Effects Of Energy Storage On Reproductive Input And Success In The Asiatic Toad(Bufo Gargarizans)

Acquisition and consumption of energy are two important factors leading to variations on animals' life histories.Different life-history strategies are mainly produced by different ways in which the organisms distribute available energy among survival,growth,defense against predators,and reproduction.Energy allocation strategy plays a key role in balancing energy consumptions between survival and reproduction,and,in addition,determines the cost of fertility and reproduction.It is important to understand the effects of energy storage on reproductive success as different levels of energy storage might lead to significant differences on reproductive strategy.For the species that have no energy income for a long time before breeding(such as amphibians),the energy consumptions during reproduction are heavily relying on their previous energy storages.Individuals can also re-distribute their energy storages,and different energy allocation strategies can lead to differences in reproductive benefits.A lot of studies has focus on the organisms,for instance,birds,mammals,and reptiles,but there is still a lack of research on the effects of energy storage on reproductive strategy in amphibians.Studying the impact of energy storage and allocation of Bufo gargarizans on reproductive success is of great significance for understanding the life history strategy of amphibians.Here,we chose Bufo gargarizans,a species belonging to the genus Bufonidae,which is widely distributed in China and easily observed in the wild.It is an ideal species for the research of energy storage effects on reproductive strategy.We detect the energy storage effects on reproductive strategy of Asiatic toad during the breeding period,based on the field data collection and indoor breeding experiments.We use the Body Condition Index(BCI)to evaluate the condition of the Asiatic toad(Bufo gargarizans),this method is reliable and noninvasive and has been widely used in birds,mammals,and reptiles.During February to April of 2016 and 2017,we collected the data of body weights and body lengths of B.gargarizans before and after breeding,respectively,and measured their cluth size,hatchability,egg weight,and egg diameter in the Badagongshan National Nature Reserve,Hunan Province,China.The fertilized eggs were brought back to the laboratory for hatching under the same condition(20?constant temperature,12h-12h of light-dark,the same food supply).We recorded the durations and measured morphological traits(body length,weight,head width)when tadpoles reached different developmental stages.We compared the BCIs of amplectant and un-amplectant males using one-way ANOVA,and linear regressions were used to detect the relationships among BCIs of amplectant males and their reproductive energy consumptions,fertility rates,hatchability,and offspring growth rate,and the relationship between BCIs of females and their clutch sizes.Our results are as follows:(1)Male-male competition might be obvious in B.gargarizans during the breeding period as the significant higher BCI was detected in amplectant males than un-amplectant males(F1,154 = 29.666,P<0.001);(2)Male BCI has a significantly positive linear relationship with energy consumption during reproduction of B.gargarizans(R2 = 0.212,P = 0.007).Higher male BCI can lead to greater energy input during reproduction.For females,BCI also had a significantly positive linear relationship with energy consumption(R2 = 0.681,P<0.001).Higher female BCI can lead to greater energy input during reproduction;(3)No significant relations were found between BCIs and fertility rates in both male and female individuals of B.gargarizans(male,R2 = 0.02,P = 0.347;female,R2 =0.002,P=0.795);(4)Male BCI was significantly and negatively correlated with the duration of offspring development(G45 period:R2 = 0.297,P = 0.044).That means offsprings from males with high BCIs develops faster than those from males with low BCIs.There was no obvious correlation between female BCI and developmental duration their tadpoles(R2 = 0.018,P = 0.603);(5)A positively linear relationship between female BCIs and their clutch size was showed by our results(R2 = 0.181,P<0.001).That is,higher BCI can result to larger clutch size in this species;Our results indicated that different levels of energy storage can have different influences on male-male competition,energy input on reproduction,developmental rate of offspring,and clutch size in B.gargarizans.Males with high energy storages had superiorities in competing mates and enjoyed faster development of offspring.Individuals with high energy storage usually invest more energy in breeding.Females with high energy storage trend to produce large clutch sizes.Our research results provide a certain basis for exploring the life history strategies of amphibians and are of great significance.