Table 1 Estimated levels of HGT in CRISPR–spacer-containing and CRISPR–spacer-lacking genomes

From: No evidence of inhibition of horizontal gene transfer by CRISPR–Cas on evolutionary timescales

Category

0 spacers

⩾1 spacers

Wilcoxon significance

Bacteria

 N

705

532

 

 Prophages pera genome

1.267 (0)

2.094 (1)

P<0.0001

 Prophage proteins

66.85 (0)

114.883 (64)

P<0.0001

 Singleton fraction

0.040 (0.027)

0.032 (0.020)

P=0.0067

 Fraction of HGT (dinucleotide based)b

0.186

0.227

P<0.0001

Archaea

 N

18

96

 

 Singleton fraction

0.095 (0.093)

0.070 (0.083)

P=0.68

 Fraction of HGT (dinucleotide based)c

0.222

0.249

P=0.757

  1. Abbreviations: CRISPR, clustered, regularly, interspaced, short, palindromic repeats; HGT, horizontal gene transfer.
  2. aValues of HGT-related measures represent the mean (median) across a group of genomes.
  3. bN=327 and N=241, respectively.
  4. cN=4 and N=38, respectively.
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