The Morphological Differences And Functional Adaptation Of Pharyngeal Bones And Teeth In Fish Distant Hybridization

The morphology and arrangement of the pharyngeal teeth and bone of parents and their offspring were studied using fish hybrids that were well-formed and well-related and genetically,in order to reveal the pharyngeal teeth and inferior pharyngeal bone morphogenesis and functional adaptation.The formation process of the experimental fish is as follows:There are four kinds of outbred strains.The parents of all of the samples are red crucian carp(Carassius auratus red var.abbreviated as 2n=100,abbreviated as RCC),blunt snout bream(Megalobrama amblycephala,2n=48,abbreviated as BSB),common carp((Cyprinus carpio 2n=100.abbreviated as CC),white crucian carp(Carassius auratus cuvieri,abbreviated as WCC).we conducted repeatable tests indicate that the distant hybridization of CC(?)×BSB(?),produce the four types of different ploidy offspring including the new diploid crucian carp-like species(2n=100,abbreviated as 2nNCRC),diploid gynogenetic common carp(2n=100,abbreviated as 2nGCOC),diploid gynogenetic mirror carp(2n=100,abbreviated as 2nGMCC).WCC(?)×RCC(?),the white crucian carp(?)×red crucian carp(?)(WR)was formed.RCC(?)×BSB(?),sterile triploid hybrid(3n=124,abbreviated as 3nJF124),fertile alloteraploid hybrid(4n=148,abbreviated as JF148 I)were formed,and JF148 can produce autotetraploid hybrid(4n=200,abbreviated as JF200).WCC(?)×BSB(?),the alloteraploid hybrid(4n=148,abbreviated as JF148?)was formed.1)It was found that the pharyngeal teeth of each of the four hybrids used in the experiment were all 1-3 lines of pharyngeal teeth and pharyngeal teeth in each line has different numbers.Most of the pharyngeal teeth of the hybrid strain are biased towards the female parent(2nGCOC,2nGMCC,JF148 I,WR,JF148?),but there is still a situation in the hybrid offspring that does not favor the female parent nor the male parent(2nNCRC?JF200).The study found that the teeth of different individuals of the same fish were sometimes different but mostly converged.The BSB is 2.3.5-5.3.2(most individuals)or 2.4-4.4.2(a small number of individuals).This phenomenon may be in the process of fish development,the conversion of fish feeding makes the activities of the muscles affect the pharynx pharyngeal morphology,pharyngeal bone shape restricts the development of pharyngeal teeth,and ultimately affect the phylogenetic evolution of fish.2)All the strains of the fish pharyngeal tooth shape can be divided into five kinds of morphological types(molar,conical,compressed,coarsely compressed,extremely compressed),pharyngeal teeth bones can be divided into three kinds of morphological types(short and broad,intermediate,long and narrow).The main teeth are composed of a single type and a mixed type.There are many combinations of pharyngeal and pharyngeal teeth types,which are adapted to different ecological and eating habits,Which the intermediate pharyngeal bone and pharyngeal teeth combination of the most ways.The intermediate pharyngeal bone and molar-coarsely compressed pharyngeal teeth combination(CC,JF148?);The intermediate pharyngeal bone and compressed-coarsely compressed pharyngeal teeth combination(BSB);The intermediate pharyngeal bone and molar-compressed pharyngeal teeth combination(WCC,RCC,WR);Finally the intermediate pharyngeal bone and molar-conical pharyngeal teeth combination(JF200,JF148 ?);There are combinations of short and broad pharyngeal bone and molar-coarsely compressed pharyngeal teeth(2nGCOC);The long and narrow pharynge-al bone can have a group of molar-compressed pharyngeal teeth(2nNCRC);The pharyngeal bone shape corresponding to the feeding habits can be divided into herbivorous,carnivorous,omnivorous.These combinations can improve the ability of fish to adapt to the environment.3)Nine variables were selected on the measurement site in the pharyngeal bone for detailed measurement,which include four pharyngeal bone morphological variables,one pharyngeal teeth morphological variables,four ratio variables.After correcting the data,using SPSS22.0 statistics software,statistical methods are mainly used in principal component analysis(PCA).The results of principal component analysis shows that we can extract three factors from nine variables,explaining the total variation of the original variable,and can explain the total variation of the 97.201%original variable,reflecting the degree of correlation between variables.A few factors that can be extracted from the pharyngeal variables can explain multiple independent variables.And the preliminary establishment of a mathematical model to comprehensiv-ely evaluate the relationship between the morphological variables of the pharyngeal bone and its environmental adaptability.