Eliminating autocorrelation reduces biological relevance of home range estimates

1. Destructive subsampling or restrictive sampling are often standard procedures to obtain independence of spatial observations in home range analyses. We examined whether home range estimators based upon kernel densities require serial independence of observations, by using a Monte Carlo simulation, antler flies and snapping turtles as models.
2. Home range size, time partitioning and total straight line distances travelled were tested to determine if subsampling improved kernel performance and estimation of home range parameters.
3. The accuracy and precision of home range estimates from the simulated data set improved at shorter time intervals despite the increase in autocorrelation among the observations.
4. Subsampling did not reduce autocorrelation among locational observations of snapping turtles or antler flies, and home range size, time partitioning and total distance travelled were better represented by autocorrelated observations.
5. We found that kernel densities do not require serial independence of observations when estimating home range, and we recommend that researchers maximize the number of observations using constant time intervals to increase the accuracy and precision of their estimates.     

大数据时代下的生态系统观测发展趋势与挑战

随着观测技术的发展, 生态学研究尺度不断扩大。生态系统观测从小规模合作、短时间个人观测向大规模、长时间、跨学科、多因子联合观测转变。传感器技术的革新带来了生态观测在时空尺度的扩展与精确度上的提升, 致使生态学观测数据的容量、产生速度与数据种类飞速增长。对生态系统数据获取、存储与管理的传统方法无疑不再能满足现代生态学研究的要求。因此, 我们建议以大数据时代的数据存储、管理与处理技术为基础, 整合生态物联观测网络(Internet of Ecology)、公民科学观测网络以及基于标准化数据管理的研究者网络互联, 建立整合生态系统观测平台来应对这一困境。为生态学研究者打造一站式生态观测服务, 是大数据时代下生态系统观测的大势所趋。     

Aristotle's study of the animal world: the case of the kobios and phucis

Aristotle was a remarkable observer of the living world. He made detailed observations on the anatomy and life history characteristics of many organisms as part of a larger study into the differentiae (diaphora) of groups of animals. This reexamination of Aristotle's observations of two small fishes is a study into the work or the way of being of particular organic wholes. As such, it is directed by three main objectives: to evaluate the accuracy of those observations Aristotle makes with regard to the kobios and phucis in the History of Animals, as well as to understand how he might have conducted his research; to determine whether aspects of those observations would ground more philosophical arguments; and to contribute to the understanding of the basic biology of these fishes. In so doing, this article also may introduce a new generation of biologists to the richness of Aristotle's biological observations and the questions that motivated them.     

中国草原/荒漠植物多样性监测网 模式植物群落监测方案

“模式群落”是指能够反映某种植被分类单元基本特征, 并可作为准确描述该植被类型“标准”的典型植物群落。中国生物多样性监测网络——草原/荒漠植物多样性监测网旨在统一监测方法和技术规范的基础上, 在草原/荒漠植被主要群系分布的典型地段建立模式植物群落监测固定样方, 定期复查, 长期监测草原和荒漠的植物多样性变化。文章强调了典型植物群落监测是生物多样性监测的重要组成部分, 阐述了模式群落的概念, 介绍了草原/荒漠植物多样性监测网的总体思路和布局, 以及主要监测内容、方法、指标和预期产出。     

Citizen science can complement professional invasive plant surveys and improve estimates of suitable habitat

Aim

Citizen science is a cost-effective potential source of invasive species occurrence data. However, data quality issues due to unstructured sampling approaches may discourage the use of these observations by science and conservation professionals. This study explored the utility of low-structure iNaturalist citizen science data in invasive plant monitoring. We first examined the prevalence of invasive taxa in iNaturalist plant observations and sampling biases associated with these data. Using four invasive species as examples, we then compared iNaturalist and professional agency observations and used the two datasets to model suitable habitat for each species.

Location

Hawai'i, USA.

Methods

To estimate the prevalence of invasive plant data, we compared the number of species and observations recorded in iNaturalist to botanical checklists for Hawai'i. Sampling bias was quantified along gradients of site accessibility, protective status and vegetation disturbance using a bias index. Habitat suitability for four invasive species was modelled in Maxent, using observations from iNaturalist, professional agencies and stratified subsets of iNaturalist data.

Results

iNaturalist plant observations were biased towards invasive species, which were frequently recorded in areas with higher road/trail density and vegetation disturbance. Professional observations of four example invasive species tended to occur in less accessible, native-dominated sites. Habitat suitability models based on iNaturalist versus professional data showed moderate overlap and different distributions of suitable habitat across vegetation disturbance classes. Stratifying iNaturalist observations had little effect on how suitable habitat was distributed for the species modelled in this study.

Main Conclusions

Opportunistic iNaturalist observations have the potential to complement and expand professional invasive plant monitoring, which we found was often affected by inverse sampling biases. Invasive species represented a high proportion of iNaturalist plant observations, and were recorded in environments that were not captured by professional surveys. Combining the datasets thus led to more comprehensive estimates of suitable habitat.     

Note on a binomial test against sectoral preference of circular observations

A binomial test is proposed to test the nullhypothesis of uniform distribution of circular observations against the alternative of sectoral preference where the sector in which the observations are expected to cluster must be chosen prior to sampling. This binomial test against sectoral preference is illustrated by an example from psychopharmacology. The method is modified for comparing the sectoral proportions of two independent as well as two paired samples of circular observations.     

Analysis and description of the evolution of alginate immobilised cells systems

Different immobilised cells models, including very simple ones, can be useful in the fitting of experimental results. However, goodness or the ability to extrapolate results needs to be in accordance with basic observations and these will also suggest models to be proposed. In this paper, observations of calcium alginate/bacteria systems are used to show the ability of basic models to fit classic observations, as well as how new observations, in this case from electronic microscopy, oblige us to think about more complex mechanisms and mathematical treatments. Nevertheless it is not only important to discuss the model type, but also the type of kinetics assumed in the interior of the beads, as well as the internal structure, the boundary conditions related to bead shredding and cell escape and finally, geometrical effects.     

Consistency of fish‐shoal social network structure under laboratory conditions

We investigated the consistency of association network structure for groups of sticklebacks Gasterosteus aculeatus. Each group was observed twice and we varied the duration between observations and the size of the experimental arena that they were observed in. At the dyad level, we found positive correlations between dyad interaction frequencies across observations. At the group level we found variation in four network metrics between observations, but only in treatments where the duration between observations was short. Specifically, fish formed more and smaller groups in the second observation in this treatment. Fish were also organized into more subunits in the larger arenas. Finally, we saw positive correlations between some group network metrics across observations suggesting relative consistency at the group level. There are several processes that might drive these interaction patterns. Our findings have implications for experimental design and the comparison and integration of findings of experiments from different studies carried out under different conditions.     

Chisquare Tests From Clusters of Observations

A simple model for categorical observations that are correlated in clusters is developed. The implied correlation coefficient is used to define an effective number of observations, and a natural estimation procedure for the correlation coefficient is proposed. By grouping the clusters of observations, and by relating them to models of the probabilities for the implied categories, common chisquare tests are formulated and motivated asymptotically. As an example of applications we look at forage registrations for radio-collared moose.     

Cultural transmission of snake-mobbing in free-ranging Hanuman langurs

A focal troop of free-ranging Hanuman langurs (Presbytis entellus) living in an open scrub forest around Jodhpur was observed mobbing poisonous snakes on two different occasions during field observations of about 4,109 h. These observations of snake-mobbing demonstrate that langurs exhibit a special behaviour against 'potentially dangerous animals' which is similar to the mobbing displays of birds, and of other primates. It is suggested that the adaptive significance of snake-mobbing among langurs lies in the 'cultural transmission' of this information. These observations further support the 'kin-selection' model.     

Adult male replacement in a group of silvered leaf-monkeys (Presbytis cristata) at Kuala Selangor,Malaysia

During observations of silvered leaf-monkeys at Kuala Selangor, Malaysia, the resident adult male in one group was replaced by an immigrant male. Three months after the replacement, all of the dependent infants in the group disappeared. The similarity of these observations to observations of male-takeovers and subsequent infanticide among Indian and Ceylonese langurs suggests a similar pattern of social change among all langurs which live in one-male groups.     

Estimation of Heritability in Heteroscedastic One‐Way Unbalanced Random Model

A modified estimator of heritability is proposed under heteroscedastic one way unbalanced random model. The distribution, moments and probability of permissible values (PPV) for conventional and modified estimators are derived. The behaviour of two estimators has been investigated, numerically, to devise a suitable estimator of heritability under variance heterogeneity. The numerical results reveal that under balanced case the heteroscedasticity affects the bias, MSE and PPV of conventional estimator, marginally. In case of unbalanced situations, the conventional estimator underestimates the parameter when more variable group has more observations and overestimates when more variable group has less observations, MSE of the conventional estimator decreases when more variable group has more observations and increases when more variable group has less observations and PPV is marginally decreased. The MSE and PPV are comparable for two estimators while the bias of modified estimator is less than the conventional estimator particularly for small and medium values of the parameter. These results suggest the use of modified estimator with equal or more observations for more variable group in presence of variance heterogeneity.     

A note on the effect of observations with missing data on genetic correlation estimates

Summary Various studies have estimated covariance components as half the difference between the variance component of the sum of the variable values, for each observation, and the sum of the corresponding variable variance components. Although the variance components for the separate variables can be computed using all available data, the variance components of the sum can be computed only from those observations with records for both variables. Previous studies have suggested eliminating observations with missing data, because of possible selection bias. The effect of missing data on estimates of covariance components and genetic correlations was tested on sample beef cattle data and simulated data by randomly deleting differing proportions of records of one variable for each pair of variables analyzed. Estimates of genetic correlations computed with observations with missing data eliminated, were more accurate than estimates computed using all available data. Furthermore, when observations with missing data were included, estimates of genetic correlation far outside the parameter space were common. Therefore, this method should be used only if observations with missing data have been eliminated.     

Sampling field distributions of Mnemiopsis leidyi (Ctenophora, Lobata): planktonic or benthic methods?

SCUBA observations confirm dense aggregations of the ctenophoreMnemiopsis leidyi in surface and bottom layers of waters offsouthern Argentina. These observations are consistent with resultsfrom prior studies indicating directed vertical migration ofM. leidyi.     

Spontaneous tool-use: an observation of a dingo (Canis dingo) using a table to access an out-of-reach food reward

Opportunities to observe non-human animals exhibiting naturalistic 'high-order' behaviour are rare. Examples featuring canids, although often anecdotal and involving captive animals are potentially valuable, as they may provide an opportunity to examine complex problem-solving behaviour not easily observed in free-ranging settings. This paper describes observations of two captive male dingoes (Canis dingo), representing possible examples of high-order behaviour. The first set of observations involved a sub-adult male that spontaneously (i.e., without training) learned to move objects around his enclosure, apparently to multiple ends, such as in an effort to gain the additional height required to attain objects otherwise out of reach, or to attain a better view of his surroundings. The second set of observations involved an adult male that learned to open a gate, possibly in an effort to gain access to a female. These observations add to the small number of anecdotal accounts offering a window into the cognitive abilities of canids, and the observations involving the sub-adult male appear to be the first documented cases of tool-use in a canid.     

Temporal pooling of point transect data increases precision in density estimates of southern chamois

Estimating animal abundances in small areas is a difficult task and because a limited number of observations often results in low-precision estimates whose inaccuracies may even be exacerbated if surveys are focussed on clustered populations and/or are only carried out once a year. In an attempt to overcome this problem, we used point transects to monthly survey two small areas of a game reserve to assess the density of Pyrenean chamois (Rupicapra p. pyrenaica). The coefficient of variation associated with the density estimates after pooling observations by season was still high but decreased to reasonable values (<20%) when observations were over 29 chamois groups (clusters). Our results suggest that Distance Sampling may be a useful way of estimating the population density of mountain ungulates such as Pyrenean chamois in small rugged areas where only a small or moderate number of observations are to be expected.     

Adapting to an Uncertain World: Cognitive Capacity and Causal Reasoning with Ambiguous Observations

Ambiguous causal evidence in which the covariance of the cause and effect is partially known is pervasive in real life situations. Little is known about how people reason about causal associations with ambiguous information and the underlying cognitive mechanisms. This paper presents three experiments exploring the cognitive mechanisms of causal reasoning with ambiguous observations. Results revealed that the influence of ambiguous observations manifested by missing information on causal reasoning depended on the availability of cognitive resources, suggesting that processing ambiguous information may involve deliberative cognitive processes. Experiment 1 demonstrated that subjects did not ignore the ambiguous observations in causal reasoning. They also had a general tendency to treat the ambiguous observations as negative evidence against the causal association. Experiment 2 and Experiment 3 included a causal learning task requiring a high cognitive demand in which paired stimuli were presented to subjects sequentially. Both experiments revealed that processing ambiguous or missing observations can depend on the availability of cognitive resources. Experiment 2 suggested that the contribution of working memory capacity to the comprehensiveness of evidence retention was reduced when there were ambiguous or missing observations. Experiment 3 demonstrated that an increase in cognitive demand due to a change in the task format reduced subjects’ tendency to treat ambiguous-missing observations as negative cues.     

Nested ANOVA for Repeated Surveys with Autocorrelated Errors

Diet surveys in the science of human nutrition involve longitudinal observations on the same individuals repeated at distinct time points. Consequently a common feature of such surveys is inherent correlation between successive observations. In this paper, an autoregressive model of order 1 is assumed for the successive observations on the same individual in a survey. Further, observations on the same individual in two different surveys are assumed to be correlated. The technique of analysis of variance is modified suitably for this set up and applied to two nutritional surveys carried on army recruits.     

Use of zoospore concentrations and life cycle parameters in determining the population of anaerobic fungi in the rumen ecosystem

An indirect approach to quantification of the fibrolytic anaerobic fungi in the rumen is described. A mathematical model of the life cycle of anaerobic fungi, based upon observations of the life histories and growth kinetics of these organisms in vitro and in vivo, is constructed and solved in the steady-state to determine the population of particle-attached (substrate-associated) fungal thalli from the concentration of free-swimming zoospores in rumen liquid. The values obtained are broadly consistent with ruminal observations and with observations on faecal populations, which assume that a significant proportion of fungi leaving the rumen (as cysts or spores) can ultimately be accounted for in the faeces.     

Optimal crossover designs in the presence of carryover effects

Under either the random patient-effect model with sequence effects or the fixed patient-effect model, the usual two-period, two-treatment crossover design, AB,BA, cannot be used to estimate the contrast between direct treatment effects when unequal carryover effects are present. If baseline observations are available, the design AB,BA can validly be used to estimate a treatment contrast. However, the design AB,BA,AA,BB with baseline observations is more efficient. In fact, we show that this design is optimal whether or not baseline observations are available. For experiments with more than two periods, universally optimal designs are found for both models, with and without carryover effects. It is shown that uncertainty about the presence of carryover effects is of little or no consequence, and the addition of baseline observations is of little or no added value for designs with three or more periods; however, if the experiment is limited to only two periods the investigator pays a heavy penalty.