Botha-Brink Jennifer, Codron Daryl, Huttenlocker Adam K, Angielczyk Kenneth D, Ruta Marcello
Karoo Palaeontology, National Museum, Box 266, Bloemfontein, 9300, South Africa.
Department of Zoology and Entomology, University of the Free State, Bloemfontein, 9300, South Africa.
Sci Rep. 2016 Apr 5;6:24053. doi: 10.1038/srep24053.
Studies of the effects of mass extinctions on ancient ecosystems have focused on changes in taxic diversity, morphological disparity, abundance, behaviour and resource availability as key determinants of group survival. Crucially, the contribution of life history traits to survival during terrestrial mass extinctions has not been investigated, despite the critical role of such traits for population viability. We use bone microstructure and body size data to investigate the palaeoecological implications of changes in life history strategies in the therapsid forerunners of mammals before and after the Permo-Triassic Mass Extinction (PTME), the most catastrophic crisis in Phanerozoic history. Our results are consistent with truncated development, shortened life expectancies, elevated mortality rates and higher extinction risks amongst post-extinction species. Various simulations of ecological dynamics indicate that an earlier onset of reproduction leading to shortened generation times could explain the persistence of therapsids in the unpredictable, resource-limited Early Triassic environments, and help explain observed body size distributions of some disaster taxa (e.g., Lystrosaurus). Our study accounts for differential survival in mammal ancestors after the PTME and provides a methodological framework for quantifying survival strategies in other vertebrates during major biotic crises.
关于大规模灭绝事件对古代生态系统影响的研究，主要聚焦于分类多样性、形态差异、丰度、行为以及资源可利用性的变化，将其视为生物类群生存的关键决定因素。至关重要的是，尽管生活史特征对种群生存能力起着关键作用，但陆地大规模灭绝事件中这些特征对生物生存的贡献尚未得到研究。我们利用骨骼微观结构和体型数据，来探究二叠纪 - 三叠纪大灭绝（PTME）（显生宙历史上最具灾难性的危机）前后哺乳动物的兽孔目祖先生活史策略变化的古生态意义。我们的研究结果表明，灭绝后的物种存在发育截断、预期寿命缩短、死亡率升高以及灭绝风险增加的情况。各种生态动力学模拟表明，繁殖提前开始导致世代时间缩短，这可以解释兽孔目动物在不可预测、资源有限的早三叠世环境中的存续情况，并有助于解释一些灾难类群（如二齿兽）的体型分布情况。我们的研究解释了二叠纪 - 三叠纪大灭绝后哺乳动物祖先的差异化生存情况，并为量化其他脊椎动物在重大生物危机期间的生存策略提供了一个方法框架。
