Download or read book Circadian Systems and Aging in White Throated Sparrows written by Mary Phalen and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The main objective of my work was to determine how the circadian system responds to aging in White-Throated Sparrows. The study used geriatric sparrows, aged at least 10 years in captivity, and monitored locomotor activity continuously. Birds were held under a 12/12 light dark cycle and then experienced a four hour phase shift forward, followed by a shift back to the original light cycle after entrainment for approximately one month in order to measure their ability to synchronize to new light schedules. The resulting data showed a variety of unique circadian manifestations including arrhythmic, nocturnal, with many birds maintaining their original phase of activity despite a shift in the light cycle. The second was to use MRI to compare the brain structure of three geriatric sparrows to three younger sparrows, aged around 2 years. A 7 Tesla machine was used to perform a series of MRI scans and Avizo 9.0 software was used to calculate volumes of the total brain, ventricles, hippocampus, hypothalamus, and the cerebellum. The older birds exhibited smaller hypothalamic volumes. From the actogram data we propose that the previously reported dawn and dusk oscillators are less coupled and their photic input has been differentially affected in the aged birds. The dawn oscillator correctly shifted and entrained to a new light schedule, while the dusk oscillator had reduced photic input and did not shift accordingly. These results are consistent with the hypothesis that the dusk oscillator relies on circadian time memory instead of reentraining to new light cycles.
Download or read book Control of Bird Migration written by P. Berthold and published by Springer Science & Business Media. This book was released on 1996 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: Considers all aspects of research since experimentation began on the subject in 1925
Download or read book The Inconstant Gene written by Lawrence Dillon and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 585 pages. Available in PDF, EPUB and Kindle. Book excerpt: Why should the gene be suggested to be inconstant when the contrary view, that gene structure is invariant except through mutagenic processes induced by potent external factors, has long been a universal doctrine of genetics? Indeed, during the early part of the present century before mutation was recognized as being of general occurrence, the seeming unvarying nature of the gene led to skepticism regarding the validity of the evolutionary theory; only later could the origins of the morphological differences between individuals and species be attributed to a combination of mutation and evolution, involving natural forces selecting between favorable and unfavorable genetic changes. But during the past several decades, as knowledge of the macromolecular constitution of or ganisms has increased to the point where even the primary structures of the genes themselves are being revealed on a routine basis, it has become increas ingly difficult to ascribe all the resulting observations to ordinary mutagenesis and natural selection. Some more profound mechanism often seems to be present that influences both the constancy and inconstancy of the genes, an ap paratus whose existence this study hopes to reveal. In seeking to demonstrate the universality of this mechanism, data are sought through the numerous activities of organisms of many types wherever gene action changes are manifest.
Download or read book Society for Neuroscience Abstracts written by Society for Neuroscience. Annual Meeting and published by . This book was released on 1999 with total page 1372 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Pavo written by and published by . This book was released on 1994 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Behavioural Biology Abstracts written by and published by . This book was released on 1981 with total page 958 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book XII International Conference Washington August 10 13 1975 written by International Society for Chronobiology and published by . This book was released on 1977 with total page 824 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Animal Behaviour Abstracts written by and published by . This book was released on 2002 with total page 924 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bird Migration written by Eberhard Gwinner and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: E. GWINNER! The phenomenon of bird migration with its large scale dimensions has attracted the attention of naturalists for centuries. Worldwide billions of birds leave their breeding grounds every autumn to migrate to areas with seasonally more favor able conditions. Many of these migrants travel only over a few hundred kilo meters but others cover distances equivalent to the circumference of the earth. Among these long-distance migrants are several billion birds that invade Africa every autumn from their West and Central Palaearctic breeding areas. In the Americas and in Asia the scope of bird migration is of a similar magnitude. Just as impressive as the numbers of birds are their achievements. They have to cope with the enormous energetic costs of long-distance flying. particularly while crossing oceans and deserts that do not allow replenishment of depleted fat reserves. They have to appropriately time the onset and end of migrations. both on a daily and annual basis. And finally. they have to orient their migratory movements in space to reach their species- or population-specific wintering and breeding grounds, irrespective of the variable climatic conditions along their migratory routes.
Download or read book Animal Behavior Mechanisms Ecology Evolution written by Lee C. Drickamer and published by McGraw-Hill Science, Engineering & Mathematics. This book was released on 2001-07-17 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: Designed for a one-semester introductory course in Animal Behavior. Animal behavior is a broad discipline with investigators and contributions from diverse perspectives, including anthropology, comparative psychology, ecology, ethology, physiology, and zoology. The authors goal in this textbook is to use evolutionary principles as a unifying theme to provide students exposure to a number of approaches to the field of animal behavior. They also demonstrate that the varied perspectives used to study behavior are complementary and often integrated; they are not mutually exclusive. The subtitle, “Mechanisms, Ecology, and Evolution,” reflects the broad themes that dominate the book.
Download or read book Cumulated Index Medicus written by and published by . This book was released on 1972 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Circannual Rhythms written by Eberhard Gwinner and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt: In addition to the more or less static properties of the environ ment, plants and animals must cope with its temporal variations. Among the most conspicuous temporal changes to which organisms are exposed are periodic phenomena generated by the rotation of the earth about its axis, its revolution around the sun, and the more complex movements of the moon in relation to both sun and earth. The first two of these astronomical cycles are basic to the familiar daily and annual rhythms, respectively, in the environment. The third generates somewhat more complex cycles, such as those in moonlight and variations in tides. These environmental cycles have provided challenges and opportunities for organisms to adjust their physiology and behavior to them. Indeed, the predictability inherent to these periodic processes has enabled organisms to evolve innate endogenous rhythmic programs that match the environmental cycles and allow, in a variety of different ways, adjustment of biological activities to the cycles of environmental changes. The endogenous nature of rhythmicity was first clearly recognized in the 1930's in daily periodicities, the most widely distributed and best investigated class of biological rhythms of this type. In the 1950's, demonstrations of endogenous tidal and lunar rhythms, which occur in some littoral and marine organisms, ensued. Another decade passed before endogenous annual periodicities were first demonstrated unambiguously.
Download or read book Animal Breeding Abstracts written by and published by . This book was released on 1966 with total page 820 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Marshall s Physiology of Reproduction Reproductive cycles of vertebrates written by Francis Hugh Adam Marshall and published by . This book was released on 1984 with total page 872 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Tracking Animal Migration with Stable Isotopes written by and published by Academic Press. This book was released on 2008-04-09 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tracking Animal Migration with Stable Isotopes provides a consolidated overview of the current knowledge of stable isotopes in terrestrial migration research questions. It offers ecologists and conservation biologists provide a practical handbook for those considering using stable isotopes in their migration research. - Presents information for readers to understand how to apply isotopic methods for tracking - Critical information on areas for future research - Practical guidelines and discussions of sample collection, sample preparation, and data analysis - Enhanced understanding of data and statistical analysis in isotope-based studies of migratory animals
Download or read book Proceedings of the Society for Experimental Biology and Medicine written by Society for Experimental Biology and Medicine (New York, N.Y.) and published by . This book was released on 1971 with total page 1606 pages. Available in PDF, EPUB and Kindle. Book excerpt: List of members in each volume.
Download or read book In a Class of Their Own written by Gary Ritchison and published by Springer Nature. This book was released on 2023-11-06 with total page 2516 pages. Available in PDF, EPUB and Kindle. Book excerpt: With more than 10,000 species that vary in size, use diverse habitats that extend across latitudes and altitudes, consume a wide variety of food items, differ in how they fly (or not), communicate, and reproduce, and have different life histories, birds exhibit remarkable variation in form (anatomy) and function (physiology). Our understanding of how natural selection has generated this variation as birds evolved and as different species adapted to their unique circumstances has grown considerably in recent years. In In a Class of Their Own: A Detailed Examination of Avian Forms and Functions, this variation is explained in great detail, beginning with an overview of avian evolution and continuing with information about the structure and function of the avian skeleton, muscles, and the various body systems. Other chapters focus on avian locomotion (including flight), migration, navigation, communication, energy balance and thermoregulation, and various aspects of avian reproduction, such as nests and nest building, clutch sizes, and parental care. In a Class of Their Own: A Detailed Examination of Avian Forms and Functions will be must reading for anyone, professional or non-professional, who needs or wants to learn more about birds.
