A group discrimination method based on concentric circle-cut semi-landmark points of fish otoliths

Abstract

The present invention relates to a group discrimination method based on concentric circle cutting semi-landmark points of fish otoliths, belonging to the technical field of fish otolith identification, the method adopts the intersection points of a series of concentric circles and otolith sulci and edges as landmark points, the outermost circle of the series of concentric circles is the longest diameter of the otolith as the diameter, and its radius is equally divided into 8 to 10 parts inside, the outermost concentric circles are constructed, the intersection points of the concentric circles and the otolith sulci and contours are selected, used as landmark points, and statistical analysis is performed. The method of the present invention divides the otoliths into concentric circle points, can increase the number of punctuation points, and improves the accuracy of discriminating fish groups through otoliths.

Description

Technical Field

[0001] The invention belongs to the technical field of fish otolith identification, and specifically relates to a group discrimination method based on concentric circle cutting semi-landmark points of fish otoliths. Background Art

[0002] Fish otoliths are hard tissues in the inner ear of bony fish that play a role in balance and hearing. They are mainly composed of calcium carbonate. Their morphological characteristics are regulated by genetic factors and are species-specific. They are often used to divide fish species or populations. In the early days, the morphological research of otoliths focused on the measurement of metric indicators to describe the smoothness and protrusion of otoliths. In the 1980s, morphological analysis methods and multivariate statistical analysis tools became mature, and geometric morphometrics was developed. Geometric morphometrics mainly includes two methods: contour line method and landmark method. The landmark method is a shape statistical method based on Cartesian landmarks. By obtaining the X and Y coordinate data of landmark points on two-dimensional images, relative warping (Relative Warp) and thin plate spline analysis are performed, and grid deformation maps are drawn to analyze the morphological variation of otoliths and perform multivariate statistical analysis. Landmark points are points with obvious characteristics and easy to identify. At present, in biological applications, landmark points are often divided into three categories: Type I landmark points are contact points and intersection points between different tissues, such as the intersection of wing veins and leaf veins, and the intersection of fish fins and fish bodies. Type II landmarks are depressions or protrusions in the structure, such as the sharp curvature of teeth and protrusions of bones. Type III landmarks are endpoints or poles such as the longest point, narrowest point, and widest point in the structure. The landmark method first obtains the X, Y coordinate values ​​of the otolith landmarks, also known as Cartesian coordinate data, and then centers, rotates, and scales the coordinates to make the calculation results represent the pure morphological information of the otoliths, eliminating non-shape effects such as the position, scale, angle, and shooting magnification of the otoliths, and then quantifies the morphology of the research object. The overprint method is commonly used to remove the interference of these non-shape variations. The principle is to find the minimum distance between coordinate points through the least-square criterion, and then center, rotate, and scale to obtain the mean shape of the otolith sample. The thin plate spline analysis theory utilizes the knowledge of bending energy matrix in materials science. The deformation change produced by the object is reflected in the conversion of the corresponding function. The function conversion involves a series of complex steps, including principal warp, relative warp, partial warp, etc., and the corresponding data files are generated to compare the differences with statistical software. In addition, the morphological changes of the sample can be directly displayed visually through thin plate spline analysis. In the prior art, the tpsDig2 software is used to mark the otoliths, generate ".tps files", and then the generated ".tps files" are input into the tpsrelw32 software to extract the otolith feature information, and then the population analysis based on the otolith features is completed in combination with statistical methods.

[0003] However, the landmark point method in the prior art for the classification of fish otolith groups has the characteristics of strong subjectivity in point selection and few optional landmark points. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a group identification method based on concentric circle cutting semi-landmark points of fish otoliths. The method divides the otoliths into concentric circle points, which can increase the number of marks and improve the accuracy of distinguishing fish groups through otoliths.

[0005] The present invention is achieved through the following technical solutions

[0006] A group discrimination method based on concentric circle cutting semi-landmark points of fish otoliths. The method uses the intersection points of a series of concentric circles and the otolith groove and edge as landmark points. The outermost circle of the series of concentric circles takes the longest diameter of the otolith as the diameter, and its radius is divided into 8 to 10 parts inside. The outermost concentric circle is constructed, and the intersection points of the concentric circles, the otolith groove and the contour are selected as landmark points for statistical analysis.

[0007] Furthermore, the radius of the outermost circle is divided into 10 equal parts.

[0008] The beneficial effects of the present invention compared with the prior art are as follows:

[0009] The method of the present invention selects the intersection of the edge of the otolith, the auditory groove and the concentric circles as the landmark point by the concentric circle cutting landmark point method, on the one hand, increases the number of optional landmark points, on the other hand, by increasing the supplementary points reflecting the base page characteristics, ensures the integrity of the otolith feature extraction, and improves the discrimination rate of the group. Moreover, the selected points are all objective points, avoiding the influence of subjective factors on the point selection position, realizing the standardization of the point selection process of the tpsrelw32 software, and laying a foundation for establishing a landmark point database and subsequent in-depth application. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is the otolith diagram of the Otaki hexaline fish: the right side is the front end of the otolith, the left side is the back end of the otolith, the top is the dorsal side, the bottom is the ventral side, 1, the main groove is also the auditory groove, 2, the tail of the auditory groove, 3, the wing lobe, 4, the basal lobe;

[0011] Figure 2 Schematic diagram of original landmark point selection;

[0012] Figure 3 10×1 concentric circles to mark the points; DETAILED DESCRIPTION

[0013] The technical solution of the present invention is further explained below by examples, but the protection scope of the present invention is not limited in any form by the examples.

[0014] Example 1

[0015] Samples of Otaki six-line fish collected from 7 wild populations in Lianyungang, Qingdao, Weihai, Yantai, Qinhuangdao, Dalian, Dandong and 1 Weihai breeding area were selected to measure the body length, body weight and other information of the fish and remove the otoliths. The otoliths were cleaned with ultrapure water and placed in an oven to dry to constant weight, weighed using an electronic balance (division value 0.01 mg), and recorded. The left and right otoliths were placed in clean 1.5 ml centrifuge tubes and numbered separately for storage.

[0016] In this example, the morphological differences between the left and right sagittal otoliths were not obvious, so the left sagittal otolith of Hexaphyllum otaki was uniformly selected as the research object. In the otolith morphological analysis, an OLYMPUS SZ61 stereo microscope was used to collect images of the inner side of the sagittal otolith. When the left otolith was missing, the right otolith was used instead. Figure 1 As shown, the right side of the figure is the front end of the otolith, the left side is the back end of the otolith, the top is the dorsal side, the bottom is the ventral side, 1 is the main groove, also known as the auditory groove, 2 is the tail of the auditory groove, 3 is the wing lobe, and 4 is the basal lobe.

[0017] The collected otolith images were processed according to the original landmark point method and the concentric circle landmark point method. The specific methods and results are as follows:

[0018] 1. Original landmark method

[0019] The original landmark method, according to the requirements of landmark homology and characteristic, selects 14 landmark points on the otolith morphology of Hexagram otakii, including the outer contour of the otolith and the contour of the auditory groove. Points are taken in a clockwise direction. The number and order of landmark points of all samples remain consistent, and the 14 landmark points are classified. Type I landmark points are 6, 11, 12, 13, 14, Type II landmark points are 2, 4, 8, 10; Type III landmark points are 1, 3, 5, 7, 9, and the corresponding coordinate point numerical files are established. The landmark points finally found are as follows Figure 2 shown.

[0020] 2. Concentric circle landmark method

[0021] The intersections of concentric circles and the otolith groove and edge are used as landmark points. The longest diameter of the otolith is used as the diameter to make the outermost circle. The radius of the outermost circle is divided into 10 equal parts to construct a series of concentric circles. The intersections of the series of concentric circles with the otolith groove and outline are selected as landmark points for statistical analysis. However, the proportions of the basal lobe and wing lobe of the otolith of Otaki hexapod are different, and it is one of the important characteristics of group division. When the concentric circles are divided equally, the number of wing lobe intersections will be inconsistent. When the landmark points are used for otolith morphological analysis, it is necessary to ensure that the number of points obtained on the otolith of each individual is uniform. Therefore, non-shared intersections are discarded during analysis. 50 points are used for analysis. Figure 3Use tpsDig2 software to mark the otoliths and generate a ".tps file". Then input the generated ".tps file" into tpsrelw32 software to extract otolith feature information, and then combine statistical methods to complete the group analysis based on otolith features.

[0022] The two methods were used to make group judgments on different groups of Otaki hexapods, and the results are shown in Table 1 below.

[0023] Table 1. Comparison of the results of identifying the population of Hesperus taki using the original landmark method and the 10×1 concentric circle method.

[0024]

[0025] Example 2

[0026] This example attempts to divide the otolith sample in Example 1 into different numbers of equal parts based on the radius of the concentric circle with the longest diameter of the otolith as the diameter, and examines the effect of different numbers of equal parts on the discrimination results. The radius of the largest circle with the longest diameter as the diameter is divided into 8 and 10 parts respectively. The concentric circle method without artificial point filling is used to discriminate each group, and the discrimination results are shown in Table 2:

[0027] Table 2. Comparison of the results of distinguishing the population of Hesperus taki with different equally divided concentric circles with or without supplementary points

[0028]

[0029] It can be seen from the above embodiment that when the area is divided into 10 equal parts, the accuracy of the discrimination result reaches 98.4%. Therefore, when the radius of the outermost circle is divided into 10 equal parts, the effect is best.

Claims

1. A group discrimination method based on concentric circle cutting semi-landmark points of fish otoliths, characterized in that The method uses the intersection points of a series of concentric circles and the otolith groove and edge as landmark points. The outermost circle of the series of concentric circles takes the longest diameter of the otolith as its diameter, and its radius is divided into 8 to 10 equal parts inside it. The outermost concentric circle is constructed, and the intersection points of the concentric circles, the otolith groove and the contour are selected as landmark points for statistical analysis.

2. A method for distinguishing groups of fish otolith-based concentric circle cutting semi-landmark points according to claim 1, characterized in that Divide the radius of the outermost circle into 10 equal parts.

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