| Coilia (Coilia) is a herring-shaped head (Clupeiformes), Anchovies (Engraulidae) is generally believed that there are 13 species in central and western Pacific to the Indian Ocean coastal waters. Most Coilia species live in coastal waters, and has obvious and estuaries along the coast a short distance between the migratory habits, and only found in Vietnam and the Yangtze River C. lindmani short jaw anchovy (C. brachygnathus) of pure water and a few other species species. Previously thought 4 kinds of Coilia in China, namely, C.grayii, C.mystus, C.nasus and C.brachygnathus.C.nasus usually live in China, Japan and North Korea along the coast in spring, after sexual maturity up river from the estuary into the river, lake, breeding eggs, hatching larvae after finishing with the water back to the sea. However, in the Yangtze River downstream of the Taihu Lake, Chaohu Lake and other lakes in shape and live a life with the migratory habits of different types of fresh water to settle certain type of populations, Yuan Chuan Mi et al called the lake anchovy (C. nasus taihuensis ) as a subspecies of C. nasus. But then based on morphology, sagitta otolith morphology, isozymes, mtDNA control region and cyt b genes and other characteristics of the analysis that has not yet reached the lake anchovy subspecies level. At the same time, has been regarded as closely related species Colia species validity of the short jaw has also been questioned. In recent years, based on morphological, biochemical, mtDNA and other characteristics of the comparative study of short-jaw anchovy is also considered Coilia settle a type of freshwater species. Therefore, the existing research has been basically clarified Coilia with two ecological types of species or ecosystem type (ecotype), one for freshwater ecological settlement, including the lake anchovy and short-jaw anchovy; the other for the migratory ecotype also formerly Coilia. Fisheries, the settlement type is the low value fisheries products, and migration in C. nasus Sujiang Since ancient times, and shad, puffer fish and that "the Yangtze River San Xian."Although the number of jaw length and anal fin has been regarded as distinct from C. nasus and C. brachygnathus, and the main features of the short jaw, but these features did not previously been relatively large samples. Fish otolith is widely used in kin species identification and stock discrimination owing to their conservative morphology and elemental composition. This basis from April 2009 to November 2009 were collected Jingjiang, Jiuduansha, Taihu Lake, Poyang Lake and other places, collected 906 samples, the use of advanced digital x-ray pictures by means of the four representative populations of the maxilla length , anal fin spine number,vertebrae number and sagittal shape indices were measured and analyzed to clarify the different Coilia ecological differences between these phenotypes, the main results are as follows:1,In 4 populations in order to Jingjiang the maxilla length / head length mean the most,Jiuduansha and Lake of the second, Taihu Lake populations is the smallest. ANOVA showed the jaw length / head length were not significant from Jiuduansha,Jingjiang,Taihu Lake and Poyang Lake populations, but populations of Jingjiang and Jiuduansha Lake and Poyang Lake, respectively, the maxillary length / head length were significantly different.In 4 populations to Jingjiang populations head length / body length mean the most, Taihu Lake,Poyang Lak populations are the second, the minimum Jiuduansha populations. ANOVA analysis revealed that in addition Jiuduansha and Taihu Lake, Poyang Lake populations of head length / body length was not significant, other differences between populations were significant.2,Statistical analysis of the four populations of 906 specimens of the X-ray images from the spine, the count of the number of results can be seen in the 4 populations to Jingjiang and spine Jiuduansha populations the largest number, mean 80.68 and 80.21, respectively; Lake populations, followed by 76.67; Poyang Lake populations at least, is 74.92. Further analysis showed that the spine of each populations are pretty much normal distribution. Among them, the Jingjiang and Jiuduansha populations overlap significantly, the two populations and the Poyang Lake and Taihu larger difference between populations. ANOVA showed that the Jingjiang and the average spine Jiuduansha populations was not significant, but the Taihu Lake, Poyang Lake were significantly different populations. Jiuduansha populations have significant differences in Taihu Lake and Poyang Lake populations were significantly different. Showing the number of anal fin rays, Jingjiang and maximum Jiuduansha populations.Taihu Lake and Poyang Lake, the smaller, the number of anal fin rays are basically showing a high in the middle , both sides of the low-normal type distribution phenomenon. Among them, Jingjiang and Jiuduansha populations overlap more Taihu Lake and Poyang Lake, the former two and the large difference between the latter two. But by the single factor analysis of variance, showed four populations, the average number of anal fin rays are not significant differences.3,Withing four populations of C. nasus maxillary length / body length, maxillary length / head length, spine number, number of anal fin rays, this 4 traits for cluster analysis and draw a tree diagram, showing the same Eco-Euclidean distance is very small within the different eco-squared Euclidean distance between the larger phenomenon. Tree diagram shows the visible and Jiuduansha Jingjiang, and the Taihu Lake and Poyang Lake populations as a population can be combined, and the relationship between two distant populations.4,Selecting the number of vertebrae, anal fin rays, and the head length / body length, maxillary length / body length, maxillary length / head length can be the amount of such traits to esTablelish the amount of 3 to Bayes discriminant function, step by step discrimination and mutual authentication.In 906 individuals, only 50 were wrongly convicted, wrongly rate fell to 5.5% that determine the success rate of 94.5%. Among them, 423 migratory populations determine the success rate of 92.9%, 263 from Taihu Lake populations, 92.8% identification success rate, 220 from Poyanghu Lake discriminant populations 99.5% success rate. Eigenvectors from the first and second feature vectors by a typical discriminant analysis diagram can visually see, migratory populations, individual populations of Taihu Lake and Poyanghu Lake, separated from each other. 5,Through the same experiment 122 specimens in the shape of the sigitta otolith of the 9 indicators(roundness,format–factor, circularity, rectangularity, ellipticity, radius ratio, Feret ratio, aspect ratio, surface density). ANOVA analysis showed that the there is no significant difference in Jingjiang and Jiuduansha populations on Coilia otolith shape indices; there are five significantly different (roundness, ellipticity, radius ratio, Feret ratio, rectangularity), two significantly different (format- factor,circularity) in Jingjiang and Taihu Lake populations.The principal component analysis based on principal component 1 can be Jingjiang, Lake Jiuduansha distinction between populations, based on principal component 2 can be Jingjiang, Jiuduansha and Taihu Lake populations distinction. But regardless of the principal component 1 or the second composition, Jingjiang and Jiuduansha population have some degree of overlap. The first two principal components of the cumulative contribution rate of 84.642%, with a small number of indicators that can be summarized four different geographical populations of C. nasus otolith morphological differences.The shape index of 9 stepwise discriminant results determine the success rate to 86.89%. Jingjiang and Jiuduansha populations if combined into a population with the Taihu Lake and Poyanghu Lake populations further discriminant, discriminant equation and discrimination results can be seen in 122 individuals, only 10 were wrongly convicted, wrongly rate to 8.20%, that determine the success rate of 91.8%. Among them, 62 populations of migratory success rate of 88.71% discrimination, 29 from Taihu Lake populations identification success rate was 93.1%, 30 from Poyanghu Lake populations discriminant success rate was 96.67%. Eigenvectors from the first and second feature vectors by a typical discriminant analysis diagram can visually see, migratory populations, individual from Taihu Lake and Poyang Lake populations, separated from each other. |
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