| Parental care is very common in the animal kingdom.The form and degree of parental care vary in different animal groups.Parental care has repercussion on the display and the evolution of many other animal social behaviors such as mate competition,mating and gregariousness.Therefore,the study of parental care is has attracted much attention in behavioral ecology.Amphibians,as a transitional group from aquatic life to terrestrial life style have diverse and complex habitat types,but the difficulty in the study of reproductive behaviors in amphibians has limited the research on parental care in this taxon.In this study,we used a China-endemic amphibian species the Emei moustache toad(Leptobrachium boringii)as a model,carried out field observation,and molecular experiments,and surved literature on parental care in order to systematically expound its parental care mode and its adaptive significance.We made a four-year field study of L.boringii in Badagongshan National Nature Reserve in Hunan Province from March to May during 2013-2015 and 2017.We marked a total of 885 individual,including 427 male and 309 female individuals;and 438 egg masses during the study period.In addition,we used 9 polymorphic microsatellite loci to identify the paternity and maternity of 578 adult individuals and 4,463 tadpole samples in laboratory.The following results were obtained:1)L.boringii has a bi-parental care which includes nest building and egg attendance.By comparing the male morphological characters in the nest alternative events,we found that male weight,body length and the forearm width can significantly affect the results.This means that nest building is based on male competition rather than random.And,93.57%egg masses from 82.35%of the breeding nest,received 40±14 days of care,suggesting that parental care was not accidental but stable.Respecting the definition of parental care,we performed general linear model(GLM)analysed and found that nest size and male egg attendance have a significant effect(P<0.001)on the survival of egg masses.The greater the is the nest,the longer is the male egg attendance,and the higher is the survival.2)L.boringii's life cycle factors and ecological conditions make parental care indispensable.And our results showed that 255 egg masses with male egg attendance had hatching an average rate of 0.84±0.33,an average survival rate of 0.72±0.41 while in a similar number of egg masses without egg attendance,mean hatching rate was 0.46±0.42,and the average survival rate was 0.18±0.33.The hatchability and survival rate of offsprings were significantly different(P<0.001).Although males loss a lot of energy3)during egg attendance,their body weight,body length and forearm width are significantly decreased(P<0.001).However,the mortality rate was low and the paternity analysis showed that 96.15%of nests(n=50)contained paternal males'offspring.Of these,69.23%of the nests(n=36)belonged to the paternal male.Therefore,in the analysis of the advantages and disadvantages of the male parental care,it can be concluded that the benefit of breeding is greater than the cost of parental care,so that male parental care is maintained and tends to be stable. |
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