EGGSiting parallels between cancer and evolution – Evolutionary Genetics and Genomics Symposium 2019 in Cambridge
During his student years at Cambridge, Darwin became known as “the man who walks with Henslow”. J. S. Henslow was a priest, a geologist and a botanist that founded the Cambridge Botanic Gardens. His obsession for understanding and recording variation within “created” plant species would permeate to Darwin’s later questioning of the stability of these . Even today, understanding interactions and variation within and between species lies at the heart of evolutionary biology. The 2019 Evolutionary Genetics and Genomics Symposium (EGGS) at Cambridge was an excellent reminder of that.
The symposium was opened with a fascinating talk by keynote speaker Anne Stone from Arizona State University. She showed how ancient DNA can shed light on the interactions between humans and other species. Even though tuberculosis originated only 3000-5000 years ago in Africa, it was recently found in South American ancient DNA samples and thus must have jumped from Africa to South America after the land bridge between North America and Asia closed. It turns out that the Mycobacterium tuberculosis strains found in ancient samples of South Americans are most closely related to M. pinnipedi found in seals, suggesting that seals might have carried the bacterium to South America.
Closely related species may not only interact ecologically but also through hybridization as the talk by Ruonyun Hui (U. Cambridge) nicely illustrated with her study on Denisovan alleles in human genomes. She found evidence for multiple pulses of admixture from Denisovans into Papuans, whereas they all share a single ancestral admixture event from Neanderthals. However, as mating with other species is usually disadvantageous, a diverse array of species recognition traits has evolved. Multiple talks elucidated the genetic underpinnings of such traits including body coloration and egg spots in cichlid fishes by Emilia Santos (U. Cambridge) or pheromones in Heliconius butterflies by Kelsey Byers (U. Cambridge), each finding a single genomic region of large effect. Keynote speaker Beverley Glover (U. Cambridge) showed that nectar spurs of different lengths in Antirrhinae plants mediate reproductive isolation because they attract pollinators with different proboscis lengths. Indeed, her group finds that lineages with nectar spurs have higher speciation rates. This could help solve the abominable mystery of the extremely high species richness of flowering plants that already puzzled Darwin .
Large phenotypic variation can sometimes also be observed within species. In his talk awarded with a giant chocolate egg for the best presentation, Roman Kellenberger (U. Cambridge) showed that overdominance maintains an intraspecific polymorphism in flower coloration in the orchid Gymnadenia rhellicana. Another factor that can maintain intraspecific polymorphisms is adaptation to environmental gradients. This was exemplified by pigmentation variation in Drosophila montana determined by a locus with pleiotropic effects on mating behaviour as found by Venera Tyukmaeva (U. Jyväskylä). Wing shape variation between high and lowland populations of Heliconius erato butterflies, on the other hand, seems to have a polygenetic basis as shown by Gabriela Montejo-Kovacevich (U. Cambridge). Local adaptation may potentially also contribute to morphological and genetic differences between Baltic Sea populations of the harbour porpoise that Marijke Autenrieth (U. Potsdam) characterized.
Genetic variation can even be observed within a single individual. For example, T cells differ in somatic mutations as studied in detail by Heather Machado (Sanger Institute). The diversity is probably highest in cancers. This comes with problems regarding treatment as “there are as many cancers as there are patients with cancer” as Alejandra Bruna (U. Cambridge) pointed out, while showing the potential of mouse avatars to predict the evolutionary trajectory of specific cancers. In the second keynote talk given by Charles Swanton (UCL Cancer Institute), it became obvious that the diversity of cancers may actually exceed the number of patients, because tumours eventually branch into multiple genetically different regions. He presented his impressive TracerX project which allows to distinguish between mutations that occurred on the trunk, i.e. are shared by all tumour cells, and mutations in different tumour branches. This distinction is important for immunotherapy which should target the entire tumour and thus trunk mutations. However, many mutations typically associated with cancer are also found in healthy tissues as nicely illustrated by Jamie Blundell (U. Cambridge) for blood cells and by Luzia Moore (Welcome Sanger Institute) for the endometrium, the inner lining of the uterus. They find that age, smoking and BMI play major roles in the number of such somatic mutations detected.
As Charles Swanton pointed out, there are parallels between cancer evolution and the evolution of species. Selection and drift act in a similar manner on tumour cells that carry different mutations as they do on individuals in populations. Charles even went a step further, comparing interactions between immune cells and cancer cells to predator-prey interactions in species communities. Such far-fetched parallels only become apparent during a symposium featuring cancer, health and evolutionary talks side by side and make good food for thought. Another noticeable parallel is the similarity in methods applied by the researchers. No matter if the aim is conservation of vulnerable species, curing cancer, or understanding evolutionary principles, what unites all these studies is that they make great use of the novel sequencing and bioinformatics tools while integrating established ecological or clinical knowledge. We are extremely thankful to the funding provided by the Genetics Society that enabled this highly stimulating and diverse meeting to take place.
 Kohn, D., Murrell, G., Parker, J. and Whitehorn, M., 2005. What Henslow taught Darwin. Nature, 436(7051), p.643.
 Friedman, W.E., 2009. The meaning of Darwin’s “abominable mystery”. American Journal of Botany, 96(1), pp.5-21.
EGGS 2018 drew 150 participants from 41 institutions and 13 countries, making this the largest and most diverse audience in the meeting’s eight year history.
Our keynote speaker was Professor Katie Peichel from the University of Bern, who described how her group has used a combination of QTL mapping, genome-wide association studies and focussed dissection of selected loci in sticklebacks to disentangle the roles of pleiotropy and linkage in adaptation. Katie’s work demonstrates the power of using naturally admixed populations to identify functional genetic variation – showing for example that exactly the same SNP changes could control such different traits as schooling behaviour and armour plating.
We than had talks from seventeen selected speakers, showcasing the great diversity of questions in evolutionary biology that can be addressed using genomic tools. One strong theme of the meeting was population genetics and ecological adaptation. Talks in this area covered study systems ranging from stick insects to killer whales, and were also diverse in terms of the types of genetic variation described as well as the forces shaping that variation. Another topic addressed by multiple speakers was the evolution of pathogens and their hosts, which included talks revealing the influence of pathogens on our own evolution. Other topics covered included the dynamics of mitochondrial transmission and the role of gene regulatory changes in cancer.
The prize for the best talk, as voted for by the participants, was shared by Samuel Lewis and John Welch, both from the University of Cambridge, who spoke respectively about the evolution of piRNAs in arthropods, and how Fisher’s geometric model can explain a variety of patterns observed in speciation. We also invited poster submissions from those who were not offered a talk slot. The best poster prize went to Lara Urban from the European Bioinformatics Institute, whose poster described a citizen science effort to track the microbiome and pathogen landscape of the river Cam in Cambridge.
As in previous years, EGGS 2018 was characterised by lively discussions that continued from the formal talks to the drinks reception and then late into the night at the pub. A number of participants spoke of the open and friendly atmosphere of the meeting, which no doubt reflects the community of evolutionary geneticists. We are grateful to the Genetics Society for supporting what has become a very important annual meeting for this community.
The EGGS 2016 event was held on the 15th of March and attracted ~ 120 attendees representing 22 different institutions. We had four invited speakers: Federica di Palma (Earlham Institute), Mary O’Connell (Leed University), Magnus Nordborg (Gregor Mendel Institute, Austria) and Eric Miska (University of Cambridge). The 2016 programme can be found here.
We had 117 participants in 2015. We had three invited speakers: Aoife McLysaght, University of Dublin, Nathan Bailey, University of St Andrews and Josephine Pemberton, University of Edinburgh. The full programme of speakers can be found here.
Read an overview of EGGS 2014 written for the Genetics Society Magazine here and the 2014 programme can be found here
The 2013 meeting is reported here. The first meeting was in 2012.