Molecular phylogenetic analyses of subtribe Senecioninae, based on combining sequenced ITS and trnL-F fragments from specimens collected in the field with sequences collected from GenBank, suggest the subtribe is monophyletic, as is Senecio s.str. (including Robinsonia), and suggest an expanded monophyletic section Senecio. Many Senecio species should be removed from the genus, as they are only distantly related to it, emphasising the para- or polyphyletic nature of Senecio as it is currently circumscribed. Area optimisation suggests southern Africa as a possible geographical origin for the genus and section. Harvey’s (1865) sectional classification of South African Senecio species (the only attempt to date to impose infrageneric groupings on these taxa), was tested for monophyly which, however, was not seen in the sections tested. A number of southern African species from Harvey’s sections are suggested for inclusion in an expanded section Senecio. A clade suggested as basal to sect. Senecio, consisting of Senecio engleranus and Senecio flavus, was found to be only distantly related to the section. Resolution of the two species within the clade was not evident; a comparative study was therefore made employing RAPDs, morphometrics and breeding experiments. The two proved to be distinct entities, both genetically and morphologically, although they remain interfertile, suggesting that intrinsic postzygotic barriers between them are weak, and that hybridisation – not found in the wild - is mainly prevented by prezygotic barriers. F1 hybrids created between the two were seen to have intermediate morphologies and RAPD profiles. A single F1 individual self-pollinated to produce a vigorous F2 generation, allowing preliminary surveys of pollen number, pollen fertility and pappus type. Pappus type is seen to be under the control of allelic variations in a single major gene, while pollen numbers and pollen fertility are seen to be under more complex genetic control.

The advent of new technology enhance the speed and reduce the cost for sequencing biological data. Making biological sense of this genomic data is a big challenge to the algorithm design as well as the high performance computing society. There are many problems in Bioinformatics, such as how new functional genes arise, why genes are organized into chromosomes, how species are connected through the evolutionary tree of life, or why arrangements are subject to change. Phylogenetic analyses have become essential to research on the evolutionary tree of life. It can help us to track the history of species and the relationship between different genes or genomes through millions of years. One of the fundamentals for phylogenetic construction is the computation of distances between genomes. Since there are much more complicated combinatoric patterns in rearrangement events, the distance computation is still a hot topic as much belongs to mathematics as to biology. For the distance computation with input of two genomes containing unequal gene contents (with insertions/deletions and duplications) the problem is especially hard. In this thesis, we will discuss about our contributions to the distance estimation for unequal gene order data. The problem of finding the median of three genomes is the key process in building the most parsimonious phylogenetic trees from genome rearrangement data. For genomes with unequal contents, to the best of our knowledge, there is no algorithm that can help to find the median. In this thesis, we make our contributions to the median computation in two aspects. 1) Algorithm engineering aspect, we harness the power of streaming graph analytics methods to implement an exact DCJ median algorithm which run as fast as the heuristic algorithm and can help construct a better phylogenetic tree. 2) Algorithmic aspect, we theoretically formulate the problem of finding median with input of genomes having unequal gene content, which leads to the design and implementation of an efficient Lin-Kernighan heuristic based median algorithm. Inferring phylogenies (evolutionary history) of a set of given species is the ultimate goal when the distance and median model are chosen. For more than a decade, biologists and computer scientists have studied how to infer phylogenies by the measurement of genome rearrangement events using gene order data. While evolution is not an inherently parsimonious process, maximum parsimony (MP) phylogenetic analysis has been supported by widely applied to the phylogeny inference to study the evolutionary patterns of genome rearrangements. There are generally two problems with the MP phylogenetic arose by genome rearrangement: One is, given a set of modern genomes, how to compute the topologies of the according phylogenetic tree; Another is, given the topology of a model tree, how to infer the gene orders of the ancestor species. To assemble a MP phylogenetic tree constructor, there are multiple NP hard problems involved, unfortunately, they organized as one problem on top of other problems. Which means, to solve a NP hard problem, we need to solve multiple NP hard sub-problems. For phylogenetic tree construction with the input of unequal content genomes, there are three layers of NP hard problems. In this thesis, we will mainly discuss about our contributions to the design and implementation of the software package DCJUC (Phylogeny Inference using DCJ model to cope with Unequal Content Genomes), that can help to achieve both of these two goals. Aside from the biological problems, another issue we need to concern is about the use of the power of parallel computing to assist accelerating algorithms to handle huge data sets, such as the high resolution gene order data. For one thing, all of the method to tackle with phylogenetic problems are based on branch and bound algorithms, which are quite irregular and unfriendly to parallel computing. To parallelize these algorithms, we need to properly enhance the efficiency for localized memory access and load balance methods to make sure that each thread can put their potentials into full play. For the other, there is a revolution taking place in computing with the availability of commodity graphical processors such as Nvidia GPU and with many-core CPUs such as Cray-XMT, or Intel Xeon Phi Coprocessor with 60 cores. These architectures provide a new way for us to achieve high performance at much lower cost. However, code running on these machines are not so easily programmed, and scientific computing is hard to tune well on them. We try to explore the potentials of these architectures to help us accelerate branch and bound based phylogenetic algorithms.

Orientador: Maria do Carmo Estanislau do Amaral / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-10T06:25:59Z (GMT). No. of bitstreams: 1 Koehler_Samantha_D.pdf: 6443365 bytes, checksum: 6a01c884fb24c1fbf015cf1b2ab4e212 (MD5) Previous issue date: 2007 / Resumo: Não informado / Abstract: Not informed. / Doutorado / Biologia Vegetal / Mestre em Biologia Vegetal

Berkheya Ehrh. is a genus of daisies in the tribe Arctotideae, subtribe Gorteriinae with over 80 species, most of which occur in southern Africa. This genus has centres of diversity associated with the montane regions of South Africa, including the Drakensberg Alpine Centre and Mpumalanga escarpment regions. Previous molecular and morphological studies indicate that Berkheya is paraphyletic. I present phylogenies based on nrDNA (ITS; Internal Transcribed Spacer) and cpDNA (psbA-trnH) sequence data analysed with Bayesian Inference and Parsimony. A phylogeny of combined cp- and nrDNA is also presented. These phylogenies are used to assess generic limits and to investigate the biogeographic patterns of Berkheya and its allies. The ITS phylogeny shows five well supported clades of Berkheya, two of which (Clades I and 2) are monophyletic summer rainfall region clades. Clades 3 to 5 are all paraphyletic winter rainfall clades with Cullumia occurring in the third clade, Cuspida occurring in the fourth and Didelta in Clade 5. Both psbA-trnH and combined phylogenies show concordance with the clade distribution shown in the ITS phylogeny. The ITS phylogeny was used to analyse correspondence with Roessler’s (1959) Series. It was found that the phylogeny showed considerable agreement with Roessler’s series, but B. bipinnatifida and B. spinosa of Series Speciosae may require some revision as well as taxa of monotypic series Cruciatae and Angustae. It is suggested that the latter series be merged with Cullumia species to form a single series. Some consideration should be taken to include Didelta species into Series Fruticosae as Didelta occurs in subclade 5b of Clade 5 with other Series Fruticosae taxa. Achene morphology was examined from species from each of the five clades to investigate the relationships of Berkheya and its allies, as well as to determine if there were any consistent achene features for each clade. The structure of surface cells on the fruit, the presence, absence and morphology of twin hairs as well as the structure of the pappus scales were found to be most useful in reflecting phylogenetic relationships within the clades. When compared with the clades of the ITS phylogeny, achene morphology showed consistent characters between taxa occurring in the same clades. As the most comprehensive study involving Berkheya, this phylogenenetic investigation was able to confirm that Berkheya is a paraphyletic genus with Didelta, Cullumia and Cuspida needing to be subsumed into Berkheya. An alternative classification is that taxa of Clade 5 could possibly be erected as an expanded Didelta, separate and sister to Berkheya.