Reproductive biology of the critically endangered tropical tree Talbotiella gentii

Talbotiella gentii is a critically endangered caesalpiniaceous legume endemic to Ghana, restricted in distribution to the margins of the forest zone where there has been extensive fire damage in recent decades. It occurs as isolated, near-monospecific populations, some of which show little seedling regeneration. We studied its reproduction to determine limitations that might inform efforts to prevent its extinction. We report on flowering phenology, pollen dispersal and germination, fruit and seed set, seed size and germination, and seedling survival, using controlled and open pollination. Talbotiella gentii flowers profusely in most years. Although the flowers are coloured and scented, no animal pollinators were observed but pollen can be dispersed by wind. In open pollination, the number of pollen grains on stigmas and their germination was sufficient to fertilise the three ovules, despite competition from heavy stigmatic infestation by fungal spores and hyphae. Fruit set and seed set were low due to high flower losses and fruit abortion during development but ripe seeds showed high germination. Controlled pollination experiments (self, supplemented self, and intra- and inter-population crosses) showed that, while the species is self-compatible, selfing was the least successful treatment in all of the above steps of reproduction, whereas cross-pollination enhanced most steps, the more so for inter-population crosses. Seed size was notably greater in inter-population crosses and was positively correlated with genetic distance of the cross. The larger seeds associated with cross-pollination showed higher germination and seedling survival in the nursery. We conclude that limitations to natural reproduction in T. gentii are principally due to processes between pollen germination and fruit and seed set, including pollen quality (low genetic diversity and inbreeding), fertilisation rates, flower and fruit abortion, and resource limitation. Low seed size in open and self pollination may have implications for seedling establishment. Species fitness might be improved by introducing other genotypes to existing populations, but in situ protection of the populations is essential in the medium term.     

印度东北地区一种极频危和特有树种(Ilex khasiana Pork.)再生生态学及种群现状

在5个典型自然种群Mylliem(种群1)、Upper Shillong(种群2)、Shillong Peak(种群3)、Laitkor(种群4)和Nongpiyur(种群5)中,详细研究了冬青树(Ilex khasiana)种群结构和再生生态学,旨在探究种群结构和再生能力的影响因素.在全光照(100%),中等光照(50%)和低光照(30%)三种光强度条件下,实验观察表明:在中等和低光照条件下的种苗成活率和生长状态好于在高光照条件下的种苗成活率和生长状态.成年树种群(≥5cm dbh)的密度直径分布揭示了一种再生种群的典型特征.对植被的破坏和人类其他干扰导致森林树冠疏开使光照增强,造成自然种群(L khasiana)幼苗的高死亡率.本研究结果对制定适当的物种保护措施有重要价值.     

Low within-population genetic diversity and high genetic differentiation among populations of the endangered plant <Emphasis Type="Italic">Tetracentron sinense</Emphasis> Oliver revealed by inter-simple sequence repeat analysis

Key message

Tetracentron sinense Oliver, an endangered species from China, displays a low within-population genetic diversity and high genetic differentiation among populations, and the existing populations could be divided into three conservation and management units.

Context

The endangered tree Tetracentron sinense Oliver has great value; however, little is known regarding the within-population genetic diversity and differentiation among T. sinense populations.

Aims

We examined the genetic diversity and differentiation of T. sinense wild populations, and we tested the effect of small-size population on the level of genetic diversity within these populations.

Methods

Using inter-simple sequence repeat (ISSR), we assessed the genetic variation and structure among 174 individuals from 26 natural populations of T. sinense sampled across its distribution range in China.

Results

The ISSR primers yielded 180 amplified loci (123 were polymorphic). At the species level, the percentage of polymorphic loci (PPL), Nei’s gene diversity (H), and Shannon’s information index (I) were 68.3%, 0.196 and 0.300, respectively. The average population level PPL was 20.0%, and the Na, Ne, H, and I were 1.20, 1.13, 0.076, and 0.112, respectively. AMOVA revealed high genetic differentiation among populations (52.0% of total variance, P?=?0.001), consistent with the gene differentiation coefficient (Gst?=?0.607) and gene flow (Nm?=?0.326). The 174 individuals of the 26 T. sinense populations clustered into three groups, and T. sinense geographic and genetic distance were significantly correlated.

Conclusions

T. sinense exhibited intermediate within-species genetic diversity, indicating preserved evolutionary potential. The low within-population genetic diversity and high genetic differentiation among T. sinense populations may be one of important factors causing endangerment. Three conservation units were determined based on genetic difference and structure. Inter-population introduction of individuals within units via appropriate propagation and seedling management might be an effective strategy for increasing T. sinense within-population genetic diversity and population size.

     

Regeneration ecology and population status of a critically endangered and endemic tree species （Ilex khasiana Purk.） in north-eastern India

Detailed studies on population structure and regeneration ecology of Ilex khasiana were carried out at five representative natural populations i.e. Mylliem (Population - I), Upper Shillong (Population - II), Shillong Peak (Population - III), Laitkor (Population - IV) and Nongpiyur (Population - V) to probe into the responsible affecting factors for its population structure and regeneration ability in these populations. Experimental observation under three controlled light conditions (full sunlight (100%), intermediate sunlight (50%) and low sunlight (30%)) showed that the growth status and survival rates of seedlings under intermediate and low light were better than those under the high light condition. The density-diameter distribution in population of adult trees (≥5cm dbh) exhibited a typical character of a regenerating population. A higher seedling mortality rate in natural populations of I. khasiana was most probably due to increase in light intensity following vegetation destruction and other anthropogenic disturbances that cause opening of forest canopy. The findings of the present study would be of immense value in formulating appropriate conservation measures for the species.     

Genetic diversity and differentiation of fall webworm (Hyphantria cunea Drury) populations

The molecular variation and genetic relationships among five populations of the fall webworm (Hyphantria cunea Drury) in China were assessed using microsatellite technology. Ten microsatellite primers, producing polymorphic bands, were used across 300 samples. The percentage of polymorphic loci (PPB) was 98.36%; the percentage of polymorphic loci in five populations ranged from high to low in the following order: Cangzhou population, Yantai population, Qinhuangdao population, Dandong population, and Shijiaz...     

Genetic diversity and differentiation of fall webworm (Hyphantria cunea Drury) populations

The molecular variation and genetic relationships among five populations of the fall webworm (Hyphantria cunea Drury) in China were assessed using microsatellite technology. Ten microsatellite primers, producing polymorphic bands, were used across 300 samples. The percentage of polymorphic loci (PPB) was 98.36%; the percentage of polymorphic loci in five populations ranged from high to low in the following order: Cangzhou population, Yantai population, Qinhuangdao population, Dandong population, and Shijiazhuang population. The results showed that 34.38% of the total genetic variation of the fall webworm (GST) occurs among populations, while most variation (65.62%) exists within populations. Nei’s genetic distances ranged from 0.1386 to 0.3224. Using the unweighted pair group method with arithmetic mean (UPGMA), Nei’s genetic distances were analyzed by a clustering technique and the dendrogram shows that population differentiation is closely related to the time and geographic origin of the invasion. The major factors impacting genetic diversity of fall webworm populations are longitude, the plain area ratio, annual precipitation, latitude and time of invasion. The formation of genetic structure is correlated with characteristics of the life history and invasion ecology of the species.     

黑龙江省中国林蛙(Rana chensinensis)群体遗传多样性及区域分化的初步研究(英文)

本文运用随机扩增多态DNA (RAPD)技术对黑龙江省8个地区野外采集的中国林蛙(Rana c hensinensis)个体进行群体遗传多样性及区域分化的初步研究。实验筛选出的10个RAPD引物 共扩增出78条DNA多态片段。用NJ（Neighbor-Joining）方法分析遗传距离并构建系统树。 结果表明，中国林蛙(R. chensinensis)在8个不同采样地区已经出现明显的区域分化，且不 同地区的中国林蛙之间存在地理距离和遗传距离不相吻合。根据地理、地质学资料初步推论 ，黑龙江省中国林蛙(R. chensinensis)的中心发源区很可能位于松花江和黑龙江两江下游 的丘陵地区。并主要依靠松花江水系从三江平原进入松嫩平原，在方正地区形成向西扩散过 程中的次中心发源区。     

Population genetic diversity and regional differentiation of Chinese forest frogs (Rana chensinensis) in Heilongjiang Province

The Random Amplified Polymorphism DNA (RAPD) markers were used to study the intra-specific diversity and regional differentiation of the Chinese forest frogs (Rana chensinensis), which were sampled from the fields of 8 regions in, Heilongjiang Province. Totally 78 polymorphic DNA loci were amplified by 10 RAPD primers. By genetic distance analysis and phylogenetic tree reconstruction with the Neighbor-Joining (NJ) method the results showed that the populations of Chinese forest frogs distributed in 8 regions existed great differentiation (Average Fst=0.347, SD=0.235) while, there was the paradox between geographic distances and genetic distances. Based on geographic and geological data, a hypothesis was posed that it is very possible that the hilly lands in the downstream of the Songhua River and the Heilong River were the center of the origin of the Chinese forest frogs in Heilongjiang Province. And mainly through the Songhua River system, the Chinese forest frogs dispersed into the Songneng Plain from the Sanjiang Plain whereas the Fangzheng region became a sub-center for the western dispersion. Foundation item: This project is supported by the Natural Science Foundation of Heilongjiang Province (C9726). Biography: XIAO Xiang-hong (1960-), female, professor in College of Wildlife Resources, Northeast Forestry University, Harbin 150040, P.R. China. Responsible editor: Zhu Hong     

Spatial and microgeographical genetic differentiation of black alder (Alnus glutinosa Gaertn.) populations

Three Alnus glutinosa populations from central Slovakia were investigated by means of isozyme analysis. The average expected heterozygosity ranged from 0.151 to 0.173. Despite significant differences in allele frequencies among populations, genetic differentiation was low (F_ST=0.022). Intrapopulation fixation indices indicate no or very slight deviation from panmictic expectations towards the heterozygote deficiency. No indications were found that the investigated populations have experienced recent bottlenecks in population size. A spatial autocorrelation analysis based on Moran’s I indicates the existence of a spatial genetic structuring in the population Král’ová. Patch size was estimated to be 70–100 m, which is more than observed in other broadleaved tree species. This difference is explained by the linear shape of alder populations and a higher mobility of seeds.     

Analysis of genetic diversity and differentiation of artificial populations of yellowhorn(Xanthoceras sorbifolium) in China using ISSR markers

Yellowhorn(Xanthoceras sorbifolium Bunge)is a drought-tolerant tree in the family Sapindaceae that is native to northeastern China.Its remarkably oil-rich seeds are a reliable biodiesel source.An inter simple sequence repeat(ISSR) analysis showed genetic variation among four artificial populations in China:two in Inner Mongolia(IM),one in Liaoning(LN),and one in Shandong(SD).The average percentage of polymorphic loci was 81.25 % for these four populations.The Forest Farm in SD showed the highest number of effective alleles(Ne),Shannon index(I),and expected heterozygosity(He),i.e.,1.598,0.470,and 0.325,respectively,but the lowest number of alleles(Na) as 1.600.Based on an analysis of molecular variance,23 % of the total genetic variation was found among populations,and 77 % within populations.A principal coordinate analysis revealed two groups(Group 1:Lindonglinchang,Jianping Agriculture Research Station and Forest Farm;Group 2:Jinjilinchang).Understanding the genetic diversity among artificial yellowhorn populations in China,detected using ISSRs,will be useful for yellowhorn conservation and improvement.Additional artificial and natural populations need to be included in the future for a country-wide perspective.     

Seasonal patterns of photochemical capacity and spring phenology reveal genetic differentiation among native Scots pine (Pinus sylvestris L.) populations in Scotland

Environment-driven genetic differentiation among populations is a common feature among forest trees, and an understanding of how populations have adapted to their home site conditions is essential for management and conservation practices. In Scotland, 84 native Scots pine (Pinus sylvestris L.) woodlands are recognised by the Forestry Commission and they occupy highly diverse environments from the maritime west coast to continental sites in eastern Scotland. However, it is not known whether adaptations to local environments along sharp temperature and rainfall gradients have occurred in different populations and as a result, the seed transfer guidelines of the species are based only on data from isozymes and monoterpenes. In this study of an outdoor common-garden trial, we used chlorophyll fluorescence to examine whether seedlings from 32 open-pollinated families and eight populations from sites experiencing contrasting annual temperature regimes differed in their response to variation in natural outdoor temperatures between September 2009 and May 2010. In addition, growth initiation in spring was recorded. Photochemical capacity at photosystem II F_v/F_m showed a distinct seasonal trend and remained at relatively high levels (∼0.7) until November. Following a period of over 2 weeks with temperatures below or close to 0 °C, F_v/F_m started decreasing towards its minimum values recorded in early March when population means varied between 0.35 and 0.45. By early May and along with rising temperatures, photochemical capacity had recovered to the same level as observed in early November. Populations were found to respond differently to the cold period starting in December. The largest drop in photochemical capacity was observed in seedlings from a low-altitude population located in the maritime western Scotland, while in seedlings from higher-altitude locations in the cooler eastern Scotland, the response was smaller. In March, the recovery of photochemical capacity was slowest in seedlings from the mildest and coolest sites. Evidence of adaptive genetic differentiation was also found in spring phenology. Initiation of shoot elongation and needle flush were earlier in families from higher altitudes (cooler areas), but population differences were not significant at the α = 0.05 level. These results suggest that adaptation to the spatially heterogeneous environment in Scotland has taken place in Scots pine and that in order to minimise the risk of planting maladapted seed stock, the patterns of environmental and adaptive genetic variation should be taken into account in the management of genetic resources in this species.     

Population genetic structure and diversity of high value vulnerable medicinal plant <Emphasis Type="Italic">Acorus calamus</Emphasis> in India using RAPD and chloroplast microsatellite markers

Acorus calamus is a highly valued medicinal plant with global distribution used in several drugs of health care systems. We evaluated the genetic diversity and population structure of 50 populations of A. calamus from different geographical regions in India through RAPD and chloroplast microsatellite markers. From the total screened 82 RAPD primers and 18 cpSSR primers, 10 RAPD and nine cpSSRs were found polymorphic. The selected 10 RAPD primers produced a total of 96 reproducible bands, out of which 65 wer...     

思茅松天然群体的遗传多样性及遗传分化

采用凝胶电泳技术,检测了思茅松(Pinuskesiyavar.Langbinaensis)种子胚乳的9种同工酶。通过对9种酶系统编码的16个酶位点的遗传分析,揭示了思茅松三个天然群体的遗传多样性和遗传分化情况。思茅松天然群体的遗传多样性较高,群体的多态位点比例为0.667;平均每个位点的等位基因数为2.13;期望杂合度和观察杂合度分别为0.288和0.197。群体间的遗传分化程度较低,分化系数仅为0.052,群体间的遗传距离为0.015。表5参15。     

Molecular characterization and genetic relationships among most common identified morphotypes of critically endangered rare Moroccan species Argania spinosa (Sapotaceae) using RAPD and SSR markers

? The objective of this work is the molecular characterization of most common identified morphotypes of critically endangered rare Moroccan species Argania spinosa.

? Eighteen RAPD markers and twenty SSR markers have been assayed in 38 argan tree accessions from the three most commonly identified morphotypes: oval, spherical and spindle fruit types.

? A total of 140 polymorphic RAPD bands were detected out of 146 bands. The number of presumed alleles revealed by the SSR analysis ranged from 1 to 5 alleles per locus with a total number of 32 alleles identified. Results demonstrated an extensive genetic variability within the tested argan accessions. RAPDs presented a high level of polymorphism and greater information content than SSRs.

? Our results could indicate that Vitellaria paradoxa is genetically closer to argan than Manilkara huberi. In addition, the correlation between the clustering based on RAPD and SSR markers were in general low. The observed clustering could be better explained according to geographic proximity than morphotype. For this reason the traditional morphological characterization of the argan accessions in morphotypes (according to fruit phenotype) seem not to be in correlation to the real genetic background (genotype) of this specie. The implications of these results in the creation of effective germplasm core collection in argan have been also discussed.

     

AFLP analysis of genetic variation of Hyphantria cunea (Drury) populations in Beijing and a nearby site

Hyphantria cunea (Drury) is a severe invasive pest in Beijing. It is important to understand the reason for its successful invasion and outbreak. Accordingly, this study was tailored to assess molecular variation and genetic relationships among three H. cunea populations in Beijing and one population from Sanhe in Hebei Province as control (totally 100 individuals). A silver-labeled amplified fragment length polymorphisms (AFLP) DNA profiling method was used to detect the genetic diversity and relationship among the populations. Five EcoRI and MseI primer combinations produced a total of 171 (91.2% polymorphic) informative fragments. The average Nei’s genetic diversity in four H. cunea populations analyzed by Popgene3.2 software was 0.2287, and the level of genetic diversity ranked in the order BDR (reared population in Daxing, Beijing) > BDN (natural population in Daxing, Beijing) > HSN (natural population in Sanhe, Hebei Province) > BFN (natural population in Fengtai, Beijing). The value of genetic differentiation among populations was 0.3321, and the gene flow was 1.0057. The genetic distance between these populations ranged from 0.0735 to 0.3309, 0.0531 on average. The result of UPGMA (unweighed pair group method with arithmetic averages) clustering showed that populations BFN and HSN were closely related, while BFN and BDN had the largest genetic distance. These results indicate that H. cunea populations in Beijing might originate from several areas.     

Genetic diversity and differentiation among populations of the pedunculate oak (Quercus robur) at the eastern margin of its range based on a new set of 95 SNP loci

The aim of this study is to determine the genetic variability and differentiation among populations of pedunculate oak(Quercus robur) at the eastern margin of the species distribution range.We applied new set of 95 geographically informative nuclear SNP(single nucleotide polymorphism) loci developed using Double Digest Restriction Site Associated DNA(ddRAD),a new generation DNA sequencing technology.The study area is located in the basins of the Volga River and its two main tributaries,Kama and Belaya.Despite the strong reduction and fragmentation of pedunculate oak forests over the last several centuries and comparatively small sizes of present stands,a relatively similar genetic diversity of seven populations was observed(on average,allelic diversity v_a=1.472-1.603,observed heterozygosity H_O=0.305-0.358,expected heterozygosity H_E=0.272-0.343).The genetic distances between populations vary between 0.102 and 0.170(on average,d_0=0.128).We have identified the absence of a spatial genetic structure and the existence of genetically peculiar populations in the territory studied.The genetic distances of Gregorius between populations vary between 0.102 and 0.170(on average,d_0=0.128).Genetic differentiation among populations was statistically significant with a mean of the fixation index F_(ST) of 0.075.Populations from the Privolzhye Upplands and from northern parts of the study area make the most contribution to overall inter-population differentiation(d_0=0.137).No significant differences exist among the samples at lowlands along the Volga river(d_0=0.110).It was concluded that the multiplicity and different ages of local populations and the complexity of migration routes of the pedunculate oak from Pleistocene refugia and secondary Holocene shelters can cause this phenomenon.     

High differentiation among populations of the woody legume Sesbania sesban in sub-Saharan Africa: Implications for conservation and cultivation during germplasm introduction into agroforestry systems

Cultivation of the woody legume Sesbania sesban in agroforestry systems has been widely promoted for soil fertility improvement in Africa. Despite the existence of natural populations in eastern Zambia, considerable seed originating from Kenya has been introduced to the area, while further introductions from Malawi are planned. Large-scale anthropogenic seed dispersal raises concerns regarding genetic management, which were addressed here by random amplified polymorphic DNA (RAPD) analysis. Eleven populations of Sesbania from southern and East Africa were assessed, including S. sesban populations already or likely to be introduced into eastern Zambia and reference taxa. Seventeen primers revealed a very large number of polymorphisms (538) in surveyed material. Differentiation among S. sesban populations was unusually high for a woody perennial (70% of variation among populations), with all individuals stringently assigned to specific populations in cluster analysis, even for geographically proximate sites. High differentiation, combined with the unusually large number of polymorphisms determined, resulted in the identification of a number of population-diagnostic markers. High differentiation may reflect the restricted ecology of S. sesban, human disturbance and frequent natural fluctuations in niche availability. Hydrochory, posited as a mechanism for gene flow between populations located along the same drainage system, appears to be discounted. Geographic proximity was not always a good guide for genetic similarity among S. sesban populations. In particular, rather proximate populations from Zambia and Malawi appeared highly differentiated genetically, while Zambian populations were relatively similar to a geographically distant population from Namibia. Differentiation was consistent with the presence of two botanic varieties in the southern Africa region, vars. nubica and zambesiaca. Estimates of Nei's genetic diversity suggested that S. sesban populations from East Africa were most diverse. Overall, population diversity estimates were low, possibly due in part to frequent bottlenecks, short longevity and a short juvenile phase. The unusually large number of polymorphisms detected here provided an opportunity to test for data redundancy and primer selection methodologies during RAPD analysis. Combined data from a subset of eight primers selected according to three different approaches provided a very good overall fit to the complete data set (r_M > 0.95). Different primer selection approaches influenced the reliability of clustering and diversity analysis, with a minimum of eight primers required for reliable ranking of diversity estimates. The implications of our data for conservation, cultivation and monitoring of S. sesban in the southern Africa region are discussed. Caution is advised during the introduction of germplasm into eastern Zambia from both distant (Kenya) and relatively proximate (Malawi) sources.     

马尾松毛虫种群动态趋势探讨——用临界分化日预测二、三代分化率

马尾松毛虫 ( Dendrolimus punctatus Walker)在我国长江沿岸各省 ,即相当 30°N地区 ,存在着二、三代分化现象。所谓二、三代分化 ,就是在同一地区 ,每年第二代松毛虫卵孵出的幼虫中 ,一部分可以生长发育至结茧、化蛹、羽化 ,即每年出现 3次成虫 ,以第三代幼虫越冬 ;而另一部分 ,幼虫生长至四、五龄后即进入冬蛰 ,就以第二代幼虫越冬。它们出现的比例 ,在同一地区 ,又随着年份和其它条件的不同而不同。至于二、三代分化对种群动态的影响 ,过去在实践中往往遇见 ,在高虫口区 ,二代虫也会突发成灾。这是由于当年三代虫的比例增加 ,二代老龄…     

Variation in seed and seedling traits among natural populations of <Emphasis Type="Italic">Trigonobalanus doichangensis</Emphasis> (A. Camus) Forman (Fagaceae), a rare and endangered plant in southwest China

The extent of genetic variation in seed and seedling traits of Trigonobalanus doichangensis, a rare and endangered tree in southwest China, was evaluated at the population level. Seeds were collected from four natural populations in the south and southwest Yunnan province, China. Significant differences (P < 0.05) between populations were observed in seed length, seed weight and seedling morphological characters. The analyses revealed that none of the seed and seedling traits had significant correlations with the geo-climatic variables of the populations. Among seed and seedling traits, significant correlations (P < 0.05) were discovered among seed length, seed weight and height of 30-day-old seedlings. Significant correlation (r = 1.00, P < 0.01) occurred also between the height and root collar diameter of 4-year-old seedlings. With the exception of seed width and seed germination percentage, 51–96% of total variation in other seed and seedling related traits was attributed to population effect, as determined by the broad sense heritability. In conclusion, these observations on variation in seed and seedling traits should be a reference point, when considering seed collection of this species for ex situ conservation and species restoration.