Reconstructing the Pleistocene geography of the Aphelocoma jays (Corvidae)

Understanding historical distributions of species and evolving lineages has been a topic of considerable interest, yet methods used to date have not provided detailed, quantitative distributional hypotheses. Here, we present a technique based on models of species’ ecological niches and Pleistocene climate reconstructions that provides such hypotheses, providing the example of reconstructions for the Aphelocoma jays. We demonstrate in general a greater degree than expected of stability in jay species’ distributional areas back through at least the most recent glaciation event, and that existing patterns of genetic differentiation may date to before the Late Pleistocene glaciations. More generally, the method offers the potential for reconstructing historical distributions of species or lineages, and providing a detailed geographic framework for addressing many biogeographic and systematic questions.     

On a property of the exponential distribution

If t is an independent exponentially distributed random variable, the distribution p = [t - x] is a modified geometric distribution, similar to the result of HAWKINS and KOTZ (1976), x is uniform.     

On the Discrete POISSON-Inverse GAUSSian Distribution

The discrete POISSON-inverse GAUssian distribution is obtained by compounding the POISSON distribution with the inverse-GAUssian distribution. The maximum likelihood of the parameter is discussed. Comparison with the POISSON, negative binomial, POISSON-LINDLEY and the generalized WARING distribution when fitting a distribution to accident statistics data is given.     

Comments on "Improving estimates of the basic reproductive ratio: using both the mean and the dispersal of transition times"

Comments on Heffernan, J. M., Wahl, L. M. (2006). Improving estimates of the basic reproductive ratio: Using both the mean and the dispersal of transition times. Theoretical Population Biology, 70, 135-145.     

A note on the statistical properties of animal locations

A statistical model of the successive locations of an animal in the plane induces a statistical model of the relative positions of successive locations. A common locational model is that the Cartesian coordinates of successive locations in the plane are independent bivariate normal random variables. This note gives the statistical properties of the direction and length of the vector joining successive locations.     

Recall of sequences based on the position of the first cue stimulus in rats

We investigated the ability of rats to recall sequences of nose-poke holes with a modified serial reaction time task. In each trial, a sequence was randomly selected and the position of the first illuminated hole, which functioned as a cue stimulus, informed the rats whether the following sequence was a predictable one or not, based on prior training. The rats responded predictively only when the cues of the predictable sequences were presented. They did not show predictive responses when the cues of unpredictable sequences were presented, even though the unpredictable sequences partially had the same order of holes as the predictable sequences. These results indicate that the rats can recall sequences on the basis of presentation of the first cue stimulus informing predictable or unpredictable sequences. Recording neuronal activity while rats perform this behavioral task would be useful to elucidate neuronal mechanisms that mediate sequence recall.     

Limits to the estimation of species richness: The use of relative abundance distributions

The present study demonstrates the possibility of estimating species numbers of animal or plant communities from samples using relative abundance distributions. We use log‐abundance–species‐rank order plots and derive two new estimators that are based on log‐series and lognormal distributions. At small to moderate sample sizes these estimators appear to be more precise than previous parametric and nonparametric estimators. We test our estimators using samples from 171 published medium‐sized to large animal and plant communities taken from the literature. By this we show that our new estimators define also limits of precision.     

Turbellaria from intertidal flats and salt-marshes in the estuaries of the south-western part of the Netherlands

A list of 91 species of Turbellaria from intertidal flats and saltmarshes in the estuaries of the south-western part of the Netherlands is given.     

The statistical analysis of the differential blood count

The differential blood count obtained by unbiased sampling mathematically follows a multinomial distribution. The variation between individuals can be formalized by a mixing distribution of the parameters of the multinomial distribution. By DIRICHLET-distributions used as mixing distributions the main phenomena of the observed data can be described, and they are useful in estimating and testing treatment effects. If the correlation between the different types of leucocytes is taken into account in an appropriate manner, univariate test procedures can be applied also.     

Use of the Likelihood Ratio Test on the Uniform Distribution

In this article we give a simple procedure to determine the exact distribution of the likelihood ratio test of a statistical hypothesis regarding the parameter of the uniform distribution. The resulting distribution will be shown to serve as an approximation to the distribution of the likelihood ratio statistic for testing the equality of scale parameters of k independent Exponential populations.