BioGenomics2017 - Global Biodiversity Genomics Conference
February 21-23, 2017
Smithsonian National Museum of Natural History | Washington, D.C.

Program - Single Session

[Back to Session Listing]

Evolutionary Genomics

Room: Baird Auditorium, NMNH

11:55 - 13:05

Moderator: Kristen Saltonstall, Smithsonian Tropical Research Institute

2.1  12:00  Discovering the world of microbial symbiosis using genomics. Nancy Moran *, University of Texas- Austin

The world of animals and plants is immensely diverse, and, for the most part, we can see this diversity with our own eyes. But the microbial world is far more diverse, by almost any measure except our visual system. Compared to animals or plants, microorganisms show far more metabolic and habitat diversity, more nucleotide sequence divergence, and a far greater variety of gene repertoires. This is no surprise if we consider that the microbial world predates that of large organisms by some two billion years. However, we can't see this small world, and relatively few of us took serious note of it until just the last few decades. This is when DNA sequencing and genomics first facilitated the exploration of microbial life outside the laboratory. The result was an explosion of knowledge including the identification of some of the oldest branches in the Tree of Life and the proof that we ourselves are chimeras of multiple ancestral microbial cell types. One of the most remarkable arenas of discovery in microbial diversity and in biology in general is that of symbiotic relationships between microorganisms and various animal hosts, including humans. Many of the most important ecological interactions in both terrestrial and marine ecosystems are based on symbioses between animals and bacteria, which enable novel means of exploiting ecological niches otherwise unavailable. Phylogenetic studies have shown that these associations often have been sustained for millions of years, sometimes hundreds of millions of years. Functional analyses of genomic data, complemented by experiments, have revealed that animal symbionts provide obligate nutrients or defenses for hosts. And symbiont genomes repeatedly have been the source of novel, functional genes integrated into the nuclear genomes of animal hosts. While symbionts are generally a source of ecological and evolutionary novelty in their hosts, they also can be evolutionary encumbrances, due to the ongoing genomic degradation that often characterizes genomes of obligate symbionts. The deterioration of symbiont genomes may sometimes lead to host extinction, but it also has often led to replacement of ancestral symbionts with novel ones, and further evolutionary innovation. These processes are illustrated with studies mostly from insect symbioses.

2.2  12:20  Palaeogenomic contributions to domestication. Thomas Gilbert *, Natural History Museum of Denmark

The genetics of domestication has long been an area of interest for evolutionary biologists. As we now enter era in which whole genome sequencing techniques can be applied to an increasing array of evolutionary questions, so have we seen the rise of domestication genomic studies. The questions targeted are wide, ranging from where and when our domestics first arose, what the ancestral species was, and what are the key changes undergone by their genomes as they were shaped into their modern forms. Such studies are predominantly applied to modern samples, and while the gains made are astounding, they are not without their limits. For example, while we can today catalogue the precise genomic differences between maize and its ancestral form teosinte, we lack the ability to reconstruct the order in which these differences were selected on '' information that can be key to reconstructing the early stages of the domestication process. Similarly, while we know dogs were domesticated from wolves, should the original source population now be extinct as some have argued '' comparisons of modern dogs and wolves cannot provide accurate insights into where and when the domestication happened. In an attempt to resolve such challenges, an increasing number of teams are turning to the field of paleogenomics '' literally the recovery of genome scale data from ancient samples. What these studies may do, and what limits remain, will be the focus of this talk.

2.3  12:40  Eutherian Chromosomes in the Light of Evolution . Harris Lewin *, University of California- Davis

Chromosome rearrangements are a hallmark of genome evolution and essential for understanding the mechanisms of speciation and adaptation. Determining the types and chronological order of chromosome rearrangements over evolutionary time scales has been a difficult problem due primarily to the lack of high quality, chromosome-scale genome assemblies that are necessary for reliable reconstruction of ancestral genomes. In addition, for genome-wide comparisons that require resolving large numbers of rearrangements of varying scale, determining ancestral chromosomal states is challenging both methodologically and computationally. In my talk, I will present recent chromosome reconstruction results obtained using a new method developed by our chromosome evolution collaborative group, called DESCHRAMBLER, which uses as input syntenic fragments constructed from whole-genome comparisons of both high quality chromosome-scale and fragmented assemblies. We applied DESCHRAMBLER to sequenced genomes of 21 species that included representatives of 10 eutherian orders. Seven ancestral genomes leading to human were reconstructed, including the ancestor of all placental mammals. From these reconstructions, a detailed picture of chromosome rearrangements that occurred during ~105 million years of eutherian evolution was revealed. Our results provide an evolutionary basis for comparison of genome organization of all eutherians, and will facilitate greater understanding of the role of chromosome rearrangements in adaptation, speciation, and the etiology of inherited and spontaneously occurring diseases. Furthermore, with the effort to sequence 10,000 vertebrate genomes, it will be possible to extend reconstructions deeper into evolutionary time, and thus provide a more detailed picture of chromosome evolution in other vertebrate classes. Ultimately, it should prove possible to determine the ancestral vertebrate karyotype with high confidence order and orientation of syntenic fragments.

13:00 Questions & Discussion
13:05 - 14:30 Lunch

[Back to Session Listing]