Orientation of the snail Biomphalaria straminea (Dunker, 1848) in response to light in a situation of selection

The behavioral response of Biomphalaria straminea to light was evaluated in terms of location of the snail in a Y-shaped aquarium in a situation of selection and of the rate (cm/hour) and direction of locomotion under homogeneous (vertical) or differential (horizontal) lighting upon only one arm of the aquarium. The light source consisted of daylight fluorescent lamps with a spectrum close to that of natural light, with illumination varying from 2.8 to 350 lux. Analysis of the data showed that all animals, whether in groups or isolated, were attracted to light, although the time needed to approach the light source was 50% shorter for the former than for the latter. The rate of locomotion of B. straminea was 35% higher than that observed in B. glabrata and 51% higher than that observed in B. tenagophila studied under similar conditions. The results are discussed in terms of social factors and geographical distribution of the three species.     

Seed rain into upland plant communities in Hong Kong, China

Hong Kong is an extreme example of tropical landscape degradation, with no substantial remnants of the original forest cover and a highly impoverished disperser fauna. Seed availability is a potential limiting factor in vegetation recovery in such landscapes. To assess the quantity and quality of the seed rain of woody taxa, seed traps were placed in the major upland vegetation types: fire-maintained grassland, shrubland, and secondary forest. Within the grassland site, traps were placed under isolated trees, isolated male and female shrubs of Eurya chinensis, and in the open. Seeds were collected every 2 weeks for 2 years. The seed rain was highest under female shrubs in grassland (6455 seeds m⁻² year⁻¹), where it was almost entirely confined to their fruiting period. Next highest were isolated trees (890 seeds), followed by male isolated shrubs (611 seeds), shrubland (558 seeds), forest (129 seeds) and open grassland (47 seeds). The number of seed taxa was highest in shrubland (59), followed by isolated trees (42), forest (42), female isolated shrubs (28), male isolated shrubs (15), and open grassland (9). The seed rain differed in species composition between the forest, shrubland, and grassland sites, while the differences within the grassland site were largely in terms of quantity. Birds (particularly bulbuls, Pycnonotus spp.) are known or inferred to be the major dispersal agents for 85% of the seed taxa trapped, 99% of the total number of seeds trapped, and 99.8% of the seeds trapped in the grassland site. Few taxa and of the total seeds were dispersed by wind and no seed taxa were definitely dispersed by fruit bats. The results suggest that even in the most degraded landscape the seed rain is adequate for the development of woody vegetation cover, but that human intervention will be needed for the restoration of plant diversity.     

Life-history characteristics and sexual strategy of Mytilopsis sallei (Bivalvia: Dreissenacea), introduced into Hong Kong

First recorded from Hong Kong in 1980, Mytilopsis sallei now dominates the intertidal pier community within the Government Dockyard, Victoria Harbour. Analysis of monthly samples of M. sallei has demonstrated aspects of the reproductive strategy and life-history characteristics correlated with seasonal changes in local water quality.
Mytilopsis sallei is dioecious, has a high fecundity, matures early (at 8–10 mm shell length), grows fast and the majority of the population is probably semelparous. These are characteristic traits of opportunistic r -strategists. Comparable characteristics are typical of other introduced bivalves. Maximum life span of M. sallei in the Dockyard is probably less than 20 months with, however, most of the population dying before that. Heavy recruitment, particularly during spring-summer, suffocates older individuals. The shells of dead animals similarly last for little more than one year, dissolution and crushing effecting this. A mat of byssal threads serves to bind the mass and anchor it to the substratum.
Mytilopsis sallei exhibits two periods of reproductive activity and settlement per year. These are possibly two elements of a single recruitment divided into minor (autumn-winter) and major (spring-summer) components by either high summer temperatures or low salinities. Summer and winter recruits of M. sallei , respectively, mature to produce the summer and winter juveniles of the following year. Over-stepping generations plus survival of a few individuals into their second year thus ensure continued success of M. sallei , and account for its spread and dominance in its introduced range. Such a bimodal pattern appears typical of many Hong Kong intertidal, estuarine and freshwater bivalves.     

Population genetics of Cordia alliodora (Boraginaceae), a neotropical tree. 2. Mating system

A multilocus mixed mating model was used to evaluate the mating system of a natural population of Cordia alliodora (Boraginaceae), a neotropical tree. The population was highly outcrossed (t_m = 0.966 ± 0.027), in agreement with results from controlled crosses. Departures from the mixed mating model were evident, suggesting some nonrandom, correlated mating. Pollen pool heterogeneity and variation in estimates of individual outcrossing rates indicated that the population may be genetically substructured. Individual outcrossing rates obtained for the samples taken from within different parts of the same tree indicated reduced levels of outcrossing due to limited sampling of the pollen pool. The incompatibility mechanism in C. alliodora, combined with variation in flowering and stand density, appears to lead to both temporal and spatial substructuring of the population.     

Population genetics of Cordia alliodora (Boraginaceae), a neotropical tree. 1. Genetic variation in natural populations

We provide an estimate of genetic differentiation within and among 11 populations of Cordia alliodora, an economically important timber tree Cordia alliodora is a widespread species that is distributed throughout Central and South America. Our survey of isozyme variation was conducted on material gathered for international provenance trials over approximately 1,000 km in Central America. Results from provenance trials indicate that there are significant differences between Atlantic and Pacific coast provenances for quantitative characters. Genetic data support some of these findings. Populations of C. alliodora show significant differences in allele frequency at various loci. Significant differences in multilocus allele frequencies occur at 13 of the 55 possible combinations. Eight of these 13 populations are situated on opposite coasts. This physical separation corresponds well with the results of provenance trials that indicate differentiation among the Atlantic and Pacific populations in quantitative morphological traits. We also found a significant negative correlation between levels of heterozygosity and the amount of rainfall, indicating that populations from the drier zone are genetically more heterogenous than populations from the wet zone. Our study indicates that in situ and ex situ conservation should accord high priority to the dry zone populations; furthermore, conservation of this widespread species would require preservation of multiple populations.     

Reverse genetics approach towards understanding pathogenesis of H5N1 Hong Kong influenza A virus infection.

In 1990, Palese and colleagues established a method (reverse genetics) that allowed one to generate influenza virus containing a gene segment derived from cloned cDNA. Although this method contributed tremendously to our understanding of influenza pathogenesis, the requirement of helper viruses limited its use in many experimental settings. Recently, we and others established systems for the generation of influenza viruses entirely from cloned cDNAs. These systems require only DNA cloning and transfection techniques, and can therefore be easily implemented by laboratories working in the fields of molecular biology and virology. Thus, for the first time, a system is now available that allows highly efficient generation of influenza virus without technical limitations. Using this technology, we generated the same strain of H5N1 influenza viruses that caused an outbreak in Hong Kong in 1997, killing six people.     

Population dynamics of the feral macaques in the Kowloon Hills of Hong Kong

Hong Kong's feral monkey population is controversial. Many people complain about the aggressiveness of the monkeys, while some conservationists urge the government to deal with the problem in a way that will not harm the monkeys. The population dynamics of the macaques in the Kowloon Hills were studied in 1992 and 1993. Vital statistics are provided from this study as a first step in resolving the problems of human provisioning and wildlife management. It is unlikely that these macaques are indigenous to the area. They are the descendents of macaques that were released in the early twentieth century to control the spread of a local poisonous plant, the strychnos, which contains alkaloids poisonous to livestock and humans but which is a favorite food of the macaques. The macaque population expanded dramatically during the 1980s. The census method employed in this study is direct head count and photo-identification. At the end of 1993, the estimated abundance was 690 (+/-6) in eight social groups in the Kowloon Hills. Species found were rhesus (Macaca mulatta) 65.3%, longtailed (M. fascicularis) 2.2%, Tibetan (M. thibetana) 0.2%, and hybrids 32.3%. The overall home ranges occupied 2.15 km2, resulting in a very high macaque density of 326 per km2. The birth rates were 56.9% and 69.4% in 1992 and 1993, respectively. Mean adult sex ratio (M:F) was 1:2.2 for social groups and 1:1.6 including all peripheral males. The main mortality factor was road accidents and these contributed to the "missing rate" of 9.8% and 10.6% in 1992 and 1993, respectively. Population growth was 5.6% in 1992 and 7.8% in 1993. The estimated macaque population in the year 2000 will be around 1,100 if conditions remain favorable. Management strategies are recommended.     

Population genetics of Scirtothrips perseae: tracing the origin of a recently introduced exotic pest of Californian avocado orchards, using mitochondrial and microsatellite DNA markers

The Californian avocado industry has recently been impacted by the establishment of three exotic arthropod pests that are native to Mexico and Central America. Establishment of all three pests is thought to have resulted from illegal movement of host plants (avocado) into California. To identify likely sources and routes of entry of such pest invasions, we examined the population genetics of the most recent invader, avocado thrips [Scirtothrips perseae Nakahara (Thysanoptera: Thripidae)], using mitochondrial DNA (mtDNA) and microsatellite markers. The mtDNA sequences revealed three geographically distinct and divergent lineages, of which the mtDNA haplotypes of Californian individuals were most closely related to populations in the center of the pest's native range. Analysis of allele frequencies at four microsatellite loci added resolution, indicating Coatepec Harinas, Mexico, as the most likely source of the Californian population. Statistically, we did not detect any bottleneck in population size associated with the invasion of California. However, estimates of the effective population size of the invading population suggest that a severe bottleneck occurred, indicating that the quantity of host‐plant material entering California was small. Our findings implicate Coatepec Harinas, a large avocado germplasm and breeding center, as the most likely source of the introduced Californian population of S. perseae and as a likely source of previous and future avocado pest introductions. Efforts to identify natural enemies of S. perseae for biological control should focus on Coatepec Harinas and immediate surrounds. Moreover, identification of the source of invasive pests enables the establishment and enforcement of plant quarantine and free‐trade protocols.     

Nodulation of native woody legumes in Hong Kong, China

Woody legumes can play an important role in forest restoration on degraded land but the knowledge of woody legumes has lagged behind their uses. This study is a pioneer investigation to explore the ability of native woody legumes to form root nodules and fix nitrogen in Hong Kong. Nine sites of different habitat types were surveyed during both wet and dry seasons for two years. Young plants of woody legumes along studied transects were excavated. The patterns of nodulation and nodule morphology were recorded and the nitrogen fixing ability was tested by acetylene-reduction-assay. Twenty-eight species in 16 genera were examined, of which 20 species were nodulating and eight non-nodulating, including all six species in the Caesalpinioideae. Five species were new records to the world’s nodulation inventory. Bowringia callicarpa was a new species and genus examined, which was non-nodulating. The overall nodulation pattern was consistent with previous studies. Nodulation was more profuse in some shrub species while inconsistent in most tree species. Species with higher proportion of nodulated individual plants also tended to have more nodules in each plant. Spherical nodules were common in shrub and woody climber species whilst tree species usually had woody indeterminate nodules. Seasonal difference in the amount of senescent nodules was noted in most species. All the nodules tested by acetylene-reduction-assay were effectively nitrogen-fixing, with nitrogenase activity ranging from 4 μmol C₂H₄ g^?1 h^?1 to 20 μmol C₂H₄ g^?1 h^?1, which was comparable to other tropical tree species. The findings in nodulation pattern and nitrogen fixing ability of these species are essential in their application in forest restoration on degraded lands.     

中国香港淡水鱼类的生物多样性与保护

Hong Kong Special Administrative Region,China,has an area of1095km2and is located at the edge of thenorthern tropical zone.The landscape is dominated byhills and ravines withflat landrestrictedtothe lowflood-plains and coastal regions.Inthis hilly domain,the smallrocky streams are typically fast flowing at their uplandsources,and graduallyreduceinspeed asthey wind alonghill cuttings to reach the lowlands.While streams arecommonlyfound,rivers are very limited in number.Thefewlong and meanderi…     

Population genetics and evolutionary history of Miscanthus species in China

Miscanthus species have received considerable attention as a potential biomass source for renewable energy production because of their ability to produce high yields of biomass and adapt to a wide range of climates and soils. To explore the genetic diversity and phylogenetic relationship of Miscanthus species in China, we used 24 simple sequence repeat markers to genotype 100 natural populations representing all four Chinese Miscanthus species (M. sinensis Andersson, M. floridulus (Lab.) Warb. ex K. Schum. & Lauterb., M. sacchariflorus (Maxim.) Hack., and M. lutarioriparius L. Liu ex Renvoize & S. L. Chen). Based on phylogenetic, principal coordinate, and Structure analyses, we found that the 100 populations formed two major groups corresponding to sect. Triarrhena and sect. Miscanthus. Group 1 (i.e., sect. Triarrhena) was further subdivided into two subgroups corresponding to M. sacchariflorus and M. lutarioriparius; Group 2 (i.e., sect. Miscanthus) was subdivided into three subgroups, group 2a (M. sinensis populations in southern China), group 2b (M. sinensis populations in northern China), and group 2c (all the M. floridulus populations). Population genetics analyses indicated high levels of the genetic diversity at both population (H_E = 0.468–0.599) and species (H_E = 0.559–0.708) levels, indicative of the potential of these wild resources in future breeding programs. The species distribution modeling showed that M. sacchariflorus and M. lutarioriparius have experienced population reductions during the last glacial maximum and population expansion afterward; in contrast, M. sinensis and M. floridulus both underwent gradual population expansions from the last interglaciation to the present. We also suggest that M. floridulus originated from M. sinensis in southeast China through ecological speciation. The understanding of the evolutionary history and population dynamics of these species not only provides valuable information for further genetic improvement and breeding of this energy crop but also gives important insights into the origin and speciation processes of the Miscanthus species.     

Habitat and integration within indigenous communities of Xeropicta derbentina (Gastropoda: Hygromiidae) a recently introduced land snail in south-eastern France

Xeropicta derbentina is a recently introduced land snail in Provence, France. The present work aims at describing the habitats and the land snail communities that it has invaded. Also, its impact on the species richness and diversity of indigenous communities is assessed. Two areas have been studied in order to cover the range of conditions that X. derbentina is encountering within its current French distribution. Sixty‐five samples were analysed from the most Mediterranean site, Auriol, and 140 from a northern site, Craus de St‐Michel‐l’Observatoire. From these samples, X. derbentina is found to be a thermophilous open‐land species mostly inhabiting human‐impacted habitats. It occurs in large populations (more than 100 individuals collected in 15 min) in habitat characterizing the first stages of secondary successions, from cultivated crops to dense fallow lands. However, within a heterogeneous landscape and if enough time has allowed its dispersal, X. derbentina can be found in almost any kinds of habitat, such as garrigues and woodlands. Consequently, X. derbentina occurs in diverse land snail communities. At the local scale, its large populations could result in a significant decrease in species richness and diversity. At the regional scale, however, the introduction of X. derbentina seems to have increased land snail species richness.     

A fine-scale gap analysis of the existing protected area system in Hong Kong, China

As well as being one of the most densely populated areas on Earth, Hong Kong also has the highest percentage of protected areas (38% of the 1098 km² land area) of any administrative region in the Asia Pacific. Overlay of field records from a biodiversity survey of eight taxa (amphibians, reptiles, mammals, breeding birds, ants, butterflies, dragonflies and rare vascular plants) in 1 km grid squares with protected areas indicated that over half of the 623 species of conservation concern (globally, regionally, or locally restricted species) were under-represented. Ants, butterflies and reptiles were most poorly represented. The hotspots of different taxa also received differing levels of protection. Hong Kong's protected areas are biased towards high-altitude habitats, so the under-represented species are mostly associated with the lowland habitats (freshwater wetlands, abandoned agriculture and feng shui woods). Since the restricted species are scattered and the hotspots of different taxa do not overlap, a large protected area network will be required to represent all species. This indicates the challenge that will be encountered in the conservation of many other parts of Asia that support burgeoning human populations, and where landscapes are increasingly human-dominated.     

Intraspecific variations in the hemolymph of Biomphalaria glabrata, a snail host of Schistosoma mansoni.

An attempt was made to characterize the hemolymph of Biomphalaria glabrata with reference to "normal" intra-specific variation, i.e., both inter- and intra-strain differences. Total protein concentration, per cent hemoglobin, pH, and osmolarity were studied. Seven geographic strains of B, glabrata were examined. In addition, observations were made on the hemolymph of Biomphalaria straminea, several strains of Helisoma caribaeum, and on B. glabrata subjected to infection with Schistosoma mansoni or to periods of starvation. Intra-strain differences in total protein concentration and total hemoglobin concentration in B. glabrata appeared to be more closely related with snail size than with absolute age. Inter-strain variation in B. glabrata was also noted, but the differences were of the same magnitude as those from intra-strain samples. Significant differences in total protein concentration were observed, however, between the means of similar size B. glabrata, B. straminea and H. caribaeum. The osmolatity of the hemolymph from different size B. glabrata was similar as were the osmolalities of the hemolymph from similar size snails of different strains. However, all B. glabrata strains exhibited hemolymph osmolalities lower than observed in strains of H. caribaeum. Infection with S. mansoni reduced the protein concentration of B. glabrata hemolymph. Differences were noted as early as 1.5-24 hr post-infection, with significant alterations occurring at about 11 days post-infection. To a lesser extent, starvation also depleted the protein content of the hemolymph.     

Seasonality of a forest bird community in Hong Kong, South China

We studied the composition of a secondary forest bird community in Hong Kong (22^°N) between December 1992 and June 1995, using the variable point count method. The visual detectability of each bird species had a significant positive relationship with body length. A total of 71 bird species was recorded but three resident habitat-generalists, the Great Tit Parus major, Light-vented Bulbul Pycnonotus sinensis and Japanese White-eye Zosterops japonicus, accounted for 65% of the mean total bird density of 38 per ha. The number of species seen was highest between December and April and lowest from July to September, but the total bird density was highest between December and June and lowest from August to September. The main breeding season was from March to August. Insectivores and insectivore-frugivores accounted for 80% of the species and 98% of the total bird density. The percentages of migrant species and individuals are similar to those reported at equivalent latitudes in North America. Bird community diversity and composition differed considerably from that of larger, older forest areas in South China, presumably as a result of differences in forest age, area and isolation.     

Cervical cytology screening in Vietnamese asylum seekers in a Hong Kong detention center. Population demographics and historical perspectives

OBJECTIVE: To provide a brief review of the history and demographics of the Vietnamese asylum-seeking population in Hong Kong and their possible effects on the initiation of a cervical cytology screening program at a Hong Kong detention center. STUDY DESIGN: Analysis of case histories, questionnaires and interviews with women in a detention center identified demographic features related to Pap smear history, knowledge of the Pap test, age at first intercourse and cigarette smoking status among women aged 17 years and over. Analysis of Pap smear uptake following initiation of a screening program was undertaken. RESULTS: Of the 1,171 women in the detention center who were eligible for a Pap smear, 536 (45.8%) actually obtained one, although enrollment, which was strong at the initial offering, slowed considerably as the program progressed. None of the women had had a Pap smear prior to leaving Vietnam. Knowledge of the utility and risk status criteria for Pap testing was very limited. The majority (77.9%) of the subjects started sexual activity after age 20 years, and three (0.6%) smoked. There were four (0.2%) abnormal smears identified among those tested. CONCLUSION: Convincing evidence was obtained that the Pap test was not widely used in Vietnam among the asylum-seeking population, and its role in preventing cervical cancer was not well known to the women studied. The initial strong uptake of the Pap smear was not maintained. That may be attributable to psychosocial factors associated with detention under harsh conditions and trauma associated with fleeing Vietnam.     

Population genetics study of hemoglobinopathies in Uzbekistan. II. Population dynamics of hemoglobinopathies

It was shown that on comparing variability of selective neutral genetic marker systems with that of the beta-thalassemia system for the populations of different hierarchical level, the relative importance of selection and genetic drift could be evaluated. The genetic differentiation of the beta-thalassemia gene frequencies in elementary populations (villages) could be solely explained by genetic drift. On the other hand, the differentiation of district populations (the sizes of the populations being 10(6] for beta-thalassemia gene frequencies could be explained by selection forces. This is supported by the fact that the genetic distances and FST values are only significant for the beta-thalassemia gene and not for the neutral genetic systems, when the district populations are compared.     

Changes of a forest bird community in Hong Kong of China in 10 years

The changes in the bird community structure of the largest natural secondary forest of Hong Kong over 10 years were investigated. Densities of the 10 most abundant species in 1993–1995 and 2003–2005 were compared using t-test. All resident habitat generalists showed significant decline in densities. Two forest specialists showed significant increase in densities: one is native and the other is exotic species. The trend of changes in the forest bird community of Hong Kong is mainly related to the absence of nearby forests that could act as “source” of forest dependent species to colonize the local secondary forests, and the invasion of exotic species.