| Mating system of birds refers to the number of received spouse,spouse relationship duration,and the responsibilities assumed by the male and female in the reproduction process.As an evolutionary stable strategy,mating system is the result of animal's adaptiion to the natural environment including the inter-specific environment,it plays an important role in animal reproductive process.In the breeding process birds will form some kind of matching relations,and different birds are in very different relations between spouses.In the 1980s,extrapair paternity(EPP)was first testified in a Great Tit,Parus major by Oxford.Great Tit is an eurychoric species,many studies indicated that morphology,physiology,behavior,ecological characteristics and mating system of eurychoric species differ in areas or populations,thus,we determined the paternity with molecular biological technology to judge if there was Extra-Pair Copulations(EPC)phenomenon in Great Tit(P.m.minor)from national nature reserve of Liaoning area.In this study,we preliminary test and verify the applicability of"good genes" hypothesis and "genetic compatibility" hypothesis in explaining the reason of the occurrence of EPP in Great Tit.We collected total parents-offsprings blood samples in 43 broods and recorded their physical indicators.We counted the sex ratio of offspring and assigned parent to each offspring.We performed the analysis of the physical indicators of the parents and offspring,and the genetic similarity of parents between mixed-paternity nests and pure paternity nests.Results:(1)We determined 8 hypervariable locus from 11 microsatellite locus,the accuracy of paternity testing could reach to 99.98%in the condition of known female parent;(2)Results of paternity testing showed that 14 of 43 broods(32.6%)had extra-pair nestlings,and 39 of 373 nestlings(10.5%)were the result of extra-pair fertilizations;(3)We counted the breeding nests in different reproductive peak period:9 of 27 broods(33.3%)had extra-pair nestling in first reproductive peak period and 5 of 16 broods(31.2%)in second reproductive peak period.(4)The sex ration of all 373 offspring was 1.13:1(198:175)and there was no significant deviation from 1:1.The sex ratio of WPO was 1.17:1(180:154)and EPO sex ratio was 0.857:1(18:21),and they did not reach a significant deviation.(5)There was no significant difference in male physical indicators between mixed paternity and pure paternity.(6)There was no significant variations in all physical indicators between WPO and EPO.(7)there was no difference in the long diameter of the egg wight,the hatching rate and flying rate.(8)as for the relatedness coefficient of parents,we found there was no remarkable difference between mixed-paternity broods and pure paternity broods.The EPP rate of the Great Tit in this study is obviously lower than those in other passerine forest birds,but have proximity rate compare with Great Tit which in the other area.The proportion of extra-pair offspring among nests range from 81.8%to 9.1%,however,we did not find any rule about it.Our results do not support "good gene" hypothesis,Meanwhile,and from the perspective of parental,our results do not support "genetic compatibility" hypothesis. |
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