Global meta‐analysis of over 50 years of multidisciplinary and international collaborations on transmissible cancers

International audienceAlthough transmissible cancers have, so far, only been documented in three independent animal groups, they not only impact animals that have high economic, environmental and social significance, but they are also one of the most virulent parasitic life forms. Currently known transmissible cancers traverse terrestrial and marine environments, and are predicted to be more widely distributed across animal groups; thus, the implementation of effective collaborative scientific networks is important for combating existing and emerging forms. Here, we quantify how collaborative effort on the three known transmissible cancers has advanced through the formation of collaborative networks among institutions and disciplines. These three cancers occur in bivalves (invertebrates—disseminated neoplasia; DN), Tasmanian devils (vertebrate—marsupial; devil facial tumour disease; DFTD) and dogs (vertebrate—eutherian mammal; canine transmissible venereal tumour; CTVT). Research on CTVT and DN has been conducted since 1876 and 1969, respectively, whereas systematic research on DFTD only started in 2006. Yet, collaborative effort on all three diseases is global, encompassing six major Scopus subject areas. Collaborations steadily increased between 1963 and 2006 for CTVT and DN, with similar acceleration for all three cancers since 2006. Network analyses demonstrated that scientists are organizing themselves into efficient collaborative networks; however, these networks appear to be far stronger for DFTD and DN, possibly due to the recent detection of new strains adding impetus to research and associated publications (enhancing citation trajectories). In particular, global and multidisciplinary collaborations formed almost immediately after DFTD research was initiated, leading to similar research effort and relatively greater research outputs compared to the other two diseases. Therefore, in the event of outbreaks of new lineages of existing transmissible cancers, or the discovery of new transmissible cancers in the future, the rapid formation of international collaborations spanning relevant disciplines is vital for the efficient management of these diseases

Fifth International Biannual Evolution and Ecology of Cancer Conference (Cooperation, Conflict and Parasitism) meeting report—Wellcome Genome Campus, Hinxton, UK

International audienceThe fifth biannual conference of the International Society of Evolution and Ecology of Cancer (ISEEC) was held between the 17th and 19th of July 2019 in Hinxton (UK) at the Wellcome Genome Campus. The main theme of the conference: cooperation, conflict and parasitism reflected our growing understanding of the role cancer has played in the evolution of multicellular organisms, as well as the urgent need of translating these Darwinian processes to treatment strategies. Below we provide a brief summary of each plenary sessions and other oral presentations, to bring the conference to the broader audience of evolutionary biology and applications

Machine learning is a powerful tool to study the effect of cancer on species and ecosystems

International audienceCancer is an understudied but important process in wildlife. Cancerous cells are proposed to have had significant effect on the evolution of metazoan species due to their negative effect on host fitness. However, gaining knowledge on the impact of cancer on species and ecosystems is currently relatively slow as it requires expertise in both ecology and oncology. The field can greatly benefit from automation to reduce the need of excessive manpower and analyse complex ecological datasets. In this commentary, we examine how machine learning has been used to gain knowledge on oncogenic processes in wildlife. Using a landscape ecology approach, we explore spatial scales ranging from the size of a molecule up to whole ecosystems and detail, for each level, how machine learning has been used, or could contribute to obtain insights on cancer in wildlife populations and ecosystems. We illustrate how machine learning is a powerful toolbox to conduct studies at the interface of ecology and oncology. We provide guidance for the readers of both fields on how to implement machine learning tools in their research and identify directions to move the field forward using this promising technology. We demonstrate how applying machine learning to complex ecological datasets will (a) contribute to quantitating the effect of cancer at different life stages in wildlife; (b) allow the mining of long-term datasets to understand the spatiotemporal variability of cancer risk factors and (c) contribute to mitigating cancer risk factors and the conservation of endangered species. With this study, we aim to facilitate the use of machine learning to wildlife species and to encourage discussion between the scientists of the fields of oncology and ecology. We highlight the importance of international and pluridisciplinary collaborations to collect high-quality datasets on which efficient machine learning algorithms can be trained

Genetic divergence of farmed blue mussels (Mytilus sp.) in Australian waters

International audienceAs valuable ecosystem engineers, blue mussels, are one of the most ecologically and economically important bivalve species in Australia. The need for understanding levels of genetic diversity in both wild and farmed populations of Australian mussels is ever-growing due to the increased risk of disease and decreased fitness associated with the constantly changing global environment. This study, therefore, investigated the phylogenetic relationship, and the genetic variation of farmed blue mussels (Mytilus sp., previously noted as M. galloprovincialis, M. planulatus or a hybrid of both) at four sites along the south coast of Australia, Victoria, South Australia, Western Australia, and Tasmania. Analyses of two genes, Cytochrome c oxidase subunit 1 gene (mtCOI) and the nuclear gene Elongation factor 1 alpha (EF1a) was completed for all mussels sampled. The phylogenetic reconstruction of mtDNA sequences was not able to cluster the samples into species. The analyses of the nuclear marker (EF1a) returned similar results, except that we could conclude the Australian samples not being M. chilensis. Furthermore, the analyses of EF1a revealed the presence of hybridisation, a pattern commonly observed in mussels. The genetic diversity analysis of mtCOI demonstrated that samples from Victoria and Western Australia had the highest genetic diversity, while South Australia had the lowest. When analysing the nuclear EF1a sequences, mussels from Western Australian had the lowest genetic diversity, and the Victorian samples had the highest.The study extended our knowledge on the population genetic variation of farmed blue mussels (Mytilus sp.) along the south coast of Australia. The identified genetic differences between the four southern states of Australia could be interesting for the aquaculture industry when aiming for more adaptable and profitable stocks

Hatchery-Imposed Selection Does Not Impact the Genetic Diversity of Australian Farmed Blue Mussels (Mytilus spp.)

International audienceAustralian blue mussels (Mytilus spp.) are an increasingly important sustainable product of the Australian aquaculture industry. Although important for commercial fisheries, aquaculture may have adverse environmental and ecological impacts. This study assessed the impact of standard hatchery-imposed selection practices on the genetic diversity of farmed blue mussels. Using microsatellite markers, relatedness and genetic structure analyses showed that hatchery-reared larvae have high levels of genetic diversity without a significant decline as they move through the hatchery rearing process. Selection and/or genetic drift does appear to be operating during the hatchery rearing process, however, evidenced by an increase in relatedness among larvae over time. Significant shifts in allele frequency as well as genetic clusters provides further evidence that selection is acting on larvae due to the selection practice applied at the hatchery. Comparison of the level of genetic diversity and genetic differentiation of adults from wild and farmed populations provided no evidence that farmed mussels have lower diversity, or that they are genetically swamping local natural populations. The data suggest that careful design and implementation of mussel breeding programs can maintain high genetic diversity among larvae that does not lead to genetic swamping of natural mussel populations in the surrounding area

Transmissible Cancers in an Evolutionary Perspective

International audienceInter-individual transmission of cancer cells represents an intriguing and unexplored host-pathogen system, with significant ecological and evolutionary ramifications. The pathogen consists of clonal malignant cell lines that spread horizontally as allografts and/or xenografts. Although only nine transmissible cancer lineages in eight host species from both terrestrial and marine environments have been investigated, they exhibit evolutionary dynamics that may provide novel insights into tumor-host interactions particularly in the formation of metastases. Here we present an overview of known transmissible cancers, discuss the necessary and sufficient conditions for cancer transmission, and provide a comprehensive review on the evolutionary dynamics between transmissible cancers and their hosts

The effect of mitochondrial recombination on fertilization success in blue mussels

International audienceThe presence of doubly uniparental inheritance (DUI) in bivalves represents a unique mode of mitochondrial transmission, whereby paternal (male-transmitted M-type) and maternal (female-transmitted F-type) haplotypes are transmitted to offspring separately. Male embryos retain both haplotypes, but the M-type is selectively removed from females. Due to the presence of heteroplasmy in males, mtDNA can recombine resulting in a 'masculinized' haplotype referred to as Mf-type. While mtDNA recombination is usually rare, it has been recorded in multiple mussel species across the Northern Hemisphere. Given that mitochondria are the powerhouse of the cell, different mtDNA haplotypes may have different selective advantages under diverse environmental conditions. This may be particularly important for sperm fitness and fertilization success. In this study we aimed to i) determine the presence, prevalence of the Mf-type in Australian blue mussels (Mytilus sp.) and ii) investigate the effect of Mf-mtDNA on sperm performance (a fitness correlate). We found a high prevalence of recombined mtDNA (≈35 %) located within the control region of the mitochondrial genome, which occurred only in specimens that contained Southern Hemisphere mtDNA. The presence of two female mitotypes were identified in the studied mussels, one likely originating from the Northern Hemisphere, and the other either representing the endemic M. planulatus species or introduced genotypes from the Southern Hemisphere. Despite having recombination events present in a third of the studied population, analysis of sperm performance indicated no difference in fertilization success related to mitotype