamous self-pollination measured by fruit set and mean number of seeds per fruit. Under natural conditions, 39% of pollen grains deposited per flower were from autogamous self-pollination via movement herkogamy resulting in contact between anthers and stigmas. The relationship between the amount of pollen grains and the number of seeds per capsule was highly significant. Flowers producing four or five seeds received more pollen grains than those producing only one seed. Our data provides experimental evidence that movement herkogamy, which decreases the separation between anthers and stigmas and results in delayed self-pollination, contributes to pollen receipt and further enhances seed set when pollinators are scarce or absent.     

Relationship between reproductive assurance and mixed mating in perennial Kosteletzkya virginica

Recent works have shown that mixed mating systems often evolve despite strong inbreeding depression and reproductive assurance, which is one of the widely accepted explanations for the evolution of selfing. However, there have been few empirical studies on the relationship between mixed mating and reproductive assurance in perennial plants. In the herbaceous perennial, Kosteletzkya virginica, delayed selfing induced from context-dependent style curvature offers reproductive assurance, and adverse weather conditions significantly reduce pollinator visitation rates. In this study, our goals were (i) to experimentally evaluate pollinator failure rate, reproductive assurance, selfing rate and the relationships between them, and (ii) to measure inbreeding depression across multiple growth seasons. Results indicate that both population selfing rates and reproductive assurance are significantly and positively correlated with field estimates of pollinator failure rates, and there is a strong relationship between selfing rates and reproductive assurance. Inbreeding depression across multiple growth seasons ranged from 0.621 to 0.665, and there were no significant differences among different seasons. Our data demonstrates that a mixed mating system is beneficial because frequent pollinator failure has allowed reproductive assurance to evolve through delayed selfing which minimizes the risk of seed discounting and is still advantageous despite high inbreeding depression.     

Floral density,pollen limitation,and reproductive success in<Emphasis Type="Italic"> Trillium grandiflorum</Emphasis>

Decreases in floral density can disrupt mutualistic interactions between plants and their pollinators, and decrease reproductive success. I addressed the relationship between floral density and plant reproductive success using two experimental approaches: a pollen supplementation experiment in 12 populations of Trillium grandiflorum that naturally varied in floral density, and a transplant experiment in which floral density was manipulated in plots at four experimental sites. In the pollen supplementation experiments, the degree of pollen limitation, in terms of fruit set and seed set, decreased with floral density. Further, in the experimental sites, plant reproductive success increased asymptotically with floral density. These results demonstrate the value of simultaneously conducting experiments in both experimental sites and natural populations to understand how population density influences plant reproductive success. Factors that reduce the density of this perennial herb, such as habitat fragmentation and herbivory by white-tailed deer (Odocoileus virginianus), should be expected to limit its reproduction.Due to an error in the citation line, this revised PDF (published in December 2003) deviates from the printed version, and is the correct and authoritative version of the paper.     

Malarial parasites decrease reproductive success: an experimental study in a passerine bird

Malarial parasites are supposed to have strong negative fitness consequences for their hosts, but relatively little evidence supports this claim due to the difficulty of experimentally testing this. We experimentally reduced levels of infection with the blood parasite Haemoproteus prognei in its host the house martin Delichon urbica, by randomly treating adults with primaquine or a control treatment. Treated birds had significantly fewer parasites than controls. The primaquine treatment increased clutch size by 18%; hatching was 39% higher and fledging 42% higher. There were no effects of treatment on quality of offspring, measured in terms of tarsus length, body mass, haematocrit or T-cell-mediated immune response. These findings demonstrate that malarial parasites can have dramatic effects on clutch size and other demographic variables, potentially influencing the evolution of clutch size, but also the population dynamics of heavily infected populations of birds.     

The relationship of the female reproductive success of Eucalyptus globulus to the endogenous properties of the flower

Low capsule and seed set is a major factor limiting seed production in Eucalyptus globulus seed orchards. Controlled pollination studies showed that the reproductive success (number of seeds produced per flower pollinated) was primarily determined by the female. We aimed to identify the factors contributing to the differences in reproductive success between female genotypes in terms of the physical and anatomical properties of the flower. We studied pairs of genotypes of high and low reproductive success from each of three races (Furneaux Group, Strzelecki Ranges and Western Otways) growing in a seed orchard. Controlled pollinations were performed on six females and along with flower physical measurements, pollen tube growth and seed set were assessed. Overall tree reproductive success was positively correlated with flower size, ovule numbers, style size, cross-sectional area of conductive tissue within the style (all of which were inter-correlated) and the proportion of pollen tubes reaching the bottom of the style. Significant positive correlations of reproductive success and flower physical properties between different ramets of the same genotypes across seasons suggests a genetic basis to the variation observed. The majority of pollen tube attrition occurred within the first millimetre of the cut style and appeared to be associated with differences in style physiology. When examined as pairs within races the difference in reproductive success for the Western Otways pair was simply explained by differences in flower size and the number of ovules per flower. Physical features did not differ significantly for the Strzelecki Ranges pair, but the proportion of pollen tubes reaching the bottom of the style was lower in the less reproductively successful genotype, suggesting an endogenous physiological constraint to pollen tube growth. The difference in reproductive success between the females from the Furneaux Group was associated with a combination of these factors.     

气候条件对海滨锦葵（Kosteletzkya virginica）延迟自花传粉的影响

延迟自交被认为是一种生殖适应性,因为它保证了传粉者稀少情况下的种子生产,但当传粉者丰富时,又允许异交占优势。海滨锦葵花在传粉者不足或缺乏时能通过主动的柱头裂片弯曲运动成功实现延迟自花传粉。2002~2005年对江苏盐城滩涂海滨锦葵栽培群体花中发生延迟自花传粉花所占的百分比进行了观测,并于2005年对花内不同停止类型的柱头裂片比进行了调查,结果表明,2002 ~ 2005年间发生延迟自花传粉花所占百分比分别为13.50%±1.62%、14.39%±1.50%、1405%±1.82%和13.47%±1.51%,不同年份间并无显著差异 (F _(3, 189) = 6.128, P = 0.085 )。发生延迟自花传粉花所占百分比与气候条件有密切关系,不利天气(多云/雨) (22.11%±0.94%) 明显高于有利天气(晴天) (5.43%±0.43%) (F_(1, 189) = 8009.780, P < 0.001)。花内通过花部运动实现自花传粉而停止运动的柱头裂片比在有利天气(晴天)下(18.64%±1.61%)明显低于不利天气(多云/雨天) (70.58%±2.06%) (U = 0.000, W = 465.000, P <0.001)。海滨锦葵这种直接响应于影响传粉者环境之气候条件的延迟自花传粉策略为从个体或花水平上验证繁殖保障假说提供了可能。     

Density and reproductive success in wild populations of Diplotaxis erucoides (Brassicaceae)

Summary One possible consequence of low population density, particularly in self-incompatible plants, is reproductive failure. I surveyed seed set per flower in two populations of the self-incompatible annual Diplotaxis erucoides (Brassicaceae) in Jerusalem, Israel. Widely spaced plants had lower fruit set and fewer seeds per filled silique than did plants growing close to conspecific neighbors. Such density-dependent reproductive success could help explain the maintanence of spatial patchiness in plant populations, and could also have implications for population dynamics of rare species.     

The reproductive assurance benefit of selfing: importance of flower size and population size

Autonomous selfing can provide reproductive assurance (RA) for flowering plants that are unattractive to pollinators or in environments that are pollen limited. Pollen limitation may result from the breakdown of once-continuous habitat into smaller, more isolated patches (habitat fragmentation) if fragmentation negatively impacts pollinator populations. Here we quantify the levels of pollen limitation and RA among large and small populations of Collinsia parviflora, a wildflower with inter-population variation in flower size. We found that none of the populations were pollen limited, as pollen-supplemented and intact flowers did not differ in seed production. There was a significant effect of flower size on RA; intact flowers (can self) produced significantly more seeds than emasculated flowers (require pollen delivery) in small-flowered plants but not large-flowered plants. Population size nested within flower size did not significantly affect RA, but there was a large difference between our two replicate populations for large-flowered, small populations and small-flowered, large populations that appears related to a more variable pollination environment under these conditions. In fact, levels of RA were strongly negatively correlated with rates of pollinator visitation, whereby infrequent visitation by pollinators yielded high levels of RA via autonomous selfing, but there was no benefit of autonomous selfing when visitation rates were high. These results suggest that autonomous selfing may be adaptive in fragmented habitats or other ecological circumstances that affect pollinator visitation rates.     

<Emphasis Type="Italic">Kosteletzkya virginica</Emphasis> displays mixed mating in response to the pollinator environment despite strong inbreeding depression

Mixed mating systems often evolve despite strong inbreeding depression, but there have been few experimental tests of this observation. Kosteletzkya virginica, a perennial dicot halophytic species of the Family Malvaceae, is native to brackish portions of coastal tidal marsh in the United States of America and was introduced into China in 1993. Pollination of K. virginica occurs through insect vectors and by delayed self-pollination via stylar movement. In the same two naturalized populations of K. virginica during 2005–2007, we measured (i) inbreeding depression across a range of life-cycle stages, (ii) pollination failure rate, and (iii) selfing rate estimated by AFLP markers. Results indicate that inbreeding depression values for the two naturalized populations during 2005–2007 ranged from 0.620 ± 0.036 to 0.656 ± 0.032, and mean inbreeding depression was 0.640 ± 0.006. Pollinator failure rates at the two naturalized K. virginica populations during 2005–2007 ranged from 0.091 ± 0.039 to 0.174 ± 0.061, and selfing rate ranged from 0.247 ± 0.018 to 0.468 ± 0.031. Population selfing rates are significantly and positively correlated with field estimates of pollinator failure (P = 0.008 < 0.01, R ² = 0.857). Our data provide an empirical demonstration of a mixed mating system response to the pollinator environment in the presence of strong inbreeding depression.     

Sequential variation in the components of reproductive success in the distylousJasminum fruticans (Oleaceae)

A 2-year study of three natural populations of the distylousJasminum fruticans showed that mean fruit and seed production were significantly greater in shortstyled plants (thrums) than in long-styled plants (pins). In this study, we investigated the role of four sequential factors which may differentially influence fruit and seed set in the two floral morphs: (1) differences in flowering phenology, (2) a limitation of pollen transfer towards pins, (3) a differential capacity of the two morphs to act through famale and male function and (4) differential fruit abortion in the two morphs. Fruit set was significantly influenced by differences in flowering phenology although there were no differences in flowering time between the two morphs. supplementary pollinations in a natural population significantly increased fruit set and reduced the difference in fruit set between the two morphs in relation to controls, indicating a limitation on pollen transfer which was most severe towards pin stigmas. In reciprocal crosses, seed set was significantly dependent on the paternal and maternal identity of the pin parent. There was no significant variation among thrums for their performance as male or female parent. Furthermore, individual pin plants with relatively high percentage seed set as female parents gave poor seed set as male parents and vice-versa. Whereas fruit removal had no effect on seed number in thrum plants, a greater proportion of viable seeds were produced on pin plants which were left to naturally mature their fruits than on pins which had fruits artificially removed, suggesting the occurrence of selective fruit abortion in pins but not in thrums. The initially greater maternal fitness of thrums due to their greater success as pollen recipients may thus be opposed by increased viable seed set in the pins due to factors acting after the pollination stage. The relative reproductive success of floral morphs in the distylousJ. fruticans is thus differentially influenced by ecological factors occurring at different stages of the reproductive process.     

Inter-locality variation in reproductive success of the citril finch Serinus citrinella

Habitat quality is generally thought to affect breeding success. We tested this effect comparing differences in clutch size and reproductive success between citril finch Serinus citrinella sub-populations closely located (<5 km) but differing in habitat quality, within the Port del Comte mountain, in the Catalonian Pre-Pyrenees. We found that birds in the low quality area (Bofia) showed significantly lower hatching, breeding and nesting success than finches in the high quality area (Vansa). These differences in reproductive success fit well with recently found differences in citril finch body mass, fat score, diet, survival rate and speed of moult between these two localities.     

A trematode infection with no effect on reproductive success of a sand-bubbler crab

The infection effects of the parasitic digenean trematode on the body weight and reproductive success of the sand-bubbler crab were examined. Gynaecotyla squatarolae (Trematoda: Microphallidae) infects the body cavity of Scopimera globosa (Decapoda: Scopimeridae) and uses the crab as its second intermediate host. The parasites infected all reproductive crabs examined to varying degrees. Larger crabs of both sexes had more parasites than smaller ones, probably because body size reflects age, and older crabs had a longer period of exposure to infection. Males had more parasites than females, probably because of sexual difference in acting time on the surface. Ovigerous females stay in closed burrows and do not act on the surface during incubation, and so have less chance of infection than males. The quantity of infecting parasites did not explain variations in either body weight or reproductive success of individual crabs in a field experiment. The life history of this parasite, relative body size of the crabs, and cost and the possible benefit of manipulation for the parasite may explain these results.     

A 15-year study of the association between dominance rank and reproductive success of male rhesus macaques

The reproductive success (RS) of 32 males in a captive group of rhesus macaques (Macaca mulatta) between 1978 and 1992 was determined using paternity exclusion analysis. Dominance rank of each male over age 4 was assessed at the end of each breeding season based on agonistic dyadic interactions. The dominance rank and RS of these males were strongly correlated whether or not subadult males were included. The high reproductive success of males that eventually reached alpha rank is primarily responsible for this outcome. These results support the theory that social dominance has evolved in genusMacaca by sexual selection but some changes in male dominance rank and RS during the 15-year period suggest that priority of access is not the sole focus for such selection.     

Age-related and individual differences of reproductive success in male and female barbary macaques (Macaca sylvanus)

Age-related and individual differences in longterm reproductive success were analyzed in two social groups of free-ranging Barbary macaques. Maternity data were obtained from continuous birth records and paternity was determined with oligonucleotide-fingerprinting. The fathers of 246 of 286 investigated individuals could be identified. They were born during a 14-year period and represented 73 and 34% of all known offspring from the females of the study groups B/F and C, respectively. Only these infants were considered when comparing male reproductive success with that of females. The necessary adjustment of the female data resulted in small deviations from the true values in one group, but substantially increased individual differences in female fertility in the second group. Subadult males, 4.5 – 6.5 yrs old, had a much lower reproductive success than adult males (7.5 – 25 yrs old) and same-aged females. Reproductive success of adult males was not significantly affected by age, while females invariably ceased reproduction during the first half of the third decade of life. Males were more likely than females to leave no offspring, unless they survived 9 – 10 yrs of age. The number of years with breeding opportunities was important for male reproductive success but less significant than that for females. Reproductive success of several males during the 14-year study period was similar to or even exceeded that possible for a female in her whole lifetime. Variance of male reproductive success significantly exceeded that of females in both study groups.     

Male dominance rank and reproductive success in primate groups

The relationship between male dominance rank and reproductive success has been a topic of interest since the beginning of primatology. From a theoretical point of view the existence or absence of this relationship has great implications with respect to the meaning of dominance rank and more general of the social relationships between individuals within social groups. Until fairly recently mating behaviour has been used as an indicator of reproductive success, but these two variables need not be correlated. The relations between mating success, reproductive success, and dominance rank indicate whether selective mating is involved (different mating partners at different phases of fertility, for example through male contest or female choice). With the development of genetic techniques to determine reproductive success directly, it has now become possible to investigate these relations. In our study on wild long-tailed macaques (Macaca fascicularis) we find a relatively strong correlation between rank and reproductive success which is attributable to selective mating by the alpha male during fertile periods of the females. In most previous studies no such clear results have been obtained, and we discuss the differences in outcome in relation to the study conditions, group sizes, and possible differences between species in terms of reproductive strategies.     

Experimentally induced clutch size enlargements affect reproductive success in the Pied Flycatcher

We performed a food provisioning experiment in a population of Pied Flycatchers Ficedula hypoleuca breeding at high altitude in central Spain to test if food availability before and during laying determines clutch size. Food was provided to one of two pairs with the same date of initiation of nest-building (15 dyads of subsequently reproducing pairs were thus created). Food provisioning began on the day of initiation of nest-building and ended on the day after the last egg was laid. Although laying date was unaffected by the experiment, clutch size in the experimental treatment was significantly larger. This result could indicate that food availability at laying (1) proximately constrained clutch size or (2) that females evaluated future conditions for incubating eggs and feeding nestlings based on food availability at laying. Reproductive success (proportion of eggs that resulted in fledged young) was significantly reduced in the experimental treatment. This effect suggest that supplemented females were tricked by the experiment into laying more eggs than the number of eggs they were able to incubate with success and the number of nestlings they were able to feed, a source of error in clutch size adjustment which could be common in non-experimental situations.     

Seasonal changes in components of male and female reproductive success in Raphanus sativus L. (Brassicaceae)

Summary To document seasonal changes in the reproductive behavior of the perfect-flowered, self-incompatible mustard, Raphanus sativus L., we monitored individual survival, flower and fruit production among 58 individuals in a California population over six census dates (cohorts). Population size declined dramatically and mean individual levels of fruit set changed significantly between cohorts. The frequency distribution of flower and fruit production became increasingly skewed over the first four cohorts. The phenotypic maleness of individuals, a standardized measure of phenotypic gender, oscillated during the reproductive season, peaking in the third and fourth cohorts. We calculated a simple estimate of expected male reproductive success of each plant (the number of fruits sired on conspecifics); this estimate was a function of an individual's flower production and the fruit production of its potential mates in our sampled population. Mean expected male success did not differ significantly among cohorts; expected male success per flower did, however, change significantly among cohorts. Among individuals within each cohort, maternal fruit production and expected male success were both positively correlated with flower production throughout the season. Spearman rank correlation coefficients indicate that the strength of these associations, however, changed during the season. Linear regressions of transformed variables indicated that the shape of several fitness functions also changed over time. In addition, the amount of variation in maternal or expected paternal success explained by flower production declined over the first four cohorts. If typical of wild populations, these temporal changes in these functions suggest that measurements of the intensity of phenotypic selection on flower production will depend on when and how fitness is measured in natural populations.     

Plant size,breeding system,and limits to reproductive success in two sister species of Ferocactus (Cactaceae)

Plant reproductive output can be limited by a variety of factors, bothintrinsic and extrinsic. I investigated the reproductive biologies of twospecies of unbranched short-columnar cacti, Ferocactuscylindraceus and F. wislizeni. I recordedfemalereproductive output (flowers produced, fruit set, seeds per fruit and seedmass), plant size and growth, and used hand-pollination experiments todeterminebreeding systems and pollen limitation. In both species, the ability to selfvaried among individuals, but self-pollination resulted in very few seeds,suggesting strong inbreeding depression. Neither species was pollen-limited.Numbers of flowers produced increases with plant size for both species, andseeds per fruit may also be related to plant size, although the relationship isunclear. Seed mass is not correlated with plant size. Flower production wassimilar in both species, but F. cylindraceus producedfewerseeds per fruit than F. wislizeni, and its seeds weighedless. Fruit set by F. cylindraceus was heavily impacted bya florivorous lepidopteran. Fruit set was very high (94 to 96%) inF. wislizeni, suggesting that architectural constraints(e.g., meristem limitation) are more limiting than resource levels or the levelof pollinator services. In F. cylindraceus, numbers ofseeds per fruit was positively correlated with seed mass, whereas inF. wislizeni, the relationship was negative (tradeoff).Thegrowth rates of F. wislizeni are affected by rainfall theprevious season, and growth rates increase as the plant ages.Ferocactus cylindraceus and F.wislizeni are thought to be sister species, meaning that observeddifferences between them are more likely to be the result of recentevolutionaryprocesses in their lineages rather than differing phylogenetic histories.     

Distylic Hottonia palustris shows high reproductive success in small populations despite low genetic variability

Hottonia palustris L. (Primulaceae) is characterized by a heteromorphic incompatibility system. The strategy of distylic ramets is believed to promote outcrossing, to maintain overall genetic diversity and to prevent inbreeding depression. In spite of this distyly, an extremely low amount of allozymic diversity was observed in 545 individual ramets from 14 populations in Flanders (Belgium). A possible explanation for such low genetic variation is discussed in relation to the vegetative propagating abilities and the ecological niche width of the species. In contrast to the uniformity in allozymes as well as to the feature of single morph populations, there was a high variability in reproductive success between populations such as the number of seeds per ramet (425–2633), the number of flowers per ramet (9–36) and the mean weight of seeds (0.03–0.17 mg). Small populations and even those consisting of only one style morph may show a high reproductive success. As a whole, H. palustris showed a negative relationship of reproductive success with the surface area of its populations.