Long-term cycles in the history of life: Periodic biodiversity in the Paleobiology Database

An ubiquitous ~62 Myr periodic fluctuation superimposed on general trends in fossil biodiversity

A 62 Myr periodicity is superimposed on other longer-term trends in fossil biodiversity. This cycle can be discerned in marine data based on the Sepkoski compendium, the Paleobiology Database, and the Fossil Record 2. The signal also exists in changes in sea level/sediment, but is much weaker than in biodiversity itself. A significant excess of 19 previously identified Phanerozoic mass extinctions occur on the declining phase of the 62 Myr cycle. appearance of the signal in sampling-standardized biodiversity data, it is likely not to be a sampling artifact, but either a consequence of sea-leve…

A ubiquitous ~62-Myr periodic fluctuation superimposed on general trends in fossil biodiversity. I. Documentation

We use Fourier analysis and related techniques to investigate the question of periodicities in fossil biodiversity. These techniques are able to identify cycles superimposed on the long-term trends of the Phanerozoic. We review prior results and analyze data previously reduced and published. Joint time-series analysis of various reductions of the Sepkoski Data, Paleobiology Database, and Fossil Record 2 indicate the same periodicity in biodiversity of marine animals at 62 Myr. We have not found this periodicity in the terrestrial fossil record. We have found that the signal strength decreases …

Observations and perspectives on the variation of biodiversity

Based on statistical analysis of the complete genome sequences, a remote relationship has been observed between the evolution of the genetic code and the three domain tree of life. The existence of such a remote relationship need to be explained. The unity of the living system throughout the history of life relies on the common features of life: the homochirality, the genetic code and the universal genome format. The universal genome format has been observed in the genomic codon distributions as a common feature of life at the sequence level. A main aim of this article is to reconstruct and to…

Considering the Case for Biodiversity Cycles: Reexamining the Evidence for Periodicity in the Fossil Record

Medvedev and Melott (2007) have suggested that periodicity in fossil biodiversity may be induced by cosmic rays which vary as the Solar System oscillates normal to the galactic disk. We re-examine the evidence for a 62 million year (Myr) periodicity in biodiversity throughout the Phanerozoic history of animal life reported by Rohde & Mueller (2005), as well as related questions of periodicity in origination and extinction. We find that the signal is robust against variations in methods of analysis, and is based on fluctuations in the Paleozoic and a substantial part of the Mesozoic. Examinatio…

Whilst this Planet Has Gone Cycling On: What Role for Periodic Astronomical Phenomena in Large Scale Patterns in the History of Life?

One of the longstanding debates in the history of paleontology focuses on the issue of whether or not there have been long term cycles (operating over tens of millions of years) in biodiversity and extinction. Here we consider the history of this debate by connecting the skein from Grabau up to 2008. We focus on the evidence for periodicity that has emerged thus far, and conclude that there is indeed some evidence that periodicity may be real, though of course more work is needed. We also comment on possible causal mechanisms, focusing especially on the motion of our solar system in the Galaxy…

具有生活史阶段且无感染恢复的双斑块SI流行病模型中的源-汇动态

Source-sink dynamics in a two-patch SI epidemic model with life stages and no recovery from infection

本研究通过双斑块SI模型分析源-汇种群动态，揭示基本再生数、成熟率和扩散率对疾病传播及种群恢复的关键作用，为疾病影响下的自然种群保护提供策略依据。