Spatial and temporal dynamics of the male effective population size in bumblebees (Hymenoptera: Apidae)

Eusociality and male haploidy of bumblebees (Bombus spp.) enhance the deleterious effects of population decline and aggravate the degeneration of population fitness compared to solitary and diploid species. The highly dispersive male sex may be the prime driver to connect otherwise isolated populations. We therefore studied the temporal and spatial structure of the male population of Bombus terrestris (Linnaeus 1758) and Bombus lapidarius (Linnaeus 1758) using microsatellite DNA markers. We found that the majority of the males in a 1000 m2 sampling area originated from colonies located outside of the workers foraging range, which was consistent with the genetic distances among colonies. The analyses of temporal population sub-structure based on both colony detection rate over time and the clustering software STRUCTURE consistently suggested one large and temporally unstructured male population. Our results indicate an extended male flight distance for both species. Though the range of queen dispersal remains to be studied, the effective size (N _e) of bumblebees is increased by extended male mating flight ranges (A _m ) exceeding worker foraging distance by factor 1.66 (A _m  = 69.75 km²) and 1.74 (A _m  = 13.41 km²), B. terrestris and B. lapidarius, respectively. Thus this behaviour may counteract genetic deprivation and its effects. All populations were genetically highly diverse and showed no signs of inbreeding. We discuss the implications of our findings in context of bumblebee population dynamics and conservation. We also highlight the effects and benefits of sampling both workers and males for population genetic studies.     

Seasonal population dynamics of Eisenia fetida (Savigny, 1826) (Oligochaeta, Lumbricidae) in the field

In order to assess the response of epigeic earthworms to seasonal changes we monitored the population dynamics of Eisenia fetida (Oligochaeta, Lumbricidae) in a manure heap in the field during a year. Earthworms were hand-sorted from five 0.25 x 0.25 x 0.20 m blocks around the heap in November (autumn) 1999 and in January (winter), April (spring) and August (summer) 2000 to determine earthworm population dynamics. Earthworms of each block were classified into different age classes: mature, preclitellate, juvenile, hatchling and cocoon, and afterwards counted and weighed. Seasonality had a strong effect on the density, biomass and reproductive activity of the population. The population of E. fetida was characterized by a high density of individuals and the predominance of mature individuals throughout the year. Maximum density, mating activity and size of cocoons were achieved in spring, but there were not changes in the number of cocoons per mature earthworm throughout the year. Unexpectedly, the smallest cocoons were produced in winter by the largest individuals. These results suggest that E. fetida is able to allocate resources to growth and/or reproduction in response to environmental fluctuations.     

Modeling the interaction of physiological time, seasonal weather patterns, and delayed mating on population dynamics of codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae)

The effect of delaying female mating on population growth in codling moth (Cydia pomonella (L.)) was found to act on a physiological time (degree-day) basis and was predictable using a simple quadratic equation. When combined with previous work on degree-day based mortality, we were able to evaluate how the magnitude of population reduction and survival varied between sites, years, and generations at locations in California, Michigan, Pennsylvania and Washington states. In general, reductions in population growth associated with females mating 1–3 days after emergence were greater in warmer areas and during warmer times of the year. In any given year and location, the temperature profiles during peak flight were crucial in determining the population reductions, but over an 11-year period, the average seasonal temperature profile was more important. During the overwintering generation, conditions were relatively mild in all locations and only minor differences were observed in population growth rates between locations. Populations experiencing 1–3 days delay in female mating were reduced 8, 19 and 32 % compared to populations experiencing no delay, respectively. During the first summer generation, population reductions doubled compared to those seen in the overwintering generation. During the second summer flight, reductions in population growth rate at the three cooler locations decreased, while they increased in the warmer California location. Overall, the results show delayed mating can help understand how population growth is related to environmental conditions experienced naturally by insect populations and will help guide studies of the mechanisms of mating disruption, a technique used for pest suppression in agricultural and forest systems.     

Genomic inbreeding and population structure of northern pike (Esox lucius) in Xinjiang,China

Northern pike (Esox lucius) was widely distributed in the high latitudes of the northern hemisphere. In China, northern pike was originally distributed only in the upper reaches of the Irtysh River in Xinjiang and has appeared in many water bodies outside the Irtysh River Basin in Northern Xinjiang. A total of four populations were collected from north to south in Xinjiang, including Irtysh River (RIR), Ulungu Lake (LUL), a small lake nearby Ulungu River (LJD), and Bosten Lake (LBO). We estimated population genomic parameters, performed gene flow analysis, and estimated the effective population size of each population. The proportion of individuals with high inbreeding coefficient (F ≥ 0.0625) accounted for 36.4% (44/121) of all sequenced individuals, approximately 4.5% (1/22) in LUL, 25.9% (7/27) in LBO, 42.9% (18/42) in RIR, and 60% (18/30) in LJD. RIR had the highest mean of genomic relatedness (coancestry coefficient = 0.025 ± 0.040, IBD = 0.036 ± 0.078). Gene flow results showed that the population spreading was from RIR into two branches, one was LBO, and the other continued to split into LUL and LJD, and migration signal from LBO to LUL was detected. Our results suggested that the extinction risk of northern pike was very low in Xinjiang of China, and the controlled capture fishery of northern pike could be developed reasonably.     

A simulation study of population interaction between the greenhouse whitefly,Trialeurodes vaporariorum Westwood (Homoptera: Aleyrodidae) and the parasitoidEncarsia formosa Gahan (Hymenoptera: Aphelinidae) II. Simulation analysis of population dynamics and strategy of biological control

Simulation studies were performed to analyze factors affecting the population dynamics of the system with the greenhouse whitefly (Trialeurodes vaporariorumWestwood ) and the parasitoid Encarsia formosaGahan and to develop strategies for the introduction of E. formosa. The reduction of parasitization efficiency with an increase in parasitoid density promotes the stability of the system, which coincides with the prediction from current theory. The stability of the system is also shown to be promoted by the effect of host feeding. The population levels of the system are remarkably suppressed with an increase in searching efficiency and a decrease in host oviposition. The control effect of the parasitoids is enhanced when the number of parasitoids is divided among many introductions. An optimal time, an optimal density ratio of parasitoids to hosts and optimal densities of hosts and parasitoids exist in the introduction programme of parasitoids.     

Predicting the population dynamics of the house dust mite Dermatophagoides pteronyssinus (Acari: Pyroglyphidae) in response to a constant hygrothermal environment using a model of the mite life cycle

A generalised model of the life cycle of a house dust mite, which can be tailored to any particular species of domestic mite, is presented. The model takes into account the effects of hygrothermal conditions on each life cycle phase. It is used in a computer simulation program, called POPMITE, which, by incorporating a population age structure, is able to predict population dynamics. The POPMITE simulation is adapted to the Dermatophagoides pteronyssinus (Acari: Pyroglyphidae) (DP) mite using published data on the egg development period, total development period, adult longevity, mortality during egg development, mortality during juvenile development, and fecundity of individual DP mites held at a range of constant hygrothermal conditions. An example is given which illustrates how the model functions under constant hygrothermal conditions. A preliminary validation of POPMITE is made by a comparison of the POPMITE predictions with published measurements of population growth of DP mites held at a range constant hygrothermal conditions for 21 days. The POPMITE simulation is used to provide predictions of population growth or decline for a wide range of constant relative humidity and temperature combinations for 30 and 60 days. The adaptation of the model to correctly take account of fluctuating hygrothermal conditions is discussed.     

The life cycle, population dynamics and productivity of Melanoides tuberculata (Muller, 1774) (Gastropoda: Prosobranchia: Thiaridae) in Hong Kong

An investigation of the life cycle, population dynamics and secondary productivity of the viviparous snail Melanoides tuberculuta inhabiting flooded furrows and irrigation ditches at Ping Long, New Territories, Hong Kong, was undertaken between March 1982 and March 1983. There was a single peak in juvenile recruitment coinciding with the warmer months; hatchlings grew quickly and were sexually mature before the next breeding season. Large animals experienced high mortality and few individuals survived until a second breeding season. Secondary productivity and the production: biomass (P:B) ratio of the population (13.43 g shell–free dry weight m⁻² yr⁻¹ and 4.81, respectively) were high and exceeded values of these parameters recorded for freshwater prosobranch populations in temperate regions. Ping Long M. tuberculata were exclusively female, as is typical of most populations of this species. Animals > 3.0 mm shell width (90–120 days old) had eggs and developing larvae in the brood pouch, and fully–developed larvae were recorded from brood pouches throughout the study although release of hatchlings was distinctly seasonal.
A comparison of life cycle parameters of Malaysian M. turberculata with those of the Ping Long population revealed a marked similarity. The significance of such similarity and the importance of parthenogenicity in the life cycle of this widely distributed snail is discussed. Melanoides tuberculata exhibits the characteristics of an opportunist or 'fugitive' species and, by virtue of its reproductive strategies and high productivity, is able to colonize rapidly and temporarily dominate vacant habitats.     

Distribution,population dynamics and damage of Hessian fly,Mayetiola destructor (Diptera: Cecidomyiidae) in North Tunisia

A three years survey and monitoring studies (2013–2014–2015) were carried out through 4 regions of north Tunisia in order to follow the evolution of the distribution, the frequency of occurrence and damage caused by the Hessian fly Mayetiola destructor (Say) to bread wheat (Triticum aestivum L.) and durum wheat (Triticum durum Desf). Moreover, the effectiveness of resistance genes H3, H5, H6, H7, H8, H9, H10, H11, H12, H13, H14, H15, H22, H23, H25 and H26 to protect wheat from Hessian fly attack was assessed in natural field and under controlled laboratory conditions at INRAT-Kef Station. Results showed that Hessian fly was detected in 60.33% and 51.5% of all sampled durum and bread wheat fields, respectively. This pest was more frequent with a higher percentage of infestation in semi-arid regions. Indeed, during 2013, infestation rate attained 12.39% in Kef region against 0.9% registered in Bizerte region. In order to update information about the annual number of generations, we surveyed the population dynamic of Hessian fly in Kef region. Three generations of the fly were counted annually on wheat, with two complete and one incomplete generation. This insect affects host plant growth at different developmental stages. Plant height was the most affected parameter followed by shoot dry weight and tiller number. Field investigations on host resistance revealed that among the 16 tested resistance genes, and only three were strictly effective (H22, H25 and H26). The resistance genes H5, H9, H13 and H9H13 have also conferred high levels of protection against Hessian fly. This work indicated that H22, H25 and H26 genes could be incorporated into Tunisian wheat varieties and released to farmers to manage the threat due to Hessian fly attacks.     

The population dynamics of Orthopyxis crenata (Hartlaub, 1901) (Hydroza, Cnidaria), an epiphyte of Halimeda tuna in the northwestern Mediterranean

O. crenata on the alga Halimeda tuna were sampled every 2 wk for a year off Tossa de Mar, northeastern Spain. The hydroids were most abundant from November to April when three cohorts, identified by size frequency, were present. From April to October the population consisted of two cohorts, except in June and July when the population density was low and only one cohort, of young hydroids, was identifiable. The paucity of O. crenata in summer was attributed to the high rate of turnover of host thalli, interspecifuc competition with other epiphytes, and a possible shortage of suitable planktonic prey. Recruitment was predominantly asexual, by stolons, and occurred throughout the year. Gonozoids were found only from late October to early December when recruitment by planula larvae also occurred. In winter, when the cohorts lived for the maximum of ≈6 wk, colony sizes quintuplicated and triplicated in successive 15-day periods. Although colonies (ramets) of O. cretana on H. tuna have a short life span reproduction and dispersal to other thalli by stolons means that the genets can survive beyond the life of a host, and perhaps indefinitely.     

Reproduction strategies of Macrocystis pyrifera (Phaeophyta) in Southern Chile: The importance of population dynamics

Macrocystis pyrifera is an ecologically dominant species along the temperate Northern and Southern Pacific Coast of America, showing some similarities and differences at population and community level. In general, this kelp is reported to be reproductive all year round. Annual populations present in wave-protected areas of southern Chile suggest that the reproductive strategies of this population can be different. In this study we explore the reproductive strategies of annual M. pyrifera present in wave-protected areas and perennial populations encountered in exposed areas of southern Chile (41^∘S). Our results show that M. pyrifera present in wave-exposed locations has a reproductive strategy that is similar to populations in the northern hemisphere. These populations reproduce all year round and their strategy is to produce high numbers of sporophylls and ensure that most of them (over 90%) become sporogenous. On the other hand, the protected populations with an annual life cycle, produce more spores per area of sorus. In a few months, they are able to produce sufficient propagules to recolonize areas before the adult plants disappear in autumn.     

The life cycle, population dynamics, growth and secondary production of the snail Xeropicta arenosa Ziegler (Gastropoda: Pulmonata) in northern Greece

The life cycle, population dynamics and secondary production of the xerothermophilic land snail Xeropicta arenosa were studied in northern Greece. The study of biology and the demographic analysis of the populations of X. arenosa revealed that it is a semelparous annual species. Reproduction takes place in autumn and the majority of the adults die after egglaying. Growth is continuous throughout the year and no seasonal fluctuations occur. Estimation of annual secondary production with the Hynes' size frequency method revealed a mean standing crop ( aa ) of 0.075 g m^-2 year^-1 and a productivity ( P ) of 0.267+ 0.043 gm^-2 year^-1. The annual turnover ratio ( P/ ) was equal to 3.56.     

Preliminary studies on the reproduction and population dynamics of Monodonta lineata and Gibbula umbilicalis (Mollusca,Gastropoda) on the central coast of Asturias (N. Spain)

Summary Populations of Monodonta lineata and Gibbula umbilicalis were studied at Aramar beach (Luanco, Asturias) from October 1982 to November 1983. Both species show a sexual ratio of 1: 1 but differ in their gonadal cycle patterns. M. lineata gonadal development stages are found from November to May–June in a significant part of the population. Breeding stages occur from June–July to September, and in some individuals to November, with complete discharge of all spawn at the end of the reproductive season. Some degree of inter-annual variation is detected. Spawning stages of mature G. umbilicalis are found through the year but the higher frequencies occur in summer and autumn samples, with development phases predominating in January to May. Animals over 10 mm in shell diameter maintain their gonads close to spawning stages, completely spawned individuals being less than 10 percent. In both species variability in gonad stages for a given month reduces as size increases, indicating a certain synchrony.The new recruits of M. lineata are detected on the bare rock by September to November and are recognizable through their first year. Due to the amplitude of the breeding period and differing growth rates size distribution within an age class is wide. Size class frequencies rapidly decrease after the second year of life. The data for G. umbilicalis are difficult to interpret given the scarce number of juveniles and size overlapping.     

Heterozygosity and fitness in a California population of the labyrinth spider Metepeira ventura (Araneae, Araneidae)

Abstract. The relationship between individual heterozygosity and characteristics likely to be associated with fitness was investigated in the labyrinth spider Metepeira ventura . Adult females and their egg sacs were collected at a coastal site in southern California, and three measures of bodily condition (carapace width, weight, residual index) and six measures of reproductive output (number of egg sacs, variation in egg number among sacs [coefficient of variation], total number of eggs, mean eggs/sac, mean eggs/sac divided by carapace width, mean eggs/sac divided by weight) were determined for each spider. The sample was polymorphic at three allozyme loci that were in Hardy–Weinberg equilibrium, and individual females were heterozygous at up to two of the three loci, forming three heterozygosity classes (0, 1, and 2). None of the bodily condition measures were significantly related to the number of heterozygous loci, while four of the reproductive output estimators (total number of eggs, mean eggs/sac, mean eggs/sac divided by carapace width, mean eggs/sac divided by weight) were significantly influenced by heterozygosity. In each significant case, values for class 2 females were less than those for class 0 and 1 females, whose values were usually more similar. Thus, while female bodily condition was comparable among classes, the most heterozygous females produced fewer total eggs and eggs per sac than their less heterozygous peers. The fact that females of M. ventura engage in a reproductive investment-number trade-off suggests that high-variability and low-variability females may be pursuing distinct reproductive strategies in the wild, with more heterozygous females being K -selected (smaller clutches, heavier eggs) and more homozygous females being r -selected (larger clutches, lighter eggs). Further investigation will be needed to assess more fully the fitness value of heterozygosity in M. ventura .     

The annual number of breeding adults and the effective population size of syntopic newts (Triturus cristatus, T. marmoratus)

Pond-breeding amphibians are deme-structured organisms with a population genetic structure particularly susceptible to demographic threats. We estimated the effective number of breeding adults (Nb) and the effective population size (Ne) of the European urodele amphibians Triturus cristatus (the crested newt) and T. marmoratus (the marbled newt), using temporal shifts in microsatellite allele frequencies. Eight microsatellite loci isolated from a T. cristatus library were used, five of which proved polymorphic in T. marmoratus, albeit with high frequencies of null alleles at two loci. Three ponds in western France were sampled, situated 4-10 kilometers apart and inhabited by both species. Parent-offspring cohort comparisons were used to measure Nb; samples collected at time intervals of nine or 12 years, respectively, were used to measure Ne. The adult population census size (N) was determined by mark-recapture techniques. With one exception, genetic distances (FST) between temporal samples were lower than among populations. Nb ranged between 10.6 and 101.8 individuals, Ne ranged between 9.6 and 13.4 individuals. For the pond where both parameters were available, Nb/N (overall range: 0.10-0.19) was marginally larger than Ne/N (overall range: 0.09-0.16), which is reflected in the temporal stability of N. In line with the observed differences in reproductive life-histories between the species, Nb/N ratios for newts were about one order of magnitude higher than for the anuran amphibian Bufo bufo. Despite of the colonization of the study area by T. cristatus only some decades ago, no significant genetic bottleneck could be detected. Our findings give rise to concerns about the long-term demographic viability of amphibian populations in situations typical for European landscapes.     

Association patterns and population dynamics of bottlenose dolphins in the Strait of Sicily (Central Mediterranean Sea): implication for management

An understanding of the population dynamics and social organization of cetaceans is essential to manage the influence of anthropogenic activities. In this study, the population size, site fidelity and social interactions of bottlenose dolphins in the Strait of Sicily (Italy) were investigated to provide recommendations for their conservation. Mark-recapture analysis was based on the encounter histories of 103 marked dolphins from 2004 to 2015. The POPAN formulation of the Jolly–Seber model in MARK software was used to estimate the size of the super-population. Site fidelity and social organization were estimated for individuals re-sighted ≥3 times. The estimated population size was 140 (SE = 15.75; 95% CI = 106–164). Dolphins had low site fidelity, and both adults and sub-adults move outside the study area. Females with calves used the area longer than other individuals. Based on our results, dolphins’ home range likely extended beyond the study area. The mean value of the Half-Weight Association Index was low and the preferred association was by casual acquaintance. However, we found a distinct aggregation of post-parturition females during the final 2 years of the study. Therefore, the pattern of association was apparently a response to an ecological requirement, which was the possibility to breed in high productivity waters. Whether these individuals are part of a larger pelagic population is unknown; however, we can conclude that the management of only coastal waters is insufficient for the conservation of dolphins in the Strait of Sicily.     

Reproduction and ontogeny of Mastacomys fuscus (Rodentia: Muridae) in the Australian Alps and comparisons with other small mammals living in alpine communities

Two species of small rodents, Mastacomys fuscus and Rattus fuscipes, and one small dasyurid marsupial Antechinus swainsonii live sympatrically in the subalpine habitat of SE Australia. This paper describes the reproductive characteristics and ontogeny of M. fuscus, and shows that the three species have different reproductive strategies that, in part, are a reflection of their different phylogenies. Cold and snow in winter, and a short summer season, limit the length of time available for reproduction and development. The rodent species exhibit similar reproductive characteristics to those in alpine regions of Europe, North America and South Africa.     

Seasonal dynamics, movements and the effects of experimentally increased female densities on a population of imaginal Calopteryx aequabilis (Odonata: Calopterygidae)

Abstract. 1. A population of Calopteryx aequabilis Say was sampled daily on a tributary of Canard River, Kings County, Nova Scotia, for the entire flight season in 1983 (29 May to 13 August), using capture–mark–recapture techniques.
2. 2701 sightings of 678 individuals were obtained along a 635 m segment of the stream. A maximum daily count of 174 imagines was reached on 11 June, after which the population gradually declined.
3. More females than males were marked but sexually mature males outnumbered females at the water on all but four days.
4. Immigration rather than local emergence accounted for a large proportion of the population after 20 June.
5. Females were consistently vagile; males were site–specific but occasionally moved long distances between captures.
6. Males and females first marked as tenerals became reproductively mature after about 5 days.
7. We experimentally increased female density on a partially isolated section of the study stream to see how increased female numbers affected the demographics and movement patterns of the population.
8. Residence times for introduced and resident females were similar. In contrast, during a similar introduction of males a year earlier, most introduced males disappeared quickly.
9. Males decreased the distance they travelled daily between captures, their total distance travelled and their range following the introduction, and females showed a tendency (not statistically significant) toward increased movements and dispersal, as predicted.     

过去二十年贵州黑叶猴分布与种群动态及致危因子分析(英文)

本文通过整理相关文献与政府报告数据并结合我们在贵州的最新调查与监测数据,总结过去20年间黑叶猴在贵州的分布、种群变动及其所面临的主要威胁,并在此基础上提出相关的保护管理建议。贵州黑叶猴野生种群在过去20年间增长了约10%～20%:从20世纪90年代的约109群1000只增加到现在的约132～137群1160～1200只。但同期黑叶猴已从5个原有的分布点绝迹,现仅存于大沙河、柏箐、麻阳河、宽阔水和野钟等5个保护区,总面积约912km2。现有的5个隔离分布点保存有全球黑叶猴野生种群(1800～2000)的约62%,是黑叶猴物种保存的最关键地区,并应该给于保护管理的优先考虑。偷猎压力在贵州相对较小:在过去的20年间仅有3次偷猎的官方记录。黑叶猴在贵州所面临的主要威胁是栖息地的丧失与退化。其主要表现形式有:以农作物和烟草种植为目的的耕地扩大,以做饭、取暖以及烟叶烘烤为目的的薪材需求,以及家畜(主要是山羊)的过度放牧。