Blurring the picture:Introductions, invasions, extinctions - Biogeography in a global world

Global biogeography and phylogeography have gained importance as research topics in zoology, as attested by the steady increase in the number of journals devoted to this topic and the number of papers published. Yet, in a globalising world, with species reintroductions, invasions of alien species, and large-scale extinctions, unravelling the true biogeographic relationships between areas and species may become increasingly difficult. We present an introduction to the symposium ‘Biogeography: explaining and predicting species distributions in space and time’ held in Amsterdam in 2007, and the resulting papers as published in this special issue, including papers on crustaceans, birds and mammals

Can cohort data be treated as genuine panel data?

If repeated observations on the same individuals are not available it is not possible to capture unobserved individual characteristics in a linear model by using the standard fixed effects estimator. If large numbers of observations are available in each period one can use cohorts of individuals with common characteristics to achieve the same goal, as shown by Deaton (1985). It is tempting to analyze the observations on cohort averages as if they are observations on individuals which are observed in consecutive time periods. In this paper we analyze under which conditions this is a valid approach. Moreover, we consider the impact of the construction of the cohorts on the bias in the standard fixed effects estimator. Our results show that the effects of ignoring the fact that only a synthetic panel is available will be small if the cohort sizes are sufficiently large (100, 200 individuals) and if the true means within each cohort exhibit sufficient time variation

Effect of introduced species and habitat alteration on the occurrence and distribution of euryhaline fishes in fresh- and brackish-water habitats on Aruba, Bonaire and Curaçao (South Caribbean)

We conducted an ichthyological survey during the dry season of 2006 on the semi-arid islands of Aruba, Bonaire and Curaçao to provide information on species composition, richness and distribution in natural and non-natural aquatic habitats. The dry season species assemblages (N = 9 species) comprised less species than the wet seasons, and these data refine our knowledge of the indigenous fish fauna and its refuge localities during phases of drought and ensuing high salinity. A hierarchical cluster analysis reveals that the three islands have different species compositions with Curaçao being the most diverse, probably due to its having the most habitats and freshwaters present throughout the year. Species richness was unrelated to salinity and species diversity was highest in canalised streams. In the dry season fewer amphidromous species are present than in the wet season. We found no significant effect of human-induced changes on the presence or absence of fish species in the Netherlands Antilles. The presence of exotic species (including Xiphophorus helleri on Aruba, a first record for this island, and Oreochromis mossambicus and Poecilia reticulata occurring on all three islands) did not have a clear effect on the presence of indigenous species, nor did human alteration of the habitats have an influence on the occurrence of fish species

Eliminating Biases in Evaluating Mutual Fund Performance from a Survivorship Free Sample

Poor performing mutual funds are less likely to be observed in the data sets that are typically available. This so-called survivor problem can induce a substantial bias in measures of the performance of the funds and the persistence of this performance. Many studies have recently argued that survivorship bias can be avoided by analyzing a sample that contains returns on each fund up to the period of disappearance using standard techniques. Such data sets are usually referred to as 'survivorship free'. In this paper we show that the use of standard methods of analysis on a 'survivorship free' data-set typically still suffers from a bias and we show how one can easily correct for this using weights based on probit regressions. Using a sample with quarterly returns on U.S. based equity funds, we first of all model how survival probabilities depend upon historical returns, the age of the fund and upon aggregate economy-wide shocks. Subsequently we employ a Monte Carlo study to analyze the size and shape of the survivorship bias in various performance measures that arise when a 'survivorship free database' is used with standard techniques. In particular, we show that survivorship bias induces a spurious U-shape pattern in performance persistence. Finally, we show how a weighting procedure based upon probit regressions can be used to correct for the bias. In this way, we obtain bias-corrected estimates of abnormal performance relative to a one-factor and the Carhart [1997] four-factor model, as well as its persistence. Our results are in accordance with the persistence pattern found by Carhart [1997], and do not support the existence of a hot hand phenomenon in mutual fund performance.

The wild cat trade in Myanmar

A total of 1,320 wild cat parts, representing an absolute minimum of 1158 individual animals were observed during 12 surveys carried out in Myanmar (formerly Burma) between 1991 and 2006. These parts represented all eight species of wild cats found in Myanmar

An overview of the regulation of the freshwater turtle and tortoise pet trade in Jakarta, Indonesia (Tinjauan terhadap peraturan perdagangan kura-kura air tawar sebagai satwa peliharaan di Jakarta, Indonesia)

In an attempt to gain a greater insight into the drivers behind wildlife trade and to increase our understanding of how to regulate this trade, this survey provides an overview of the management and control of wildlife harvesting in Indonesia. TRAFFIC Southeast Asia report

Co-existing violence and self-harm: dual harm in an early-stage male prison population

Purpose: This study examined the characteristics of men in prison who have a history of both self-harm and violence (known as dual harm) and the extent to which demographic and criminogenic factors, in-prison incidents and self-harm method could differentiate men who dual harm. Methods: Official prison sample data were examined for the period April 2010 to November 2017 (n = 965). Regression analysis of all custodial incidents, demographic and offending information, and imprisonment experience, was undertaken. Results: Self harm was associated with violence in prison, representing a 3.5-fold risk of violence compared with men who did not self-harm, after controlling for time in prison, age and index offence. 60% of men who harmed themselves also engaged in custodial violence, while 32% who were violent also had a self-harm event. After controlling for age at first incident, 11% of the sample had custodial history of dual harm and they accounted for 56% of all recorded custodial incidents. They had a high probability of property damage and fire-setting in prison and spent 40% longer in custody). Men who dual harmed used a greater variety of self-harm methods, with increased use of lethal methods. Conclusion: Dual harm is prevalent, particularly amongst those who harm themselves in prison. Men who dual harm contribute excessively to the overall incident burden in prison and demonstrate behavioural variability and risk regarding both violence and self-harm. The findings challenge the usual distinctive management responses or that self-harm or violence are solely the responsibility of health or justice; with greater integration required