Influence Of Seed Tannin Content On Food Hoarding Behavior Of Rodents

As one of the most important seed predators,rodents have an important role in plant seeds dispersal.If the seeds predators can spread the seeds successfully,they will germinate in suitable environment.The relationship is complex between them;the plant must rely on its transmission but also defend their prey.There are many factors which influence seed hoarding and seedling establishment,such as environmental conditions,animal's body size and gender,the seed moisture and seed's pericarp thickness,size,nutrients and secondary metabolic compounds content,which are often considered to be the main factor determining the seed dispersal and storage.A class of plant life phenols tannin widely exists in plants,because of the combination of energy and protein,thereby reducing the seed palatability and affect rodents physiological characteristics.There are lots of researches on the effect of seed tannin content on seed dispersal and hoarding behavior,on the natural and artificial seeds seed.There are a lot of studies on tannin content affecting rodent hoarding behavior,but lack relevant study of Quercus variabilis seed tannin dynamic changes,and no relevant experiments were conducted to verify how the dynamic changes in the tannin content of Quercus variabilis affect the selection,storage and dispersal of seeds by rodents.Therefore,in March 2016-January 2017,in Jiyuan of Henan province,we collected the seeds of Quercus variabilis in different seed rain,and measured the tannin content of seeds in different periods by Folin-Ciocalteu colorimetric spectrophotometry;We measure the content of tannin in the hoarding process by rodents;The experiment was carried out on the selection and dispread of Quercus variabilis seeds in the field and artificial enclosures,and determined tannin content of seed before and after dispread;According to the tannin content of Quercus variabilis seeds,the artificial seeds with different tannin content(0%,3%,5%,7%,10%)were prepared,the feeding experiments of two kinds of mice were carried out,recorded the changes of body weight,food intake and digestibility.The main results of experiment are:1)In the process of seed rain,with the increase of time,the number of seeds increased firstly and then decreased,while the tannin content is decreased firstly and then increased.The seed amount is maximum in 20 th day,and the tannin content of seeds is lowest(about 4.5%).While tannin content change large in later period,tannin content from 2.5 to 9.5% especially in 40 day.2)Tannin content was negatively correlated with seed size,and the tannin content of moth and germination seed is higher than that of intact seed,but there is no difference between moldy and intact seeds.Tannin content showed significant changes with buried,which tannin content of buried 15 days is the lowest,about 4.8%.3)Tannin content between the intact seed of control group and the remains seeds after dispersal is significant difference both wild and fence conditions,while tannin content between the moth seed of control and the remains after dispersed seeds is not significant.4)Rodents preference feed low tannin content food(under 7%).From unit weight,the concentration of tannin of largest intake by Apodemus agrarius is 5%,which intake is 27.5%;the concentration of tannin of largest intake by Apodemus peninsulae is 7%,which intake is 33%.The results show that 1)The tannin content of Quercus variabilis seeds is low in the seed rain peak,and seed tannin content is higher in the early and late of the seed rain,and the tannin content is low in big seed,and the tannin content in small seed is higher;2)When the seeds were scatter hoarded by rodents,the tannin content firstly decreased and then increased;3)The rodents preferred to select and spread the seeds contained low tannin content;4)All the two kinds mice tended to be fed with low tannin content.In summary,in the seed rain preiod and under different conditions,the tannin content changed of Quercus variabilis seeds,this may be a regulation strategy of Quercus variabilis for rodent's predation,but rodent has specificity for selection and hoarding seeds with different tannin content,that may be an evolutionary adaptation of rodents for the seed tannin content.Therefore,this study has important implications for evolutionary and ecological significance in understanding the interaction between seeds and rodents.