Transmissible cancer in Tasmanian devils: localized lineage replacement and host population response.
Tasmanian devil facial tumour disease (DFTD) is a clonally transmissible cancer threatening the Tasmanian devil (Sarcophilus harrisii) with extinction. Live cancer cells are the infectious agent, transmitted to new hosts when individuals bite each other. Over the 18 years since DFTD was first observed, distinct genetic and karyotypic sublineages have evolved. In this longitudinal study, we investigate the associations between tumour karyotype, epidemic patterns and host demographic response to the disease. Reduced host population effects and low DFTD infection rates were associated with high prevalence of tetraploid tumours. Subsequent replacement by a diploid variant of DFTD coincided with a rapid increase in disease prevalence, population decline and reduced mean age of the population. Our results suggest a role for tumour genetics in DFTD transmission dynamics and epidemic outcome. Future research, for this and other highly pathogenic emerging infectious diseases, should focus on understanding the evolution of host and pathogen genotypes, their effects on susceptibility and tolerance to infection, and their implications for designing novel genetic management strategies. This study provides evidence for a rapid localized lineage replacement occurring within a transmissible cancer epidemic and highlights the possibility that distinct DFTD genetic lineages may harbour traits that influence pathogen fitness.
School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia rkhamede@utas.edu.au.
Rodrigo K
RK
Hamede
Department of Primary Industries, Parks, Water and Environment, Hobart, Tasmania 7001, Australia.
Anne-Maree
AM
Pearse
Department of Primary Industries, Parks, Water and Environment, Hobart, Tasmania 7001, Australia.
Kate
K
Swift
School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia.
Leon A
LA
Barmuta
Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK.
Elizabeth P
EP
Murchison
School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia.
Menna E
ME
Jones
D017677:Age Distribution; D000818:Animals; D001733:Bites and Stings / Q000453:epidemiology; D060965:Clonal Evolution; D005153:Facial Neoplasms / Q000453:epidemiology / Q000235:genetics* / Q000662:veterinary*; D059785:Karyotype; D008137:Longitudinal Studies; D008285:Major Histocompatibility Complex / Q000235:genetics*; D008394:Marsupialia / Q000235:genetics*; D011003:Ploidies; D015995:Prevalence; D013648:Tasmania / Q000453:epidemiology
Tasmanian devil facial tumour disease; aneuploidy; cancer evolution; disease ecology; emerging infectious disease