Molecular phylogenetic analysis of evolutionary trends in stonefly wing structure and locomotor behavior

Insects in the order Plecoptera (stoneflies) use a form of two-dimensional aerodynamic locomotion called surface skimming to move across water surfaces. Because their weight is supported by water, skimmers can achieve effective aerodynamic locomotion even with small wings and weak flight muscles. These mechanical features stimulated the hypothesis that surface skimming may have been an intermediate stage in the evolution of insect flight, which has perhaps been retained in certain modern stoneflies. Here we present a phylogeny of Plecoptera based on nucleotide sequence data from the small subunit rRNA (18S) gene. By mapping locomotor behavior and wing structural data onto the phylogeny, we distinguish between the competing hypotheses that skimming is a retained ancestral trait or, alternatively, a relatively recent loss of flight. Our results show that basal stoneflies are surface skimmers, and that various forms of surface skimming are distributed widely across the plecopteran phylogeny. Stonefly wings show evolutionary trends in the number of cross veins and the thickness of the cuticle of the longitudinal veins that are consistent with elaboration and diversification of flight-related traits. These data support the hypothesis that the first stoneflies were surface skimmers, and that wing structures important for aerial flight have become elaborated and more diverse during the radiation of modern stoneflies.

Recovery of hearing and vocal behavior after hair-cell regeneration

Postmitotic hair-cell regeneration in the inner ear of birds provides an opportunity to study the effect of renewed auditory input on auditory perception, vocal production, and vocal learning in a vertebrate. We used behavioral conditioning to test both perception and vocal production in a small Australian parrot, the budgerigar. Results show that both auditory perception and vocal production are disrupted when hair cells are damaged or lost but that these behaviors return to near normal over time. Precision in vocal production completely recovers well before recovery of full auditory function. These results may have particular relevance for understanding the relation between hearing loss and human speech production especially where there is consideration of an auditory prosthetic device. The present results show, at least for a bird, that even limited recovery of auditory input soon after deafening can support full recovery of vocal precision.

Visual constraints in foraging bumblebees: Flower size and color affect search time and flight behavior

In optimal foraging theory, search time is a key variable defining the value of a prey type. But the sensory-perceptual processes that constrain the search for food have rarely been considered. Here we evaluate the flight behavior of bumblebees (Bombus terrestris) searching for artificial flowers of various sizes and colors. When flowers were large, search times correlated well with the color contrast of the targets with their green foliage-type background, as predicted by a model of color opponent coding using inputs from the bees' UV, blue, and green receptors. Targets that made poor color contrast with their backdrop, such as white, UV-reflecting ones, or red flowers, took longest to detect, even though brightness contrast with the background was pronounced. When searching for small targets, bees changed their strategy in several ways. They flew significantly slower and closer to the ground, so increasing the minimum detectable area subtended by an object on the ground. In addition, they used a different neuronal channel for flower detection. Instead of color contrast, they used only the green receptor signal for detection. We relate these findings to temporal and spatial limitations of different neuronal channels involved in stimulus detection and recognition. Thus, foraging speed may not be limited only by factors such as prey density, flight energetics, and scramble competition. Our results show that understanding the behavioral ecology of foraging can substantially gain from knowledge about mechanisms of visual information processing.

The Relationships Between Child Maltreatment and Exploratory Behavior Implications for Development.

Findings from the fields of attachment theory, physiology, neurology, neurobiology and cognitive theory, when considered together, enhance understanding of the behavior and development of maltreated children. Each field describes from its own vantage how emotional trauma influences the quality and quantity of exploratory behavior. Development in many spheres is influemced by behavior. There is evidence from the field of neurobiology that experience ultimately influences the anatomy of the brain. Therefore, it can be hypothesized that constricted, overly defensive behavior in childhood ultimately compromises the development of the central nervous system itself. The altered neurobiology may help explain some of the developmental delays and failures seen in some maltreated children. Such developmental disruptions may include lowered intellectual performance, impaired ability to learn from experience, behavioral regressions under stress, and characterological abnormalities. This neurobiologic hypothesis has implications for research, intervention and training of professionals.It encourages 1) the identification of those deficit capacities most vulnerable to becoming neurologically based, 2) identification of ways to help the maltreated child explore and be accessible to developmental experiences, 3) more emphasis on the development of cognitive capacities, and 4) more breadth of training for professionals who work with maltreated children and their families.

Temperament and race,

"Annotated bibliography": p. 353-358.

Changes in motor vehicle buyer attitudes and market behavior. Final report.

National Highway Traffic Safety Administration, Office of Research and Development, Washington, D.C.

The effect of induced flocculation on the settling and thickening behavior of activated sludge /

"Supported by U.S. Public Health Service Traineeship EH66-616 and U.S. Dept. of Interior Research Project WP 01011-01."

Methods for increasing the computational efficiency of input-output and related large scale matrix operations /

Includes bibliographical references.

Victimization, fear of crime and altered behavior : a profile of the crime problem in Murphy Homes, Baltimore, Maryland.

Previous edition current.

Television and social behavior; reports and papers.

Includes bibliographies

The bacteriological and chemical behavior of silver in low concentrations /

Mode of access: Internet.

Dynamic bearing capacity of soils : dynamic loading machine and preliminary small-scale footing tests

Mode of access: Internet.