Obesity alters gut microbial ecology - Proceedings of …
The evolutionary consequences of hybridization, and more specifically distinguishing hybridization and introgression from incomplete lineage sorting (ILS), are one of the most prevalent topics in phylogenetic analysis. Yet, it is one on which progress made has been modest during the last two decades. Since the early 1990s and the realization of the main forces causing gene-trees to differ from organisms trees (paralogy, ILS, horizontal transfer), the most commonly used approach, in addition to independent direct evidence for hybridization, has been detecting incongruence between differently inherited gene trees from the same organisms. However, this criterion does not always constitute conclusive evidence. Besides, conceptual advances have sometimes limited the validity of assumptions from previously used criteria. For instance, the main hint for hybridization over ILS, besides the current sympatry or geographic proximity between involved species, was that unlike hybridization ILS should affect genes differently because it is a stochastic process. Thus, a concordance in topological patterns across different genes should point towards hybridization. However, discoveries of genome evolution such as its porous nature, whereby not all parts of the genomes are equally introgressed, suggest that when there is introgression all gene trees need not be consistent in their topological patterns. On the other hand, the availability of genome-wide surveys and specifically NGS data as well as the development of coalescent-based phylogenetic approaches have brought new possibilities to tackle the problem. Because basically ILS continues to be the explanation left when hybridization or introgression cannot be documented, new approaches most frequently aim at detecting similarities among species that would be not be expected by chance even in a coalescent scenario. Some of those new approaches have proved useful in simulation and empirical studies of limited size but all need more empirical testing.
XIX International Botanical Congress
The grass family, with more than 12,000 species, is economically and ecologically important throughout the world. Based on insights from molecular data, the family has benefited from a major reclassification at the subfamily level, and a substantial new understanding has emerged on the evolutionary history of many major lineages (i.e., supertribes, tribes, subtribes, and genera). As a consequence, realignments at generic, tribal and other ranks are being proposed in the production of new classifications that reflect phylogenetic history, a trend that is showing no signs of slowing down as levels of taxon and genome sampling increase. Phylogenetic analyses of whole plastid genomes are now routinely contributing to knowledge of grass evolutionary history and studies using low-copy nuclear genes are increasing in frequency. Many of these studies have identified webs of complex relationships and we believe a symposium covering large taxonomic groups (a single genus to the subfamily level) will help illuminate the nature, frequency, and distribution of these problems in the grass family. This symposium will bring together researchers working on the evolutionary history of major grass lineages in different subfamilies, including but not limited to the Bambusoideae, Chloridoideae, Panicoideae and Pooideae, who will present emerging molecular-based results on our changing understanding of the limits of grass genera and tribes. We hope to stimulate discussion of different molecular approaches to exposing and untangling reticulate origins, and present the current state of systematic knowledge within these taxonomic groups.
Hard as it might be to now believe, there was a time when people arguedagainst sequencing complete genomes, because we did not know what we would findand we could not guarantee that we would find something useful. This same lackof faith now clouds our decisions on which species to sequence. BGI iscommitted to sequencing as much of the planet’s biodiversity (not limited toplants) as possible, through international multi-disciplinary collaborations. Inour first session, we will describe how the sequencing of biodiverse species cansolve problems of interest to the larger community, reaching out to people not evenaware of these species. Examples include the discovery and characterization ofnovel proteins for biomedical applications, and the elucidation of themolecular mechanisms behind important agricultural processes like C4photosynthesis and nitrogen fixation. In our second session, we consider evolutionaryissues that can only be answered by biodiverse sequencing. Examples include theendosymbiotic origins of plastids, the long evolutionary road to plantterrestrialization, and novel methodological approaches for analyzing thecoming deluge of genomic data. Through it all, we are motivated by an unabashedfaith in the utility of evolutionary concepts and ultimately of speciesconservation, without which studies of this nature are impossible.