Study On The Infection Characteristics Of Blood Parasite And Its Relationship With Breeding And Extra-pair Paternity In Varied Tit(Parus Varius)

Blood parasite is an important factor affecting the health of birds and is also a model group for studying the evolution of species.At present,most of the researches of blood parasites of birds focus on the analysis of infection rates and phylogenetic relationships among Plasmodium,Haemoproteus and Leucocytozoon.But studies about effects of parasitism on birds' behavior are still deficient.This article selected the social monogamous bird Varied Tits(Parus varius)with a high proportion of extra-pair paternity as the object and Zhuanghe Xianrendong National Nature Reserve as the experimental site.812 Varied Tits samples were collected in 2016 and 2017,including 293 adult samples and 519 nestling samples.Nested PCR was used to amplify the blood parasite cytochrome b sequence.After sequencing,the blood parasite species identification results were compared with the Malvi database.The extra-pair paternity analysis was conducted on 87 breeding nests using 10 pairs of microsatellite primers.The research will further improve the birds extra-pair paternity theory and provide references for species protection and disease prevention by enriching the data of blood parasite infections of birds in northeastern China;clarify the influencing factors of blood parasite infection characteristics and infection rates and explore the relationship between blood parasites and variegated tits reproductive behavior and extra-pair paternity phenomena.The results of the study are as follows:1.A total of 28 among 293(149 males and 144 females)Varied Tits were infected with blood parasites and the infection rate was 9.56%.No infected individuals were found in 519 nestlings,indicated that blood parasites do not be transmitted from the parents to the nestlings.2.There was no gender difference in the rate of blood parasite infection of the population(P=0.345),but the blood parasite infection rate of the male social partners in breeding nest was significantly higher than that in females(P=0.036).3.A total of 11 blood parasite clades were detected in the infected samples,including 1 Haemoproteus with 12 infected individuals;4 Plasmodium with 5 infected individuals;and 6 Leucocytozoon with 15 infected individuals.There are 6 double-infected individuals.No antagonistic relationship between different types of blood parasites was found.4.The statistics of infected individuals suggests that 85.71% of Varied Tits infected individuals participated in breeding.There wre 23 nests witch had at least one parent bird were infected,of which 21 nests were found with single infected parents.The number of nests with both infected parents was 2 and the average clutch size in infected individuals was 5.87±1.01,which was similar to the average clutch size(6.50±0.55),and the reproductive success rate was 93.33%,which was higher than the average breeding success rate(65.15%).5.Whether or not bird is infected with blood parasites has a significant correlation with the length of the tarsometatarsi(P=0.046),and the relationship with the length of the wing(P=0.055)and tail length(P=0.051)is close to the level of significance.There was no significant correlation in the three indicators of beak length,beak width and the weight,indicated that long-term,large-sized adults were more susceptible to blood parasite infection.6.There were no significant differences in the signs of hosts infected with different types of blood parasites,and there were no significant differences between the signs of infection of only one clade /genus blood parasites and hosts infected with different clades /genus blood parasites,indicating different categories.The effect of blood parasites on the host is not evident on signs.7.There are 44 nests in 87 breeding nests with extra-pair paternity.The proportion of extra-pair paternity nests is 50.57%.Of the 519 offsprings,105 are the extra-pair offsprings,and the proportion of extra-pair offsprings is 20.23%..8.Among the 23 nests whose parents were infected,10 of them had extra-pair paternity,and the proportion of extra-pair fathers was 43.48%.There were 64 nests of nests without blood parasite infections,34 nests had extra-pair paternity,and 53.13% of the nests had extra-pair paternity.There was no significant difference in the proportion of reproductive patriarchal fathers with or without blood parasite infection(P=0.427).There was no significant difference in the proportion of extra-pair paternity among breeding nests with or without blood parasite infection(P=0.188).9.The beak width of social male parters infected with blood parasites is significantly wider than the males with extra-pair males(P=0.042),and all the extra-pair males of above nests are not infected by blood parasites.In summary,the infection level of blood parasites of the Varied Tits in the Xianrendong nature reserve is relatively low,and there is no effect on the reproductive quality.The infection rate of the male relative female in the breeding nest parent is higher and the dominant individual is more likely to become the host of the blood parasite.Infection of blood parasites does not affect the occurrence of extra-pair paternity and the proportion of extra-pair offspring,but may be one of the standard for females to choose an extra-pair male as the spouse.