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Selected AbstractsPopulation density affects foraging behavior of male Black-throated Blue Warblers during the breeding seasonJOURNAL OF FIELD ORNITHOLOGY, Issue 2 2007Robert C. Dobbs ABSTRACT Foraging behavior often reflects food availability, a resource that may increasingly limit breeding birds as intraspecific crowding increases. Measuring foraging behavior, therefore, provides a way to investigate effects of population density on food limitation, an important link in understanding how crowding functions to regulate populations. We quantified three components of foraging behavior (prey attack rate, foraging speed, and relative use of morphologically constrained attack maneuvers) for male Black-throated Blue Warblers (Dendroica caerulescens) breeding under experimentally manipulated density conditions. Building on the previous work showing the density of conspecific neighbors affects territory size, reproductive success, and the time budgets of males (Sillett et al. 2004, Ecology 85: 2467,2477), we further show that density affects male foraging strategies. Although not differing in attack rate or foraging speed, male Black-throated Blue Warblers on territories with reduced neighbor densities used energetically expensive aerial attack maneuvers significantly less frequently than males in control (high-density) territories during both the incubation period and when provisioning nestlings and fledglings. We conclude that males altered their foraging behavior to compensate for density-related reductions in time available for foraging and that population density may constrain the time available for foraging. SINOPSIS La conducta de forrajeo muchas veces refleja la disponibilidad de alimentos, un recurso que puede limitar la capacidad reproductiva con el aumento en el número de individuos. El medir la conducta de forrajeo, puede proveer de una forma de investigar el efecto de la limitación de alimentos en la dencidad poblacional, enlace importante para entender como el acinamiento funciona para regular una población. Cuantificamos tres componentes de la conducta de forrajeo (tasa de ataque de la presa, velocidad de forrajeo, y uso relativo de maniobras de ataque con respecto a restricciones morfológicas) para machos de Dendroica caerulescens reproduciéndose bajo densidades manipuladas experimentalmente. Utilizando como base trabajos que señalan que la densidad conespecífica vecinal afecta el tamaño del territorio, el éxito reproductivo y el presupuesto utilizado por los machos (Sillett et al. 2004, Ecology 85:2467-2477) demostramos que la densidad afecta además la estrategia de forrajeo de los machos. Aunque no hay diferencia en la tasa de ataque o velocidad de forrajeo, machos en territorios con pocos vecinos, utilizaron maniobras de forrajeo energéticamente más costosas y con una frecuencia significativamente menos costosa que el grupo control (áreas con alta densidad), tanto durante la fase de incubación como la de crianza de pichones. Concluimos que los machos alteran su conducta de forrajeo para compensar por la reducción en la densidad de individuos y en el tiempo disponible para forrajear, y que la densidad de la población puede limitar el tiempo disponible para forrajear. [source] Origin and genetic diversity of Western European populations of the potato cyst nematode (Globodera pallida) inferred from mitochondrial sequences and microsatellite lociMOLECULAR ECOLOGY, Issue 9 2008O. PLANTARD Abstract Native to South America, the potato cyst nematode Globodera pallida is one of the principal pests of Andean potato crops and is also an important global pest following its introduction to Europe, Africa, North America, Asia and Oceania. Building on earlier work showing a clear south to north phylogeographic pattern in Peruvian populations, we have been able to identify the origin of Western European populations with high accuracy. They are all derived from a single restricted area in the extreme south of Peru, located between the north shore of the Lake Titicaca and Cusco. Only four cytochrome b haplotypes are found in Western Europe, one of them being also found in some populations of this area of southern Peru. The allelic richness at seven microsatellite loci observed in the Western European populations, although only one-third of that observed in this part of southern Peru, is comparable to the allelic richness observed in the northern region of Peru. This result could be explained by the fact that most of the genetic variability observed at the scale of a field or even of a region is already observed at the scale of a single plant within a field. Thus, even introduction via a single infected potato plant could result in the relatively high genetic variability observed in Western Europe. This finding has important consequences for the control of this pest and the development of quarantine measures. [source] Nicotine and Parkinson's disease: Implications for therapyMOVEMENT DISORDERS, Issue 12 2008Maryka Quik PhD Abstract Accumulating evidence suggests that nicotine, a drug that stimulates nicotinic acetylcholine receptors, may be of therapeutic value in Parkinson's disease. Beneficial effects may be several-fold. One of these is a protective action against nigrostriatal damage. This possibility stems from the results of epidemiological studies that consistently demonstrate an inverse correlation between tobacco use and Parkinson's disease. This reduced incidence of Parkinson's disease has been attributed to the nicotine in tobacco products, at least in part, based on experimental work showing a protective effect of nicotine against toxic insults. Second, several studies suggest a symptomatic effect of nicotine in Parkinson's disease, although effects are small and somewhat variable. Third, recent data in nonhuman primates show that nicotine attenuates levodopa-induced dyskinesias, a debilitating side effect that develops in the majority of patients on levodopa therapy. Collectively, these observations suggest that nicotine or CNS selective nicotinic receptor ligands hold promise for Parkinson's disease therapy to reduce disease progression, improve symptoms, and/or decrease levodopa-induced dyskinesias. © 2007 Movement Disorder Society [source] The relative role of drift and selection in shaping the human skullAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2010Lia Betti Abstract Human populations across the world vary greatly in cranial morphology. It is highly debated to what extent this variability has accumulated through neutral processes (genetic drift) or through natural selection driven by climate. By taking advantage of recent work showing that geographic distance along landmasses is an excellent proxy for neutral genetic differentiation, we quantify the relative role of drift versus selection in an exceptionally large dataset of human skulls. We show that neutral processes have been much more important than climate in shaping the human cranium. We further demonstrate that a large proportion of the signal for natural selection comes from populations from extremely cold regions. More generally, we show that, if drift is not explicitly accounted for, the effect of natural selection can be greatly overestimated. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source] Neurodevelopmental sequelae of postnatal maternal care in rodents: clinical and research implications of molecular insightsTHE JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY AND ALLIED DISCIPLINES, Issue 3-4 2007Arie Kaffman Parental care plays an important role in the emotional and cognitive development of the offspring. Children who have been exposed to abuse or neglect are more likely to develop numerous psychopathologies, while good parent,infant bonding is associated with improved resiliency to stress. Similar observations have also been reported in non-human primates and rodents, suggesting that at least some neurodevelopmental aspects of parent,offspring interactions are conserved among mammals and could therefore be studied in animals. We present data to suggest that frequency of licking and grooming provided by the dam during a critical period in development plays an important role in modifying neurodevelopment. These findings are examined in the broader context in which exposure to other sensory modalities such as vision or hearing during a specific period in development shapes brain development with functional consequences that persist into adulthood. We also discuss recent rodent work showing that increased frequency of licking and grooming provided by the dam during the first week of life is associated with changes in DNA methylation of promoter elements that control expression of these genes and behavior. The stability of DNA methylation in postmitotic cells provides a possible molecular scaffold by which changes in gene expression and behavioral traits induced by postnatal maternal care are maintained throughout life. Finally, the relevance of findings reported in rodents to those noted in non-human primates and humans are assessed and the research and clinical implications of these observations for future work are explored. [source] Response: Most people who think that they are likely to enter psychotherapy also think it is plausible that they could have forgotten their own memories of childhood sexual abuseAPPLIED COGNITIVE PSYCHOLOGY, Issue 2 2009David C. Rubin Pezdek and Blandon-Gitlin (2008) found that 25% of their participants reported as plausible or very plausible that they themselves could have been a victim of childhood sexual abuse without being able to remember it. In addition, they found that the 25% figure increased to 61% for participants who reported that they were likely at some point in their life to seek psychotherapy. Given past work showing that it is easier to implant a false memory for plausible events, and counter to Pezdek and Blandon-Gitlin's conclusions, these data point to a substantial danger of implanting false memories of childhood sexual abuse during therapy in many people and in most people who are likely to go into therapy. Theoretical issues regarding plausibility are discussed. Copyright © 2008 John Wiley & Sons, Ltd. [source] Developmental Coordination Disorder and Joint Hypermobility Syndrome , overlapping disorders?CHILD: CARE, HEALTH AND DEVELOPMENT, Issue 5 2007Implications for research, clinical practice Abstract Background, Joint Hypermobility Syndrome (JHS) and Developmental Coordination Disorder (DCD) are two childhood disorders usually identified separately. DCD is a heterogeneous condition with little known of the underlying aetiology of the disorder. This paper examines the potential overlap between DCD and JHS and examines children with DCD for symptoms which may be consistent with a diagnosis of JHS. Implications for research and clinical practice are considered. Methods, A questionnaire covering a range of symptoms consistent with a diagnosis of JHS and related autonomic nervous systemic symptoms was completed by parents from 27 children with DCD and compared with responses from parents of 27 typically developing children. Results, Children with DCD showed a significant difference from the group of typically developing children on questions regarding hypermobility, pain and autonomic nervous system symptoms, typifying JHS. Conclusions, This study has shown a similarity in symptoms seen in some DCD children to those with a diagnosis of JHS. In addition, children are also presenting with multi-system symptomatology including those involving the autonomic nervous system. This study reinforces other recent work showing the reverse pattern of JHS children showing similar functional similarities to DCD children. This has implications for future research in DCD in order to understand the underlying aetiology of this complex disorder. In addition, it is important for clinicians to be aware of these findings in order to provide appropriate and tailored support and treatment for children presenting with differing patterns of co-ordination difficulties. Children with DCD and JHS may require appropriate podiatry as well as recognition of their symptoms of pain and how this may affect participation in physical activity. [source] EVOLUTION OF REPRODUCTIVE ISOLATION WITHIN A PARASITIC FUNGAL SPECIES COMPLEXEVOLUTION, Issue 7 2007Mickael Le Gac Despite important advances in the last few years, the evolution of reproductive isolation (RI) remains an unresolved and critical gap in our understanding of speciation processes. In this study, we investigated the evolution of RI among species of the parasitic fungal species complex Microbotryum violaceum, which is responsible for anther smut disease of the Caryophyllaceae. We found no evidence for significant positive assortative mating by M. violaceum even over substantial degrees of genetic divergence, suggesting a lack of prezygotic isolation. In contrast, postzygotic isolation increased with the genetic distance between mating partners when measured as hyphal growth. Total RI, measured as the ability of the pathogen to infect and produce a diploid progeny in the host plant, was significantly and positively correlated with genetic distance, remaining below complete isolation for most of the species pairs. The results of this study, the first one on the time course of speciation in a fungus, are therefore consistent with previous works showing that RI generally evolves gradually with genetic distance, and thus presumably with time. Interestingly, prezygotic RI due to gamete recognition did not increase with genetic distance, in contrast to the pattern found in plants and animals. [source] Awakening dynamics via passive coupling and synchronization mechanism in oscillatory cellular neural/nonlinear networksINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 5-6 2008István Szatmári Abstract We have studied synchronization mechanism in locally coupled nonlinear oscillators. Here, synchronization takes place by passive coupling based on a reaction,diffusion process. We will compare this mechanism with basic synchronization techniques, showing their similarities and specific properties. In addition to synchronization, passive and local coupling can also ,awaken' non-oscillating cell circuits and trigger oscillation, provided that cells are locally active. This result resembles Turing's and Smale's works showing that locally communicating simple elements can produce very different patterns even if separate elements do not show any activity. This property will be demonstrated for two second-order cells and also for a large ensemble of oscillatory cells. In latter case, the network of oscillatory cells exhibits very sophisticated spatio-temporal waves, e.g. spiral waves. Copyright © 2008 John Wiley & Sons, Ltd. [source] | |||||||||||||