Vertical Migration of the Rice White-Tip Nematode,Aphelenchoides besseyi

In the laboratory, the vertical migration of Aphelenchoides besseyi was favored by rough surfaces and an inverse water gradient. In relation th gravity, the nematode migrated down or up equally, a circumstance suggesting that a geotaxis was not involved. Stems of rice seedlings were effective surfaces for vertical migration of nematodes only when the stems were continuously supplied with moisture.     

SOCIAL SELECTION AND THE EVOLUTION OF ANIMAL SIGNALS

Social selection is presented here as a parallel theory to sexual selection and is defined as a selective force that occurs when individuals change their own social behaviors, responding to signals sent by conspecifics in a way to influence the other individuals' fitness. I analyze the joint evolution of a social signal and behavioral responsiveness to the signal by a quantitative-genetic model. The equilibria of average phenotypes maintained by a balance of social selection and natural selection and their stability are examined for two alternative assumptions on behavioral responsiveness, neutral and adaptive. When behavioral responsiveness is neutral on fitness, a rapid evolution by runaway selection occurs only with enough genetic covariance between the signal and responsiveness. The condition for rapid evolution also depends on natural selection and the number of interacting individuals. When signals convey some information on signalers (e.g., fighting ability), behavioral responsiveness is adaptive such that a receiver's fitness is also influenced by the signal. Here there is a single point of equilibrium. The equilibrium point and its stability do not depend on the genetic correlation. The condition needed for evolution is that the signal is beneficial for receivers, which results from reliability of the signal. Frequency-dependent selection on responsiveness has almost no influence on the equilibrium and the rate of evolution.     

Differential Effects of Tachykinins Injected Intranigrally on Striatal Dopamine Metabolism

The effects of intranigral injection of kassinin, eledoisin, and substance P on striatal dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) contents as well as circling behavior were studied in rats. Kassinin and eledoisin produced a marked dose-dependent increase of DOPAC concentrations in the ipsilateral striatum, as well as in the number of contralateral circlings. Substance P produced a similar but weaker effect. At the larger dose (5 nmol), the three tachykinins also induced an increase of DA concentrations in the ipsilateral striatum. The rank order of activity was kassinin greater than eledoisin greater than substance P. These results suggest that tachykinins stimulated the nigro-striatal dopaminergic system by accelerating the dopamine metabolism in striatum.     

The roles of ecological and behavioral observation in species recognition among primates

Closely related living mammal species present numerous difficulties of recognition and delineation, not least because populations as well as individual organisms fulfill both genetic and economic functions. However, since species are often distributed geographically across multiple ecosystems or environments, it is evident that species as wholes, except where coterminous with the local populations of which they are composed, cannot be said to play unitary ecological roles. Aspects of the economic activity of organisms thus may not be admitted as elements in species recognition. Those who study the behavior of mammals in their natural habitats must therefore focus upon behaviors which preserve the genetic integrity of species if they wish to contribute to the systematic question of species identification. «Isolation» concepts of species are not served by data of this kind, since they emphasize interspecies discontinuities; the «recognition» concept of species, however, specifically focuses upon behaviors of this kind as they contribute to the «Specific-Mate Recognition System». Among primates such behaviors are likely to involve signalling of various kinds; where this is visual it is reasonable to expect to find morphological or chromatic correlates; where such cues are auditory or, to a lesser extent, olfactory, it is less probable that such correlates will be found to exist.     

PHYLOGENETIC ANALYSIS OF THE EVOLUTION OF ALTERNATIVE SOCIAL BEHAVIOR IN THE MANAKINS (AVES: PIPRIDAE)

Phylogenetic analyses of lekking, lek spatial organization, and cooperative and coordinated lek display in the manakins (Aves: Pipridae) demonstrate that variation in social behavior in the group has a strong, phylogenetic component. Two of the three classes of social behavior examined also show significant phylogenetic constraints. Current adaptive plasticity models are insufficient to explain the phylogenetic variation in these behaviors in the manakins. These findings support the conclusion that vertebrate reproductive social behavior has an evolutionary history, and that it is not determined solely by adaptive individual plasticity to current conditions. The evolution of social behavior, particularly through sexual selection, can have historical consequences that can limit subsequent behavioral adaptation.     

Risk of sperm competition does not influence copulatory behavior in the promiscuous meadow vole (<Emphasis Type="Italic">Microtus pennsylvanicus</Emphasis>)

It is not clear whether males in all mammalian species adjust their copulatory behavior when faced with risk of sperm competition (RSC). Previous work on meadow voles, Microtus pennsylvanicus, indicated that males increase their sperm expenditure but not the number of ejaculations in the presence of odors of a conspecific male. The present study follows up on this work and asks whether male meadow voles modify any aspect of their copulatory behavior when they face a RSC. We examined 46 variables of copulatory behavior and found that the presence of odors from a conspecific male did not affect any of these variables. Thus, male meadow voles, unlike some other species of mammals, do not adjust their copulatory behavior when exposed to cues associated with an elevated RSC.     

Influence of Different Abutment Designs on the Biomechanical Behavior of One-Piece Zirconia Dental Implants and Their Surrounding Bone: A 3D-FEA

BackgroundIn a dental implant/bone system, the design factors affect the value and distributions of stress and deformations that plays a pivotal role on the stability, durability and lifespan of the implant/bone system.ObjectiveThe aim of this study was to compare the influence of different abutment designs on the biomechanical behavior of one-piece zirconia dental implants and their surrounding bone tissues using three-dimensional finite element analysis.MethodsA three-dimensional geometrical model of a zirconia dental implant and its surrounding bone tissue were created. The occlusal loading force applied to the prosthetic abutments was a combination of 114.6 N in the axial direction, 17.1 N in the lingual direction and 23.4 N toward the mesial direction where these components represent masticatory force of 118.2 N in the angle of approximately 75° to the occlusal plane.ResultsThe system included implant abutment Model 01 showed a decrease of 9.58%, 9.92% and 3.62% at least in the average value of maximum von Mises stress compared to Model 02, Model 03 and Model 04 respectively. The results also showed that the system included implant abutment Model 01 decreases the average value of maximum deformation of 16.96%, 7.17% and 9.47% at least compared to Model 02, Model 03 and Model 04 respectively.ConclusionThe one-piece zirconia dental implant abutment Model 01 presents a better biomechanical behavior in the peri-implant bone than others. It can efficiently distribute the applied load and present more homogeneous behavior of stress distribution and has less deformation than others, which will enhance the stability of implant/bone system and prolong its lifespan.     

Successful feeding enrichment for captive chimpanzees

An analysis of a feeding enrichment program for captive chimpanzees was completed to determine the effects of that program on the incidence of agonistic and abnormal behaviors by using 41 adult chimpanzees in six social groups. Four feeding enrichment procedures were implemented simultaneously in the experimental phase of this ABA design study. The procedures were planned to elicit time-consuming, noncompetitive feeding, theorizing a consequent reduction in agonism and detrimental abnormal behaviors typically occurring in captive chimpanzees. The 270 hours of data were collected over a 6-month period. A multivariate analysis of variance result supported the hypothesis, as the barrage of feeding enrichment techniques significantly reduced agonism and abnormal behaviors. This study's significance lies in its application of the scientific method to improving the husbandry of captive primates.     

Behavioral and physiological effects of chronic 2,450-MHz microwave irradiation of the rat at 0.5 mW/cm2

Adult male Long-Evans rats were intermittently exposed to 2450 MHz CW microwaves at an average power density of 0.5 mW/cm2 for 90 days. The resulting SAR was 0.14 W/kg (range 0.11 to 0.18 W/kg). The animals were exposed 7 h/day, 7 days/wk, for a total of 630 h in a monopole-above-ground radiation chamber while housed in Plexiglas holding cages. Daily measures of body mass and food and water intake indicated no statistically significant effects of microwave exposure. Monthly assessment of reactivity to electric footshock, levels of cholinesterase and sulfhydryl groups in blood, and 17-ketosteroids in urine revealed no reliable differences between 14 sham-exposed and 14 microwave-exposed rats. After the 90 days of exposure, seven rats, randomly chosen from each group, were assessed for open-field behavior, shuttlebox performance, and schedule-controlled (IRT schedule) lever pressing for food pellets. Statistically significant differences between microwave-exposed and sham-exposed rats were observed in shuttlebox performances and lever pressing. Post mortem measures of mass of several organs and microscopic examination of adrenal tissue revealed no differences between the two groups of animals.