Neighborhood aggregation effect and its effective scale on reproductive success in Shorea laxa (Dipterocarpaceae)

This study investigated whether reproductive success is affected by the intensity of neighborhood aggregation of adults in the tropical tree Shorea laxa. We focused on three processes in the early reproductive stages: seed maturation; seed survival (categorizing sound seed, predation by insects and predation by vertebrates) in pre-seed dispersal; and seedling survival in the post-seed dispersal stage. We used a model selection procedure to examine the aggregation effect on reproductive success. The intensity of neighborhood aggregation was represented by the neighborhood aggregation index, which contains the adult number within a specific radius and the distances to neighboring adults (weight of proximity). Then, we evaluated the models exhaustively with the aggregation index having different scales (radius and weight of proximity) to assess the scale on which aggregation had significant effects. In particular, the best effective neighborhood scale, which is defined as the scale of the index in the model with minimum Akaike information criterion, was examined to compare those scales among processes. We found that the probability of seed maturation, seed survival and seedling survival decreased with the aggregation index at specific scales. This suggests that aggregation influenced reproductive success negatively in both the pre- and post-seed dispersal stages. However, the selected radii differed among processes: >200 and 130 m in pre- and post-seed dispersal stages, respectively. The selected weight of proximity also seemed to have a weak effect on all processes and was not different among processes.     

Genetic structure and diversity of Shorea obtusa (Dipterocarpaceae) in Thailand

Shorea obtusa is a keystone species of the dry deciduous dipterocarp forest in Thailand. In this study, the genetic structure and diversity of this species were evaluated by means of five microsatellite markers. A total of 146 trees were collected from five populations encompassing major forest regions of Thailand. High levels of genetic diversity were found among the five populations with the average He of 0.664. Genetic differentiations between populations, although significant, were low with approximately 3% of genetic variation partitioned among populations. This may indicate that the populations sampled were recently part of a continuous population. A tree constructed using the unweighted pair group method with arithmetic average, based on Nei's genetic distance, divided the populations into three groups. This separation was consistent with the altitudinal zonation of the populations, thus indicating that altitude might play a significant role in the genetic structure of S. obtusa. Areas of high genetic diversity were identified which could be considered priorities for conservation.     

Genetic structure and diversity of Shorea obtusa (Dipterocarpaceae) in Thailand

Shorea obtusa is a keystone species of the dry deciduous dipterocarp forest in Thailand. In this study, the genetic structure and diversity of this species were evaluated by means of five microsatellite markers. A total of 146 trees were collected from five populations encompassing major forest regions of Thailand. High levels of genetic diversity were found among the five populations with the average He of 0.664. Genetic differentiations between populations, although significant, were low with approximatel...     

Morphological and molecular evidence of natural hybridization in Shorea (Dipterocarpaceae)

Shorea (Dipterocarpaceae) is a large genus in which many closely related species often grow together in Southeast Asian lowland tropical rain forests. Many Shorea species share common pollinators, and earlier studies suggested occurrence of interspecific hybridization and introgression. Here, we show morphological and molecular evidence of hybridization between Shorea species. In the census of all the trees of Shorea curtisii, Shorea leprosula, and Shorea parvifolia (>30 cm dbh) within the 164-ha area of Bukit Timah Nature Reserve in Singapore, we found 21 morphologically recognizable hybrid individuals. All of the putative hybrids could be distinguished obviously from the parental species on the basis of vegetative characters. Population genetic analysis of DNA sequences of two nuclear (GapC and PgiC) and chloroplast (trnL-trnF) regions demonstrated that each of the three species had several species-specific mutations. The nuclear sequences of the putative hybrids were heterozygote at all the species-specific sites between two parental species. Hybrid between S. curtisii and S. leprosula was found most, while S. curtisii × S. parvifolia and S. leprosula × S. parvifolia hybrids were also found. Almost no shared polymorphism between populations of the parental species suggests rarity of introgression. The study indicated that natural hybridization between sympatric Shorea species should not be uncommon, but all of the hybrid individuals were F₁, and the post-F₁ hybrids were considerably rare.     

光照和温度对望天树种子萌发的影响

在实验室内人工气候箱控制的条件下, 研究了我国重要珍稀濒危植物望天树 (Shorea wantianshuea,龙脑香科 (Dipterocarpaceae)) 种子萌发对持续光照、14小时光照 / 10小时黑暗周期性光照的反应; 同时研究了望天树种子的萌发对不同温度的反应和低温贮藏对种子活力的影响。结果表明, 不论是持续光照还是周期性光照都不能提高望天树种子的萌发率, 相反, 持续光照和周期性光照都不同程度降低了种子萌发率。光照能通过加速或延迟种子萌发的进程、或改变幼苗活力指数和萌发指数而影响种子萌发的质量; 持续光照延迟种子萌发的进程, 而周期性光照加快种子萌发的进程。30℃是种子的最适萌发温度, 虽然15℃和5℃的相对低温对幼苗活力指数影响不大, 但大大延迟了种子萌发进程, 并提高萌发率。望天树种子不能耐受5℃低温贮藏, 但具有在15℃下短期贮藏的潜力和一定程度的生理性休眠。     

光照和温度对望天树种子萌发的影响

在实验室内人工气候箱控制的条件下,研究了我国重要珍稀濒危植物望天树（Shorea wantianshuea,龙脑香科（Dipterocarpaceae））种子萌发对持续光照、14小时光照／10小时黑暗周期性光照的反应;同时研究了望天树种子的萌发对不同温度的反应和低温贮藏对种子活力的影响。结果表明,不论是持续光照还是周期性光照都不能提高望天树种子的萌发率,相反,持续光照和周期性光照都不同程度降低了种子萌发率。光照能通过加速或延迟种子萌发的进程、或改变幼苗活力指数和萌发指数而影响种子萌发的质量;持续光照延迟种子萌发的进程,而周期性光照加快种子萌发的进程。30℃是种子的最适萌发温度,虽然15℃和5℃的相对低温对幼苗活力指数影响不大,但大大延迟了种子萌发进程,并提高萌发率。望天树种子不能耐受5℃低温贮藏,但具有在15℃下短期贮藏的潜力和一定程度的生理性休眠。     

Genetic variation in nine Shorea species (Dipterocarpaceae) in Indonesia revealed by AFLPs

Shorea is the largest and most important genus of the Dipterocarpaceae. The genetic diversity and structure of nine Shorea species from two different locations, namely Nanjak Makmur in Sumatra and Sumalindo in Borneo, were evaluated using amplified fragment length polymorphism (AFLP) markers. A total of 274 trees were investigated at 85 polymorphic AFLP loci. Levels of genetic diversity of these species ranged from  = 0.100 for S. acuminata to  = 0.165 for S. blumutensis. The population of rare species S. blumutensis possessed the highest genetic diversity suggesting that geographically restricted species can have levels of genetic variation comparable to closely related widespread common congeners. Analyses of molecular variance revealed that the genetic variation was mainly found among species in both locations (57.7% in Sumatra; 56.3% in Borneo). The unweighted pairgroup method using arithmetic averages dendrogram of all samples revealed an almost complete separation of species. Thus, AFLP markers proved appropriate for phylogenetic studies of Shorea species. Specific markers have been detected showing high-frequency differences among species and between regions within species. Sequence information of these markers can be used to develop specific polymerase chain reaction markers for wood identification. The possibility of interspecific hybridization was discussed.     

Electrophoretic and morphological comparisons in ten rain forest species of Shorea (Dipterocarpaceae)

Differences identified by electrophoretic separation of enzymes and other proteins are providing increasing informative for the study of evolutionary affinities within a genus. Zymogran compared with a scheme of putative affinities derived from a standard taxonomic classi based on consciously weighted morphological characters, as well as with indices of similarity on an array of morphological criteria relating to twigs, stipules, leaves, inflorescences and structure for 10 species of Shorea from southeast Malaysia. Shorea ovalis is placed in a separate of the genus from the other nine species; S. leprosula, S. parviflia and S. curtisii are related other on R^p data and a high degree of similarity is shown between these three spec S. dasyphylla .     

Ectomycorrhizas and putative ectomycorrhizal fungi of Shorea leprosula Miq. (Dipterocarpaceae)

 The ectomycorrhizas of Shorea leprosula Miq. are described and their putative fungal associates discussed. Of the 24 ectomycorrhizal types reported from seedlings, wildlings and 20-year-old trees of Shorea leprosula, 20 were associated with the Basidiomycotina, two with the Ascomycotina and two with either members of the Ascomycotina or the Russulaceae. The dominant group of fungi associated with Shorea leprosula ectomycorrhizas were members of the Russulaceae. This was confirmed by collections of fungal fruiting bodies made under adult Shorea leprosula trees in various parts of Peninsular Malaysia over a period of 3 years. Of the 28 species of putative ectomycorrhizal fungi collected, 15 were members of the Russulaceae. Accepted: 26 March 1997     

Genetic diversity within and among populations of Shorea leprosula Miq. and Shorea parvifolia Dyer (Dipterocarpaceae) in Indonesia detected by AFLPs

The genetic diversity within and among populations of Shorea leprosula and Shorea parvifolia from Indonesia was investigated using amplified fragment length polymorphisms (AFLPs). The results indicated that S. leprosula is genetically more variable than S. parvifolia. At the population level, a higher level of genetic diversity was revealed for S. leprosula with a percentage of polymorphic loci (PPL_p) of 53.32% and an expected heterozygosity (H _ep) of 0.16 in comparison with S. parvifolia showing PPL_p of 51.79% and H _ep of 0.14. At the species level, S. leprosula showed PPL_s of 92.86% and H _es of 0.21, while S. parvifolia showed PPL_s of 85.71% and H _es of 0.21. Genetic differentiation (G _st) indicated that 25 and 31% of total genetic diversity in S. leprosula and S. parvifolia, respectively, were attributed to the differences among populations. An analysis of molecular variance (AMOVA) at two hierarchical levels exhibited that most genetic variation resided within populations with proportion of 70.2% for S. leprosula and 66.2% for S. parvifolia. The AMOVA at three hierarchical levels performed for S. leprosula and S. parvifolia together revealed that the genetic difference between the two species was remarkably higher with a proportion of 44.1% than the differences within and among populations (38.1 and 17.8%, respectively). The genetic differentiation between islands was significant for S. leprosula but not for S. parvifolia. The observed genetic diversity agreed with the life history traits of Shorea species. Highly differentiating individual AFLP markers were found for each species, which will serve as diagnostic markers for the identification of wood of different species, from different islands and regions.     

Multiple mating and its effect on the reproductive success of female Epiphyas postvittana (Lepidoptera: Tortricidae)

Abstract.

• 1 Multiple mating and its effect on reproductive performance of female Epiphyas postvittana (Walker) moths were studied under controlled conditions.
• 2 The age at which the moths mated for the first time ranged from the first to the tenth day after emergence, but 71% of first matings were during the first 3 days.
• 3 The majority (63%) of females had one or two spermatophores in the bursa copulatrix. Some (24%) were found with three to five spermatophores, whereas no successful mating occurred among 13% of individuals. The number of matings was partly dependent on the number of mates available to the female. Between the range of sex ratios of one male to one female and four males to one female maximal mating success occurred at the ratio of three males to one female.
• 4 Virgin females were capable of egg-laying, but mating stimulated and accelerated oviposition. Mated individuals laid twice as many eggs as unmated ones.
• 5 The level of copulatory activity did not influence the longevity of females irrespective of the number of males available to them.
• 6 Sex ratios with greater than one male to a female improved the reproductive success by marginally increasing fecundity and fertility.
• 7 It is concluded that multiple mating would enhance population growth, and is of particular benefit to populations with a preponderance of females, as is known to occur naturally in this species.

     

Effects of flowering tree density on the mating system and gene flow in Shorea leprosula (Dipterocarpaceae) in Peninsular Malaysia

Pristine tropical rainforests in Southeast Asia have rich species diversity and are important habitats for many plant species. However, the extent of these forests has declined in recent decades and they have become fragmented due to human activities. These developments may reduce the genetic diversity of species within them and, consequently, the species’ ability to adapt to environmental changes. Our objective in the study presented here was to clarify the effect of tree density on the genetic diversity and gene flow patterns of Shorea leprosula Miq. populations in Peninsular Malaysia. For this purpose, we related genetic diversity and pollen flow parameters of seedling populations in study plots to the density of mature trees in their vicinity. The results show that gene diversity and allelic richness were not significantly correlated to the mature tree density. However, the number of rare alleles among the seedlings and the selfing rates of the mother trees were negatively correlated with the density of the adult trees. Furthermore, in a population with high mature tree density pollination distances were frequently <200 m, but in populations with low adult tree density the distances were longer. These findings suggest that the density of flowering trees affects selfing rates, gene flow and, thus, the genetic diversity of S. leprosula populations. We also found an individual S. leprosula tree with a unique reproductive system, probably apomictic, mating system.     

Variable nursery pollinator importance and its effect on plant reproductive success

Nursery pollination, in which insects use as hosts the very plants they pollinate, ranges from obligate mutualism to parasitism. In the non-obligate interaction between Greya moths and the host Lithophragma sp., the relative density of nursery pollinators and copollinators, which do not use plant tissues for larval development, is a key determinant of the interaction’s outcome. Silene (Caryophyllaceae) nursery pollination by Hadena moths (Lepidoptera: Noctuidae), studied primarily in Europe, is considered antagonistic because copollinators comprise a substantial proportion of the pollinator community. However, there are few studies that ascertain the direction of the Silene–Hadena interaction by taking into account both pollinator service and seed predation. Here, we report a novel comprehensive evaluation of the direction of the interaction between North American Hadena ectypa on Silene stellata, by comparing the relative contributions of nursery and copollinators to S. stellata pollination and relate this to variation in fruit predation and reproductive success of S. stellata across multiple sites and years. Hadena ectypa pollinator importance (pollen deposited/visit/h) varied between years, resulting from variable visitation rate. Copollinator importance was higher than H. ectypa in 1 year and equivalent in another. In two of three sites, lowered H. ectypa activity was not correlated with a significant decrease in plant reproductive success, indicating a negative interaction. Although pollinator service by H. ectypa is substantial in this system, copollinators’ service is at least as great, and when the cost of fruit predation is factored in, the net effect of the interaction is parasitism of host plants.     

Experimental investigation of the effect of spatial aggregation on reproductive success in a rewardless orchid

Plant reproductive success within a patch may depend on plant aggregation through pollinator attraction. For rewardless plants that lack rewards for pollinators, reproductive success may rely strongly on the learning abilities of pollinators. These abilities depend on relative co-flowering rewarding and rewardless plant species spatial distributions. We investigated the effect of aggregation on the reproductive success of a rewardless orchid by setting up 16 arrays in a factorial design with two levels of intraspecific aggregation for both a rewardless orchid and a rewarding co-flowering species. Our results show that increasing aggregation of both species negatively influenced the reproductive success of the rewardless plants. To our knowledge, this is the first experimental study demonstrating negative effects of aggregation on reproductive success of a rewardless species due both to its own spatial aggregation and that of a co-flowering rewarding species. We argue that pollinator learning behaviour is the key driver behind this result.The authors declare that the experiments presented here comply with the current laws applicable in the country in which they were performed (France).     

Beetle pollination of Shorea parvifolia (section Mutica, Dipterocarpaceae) in a general flowering period in Sarawak, Malaysia

Pollination ecology of an emergent tree species, Shorea (section Mutica) parvifolia (Dipterocarpaceae), was studied using the canopy observation system in a lowland dipterocarp forest in Sarawak, Malaysia, during a general flowering period in 1996. Although the species has been reported to be pollinated by thrips in Peninsular Malaysia, our observations of flower visitors and pollination experiments indicated that beetles (Chrysomelidae and Curculionidae, Coleoptera) contributed to pollination of S. parvifolia in Sarawak. Beetles accounted for 74% of the flower visitors collected by net-sweeping, and 30% of the beetles carried pollen, while thrips accounted for 16% of the visitors, and 12% of the thrips carried pollen. The apical parts of the petals and pollen served as a reward for the beetles. Thrips stayed inside the flower almost continuously after arrival, and movements among flowers were rare. Fruit set was significantly increased by introduction of beetles to bagged flowers, but not by introduction of thrips. Hand-pollination experiments and comparison of fruit set in untreated, bagged, and open flowers suggested that S. parvifolia was mainly outbreeding.     

Phylogeny of PgiC gene in Shorea and its closely related genera (Dipterocarpaceae), the dominant trees in Southeast Asian tropical rain forests

Dipterocarpaceae, trees that dominate tropical rain forests in Southeast Asia consist of many economically and ecologically important species. We determined partial sequences of the PgiC gene from species of Shorea, Hopea, Neobalanocarpus, and Parashorea to elucidate phylogenetic relationships among the species of these genera, which have been regarded as interrelated. The sequences generated a gene tree with better resolution than previous cpDNA trees. The PgiC tree is essentially consistent with cpDNA trees, except for the placement of Neobalanocarpus. The PgiC tree shows that Neobalanocarpus is nested within White Meranti of Shorea, whereas this genus forms a clade with Hopea in cpDNA trees. This conflict suggests that Neobalanocarpus is derived via hybridization between White Meranti of Shorea and Hopea. Species belonging to each of three timber groups (Yellow Meranti, Balau, and Red Meranti) within Shorea are monophyletic. Together they form a monophyletic clade distinct from White Meranti. Botanical sections within Red Meranti appear not to be monophyletic. An extensive number of shared polymorphisms among species and consequential lack of monophyly of intraspecific haplotypes are found in Red Meranti. Potential causes of this phenomenon, including persistence of ancestral polymorphisms and gene flow via interspecific hybridization, are discussed.     

Size-related flowering and fecundity in the tropical canopy tree species, Shorea acuminata (Dipterocarpaceae) during two consecutive general flowerings

We monitored the reproductive status of all trees with diameters at breast height (dbh) >30 cm in a 40-ha plot at Pasoh, west Malaysia, and investigated the individual fecundity of 15 Shorea acuminata Dyer (Dipterocarpaceae) trees using seed-trapping methods during two consecutive general flowering periods in 2001 (GF2001) and 2002 (GF2002). The proportion of flowering trees was higher, and not dependent on size, in GF2002 (84.2%), than in GF2001 (54.5%), when flowering mainly occurred in trees with a dbh ≤70 cm. Fecundity parameters of individual trees per event varied widely (221,000–35,200,000 flowers, 0–139,000 mature seeds, and 1.04–177 kg total dry matter mass of fruit (TDM) per tree). Monotonic increases with increasing tree size were observed for flower production and TDM amongst trees up to 90 cm in dbh, but not for mature seed production or for any of these parameters amongst larger trees. The pattern of reproductive investment during the two consecutive reproductive events clearly differed between medium-sized and large trees; the former concentrated their reproductive investment in one of the reproductive events whereas the latter allocated their investment more evenly to both reproductive events. Our results suggest size-related differences in the resource allocation pattern for reproduction. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Habitat scale, female cannibalism, and male reproductive success in three-spined sticklebacks (Gasterosteus aculeatus)

We studied the effects of habitat scale (pool size) on the riskof egg cannibalism and the breeding behavior of three-spinedsticklebacks (Gasterosteus aculeatus). Laboratory experimentsshowed that in pools with similar population density, a largerfraction of males nested in pools of 4.8-m² surface area thanin 15-m² pools. Breeding males in the 4.8-m² pools also hadbigger territories, obtained more eggs, and were more aggressivetoward intruders than those in the 15-m² pools. The numbersof raids attempted on nests were similar in the two pool sizes.However, raiding-shoal sizes were larger, and hence individualsin these larger shoals were more succesful at overwhelming maleterritorial defenses in the 15-m² pools than in the 4.8-m² pools.At the field site, a salt marsh containing hundreds of tidepools of different sizes, sticklebacks settled at similar densitiesin small (<30 m² surface area) and large (>355 m²) pools.This resulted in significantly more fish being present in largepools than in small pools, a concomitant increase in the amountof nest raiding, and a decrease in individual male reproductivesuccess in large compared to small pools. A photogrammetry analysisof the salt-marsh pools suggests that the majority of fish breedingat the site will be subjected to a high risk of cannibalismbecause most fish nest in large pools. We conclude that spatialscale has a major influence on this species' breeding behaviorand reproductive success.