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Character Change (character + change)
Selected AbstractsRapid evolution and the convergence of ecological and evolutionary timeECOLOGY LETTERS, Issue 10 2005Nelson G. Hairston Jr Abstract Recent studies have documented rates of evolution of ecologically important phenotypes sufficiently fast that they have the potential to impact the outcome of ecological interactions while they are underway. Observations of this type go against accepted wisdom that ecological and evolutionary dynamics occur at very different time scales. While some authors have evaluated the rapidity of a measured evolutionary rate by comparing it to the overall distribution of measured evolutionary rates, we believe that ecologists are mainly interested in rapid evolution because of its potential to impinge on ecological processes. We therefore propose that rapid evolution be defined as a genetic change occurring rapidly enough to have a measurable impact on simultaneous ecological change. Using this definition we propose a framework for decomposing rates of ecological change into components driven by simultaneous evolutionary change and by change in a non-evolutionary factor (e.g. density dependent population dynamics, abiotic environmental change). Evolution is judged to be rapid in this ecological context if its contribution to ecological change is large relative to the contribution of other factors. We provide a worked example of this approach based on a theoretical predator,prey interaction [Abrams, P. & Matsuda, H. (1997). Evolution, 51, 1740], and find that in this system the impact of prey evolution on predator per capita growth rate is 63% that of internal ecological dynamics. We then propose analytical methods for measuring these contributions in field situations, and apply them to two long-term data sets for which suitable ecological and evolutionary data exist. For both data sets relatively high rates of evolutionary change have been found when measured as character change in standard deviations per generation (haldanes). For Darwin's finches evolving in response to fluctuating rainfall [Grant, P.R. & Grant, B.R. (2002). Science, 296, 707], we estimate that evolutionary change has been more rapid than ecological change by a factor of 2.2. For a population of freshwater copepods whose life history evolves in response to fluctuating fish predation [Hairston, N.G. Jr & Dillon, T.A. (1990). Evolution, 44, 1796], we find that evolutionary change has been about one quarter the rate of ecological change , less than in the finch example, but nevertheless substantial. These analyses support the view that in order to understand temporal dynamics in ecological processes it is critical to consider the extent to which the attributes of the system under investigation are simultaneously changing as a result of rapid evolution. [source] Presenile dementia mimicking Pick's disease: An autopsy case of localized amygdala degeneration with character change and emotional disorder,NEUROPATHOLOGY, Issue 3 2005Sumiko Shibuya-Tayoshi This report concerns an autopsy case showing localized amygdala degeneration. The patient was a Japanese single woman without hereditary burden who was 58 years old at the time of death. At the age of 55 years, the patient began to feel anxiety, agitation and depressive in mood. At age 58 years, she developed marked character changes and emotional disorders, although disorientation and memory disturbance were slight. We suspected her disease was a variant of presenile dementia, especially Pick's disease, and some neuroradiological examinations disclosed bilateral temporal involvements. We could not make a definitive diagnosis from the clinical findings. She choked to death 3 years after the disease onset. From the neuropathological examinations, the known neurodegenerative diseases causing dementia, including Pick's disease, were excluded and we diagnosed our case as having localized amygdala degeneration. Localized amygdala degeneration itself is very rare. Moreover, in this case, the amygdala degeneration was presumed to be idiopathic, without any apparent cause. To our knowledge, this is the first case of idiopathic localized amygdala degeneration. This case indicates that localized amygdala degeneration can cause presenile dementia, and that character changes and emotional disorders are predominant over memory disturbance and/or disorientation. [source] Sources of character conflict in a clade of water striders (Heteroptera: Gerridae)CLADISTICS, Issue 6 2003Jakob Damgaard Incongruence among trees reconstructed with different data may stem from historical (gene tree-species tree conflict) or process (character change biases) phenomena. Regardless of the source, incongruent data, as determined with "global" measures of homoplasy, have often been excluded from parsimony analysis of the combined data. Recent studies suggest that these homoplasy measures do not predict the contribution of each character to overall tree structure. Branch support measures identify, on a character to node basis, sources of support and conflict resulting from a simultaneous analysis of the data. We implement these branch support measures to identify sources of character conflict in a clade of water striders consisting of Gerris Fabricius, Aquarius Schellenberg, and Limnoporus Stål species. Separate analyses of morphology, mitochondrial cytochrome oxidase I (COI), large mitochondrial ribosomal subunit (16SrRNA), and elongation factor-1, (EF-1,) data resulted in cladograms that varied in resolution and topological concordance. Simultaneous analysis of the data resulted in two trees that were unresolved for one node in a strict consensus. The topology agreed with current classification except for the placements of Aquarius chilensis and the Aquarius remigis species group closer to Gerris than to congeneric species. Branch support measures indicated that support derived from each data set varied among nodes, but COI had an overall negative effect on branch support. However, Spearman rank correlation of partitioned branch support values indicated no negative associations of branch support between any data sets and a positive association between EF-1, and 16SrRNA. Thus incongruence among data sets was not drastic and the gene-tree versus species tree phenomenon was not implicated. Biases in character change were a more likely reason for incongruence, although saturation curves and incongruence length difference for COI indicated little potential for homoplasy. However, a posteriori inspection of COI nucleotide change with reference to the simultaneous analysis tree revealed AT and codon biases. These biases were not associated with branch support measures. Therefore, it is difficult to predict incongruence or identify its cause. Exclusion of data is ill advised because every character is potentially parsimony informative. [source] Presenile dementia mimicking Pick's disease: An autopsy case of localized amygdala degeneration with character change and emotional disorder,NEUROPATHOLOGY, Issue 3 2005Sumiko Shibuya-Tayoshi This report concerns an autopsy case showing localized amygdala degeneration. The patient was a Japanese single woman without hereditary burden who was 58 years old at the time of death. At the age of 55 years, the patient began to feel anxiety, agitation and depressive in mood. At age 58 years, she developed marked character changes and emotional disorders, although disorientation and memory disturbance were slight. We suspected her disease was a variant of presenile dementia, especially Pick's disease, and some neuroradiological examinations disclosed bilateral temporal involvements. We could not make a definitive diagnosis from the clinical findings. She choked to death 3 years after the disease onset. From the neuropathological examinations, the known neurodegenerative diseases causing dementia, including Pick's disease, were excluded and we diagnosed our case as having localized amygdala degeneration. Localized amygdala degeneration itself is very rare. Moreover, in this case, the amygdala degeneration was presumed to be idiopathic, without any apparent cause. To our knowledge, this is the first case of idiopathic localized amygdala degeneration. This case indicates that localized amygdala degeneration can cause presenile dementia, and that character changes and emotional disorders are predominant over memory disturbance and/or disorientation. [source] | ||||||||||