Assessing the suitability of mitochondrial and nuclear DNA genetic markers for molecular systematics and species identification of helminths

Table 2 Properties of different classes of genetic marker in terms of their quantitative suitability for molecular systematics of helminths

Class of marker	Genetic marker	Nematodes^a		Trematodes^a		Cestodes^a
Class of marker	Genetic marker	Mean ± SD [95 CI%]	Recovered orders as monophyletic^b	Mean ± SD [95 CI%]	Recovered suborders as monophyletic^b	Mean ± SD [95 CI%]	Recovered orders as monophyletic^b
Nuclear rRNA	18S rRNA	0.029* ± 0.019 [0.024–0.034]	3/6	0.036* ± 0.015 [0.033–0.038]	3/4	0.039* ± 0.021 [0.039–0.043]	4/6
Nuclear rRNA	28S rRNA	0.050* ± 0.026 [0.039–0.061]	3/6	0.120* ± 0.049 [0.116–0.124]	3/4	NA	4/6
Nuclear spacer	ITS1	0.356 ± 0.227 [0.287–0.425]	0/6	0.262 ± 0.115 [0.2478–0.277]	3/4	0.546* ± 0.198 [0.481–0.612]	2/3
Nuclear spacer	ITS2	0.537* ± 0.222 [0.429–0.644]	3/6	0.171 ± 0.078 [0.160–0.181]	3/4	0.550* ± 0.106 [0.491–0.609]	5/5
Mt protein-coding	COI	0.215 ± 0.103 [0.197–0.234]	3/6	0.264 ± 0.047 [0.258–0.271]	2/4	0.136 ± 0.056 [0.127–0.146]	5/6
	COII	0.249 ± 0.139 [0.224–0.274]	4/6	0.359 ± 0.069 [0.345–0.364]	2/4	0.179 ± 0.075 [0.167–0.191]	4/5
	cytB	0.249 ± 0.097 [0.232–0.267]	3/6	0.259 ± 0.040 [0.254–0.265]	1/4	0.183 ± 0.080 [0.170–0.197]	5/5
	NAD1	0.232 ± 0.100 [0.214–0.250]	5/6	0.289 ± 0.052 [0.282–0.296]	2/4	0.193 ± 0.066 [0.982–0.203]	6/6
Mt rRNA	12S rRNA	0.198 ± 0.106 [0.178–0.217]	4/6	0.272 ± 0.055 [0.265–0.280]	2/4	0.140 ± 0.063 [0.129–0.150]	5/6
Mt rRNA	16S rRNA	0.227 ± 0.091 [0.2109–0.244]	4/6	0.264 ± 0.051 [0.257–0.271]	3/4	0.149 ± 0.072 [0.137–0.160]	5/6

NA, No data available
*Statistically significant difference of the mean genetic distances between the markers at P < 0.000001), according to Kruskal–Wallis test with Dunn’s posthoc analysis
^aGenetic distances among nematodes (Ascaridida and Spirurida), trematodes (Opisthorchiata, Echinostomata and Xiphidata), and cestodes (Taeniidae and Hymenolepididae) were used to calculate mean genetic distances
^bThe number of orders/suborders recovered as monophyletic out of the total number of recognized orders/suborders represented among available sequences (6 for nematodes, 4 for trematodes, 6 for cestodes)

ISSN: 1756-3305