The zebrafish is an important model organism in developmental genetics, neurophysiology and biomedicine, but little is known about its natural ecology and behaviour. It is a small, shoaling cyprinid, native to the flood-plains of the Indian subcontinent, where it is found in shallow, slow-flowing waters. Zebrafish are group spawners and egg scatterers, although females are choosy with respect to sites for oviposition and males defend territories around such sites. Laboratory studies of zebrafish behaviour have encompassed shoaling, foraging, reproduction, sensory perception and learning. These studies are reviewed in relation to the suitability of the zebrafish as a model for studies on cognition and learning, development, behavioural and evolutionary ecology, and behavioural genetics.

Many marine fish and invertebrates show a dual life history where settled adults produce dispersing larvae. The planktonic nature of the early larval stages suggests a passive dispersal model where ocean currents would quickly cause panmixis over large spatial scales and prevent isolation of populations, a prerequisite for speciation. However, high biodiversity and species abundance in coral reefs contradict this panmixis hypothesis. Although ocean currents are a major force in larval dispersal, recent studies show far greater retention than predicted by advection models. We investigated the role of animal behavior in retention and homing of coral reef fish larvae resulting in two important discoveries: (i) Settling larvae are capable of olfactory discrimination and prefer the odor of their home reef, thereby demonstrating to us that nearby reefs smell different. (ii) Whereas one species showed panmixis as predicted from our advection model, another species showed significant genetic population substructure suggestive of strong homing. Thus, the smell of reefs could allow larvae to choose currents that return them to reefs in general and natal reefs in particular. As a consequence, reef populations can develop genetic differences that might lead to reproductive isolation.coral reef ͉ olfaction ͉ population genetics

G ST -values and its relatives (F ST ) belong to the most used parameters to define genetic differences between populations. Originally, they were developed for allozymes with very low number of alleles. Using highly polymorphic microsatellite markers it was often puzzling that G ST -values were very low but statistically significant. In their papers, Jost (2008) and Hedrick (2005) explained that G ST -values do not show genetic differentiation, and Jost suggested calculating D-values instead. Theoretical mathematical considerations are often difficult to follow; therefore, we chose an applied approach comparing two artificial populations with different number of alleles at equal frequencies and known genetic divergence. Our results show that even for more than one allele per population G ST -values do not calculate population differentiation correctly; in contrast, D-values do reflect the genetic differentiation indicating that data based on G ST -values need to be re-evaluated. In our approach, statistical evaluations remained similar. We provide information about the impact of different sample sizes on D-values in relation to number of alleles and genetic divergence.

Based on a bio-social-ecological systems model of the development and maintenance of obesity, there has been in the last few years a growing research interest in the association of obesity and personality traits. The aim of the present review was a comprehensive and critical evaluation of the existing literature taking into account the methodological quality of studies to enhance our understanding of personality traits associated with body weight, the development of overweight and obesity as well as the effectiveness of weight loss interventions including bariatric surgery. Personality traits play an important role both as risk as well as protective factors in the development of overweight and obesity. While thus in particular 'neuroticism', 'impulsivity' and 'sensitivity to reward' appear as risk factors, 'conscientiousness' and 'self-control' have been shown to have a protective function in relation to weight gain. Conscientiousness is a measure of regulation of internal urges and self-discipline, and may thus provide a potential source of control over impulsive reward-oriented behaviour. The results of the present review suggest that, within the context of therapeutic weight reduction measures, it is meaningful to identify subgroups of patients for whom specific treatment options need to be developed, such as measures for strengthening self-control skills.

The incredible range of morphological plasticity present in scleractinian corals has confused the taxonomy of the group, prompting the introduction of ''ecomorphs'' to explain the observed correlation between local environmental conditions and phenotypic variation. Pocillopora damicornis (Linnaeus, 1758) represents one of the best known examples of eco-phenotypic variation in scleractinian corals with a variety of forms and reproductive strategies reported across its global distribution range. Here, we reconstruct genealogical relationships of P. damicornis colonies collected from thirteen locations along the East Australian coast to examine the relationship between genetic and phenotypic diversity in this species. Haplotype networks computed from two mitochondrial DNA regions (CR, ORF) indicate that the range of morphotypes observed within this taxon fall into at least five genetically distinct mitochondrial lineages. Nuclear (HSP70, ITS2) haplowebs on the other hand recover sharp genetic discontinuities among three of the morphological groups. We conclude that P. damicornis from Eastern Australia constitutes a cryptic species complex. The misinterpretation of taxonomical units within P. damicornis may well explain its perceived variation in the ecology, biology and life history across its range.

While evidence is mounting that larval reef fish are active participants in the process of dispersal and settlement, the sensory and behavioural mechanisms by which these fishes disperse and return from their oceanic phase to the reefs remain unknown. On One Tree Island (Great Barrier Reef, Australia), we tested freshly collected animals in a large choice-flume on the shore. Here, we present the first evidence that larval reef fish (primarily apogonids) approaching the time of settlement are capable of detecting differences between ocean and lagoon water and prefer lagoon water. We also demonstrate that they sniff actively with well-innervated noses and that attraction to lagoon water was not affected by warmer or colder temperatures. We conclude that they used chemical signals to orient toward lagoon water. Finally, we describe ebb tide plumes of lagoon water that extend many kilometers from reefs. Such plumes could provide chemosensory cues for dispersal and settlement stages of reef fish as they develop swimming efficiency. We argue that fishes may imprint to reef odour as embryos and/or early larvae and that this could facilitate both retention near the natal reef and navigation toward reefs from greater distances.

We studied the barrier effects of various roadways on the genetic subdivision of bank vole (Clethrionomys glareolus) populations. Allele frequencies, genetic variability, and genetic distances of natural populations were calculated based on polymorphism of seven microsatellite markers. We compared bank vole populations in control areas without such barriers with animals from both sides of a country road, a railway, and a highway. Using F and R statistics, we demonstrated significant population subdivision in bank vole populations separated by the highway, but not in populations on either side of the other roadways or in the control area. Correlations between geographic and genetic distances were revealed by an extended method based on a Mantel analysis. This allowed us to measure genetic barrier effects and express them as additional geographic distances. For instance, statistically significant differences in allele frequencies in all seven loci examined existed among populations in southern Germany and Switzerland, which are separated by the Rhine River and Lake Constance. The real geographic distance between bank vole populations in Konstanz and those in Lengwil, Switzerland, was 6 km. According to this analysis the genetic barrier effect of the Rhine could be defined as an additional distance of 7.7 km. This study shows for the first time that not only old geographic barriers but also more recent fragmentation of landscape by, for example, highways has an important effect on gene flow and the genetic substructuring of populations, which should be considered in future environmental impact assessments.

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