Coronaviruses are single-stranded positive-sense enveloped RNA viruses that are distributed broadly among humans, other mammals, and birds and that cause respiratory, enteric, hepatic, and neurologic diseases [1, 2] . The family Coronaviridae contains 4 genera, namely Alphacoronavirus, Betacoronavirus, Deltacoronavirus, and Gammacoronavirus [3] . Six coronavirus species are known to cause human disease [4] . Among which HCoV-OC43, HCoV-HKU1, SARS-CoV, and Middle East respiratory syndrome coronavirus (MERS-CoV) are belong to the genus Betacoronavirus [5] [6] [7] [8] . The other two strains, HCoV-229E and HCoV-NL63, are belong to the genus Alphacoronavirus [4, 5] . In the end of 2019, a pneumonia disease that caused by 2019-nCoV outbreaks in Wuhan, and the disease was assumed started from a local seafood market [9] . The outbreak has grown With the advent of BLAST based tools, alignment-based sequence analyses reveal many new discoveries [11] [12] [13] . Phylogenetic analysis of the RNA-dependent RNA polymerase (RdRp) protein, spike proteins, and full-length genomes found that 2019-nCoV is most closely related to two bat SARS-like coronaviruses, bat-SL-CoVZXC21 and bat-SL-CoVZC45, and the 2019-nCoV is thought to belong to Sarbecovirus of Betacoronavirus [14 -18] . From phylogenetic analysis of full genome alignment and similarity plots, it was found that 2019-nCoV has the highest similarity to the bat coronavirus RaTG13 sampled from a Rhinolophus affinis bat in Yunnan in 2013 [19, 20] . A recombination analysis performed revealed that bat-SL-CoVZXC21 and bat-SL-CoVZC45 are likely recombinants, containing genome segments from multiple SARS-CoV related lineages and 2019-nCoV related lineages including that from pangolins (Manis javanica) [21] . There is still ongoing debate whether the 2019-nCoV strain arose following recombination with previously identified bat and unknown coronaviruses [22] or arose independently as a new lineage to infect humans [19] . The alignment-based methods often give high accuracy and may reveal the relationships among sequences. However, alignment methods meet huge challenges when the recombination, shuffling, and rearrangement events frequently occur in the genome evolution. Simultaneously, the whole-genome multiple alignments are very time-consuming and expensive in memory usage [23] .
Alignment-free genome comparison methods are becoming an attractive alternative to address the limitations of alignment-based methods [23] . Several approaches derived from the standpoint of information theory, the way in which the base correlation property of DNA sequence is emphasized ， have been proposed for sequence comparison [24] [25] [26] [27] [28] . The average mutual information (AMI) profiles have been used to differentiate between coding and noncoding regions [24] , and to group HIV-1 viruses [25，26]. The base correlation method has been used to infer coronavirus phylogeny and analysis Hepatitis E virus genotyping and subtyping [27, 28] . Previously, we proposed the IC-PIC method, and studied the phylogeny of 13 dsDNA families, papillomaviruses from 22 genera, and viruses of Parvoviridae family [29] . Recently, Randhawa et al. [30] using alignment-free method reconstructed the phylogenetic tree and confirmed that the 2019-nCoV belongs to the Betacoronavirus and its genomic similarity to the sub-genus Sarbecovirus corroborated a possible bat origin.
With the wide application of genome sequence data we eager to know what is the imprinting characterizing the characteristics of a genome. We suggested that AMI and k-departed base correlation can be looked as the signature of a given genome sequence [29] . The average mutual information is called information correlation (IC) defined by
where pi means the probability of base i in the sequence and pi(k)j means the joint probability of base pair ij departed by distance k (k=0,1,2,…). In the following we shall study the 2019-nCoV phylogeny by using IC-PIC algorithm based on the above set of signatures of the genome sequence . Figure 1 and Figure 2 were downloaded from the GISAID Neighbor-Joining tree is generated. Finally, K phylogenetic trees are combined to generate a consensus tree. All these trees were constructed by using NEIGHBOR and CONSENSE program in the PHYLIP package [32] . The robustness of the tree topology was estimated by branch support.
The whole-genome-based phylogenetic trees for Betacoronavirus and 2019-nCoV are deduced by use of IC-PIC method and given in Fig 1 and Fig 2 respectively 1) or 100 (K=100 for Fig 2) trees based on IC-PIC matric, with Gamacoronavirus as out group.
The robustness of the tree topology was estimated by branch support. It is unrooted tree and not drawn to scale.
The phylogenetic tree of Betacoronavirus genus is shown in Fig. 1 The phylogentic tree of 2019-nCoVs is given in Fig 2. The branching order of IC-PIC tree shows location-virus linkage. The picture also shows the details of how the disease spreads from one place to another. Thus the present phylogenetic tree may give a clue to searching for the origin of the outbreak in Wuhan. Furthermore, the mutation rate of viruses is an interesting problem. The rate calculation and prediction is closely related to the set of evolutionary clock. In our approach the evolutionary clock could be calibrated by evolutionary distance. It has been noted that coronavirus RdRp have high mutation rates during replication, and the mechanism which contribute to high rate of recombination is diversity [33 -36] .
How to make prediction on the mutation rate of viruses the further work based on IC-PIC tree is awaited for.
We The consensus tree of 124 novel Coronavirus infection events is derived from 100 trees based on IC-PIC matric, with Gamacoronavirus as out group. The robustness of the tree topology was estimated by branch support. It is unrooted tree and not drawn to scale.