Khlebodarova T M, Likhoshvai V A
Institute of Cytology and Genetics of Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.
Vavilovskii Zhurnal Genet Selektsii. 2020 Jul;24(4):407-419. doi: 10.18699/VJ20.633.
Paleontologists define global extinctions on Earth as a loss of about three-quarters of plant and animal species over a relatively short period of time. At least five global extinctions are documented in the Phanerozoic fossil record (500-million-year period): ~65, 200, 260, 380, and 440 million years ago. In addition, there is evidence of global extinctions in earlier periods of life on Earth - during the Late Cambrian (500 million years ago) and Ediacaran periods (more than 540 million years ago). There is still no common opinion on the causes of their occurrence. The current study is a systematized review of the data on recorded extinctions of complex life forms on Earth from the moment of their occurrence during the Ediacaran period to the modern period. The review discusses possible causes for mass extinctions in the light of the influence of abiogenic factors, planetary or astronomical, and the consequences of their actions. We evaluate the pros and cons of the hypothesis on the presence of periodicity in the extinction of Phanerozoic marine biota. Strong evidence that allows us to hypothesize that additional mechanisms associated with various internal biotic factors are responsible for the emergence of extinctions in the evolution of complex life forms is discussed. Developing the idea of the internal causes of periodicity and discontinuity in evolution, we propose our own original hypothesis, according to which the bistability phenomenon underlies the complex dynamics of the biota development, which is manifested in the form of global extinctions. The bistability phenomenon arises only in ecosystems with predominant sexual reproduction. Our hypothesis suggests that even in the absence of global abiotic catastrophes, extinctions of biota would occur anyway. However, our hypothesis does not exclude the possibility that in different periods of the Earth's history the biota was subjected to powerful external influences that had a significant impact on its further development, which is reflected in the Earth's fossil record.
古生物学家将地球上的全球灭绝定义为在相对较短的时间内约四分之三的动植物物种消失。在显生宙化石记录（约5亿年的时间段）中记录了至少五次全球灭绝事件：分别发生在约6500万、2亿、2.6亿、3.8亿和4.4亿年前。此外，在地球生命的早期阶段——晚寒武纪（约5亿年前）和埃迪卡拉纪（超过5.4亿年前）也有全球灭绝的证据。关于这些灭绝事件发生的原因仍然没有共识。当前的研究是对从埃迪卡拉纪时期复杂生命形式出现到现代地球记录的灭绝数据进行的系统综述。该综述根据非生物因素（行星或天文因素）的影响及其作用后果，讨论了大规模灭绝的可能原因。我们评估了显生宙海洋生物群灭绝存在周期性这一假说的利弊。讨论了有力证据，这些证据使我们能够假设与各种内部生物因素相关的其他机制是复杂生命形式进化中灭绝事件出现的原因。在发展进化中周期性和间断性的内部原因这一观点时，我们提出了自己的原创假说，根据该假说，双稳态现象是生物群发展复杂动态的基础，这种动态以全球灭绝的形式表现出来。双稳态现象仅出现在以有性生殖为主的生态系统中。我们的假说表明，即使没有全球非生物灾难，生物群的灭绝无论如何都会发生。然而，我们的假说并不排除在地球历史的不同时期生物群受到强大外部影响并对其进一步发展产生重大影响的可能性，这在地球化石记录中有所体现。
