陆桥岛屿环境下社鼠种群数量的估算方法

根据2010年3月—11月在千岛湖地区2个岛屿上社鼠(Niviventer confucianus)的标志重捕数据,分别用Jolly-Seber法、修正Lincoln指数法、Schnabel法和MNA法计算两个岛屿上社鼠种群数量,并深入探讨在陆桥岛屿环境下估算社鼠种群数量的适用方法。研究结果显示,在满足Jolly-Seber法的条件下,通过该方法计算的结果与修正Lincoln指数法无显著差异。但在野外实验中,并不是所有的重捕数据都满足Jolly-Seber法的条件,而且该方法不能估算头尾两月的数量。因此,修正Lincoln指数法更适于估算陆桥岛屿环境下社鼠的种群数量。可为今后开展陆桥岛屿环境下鼠类种群生态学研究奠定基础。     

Constant-parameter capture-recapture models

Jolly (1982, Biometrics 38, 301-321) presented modifications of the Jolly-Seber model for capture-recapture data, which assume constant survival and/or capture rates. Where appropriate, because of the reduced number of parameters, these models lead to more efficient estimators than the Jolly-Seber model. The tests to compare models given by Jolly do not make complete use of the data, and we present here the appropriate modifications, and also indicate how to carry out goodness-of-fit tests which utilize individual capture history information. We also describe analogous models for the case where young and adult animals are tagged. The availability of computer programs to perform the analysis is noted, and examples are given using output from these programs.     

Population size and structure of the African Softshell Turtle,Trionyx triunguis,in Dalaman,southwestern Turkey

We assessed the size of the population of the African Softshell Turtle, Trionyx triunguis, in Dalaman (Mu?la, Turkey), which is considered to be the largest population of the species in the Mediterranean, by using the Jolly-Seber mark-recapture method. A total of 415 individuals were caught during the summer months of 2009 to 2011, of which 148 were recaptures. From 267 marked individuals, 148 (55%) were male, 69 (26%) were female and 50 (19%) were juveniles and subadults of indeterminate sex. The male:female ratio was calculated to be 2.14:1. By using Model A' of the Jolly-Seber mark-recapture method, which includes deaths but no immigration, the mean population size in Kükürt and Küçükdalyan (Karg?n) lakes, together with Tersakan and Ta?l?çay creeks, were estimated to be 396±36. Based on this estimation, the population density was calculated to be 14 turtles/ha. Approximately 67.4% of the estimated population was marked. The mean capture probability (p) and mean survival ratio (Φ) were 0.094±0.009 and 0.957±0.076, respectively. Our results showed that the species’ population size is larger than previously estimated based on visual counts. The status “Vulnerable” C2a of the IUCN Red Data Book categories seems therefore more appropriate for the Mediterranean subpopulation of Trionyx triunguis than “Endangered” C2a.     

Comparison of enumeration and Jolly-Seber estimation of population size in the common voleMicrotus arvalis

Capture-recapture data on common volesMicrotus arvalis (Pallas, 1779) in central Europe have been almost exclusively analysed by means of the enumeration technique (minimum number alive or calendar of catches). Here we compare enumeration and Jolly-Seber (JS) estimation of population size in the common vole using live-trapping data from an alfalfa field-population in southern Moravia, Czech Republic. Over the entire study the enumeration estimate of the population size was smaller by an average of 28% than the JS estimate. The negative bias increased with density, decreased with both capture probability and the survival rate, and was more pronounced in males at high density. We conclude that the method of direct enumeration is not reliable for estimating population size in the common vole.     

Acute and chronic testosterone response to blood flow restricted exercise

The American College of Sports Medicine recommends lifting a weight of at least 70% 1RM to achieve muscular hypertrophy as it is believed that anything below this intensity rarely produces substantial muscle growth. At least part of this recommendation is related to elevated systemic hormones following heavy resistance training being associated with skeletal muscle hypertrophy. Despite benefits of high intensity resistance training, many individuals are unable to withstand the high mechanical stresses placed upon the joints during heavy resistance training. Blood flow restricted exercise offers a novel mode of exercise allowing skeletal muscle hypertrophy at low intensities, however the testosterone response to this exercise has yet to be discussed. The acute and chronic testosterone response to blood flow restricted exercise appears to be minimal when examining the current literature. Despite this lack of response, notable increases in both size and strength are observed with this type of exercise, which seems to support that systemic increases of endogenous testosterone are not necessary for muscular hypertrophy to occur. However, definitive conclusions cannot be made without a more thorough analysis of responses of androgen receptor density following blood flow restricted exercise. It may also be that there are differing mechanisms underlying hypertrophy induced by high intensity resistance training and via blood flow restricted exercise.     

Estimation of the size of an open population from capture-recapture data using weighted martingale methods

A weighted martingale method, akin to a moving average, is proposed to allow the use of modified closed-population methods in the estimation of the size of a smoothly changing open population when there are frequent capture occasions. We concentrate here on modifications to martingale estimating functions for model Mt, but a wide range of closed-population estimators may be modified in this fashion. The method is motivated by and applied to weekly capture-recapture data from the Mai Po bird sanctuary in Hong Kong. Simulations show that the weighted martingale estimator compared well with the Jolly-Seber estimator when the conditions for the latter to be valid are met, and it performed far better when individuals were allowed to leave and reenter the population. Expressions are derived for the asymptotic bias and variance of the estimator in an appendix.     

The effect of temperature and saturation deficit on mortality in populations of male Glossina m. morsitans (Diptera: Glossinidae) in Zimbabwe and Tanzania

The methods of Bailey and of Jolly and Seber were used to provide maximum likelihood estimates of population parameters for Jackson's classical mark-recapture experiments on males of the tsetse fly Glossina m. morsitans Westwood. These were compared with Jolly-Seber (J-S) estimates for the same fly from more recent work on Antelope Island, Lake Kariba, Zimbabwe. The Bailey estimates of birth and death rates and total population size had markedly lower variances than Jackson's originals. Both sets of estimates provided moving averages over 6-week periods, whereas the Jolly-Seber analysis provided independent weekly estimates and their variance is consequently higher. Saturation deficit and maximum temperature (Tmax) accounted for 11 and 16% respectively of the variance in independent 4-week means of the weekly J-S survival probabilities. Analysis of covariance, carried out on a joint data set of smoothed J-S estimates of the survival probability in Tanzania and Zimbabwe, showed a significant effect of Tmax on survival. When this effect was removed, the survival probability in the Tanzania studies was found to be 8% lower than on Antelope Island. The two effects accounted for 50% of the variance in the joint data. When saturation deficit was substituted for Tmax, regression only accounted for 35% of the variance. If saturation deficit is important in determining tsetse survival, it must act on stages other than the post-teneral adult. Given the continuous increase in mortality, even at moderate temperatures, it is hard to envisage a direct effect of Tmax. There may be an indirect effect, however, via the number of hunger-related deaths resulting from the increase in the feeding rate with increasing temperature.     

SURVIVAL RATES OF PHOTOGRAPHICALLY IDENTIFIED HECTOR'S DOLPHINS FROM 1984 TO 1988

Re-sightings of photographically identified individuals were used to estimate survival rates for a free-living population of Hector's dolphins Cephalorhynchus hectori , a species endemic to New Zealand waters. Most individuals were identified from injuries to the dorsal fin. Consequently, the photographic catalog contained very few young individuals. Our analysis included no newborn calves or yearlings, and provided estimates of survival rates only after the first year of life. We used two complementary methods for calculating survival rates: a modified Jolly-Seber model, and a simpler method which corrects in a more explicit way for individual dolphins being alive but not sighted. Selection of the most reliable subset of the data had a greater effect on computed survival rates than did the difference between the two methods. We conclude that careful inspection of resighting data before analysis, and, if necessary, selection of a subset, is very important in studies of this kind. Survival rate estimates came from a population which was subject to relatively heavy mortality from gillnet entanglement. Standard errors of the survival rate estimates have been used to assess the conditional probability of population decline given three fertility scenarios. The high probability that the Banks Peninsula Hector's dolphin population was decreasing during the study period (0.78 to 0.99) suggests that gillnet entanglement constituted a serious risk to this population.     

Jolly-Seber法对大仓鼠和黑线仓鼠种群若干参数的估算

本文利用Jolly-Seber法估算了1986和1988年河北省饶阳县大仓鼠和黑线仓鼠的种群大小、存留率等参数。结果表明,大仓鼠的存留率比黑线仓鼠小,而且和密度负相关。大仓鼠和黑线仓鼠对铁丝活捕笼均不存在非等捕性。该方法对大仓鼠和黑线仓鼠种群参数估计是可行的。     

Marksmanship deficits caused by an exhaustive whole-body lifting task with and without torso-borne loads

Studies of exhaustive exercise on marksmanship are inconclusive and have not measured trigger pull latencies (LAT) nor considered impact of added torso loads. This study examined the impact of exhaustive whole-body exercise and torso loading on accuracy, precision, and latency during a marksmanship test. Twelve men lifted a 20.5-kg box on to a 1.55-m high shelf until they could not maintain a 12 lifts·min?1 pace. Within 25 seconds of ending the lifting task, the subjects started a 10-minute rifle marksmanship test (8 shots·min?1). During lifting and shooting, the subjects wore 2 different loads: NOLOAD = boots, uniform, and helmet (5.9 kg) and LOAD = a torso-borne load (29.9 kg) + NOLOAD. With the LOAD, the subjects were only able to work for 69% as long, perform 31% as many lifts, or do 38% as much total work compared with the NOLOAD condition. Despite performing less total external work during LOAD, the heart rate (HR) was more than 25% higher than NOLOAD. Measures of accuracy and precision improved and stabilized after minute 3. Overall, LAT increased (p < 0.025) for LOAD (mean ± SE, 2,522 ± 81 milliseconds), compared with NOLOAD (2,240 ± 121). During 0-4 minutes, LAT for LOAD was 14% greater than for NOLOAD (p < 0.05); from 4 to 10 minutes, LAT did not differ. Exhaustive whole-body exercise transiently degraded accuracy regardless of load. In the LOAD condition, LAT was immediately increased and sustained for 10 minutes; in the NOLOAD condition, LAT increased gradually. Although load did not decrease accuracy, it increased the time to engage targets, which can impact fighting effectiveness and survivability.     

A bayesian approach to the multistate Jolly-Seber capture-recapture model

This article considers a Bayesian approach to the multistate extension of the Jolly-Seber model commonly used to estimate population abundance in capture-recapture studies. It extends the work of George and Robert (1992, Biometrika79, 677-683), which dealt with the Bayesian estimation of a closed population with only a single state for all animals. A super-population is introduced to model new entrants in the population. Bayesian estimates of abundance are obtained by implementing a Gibbs sampling algorithm based on data augmentation of the missing data in the capture histories when the state of the animal is unknown. Moreover, a partitioning of the missing data is adopted to ensure the convergence of the Gibbs sampling algorithm even in the presence of impossible transitions between some states. Lastly, we apply our methodology to a population of fish to estimate abundance and movement.     

On adaptive accuracy and precision in natural populations

Adaptation is usually conceived as the fit of a population mean to a fitness optimum. Natural selection, however, does not act only to optimize the population mean. Rather, selection normally acts on the fitness of individual organisms in the population. Furthermore, individual genotypes do not produce invariant phenotypes, and their fitness depends on how precisely they are able to realize their target phenotypes. For these reasons we suggest that it is better to conceptualize adaptation as accuracy rather than as optimality. The adaptive inaccuracy of a genotype can be measured as a function of the expected distance of its associated phenotype from a fitness optimum. The less the distance, the more accurate is the adaptation. Adaptive accuracy has two components: the deviance of the genotypically set target phenotype from the optimum and the precision with which this target phenotype can be realized. The second component, the adaptive precision, has rarely been quantified as such. We survey the literature to quantify how much of the phenotypic variation in wild populations is due to imprecise development. We find that this component is often substantial and highly variable across traits. We suggest that selection for improved precision may be important for many traits.     

Jolly-Seber法中种群存活率估算的探讨

在Jolly Seber法中 ,存活率为其核心参数之一。一些作者指出 ,采用Jolly Seber法估算标志重捕数据有时候会出现存活率大于 1的情形。本文就这一情形做了相应的分析 ,认为产生这一现象的原因为标志个体间不具有等捕性或等存活率所致。在设计标志重捕取样的野外调查中 ,应设法提高重捕率以增加估计精度     

Jolly—Seber法中种群存活率估算的探讨

在Jolly-Seber法中,存活率为其核心参数之一。一些作者指出,采用Jolly-Seber法估算标志重捕数据有时候会出现存活率大于1的情形。本文就这一情形做了相应的分析,认为产生这一现象的原因为标志个体间不具有等捕性或等存活率所致。在设计标志重捕取样的野外调查中,应设法提高重捕率以增加估计精度。     

Fort Peck paddlefish population survival and abundance in the Missouri River

Excessive fishing pressure can induce population declines or complete collapse of fisheries. Unless commercial and recreational fisheries for K-selected fishes, or those with slow growth and late maturation, are carefully managed, declines in abundance or fishery collapse is probable. Paddlefish Polyodon spathula,are a K-selected species that experienced historical declines in abundance as a result of habitat degradation and overfishing. Mark-recapture studies are well-suited for long-lived fishes by providing information on population density and vital rates. For sustainable commercial or recreational fisheries targeting species such as the paddlefish, managers require accurate estimates of population vital rates including survival, abundance, and exploitation. We used a Montana Fish, Wildlife & Parks (MFWP) mark-recapture dataset and modified Jolly-Seber (POPAN) models to estimate survival, recapture, probability of entry, and abundance of 8,518 tagged paddlefish over a 25-year period. With many supporting estimates including stable survival (0.92 for females, mean of 0.82 for males), low exploitation rates (means of 2.6% for females and 2.9% for males), and stable abundance estimates (25-year mean of 12,309 individuals for both sexes), the Fort Peck paddlefish population appears to be stable and well-managed over the past 25 years. Presently, this is the only study focused on paddlefish in North America that has estimated survival and abundance for both male and female paddlefish using contemporary analyses. This research provided a unique opportunity to highlight that the effort exerted by management agencies to collect long-term field data is extremely useful to our understanding of fish populations and management.     

Enhancing Bayesian risk prediction for epidemics using contact tracing

Contact-tracing data (CTD) collected from disease outbreaks has received relatively little attention in the epidemic modeling literature because it is thought to be unreliable: infection sources might be wrongly attributed, or data might be missing due to resource constraints in the questionnaire exercise. Nevertheless, these data might provide a rich source of information on the disease transmission rate. This paper presents a novel methodology for combining CTD with rate-based contact network data to improve posterior precision, and therefore predictive accuracy. We present an advancement in Bayesian inference for epidemics that assimilates these data and is robust to partial contact tracing. Using a simulation study based on the British poultry industry, we show how the presence of CTD improves posterior predictive accuracy and can directly inform a more effective control strategy.     

The neglected tool in the Bayesian ecologist's shed: a case study testing informative priors' effect on model accuracy

Despite benefits for precision, ecologists rarely use informative priors. One reason that ecologists may prefer vague priors is the perception that informative priors reduce accuracy. To date, no ecological study has empirically evaluated data‐derived informative priors' effects on precision and accuracy. To determine the impacts of priors, we evaluated mortality models for tree species using data from a forest dynamics plot in Thailand. Half the models used vague priors, and the remaining half had informative priors. We found precision was greater when using informative priors, but effects on accuracy were more variable. In some cases, prior information improved accuracy, while in others, it was reduced. On average, models with informative priors were no more or less accurate than models without. Our analyses provide a detailed case study on the simultaneous effect of prior information on precision and accuracy and demonstrate that when priors are specified appropriately, they lead to greater precision without systematically reducing model accuracy.     

Jolly - Seber 法估算长爪沙鼠种群参数的适用性探讨

以2000 年6 月～10 月群居性长爪沙鼠野生种群的标志重捕资料为依据, 采用Jolly - Seber 模型估算了该鼠种群参数, 结果表明, 长爪沙鼠个体间具等捕性(Leslie 法检验) , 研究期间取样个体的重捕率平均为89.7 %(77.4 % ～ 100 %) ; 参数估计结果具有合理的生物学意义, 认为采用该模型估算长爪沙鼠种群参数是适用的。     

Separating Population Structure from Population History: A Cladistic Analysis of the Geographical Distribution of Mitochondrial DNA Haplotypes in the Tiger Salamander, Ambystoma Tigrinum

Nonrandom associations of alleles or haplotypes with geographical location can arise from restricted gene flow, historical events (fragmentation, range expansion, colonization), or any mixture of these factors. In this paper, we show how a nested cladistic analysis of geographical distances can be used to test the null hypothesis of no geographical association of haplotypes, test the hypothesis that significant associations are due to restricted gene flow, and identify patterns of significant association that are due to historical events. In this last case, criteria are given to discriminate among contiguous range expansion, long-distance colonization, and population fragmentation. The ability to make these discriminations depends critically upon an adequate geographical sampling design. These points are illustrated with a worked example: mitochondrial DNA haplotypes in the salamander Ambystoma tigrinum. For this example, prior information exists about restricted gene flow and likely historical events, and the nested cladistic analyses were completely concordant with this prior information. This concordance establishes the plausibility of this nested cladistic approach, but much future work will be necessary to demonstrate robustness and to explore the power and accuracy of this procedure.     

Declining winter survival and fitness implications associated with latitudinal distribution in Norwegian Greylag Geese Anser anser

The Norwegian Greylag Goose Anser anser population has been increasing steadily over the past few decades, causing increasing nuisance in terms of agricultural crop damage. This, in combination with the importance of Greylags as a hunting target, has called for demographic estimates for the population to assist in management decisions. To this end, we analysed long-term mark–recapture data using Cormack–Jolly-Seber models embedded in program MARK to obtain survival estimates for the population. No sex-specific difference, or age effect on survival after juveniles had completed their first migration (3 months of age), was evident. Mean first-year survival was reported as 0.485 and annual survival of older birds as 0.700. On a monthly basis, survival in Greylags during summer and winter was very similar over the study period. A significant linear decline in winter survival from 0.909 to 0.807 was, however, apparent during the study period. Over the second half of the study (1994–2002), summer survival was about 3% lower than in the first half (1986–94) but no linear relationship was evident. We found a significant inverse relationship between Greylag survival during summer and latitudinal distribution in Norway. A similar relationship was evident between survival and annual bag numbers. The changes in adult survival observed in this study are likely to have had a substantial impact on the growth rate of the Norwegian Greylag population.