Table 1 Taxonomic distribution, gene content, distinct genome architecture and gene strand asymmetry of the available metazoan mtDNAs

From: Evolution of the mitochondrial genome of Metazoa as exemplified by comparison of congeneric species

Phylum, classification

No. of mtDNA

No. of genes b

No. of AR

AR rate c

GSA d

 

C

P a

All

tRNA

All

−tRNA

All

−tRNA

Δ%

 

Chordata, Tunicata

7

 

39.3±0.8

24.3±0.8

7

6

100

83.3

14.3

1

Chordata,Cephalochordata

9

 

37

22

3

2

25

12.5

33.3

0.41–0.51

Chordata, Vertebrata

849

41

37.0±0.3

22±0.2

43

13

4.9

1.4

69.7

0.41–0.62

 Hyperotreti

2

 

37

22

1

1

0

0

—

0.51

 Hyperoartia

2

 

37

22

1

1

0

0

—

0.51

 Polypteridae

3

 

37

22

1

1

0

0

—

0.51

 Chondrostei

7

 

37

22

1

1

0

0

—

0.51

 Neopterygii

374

27

37.0±0.1

22.0±0.1

14

7

3.5

1.6

50.0

0.46–0.60

 Chondrichthyes

8

 

37

22

1

1

0

0

—

0.51

 Coelacanthiformes

2

 

37

22

1

1

0

0

—

0.51

 Dipnoi

3

 

37

22

1

1

0

0

—

0.51

 Amphibia

82

1

37.1±0.6

22.1±0.5

17

5

19.7

4.9

70.6

0.46–0.53

 Archosauria

81

5

37.0±0.4

22.0±0.3

3

3

2.5

2.5

0

0.41–0.51

 Lepidosauria

44

1

37.0±0.4

22.0±0.3

11

3

23.26

4.65

72.73

0.49–0.57

 Testudines

19

 

37.1±0.2

22.1±0.2

3

2

11.1

5.6

33.3

0.51–0.62

 Prototheria

3

 

37

22

1

1

0

0

—

0.51

 Metatheria

22

7

37

22

1

1

0

0

—

0.51

 Eutheria

197

 

37

22

1

1

0

0

—

0.51

Echinodermata

17

1

37

22

7

6

37.5

31.2

14.3

0.08–0.68

Hemichordata

2

 

37

22

2

2

100

100

0

0.57–0.68

Xenoturbellida

1

 

37

22

     

0.57

Annelida

6

1

37

22

5

1

80

0

80

1

Echiura

1

 

37

22

     

1

Myzostomida

0

1

>26

>14

     

1

Arthropoda

154

7

37.0±1.5

22.0±0.9

70

25

45.1

15.7

64.3

0.03–1

 Chelicerata

28

 

37.5±3.1

22.2±1.6

15

6

51.8

18.5

60

0.14–0.41

 Myriapoda

7

 

37

22

6

3

83.3

33.3

50

0.14–0.24

 Crustacea

35

1

37.1±0.4

22.1±0.4

19

11

52.9

29.4

42.1

0.03–1

 Hexapoda

84

6

36.9±0.9

21.9±0.9

27

8

38.5

9.6

72.7

0.03–1

Brachiopoda

4

 

38.5±3.0

23.3±2.5

4

4

100

100

0

1

Chaetognatha

2

 

14

1

2

2

100

100

0

0.14–0.29

Bryozoa

2

 

36.5±0.7

21.5±0.7

2

2

100

100

0

0.67–0.73

Entoprocta

2

 

37.5±0.7

22.5±0.7

2

1

100

0

50

0.35–0.37

Phoronida

0

1

>31

>16

     

0.10

Nemertea

0

1

>26

>15

     

0.77

Pogonophora

0

2

>29

>16

     

1

Sipuncula

0

1

>19

>11

     

1

Onychophora

1

 

28

13

     

0.21

Priapulida

1

 

37

22

     

0.51

Rotiferae

2

 

35.5±0.7

21.5±0.7

2

2

100

100

0

1

Mollusca

46

 

37.5±2.9

22.5±2.4

34

24

73.3

51.1

29.4

0.02–1

 Bivalvia

19

 

37.4±4.0

23.0±3.7

14

12

72.2

61.1

14.3

0.41–1

 Cephalopoda

11

 

38.6±2.8

22.3±0.5

8

6

70

50

25.0

0.02–0.19

 Gastropoda

13

 

36.9±0.3

21.9±0.3

9

5

66.7

33.3

44.4

0.19–0.57

 Polyplacophora

1

 

37

22

     

0.14

 Scaphopoda

2

 

37

22

2

2

100

100

0

0.08–0.46

Nematoda

26

 

37.6±2.9

23.2±2.4

17

14

64

52

17.6

0–1

 Chromadorea

15

 

36

22

6

4

35.7

21.4

33.3

1

 Enoplea

11

 

39.8±3.5

24.9±3.0

11

10

100

90.0

9.1

0–0.80

Platyhelminthes

24

 

36.0±0.2

22.0±0.2

11

3

43.5

8.7

72.7

1

Cnidaria

29

1

17.2±0.4

2.0±0.4

11

10

35.7

32.1

9.1

0.41–1

Porifera

20

2

36.2±8.9

20.1±9.0

18

13

89.4

63.2

27.8

0.02–1

  1. Abbreviations: All, analysis carried out on all mt genes; AR, genome architecture; C, complete mtDNA; P, partial mtDNAs; −tRNA, exclusion of tRNA genes from the analysis; tRNA, analysis carried out only on tRNA genes.
  2. Bold type indicates AR rate ⩾70, Δ% ⩾60 and maximum GSA variability (ranging from about zero to one).
  3. The number and percentage of distinct genome architectures has been calculated for the entire set of mt genes (All) and excluding tRNA genes (−tRNA). The difference between AR percentage for ‘All’ and ‘−tRNA’ dataset is also reported (Δ%).
  4. aOnly partial mtDNAs (length higher than 7 kb) belonging to the following categories are indicated: mtDNAs erroneously reported as complete genomes; unique mtDNA representatives of a taxonomic group; mtDNAs representative of a congeneric pair.
  5. bMean±standard deviation calculated for complete mtDNAs. The gene number of partial mtDNAs is highlighted by the ‘>’ symbol.
  6. cThe variability of genome arrangement (AR rate) has been calculated as (NAR−1)/(NmtDNA−1) × 100. The value is reported only for taxa with more than one complete genome. Δ% has been calculated as (NAR-All−NAR-tRNA)/NAR-All × 100.
  7. dThe gene strand asymmetry has been calculated as ∣Nmajor-strand−Nminor-strand∣/Ntotal genes. The range for each taxon is reported.
  8. eThe two circular molecules of Brachionus plicatilis (Suga et al., 2008) has been considered as a single genome.
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