School of Natural Sciences, University of Tasmania, Hobart, Australia
School of Natural Sciences, University of Tasmania, Hobart, Australia.
Proc Biol Sci. 2018 Nov 21;285(1891):20182239. doi: 10.1098/rspb.2018.2239.
Knowledge of the ecological dynamics between hosts and pathogens during the initial stages of disease emergence is crucial to understanding the potential for evolution of new interspecific interactions. Tasmanian devil () populations have declined precipitously owing to infection by a transmissible cancer (devil facial tumour disease, DFTD) that emerged approximately 20 years ago. Since the emergence of DFTD, and as the disease spreads across Tasmania, the number of devils has dropped up to 90% across 80% of the species's distributional range. As a result, the disease is expected to act as a strong selective force on hosts to develop mechanisms of tolerance and/or resistance to the infection. We assessed the ability of infected devils to cope with infection, which translates into host tolerance to the cancer, by using the reaction norm of the individual body condition by tumour burden. We found that body condition of infected hosts is negatively affected by cancer progression. Males and females presented significant differences in their tolerance levels to infection, with males suffering declines of up to 25% of their body condition, in contrast to less than 5% in females. Sex-related differences in tolerance to cancer progression may select for changes in life-history strategies of the host and could also alter the selective environment for the tumours.
在疾病出现的初始阶段，了解宿主和病原体之间的生态动态对于理解新的种间相互作用进化的潜力至关重要。袋獾（）种群由于感染了一种可传播的癌症（袋獾面部肿瘤疾病，DFTD）而急剧减少，这种癌症大约在 20 年前出现。自 DFTD 出现以来，随着疾病在塔斯马尼亚的传播，在物种分布范围的 80%的地区，袋獾的数量下降了高达 90%。因此，预计这种疾病将对宿主产生强大的选择压力，使其发展出对感染的耐受和/或抗性机制。我们通过个体肿瘤负担的身体状况反应规范来评估受感染的袋獾应对感染的能力，这转化为宿主对癌症的耐受能力。我们发现，受感染宿主的身体状况会受到癌症进展的负面影响。雄性和雌性在对感染的耐受水平上存在显著差异，雄性的身体状况下降高达 25%，而雌性则不到 5%。对癌症进展的耐受性的性别差异可能会选择宿主生活史策略的变化，也可能改变肿瘤的选择环境。
