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Here we review cases where initiation of morphogenesis, including the differentiation of specialized cells and tissues, has clearly evolved due to cyclical symbiont integration. For reasons of space, our examples are drawn chiefly from the plant, fungal and bacterial kingdoms. Partners live in symbioses and show unique morphological specializations that result when they directly and cyclically interact. We include here brief citations to relevant literature where plant, bacterial or fungal partners alternate independent with entirely integrated living. The independent, or at least physically unassociated stages, are correlated with the appearance of distinctive morphologies that can be traced to the simultaneous presence and strong interaction of the plant with individuals that represent different taxa. 相似文献
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The karyotypes of living catarrhines are correlated with the current concepts of their fossil record and systematic classification. A phylogeny, beginning at the base of the Oligocene, for those animals and their chromosome numbers is presented. Todd? (1970) theory of karyotypic fissioning is applied to this case — three fissioning events are hypothesized. A late Eocene event (the primary catarrhine fissioning) is hypothesized to underlie the diversification of the infraorder Catarrhini into its extant families, the second fissioning underlies the radiation of the Pongidae/Hominidae in the Miocene and the third accounts for the high chromosome numbers (54–72) and the Neogene (Miocene-Pliocene-Pleistocene) radiation of members of the genus Cercopithecus. Published catarrhine chromosome data, including that for “marked” chromosomes (those with a large achromatic region that is the site for ribosomal RNA genes) are tabulated and analysed. The ancestral X chromosome is always retained in the unfissioned metacentric state. The Pongidae/Hominidae have 15 pairs of mediocentric chromosomes that survived the second fissioning whereas the other chromosomes (besides the X) are thought to be fission-derived acrocentrics. Both the detailed karyology and the trend from low to high numbers is best interpreted to support Todd? concept of adaptive radiations correlated with karyotypic fissioning in ancestral populations. 相似文献
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Behavioral monitoring is the scientific collection of animal behavior data to understand normal patterns of behavior and changes in these patterns. This tool is underutilized in the zoo industry although it can be an effective indicator of many potential problems that compromise zoo animal well-being. We suggest that a behavioral monitoring program should be a core component of a zoological institution's care program. We detail the benefits of such a program and describe its components. We provide guidelines for implementing such a program and make recommendations that will help institutions to employ behavioral monitoring programs with reasonable expense. We argue that the benefits of such a program, primarily increased detection of rising or potential problems, far outweigh the minor costs of implementation. Zoo Biol 28:35–48, 2009. © 2008 Wiley-Liss, Inc. 相似文献
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An ultraviolet light induced prophage has been discovered in the red pigmented marine vibrio Beneckea gazogenes. Two spontaneously derived pigment mutants, one forming pink colonies and one lacking pigment and forming white colonies, were also irradiated. The presence of pigment was not related to phage induction; uv-induced cell lysis occurred in wildtype and mutant strains at the same dosages. Lysis was not prevented or retarded by exposure after irradiation to visible light indicating the phenomenon was not photoreactivable. Electron micrographs of the 'T-like' B. gazogenes phage are shown. A second beneckea was isolated form the anaerobic zone of cyanobacterial mats growing in the hypersaline environment of Laguna Mormona, Baja California. The Baja beneckea does not harbor a uv inducible prophage and is resistant to the B. gazogenes phage under all conditions tested. 相似文献