Interspecific Hybridization Of Quasipaa And Hybrid Tadpole Fitness Research

The distant hybridization can effectively break interspecific and intergeneric isolation of creature,which is an important method of generating abundant genetic variations and creating new crossbreeds.The genus Quasipaa(Dicroglossidae)is an important groups of phylogenetic relationships between systematics of the Ranidae,but also has a considerable research value in the geographical distribution and evolution of amphibian.The taxonomy of these species remains controversial.Analyses of nuclear and mitochondrial genes suggest introgressive hybridization among related species of Quasipaa maybe exsit in their overlapping area.Based on evidence from molecular study,we worked on hybrid experiments between species of Quasipaa,and can provide a theoretical basis to clarify phylogenetic relationship of Quasipaa,distant hybridization,species classification and biodiversity assessment.The main research contents and results are as follows:(1)Interspecific hybridization of Quasipaa:This study collected 5 Quasipaa species(Quasipaa spinosa;Q.jiulongensis;Q.exilispinosa;Q.boulengeri;Q.shini)in 6 sympatric distribution areas(Jiulongshan Zhejiang,Jinhua Zhejiang,Wuyishan Fujian,Lushan Jiangxi,Longshen Guangxi,Kaili Guizhou).The collected samples were classified in species artificial cultivation,using artificial breeding way to cross-breeding,Q.spinosa respectively hybrid with other 4 species in 2015-2016.There are 40 groups hybrid experiment,the results show that the Q.spinosa(?)x Q.shini(?)can get healthy crossbreed offspring,hatching rate of around 47.12%.Q.boulengeri(?)× Q.spinosa(?)was found only a successful incubation,hatching rate was only 3.6%,other combinations were not seen the emergence of offspring.(2)The part species of Quasipaa hybrid reproductive behavior:To use infrared camera equipment for recording the reproductive behavior of Quasipaa,and using scan sampling and focal animal method,observation and analysis of video data,the statistical results show that the hybrid breeding behavior occurs mainly in the night(22:00-00:00;0:00-3:00),Call takes the greatest percent.Comparison analysis of call of Q.spinosa,Q.boulengeri and Q.shini:the average call duration of Q.boulengeri(2.05 ± 0.46)s longer than Q.spinosa(1.40 ±0.43)s,shorter than Q.shini(3.44 ± 1.49)s,the average note number of Q.boulengeri(8.89± 1.87)longer than Q.spinosa(3.99 ± 0.86)shorter than Q.shini(10.81 ± 2.41),Compared with the Q.shini,Q.spinosa have lower fundamental frequency and higher dominant frequency.The presence of distinct silent intervals between notes of Q.boulengeri and Q.shini,Q.spinosa does not.(3)Fitness research:Selection of the offspring of Q.spinosa(?)× Q.shini(?),setting 3 different temperature groups with 14,22 and 30? and 3 different density groups with 5,15,30 ind/L,each group of two parallel and a control.The life index of offspring was studied.The results showed that the same stage crossbreed average body length and weight were higher than purebred between 20-80d at 3 temperatures;Effects of temperature and density on the growth and metamorphosis of hybrid and purebred tadpoles.The hybrid tadpoles body length and weight growth rate were higher than that of purebred tadpoles at 3 temperature groups between 20-65d;22 ? group,hybrid and purebred tadpoles body length and weight growth rate were significantly higher than 14 and 30?;There was significant difference between body length and body weight of hybrid tadpoles(SVL:F=5.156,P?0.007;BW:F=6.722,P=0.001)at 3 temperature groups between 20-95d.30?group,the survival rate of hybrid tadpoles and abnormal survival rate was significantly lower than that of the other two purebred tadpoles.Treatment group is slightly less than the purebred tadpoles,but the difference was not significant,compared with the purebred tadpoles,hybrid tadpole adapt the environment of high temperature may be worse.There was significant difference between body length and weight of hybrid tadpoles(SVL:F=4.664,P=0.01;BW:F=9.71,P=0.001)in 3 different density groups.The average body length was greater than the purebred tadpoles in 30 ind/L group;In 30 ind/L group,the swimming speed of hybrid and purebred tadpoles were more slowly than the other groups.After the late metamorphosis,the body length and weight were significantly smaller,higher mortality rate.The research shows:1)Water temperature had significant effects on the growth and development of tadpoles.The growth course of tadpoles were accelerated and shorten the time of metamorphosis at high temperature.Compared with Q.spinosa tadpoles,the growth and metamorphosis of hybrid tadpoles were significantly faster,body were significantly larger,low temperature resistance was still strong,but poor ability to resist high temperature under the same condition.2)Different culture density had significant effects on the growth and development of tadpoles.The growth rate was slower,small individual in metamorphosis,low survival rate after metamorphosis in the high density environment.Compared with purebred tadpoles,hybrid tadpoles grow rapidly in the low density environment.3)In the normal temperature(22?)and 15 ind/L,the survival rate,survival rate after metamorphosis and total metamorphosis rate of hybrid tadpoles were significant higher than those of purebred tadpoles,but the difference was not significant.4)The three density groups,hybrid tadpoles swimming speed were faster than purebred tadpoles.