534 resultados para MAMMALIA CETACEA
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Vols. 3 and 4 are in two parts each.
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Each volume in two parts, each with general engravings and special t.-p.; in v. 1-11 paged continuously.
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Each v. has also individual t.-p.
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Issued in VI fasciculi, each of which has special t.-p.
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Buffon: Histoire naturelle ... 1750-1804.
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Coloured frontis. in each vol.
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--VI. Insects, pt. II. Hymenoptera continued (Tubilifera and Aculeata), Coleoptera, Strepsiptera, Lepidotera, Diptera, Aphaniptera, Thysanoptera, Hemiptera, Anoplura. By David Sharp. 1901.--VII. Hemichordata, by S.F. Harmer. Ascidians and Amphioxus, by W.A. Herdman. Fishes (exclusive of th systematic account of Teleostei) by T.W. Bridge. Fishes (systematic account of Teleostei) by G.A. Bonlenger. 1904.--VIII. Amphibia and reptiles, by Hans Gadow. 1901.--IX. Birds, by A.H. Evans. 1900--X. Mammalia, by F.E. Beddard. 1902.
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Contains bibliographies.
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Senior thesis written for Oceanography 445
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Thesis (Ph.D.)--University of Washington, 2016-06
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As a general test of the energetic equivalence rule, we examined macroecological relationships among abundance, density and host body mass in a comparative analysis of the assemblages of trophically transmitted endoparasitic helminths of 131 species of vertebrate hosts. Both the numbers and total volume of parasites per gram of host decreased allometrically with host body mass, with slopes roughly consistent with those expected from the allometric relationship between host basal metabolic rate and body mass. From an evolutionary perspective, large body size may therefore allow hosts to escape from the deleterious effects of parasitism.
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For most of the past century, the prospect of replacing lost or damaged cells in the central nervous system (CNS) was hampered by the opinion that the adult mammalian CNS was incapable of generating new nerve cells. This belief, Like most dogmas, was essentially founded on a lack of experimental evidence to the contrary. The overturning of this 'no new neuron' hypothesis began midway through the twentieth century with a series of reports documenting neurogenesis in the postnatal and adult brain(1), continued with the isolation and in vitro culture of neurogenic cells from the adult mammalian brain(2,3), and culminated in the discovery of a population of muttipotent, selfrenewing cells in the adult CNS (that is, bona fide neural stem cells)(3-5). Although a variety of techniques were initially used, the neurosphere assay (NSA)(3,6) rapidly emerged as the assay of choice and has since become a valuable toot for isolating, and understanding the biology of, embryonic and adult CNS stem cells. Like all technologies, it is not without its limitations. In this article we will hightight several shortcomings of the assay related to its application and interpretation that we believe have led to a significant body of research whose conclusions may well be misleading.
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Cetaceans are aquatic mammals that rely primarily on sound for most daily tasks. A compendium of sounds is emitted for orientation, prey detection, and predator avoidance, and to communicate. Communicative sounds are among the most studied Cetacean signals, particularly those referred to as tonal sounds. Because tonal sounds have been studied especially well in social dolphins, it has been assumed these sounds evolved as a social adaptation. However, whistles have been reported in ‘solitary’ species and have been secondarily lost three times in social lineages. Clearly, therefore, it is necessary to examine closely the association, if any, between whistles and sociality instead of merely assuming it. Several hypotheses have been proposed to explain the evolutionary history of Cetacean tonal sounds. The main goal of this dissertation is to cast light on the evolutionary history of tonal sounds by testing these hypotheses by combining comparative phylogenetic and field methods. This dissertation provides the first species-level phylogeny of Cetacea and phylogenetic tests of evolutionary hypotheses of cetacean communicative signals. Tonal sounds evolution is complex in that has likely been shaped by a combination of factors that may influence different aspects of their acoustical structure. At the inter-specific level, these results suggest that only tonal sound minimum frequency is constrained by body size. Group size also influences tonal sound minimum frequency. Species that live in large groups tend to produce higher frequency tonal sounds. The evolutionary history of tonal sounds and sociality may be intertwined, but in a complex manner rejecting simplistic views such as the hypothesis that tonal sounds evolved ‘for’ social communication in dolphins. Levels of social and tonal sound complexity nevertheless correlate indicating the importance of tonal sounds in social communication. At the intraspecific level, tonal sound variation in frequency and temporal parameters may be product of genetic isolation and local levels of underwater noise. This dissertation provides one of the first insights into the evolution of Cetacean tonal sounds in a phylogenetic context, and points out key species where future studies would be valuable to enrich our understanding of other factors also playing a role in tonal sound evolution. ^
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Cetaceans are aquatic mammals that rely primarily on sound for most daily tasks. A compendium of sounds is emitted for orientation, prey detection, and predator avoidance, and to communicate. Communicative sounds are among the most studied Cetacean signals, particularly those referred to as tonal sounds. Because tonal sounds have been studied especially well in social dolphins, it has been assumed these sounds evolved as a social adaptation. However, whistles have been reported in ‘solitary’ species and have been secondarily lost three times in social lineages. Clearly, therefore, it is necessary to examine closely the association, if any, between whistles and sociality instead of merely assuming it. Several hypotheses have been proposed to explain the evolutionary history of Cetacean tonal sounds. The main goal of this dissertation is to cast light on the evolutionary history of tonal sounds by testing these hypotheses by combining comparative phylogenetic and field methods. This dissertation provides the first species-level phylogeny of Cetacea and phylogenetic tests of evolutionary hypotheses of cetacean communicative signals. Tonal sounds evolution is complex in that has likely been shaped by a combination of factors that may influence different aspects of their acoustical structure. At the inter-specific level, these results suggest that only tonal sound minimum frequency is constrained by body size. Group size also influences tonal sound minimum frequency. Species that live in large groups tend to produce higher frequency tonal sounds. The evolutionary history of tonal sounds and sociality may be intertwined, but in a complex manner rejecting simplistic views such as the hypothesis that tonal sounds evolved ‘for’ social communication in dolphins. Levels of social and tonal sound complexity nevertheless correlate indicating the importance of tonal sounds in social communication. At the intraspecific level, tonal sound variation in frequency and temporal parameters may be product of genetic isolation and local levels of underwater noise. This dissertation provides one of the first insights into the evolution of Cetacean tonal sounds in a phylogenetic context, and points out key species where future studies would be valuable to enrich our understanding of other factors also playing a role in tonal sound evolution.
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Serotonin or 5-hydroxytryptamine (5-HT) is a substance found in many tissues of the body, including the nervous system acting as a neurotransmitter. Within the neuro-axis, the location of the majority of the 5-HT neurons is superimposed with raphe nuclei of the brain stem, in the median line or its vicinity, so that neuronal 5-HT can be considered a marker of the raphe nuclei. Serotonergic neurons are projected to almost all areas of the brain. Studies show the participation of serotonin in regulating the temperature, feeding behavior, sexual behavior, biological rhythms, sleep, locomotor function, learning, among others. The anatomy of these groups has been revised in many species, including mouse, rabbit, cat and primates, but never before in a bat species from South America. This study aimed to characterize the serotonergic clusters in the brain of the bat Artibeus planirostris through immunohistochemistry for serotonin. Seven adult bat males of Artibeus planirostris species (Microchiroptera, Mammalia) were used in this study. The animals were anesthetized, transcardially perfused and their brains were removed. Coronal sections of the frozen brain of bats were obtained in sliding microtome and subjected to immunohistochemistry for 5-HT. Delimit the caudal linear (CLi), dorsal (DR), median (MnR), paramedian (PMnR), pontine (PNR), magnus (MgR), pallidus (RPA) and obscurus (ROb) raphe nucleus, in addition to the groups B9 and rostral and caudal ventrolateral (RVL/CVL). The serotonergic groups of this kind of cheiroptera present morphology and cytoarchitecture relatively similar to that described in rodents and primates, confirming the phylogenetic stability of these cell clusters.