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- Anderson, Cajsa Lisa
(author)
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All we need now is fossils; a new phylogenetic dating method (PATHd8) allowing thousands of taxa and multiple fossil constraints.
- 2006
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In: Ancient life and modern approaches. - 7312019560 ; , s. 45-
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Conference paper (peer-reviewed)abstract
- Estimation of divergence times in phylogenetic trees using sequence databecomes increasingly popular, but so far dating studies have given widely different results,and especially datings of the lower nodes within the angiosperms and metazoans, have givenmuch older ages than those obtained from the fossil record. It has been concluded in differentstudies that more taxa, and more fossils are needed for more reliable age estimates. For thisreason, a dating method that can handle very large data sets with multiple fossil constraints isnecessary.Chronograms obtained by e.g. penalized likelihood and Bayesian methods, oftenadds a large "ghost range" to the fossil record, and produces chronograms with a more or lesssmooth appearance, even if the corresponding phylograms have apparently veryheterogeneous rates. Compared to the other methods, our recently developed method,PATHd8, gives the results with the best agreement with the fossil record, which coincideswith the least smooth appearance of the chronograms. When other programs often run intocomputational problems when analysing trees with hundreds of leaves, PATHd8 has noproblems analysing thousands of taxa instantaneously. An arbitrary number of fossil ageconstraints can be specified, either as fixed-, minimum or maximum age.With our new method, the biggest problem in dating studies is that we needmore fossils, and these fossils must be well dated and assigned to the correct branches of thephylogeny. Therefore, to accomplish divergence time estimates, which hopefully approximatethe real ages, biologists now need to cooperate with palaeontologists.
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| 2. |
- Anderson, Cajsa Lisa, 1972-
(author)
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Dating Divergence Times in Phylogenies
- 2007
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Doctoral thesis (other academic/artistic)abstract
- This thesis concerns different aspects of dating divergence times in phylogenetic trees, using molecular data and multiple fossil age constraints.Datings of phylogenetically basal eudicots, monocots and modern birds (Neoaves) are presented. Large phylograms and multiple fossil constraints were used in all these studies. Eudicots and monocots are suggested to be part of a rapid divergence of angiosperms in the Early Cretaceous, with most families present at the Cretaceous/Tertiary boundary. Stem lineages of Neoaves were present in the Late Cretaceous, but the main divergence of extant families took place around the Cre-taceous/Tertiary boundary.A novel method and computer software for dating large phylogenetic trees, PATHd8, is presented. PATHd8 is a nonparametric smoothing method that smoothes one pair of sister groups at a time, by taking the mean of the added branch lengths from a terminal taxon to a node. Because of the local smoothing, the algorithm is simple, hence providing stable and very fast analyses, allowing for thousands of taxa and an arbitrary number of age constraints.The importance of fossil constraints and their placement are discussed, and concluded to be the most important factor for obtaining reasonable age estimates.Different dating methods are compared, and it is concluded that differences in age estimates are obtained from penalized likelihood, PATHd8, and the Bayesian autocorrelation method implemented in the multidivtime program. In the Bayesian method, prior assumptions about evolutionary rate at the root, rate variance and the level of rate smoothing between internal edges, are suggested to influence the results.
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| 3. |
- Mellner, Christin, et al.
(author)
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Boundary management strategies and work-life balance in knowledge intense, boundaryless work
- 2013
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In: Imagine the future world: How do we want to work tomorrow?. ; , s. 239-240
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Conference paper (other academic/artistic)abstract
- Boundary strategies, segmentation and integration, were explored in knowledge intense, boundaryless work. Socio-demographic, work-related and individual factors were investigated in relation to strategy choice, and further, which of these factors that discriminated between succeeding or not with the chosen strategy. Moreover, work-life balance was studied in relation to strategy choice. A questionnaire was sent to employees (n=1238, response rate 65%) at an international telecom company in Sweden. A majority, 82 percent, chose segmentation. Integrators had higher working time per week, more often worked evenings and weekends and at different places than the workplace, especially from home, than segmenters. More integrators perceived their strategy as nonsuccessful. However, these time- and place related aspects were only related to not succeeding with one´s strategy among segmenters. Especially, co-habiting women with children choosing segmentation perceived their strategy as non-successful. In contrast, male segmenters succeeded more often. Discriminating factors in both strategy groups reflected the capacity for self-regulation, i.e., being able to say no and set limits, organizing work efficiently, and work independently. Those who succeeded with the integration strategy, in particular integrating women, reported a higher degree of work-life balance as compared to others. Results needs to be confirmed in other work settings and associations between boundary management and stress and health established. Self-regulation seems a crucial competence in a working life characterized by boundarylessness. Results are of value for health promotion in flexible work organizations in supporting employees achieving successful boundary management and subsequent work-life balance.
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