| Cannibalism is a widespread phenomenon,a form of interaction prevalent in most food webs,and may be the primary cause of high population mortality.Under the strong pressure of predators,prey gradually evolved various adaptive features,namely,induced defense,which could effectively avoid predators,promote species coexistence,and stabilize population dynamics.In the aquatic ecosystem,rotifers are an important part of zooplankton,which regulate the structure and species diversity of aquatic communities to a great extent.In this paper,on this basis,to Brachionus calyciflorus Pallas arm end rotifers(Brachionus calyciflorus Pallas,hereinafter referred to as Brachionus calyciflorus Pallas)with Asplanchna brightwelli(Asplanchna brightwelli)crystal as the model,to explore the inducible defences of prey size can induce the cannibalism behavior of predators,on this basis to increase the density of the predator is influential to cannibalism behavior and prey size affect cannibalism behavior of predators.And verify the following scientific hypothesis:(1)In the case of whether the Brachionus calyciflorus Pallas has a defensive body shape,the influence of predator density on its cannibalism,and whether the growth of Brachionus calyciflorus Pallas spines will increase the cannibalism behavior of Asplanchna brightwelli in the wild water.(2)Whether the inducible defense of Brachionus calyciflorus Pallas can induce the cannibalism behavior of predators,and if it can induce the cannibalism behavior,whether the female body capsule will eat the male body capsule.(3)On the basis of whether the Brachionus calyciflorus Pallas has a defensive body shape,whether the size of Brachionus calyciflorus Pallas affects the cannibalistic behavior of the Asplanchna brightwelli.1.The results of the study on the effect of predator density on cannibalism showed that in the 100 ml system,different densities of Rotifers were set and the number of bites were recorded.After 3 days,10 capsules were randomly selected to observe the number of masticators.The results show that as the density of predators increases,the number of cannibalism increases and the cannibalism behavior strengthens.Therefore,the cannibalism behavior is affected by the density effect.2.The results of the study on the effect of prey defense size on predator cannibalism showed that in the 10 ml system,1 Asplanchna brightwelli,10 small female ones and 20 adult Brachionus calyciflorus Pallas(with or without side spines)were placed in the control group and the experimental group respectively,and the observation results were made after 6h.The sexual phase feeding experiment replaced the small female body with the male body,and the other conditions were the same as the induced defense experiment.In the laboratory microcosmic experiment,500 g of sediment was placed in a 5L system and incubated for about 3 days.Samples were sampled at a ratio of one tenth to count the number of Brachionus calyciflorus Pallas and Asplanchna brightwelli,and the results were recorded.The results showed that there were significant differences between the control group and the experimental group in the number of Brachionus calyciflorus Pallas,the number of residual crystal capsules and the number of chewers.During sexual phase eclipse,there was no significant difference between the control group and the experimental group except the remaining quantity of Brachionus calyciflorus Pallas.The results showed that calyx flowers in the control group did not induce longer lateral thorns and were easily predated by predators,while Brachionus calyciflorus Pallas in the experimental group induced longer lateral thorns,which could effectively prevent predators from swallowing,and the defensive shape of Brachionus calyciflorus Pallas enhanced the cannibalism behavior of Asplanchna brightwelli.The female rarely devours the male due to his small size and cruciform defense,so the female does not devour the male.Laboratory microcosmic results showed that the growth of Brachionus calyciflorus Pallas lateral spines enhanced the cannibalistic behavior of the Asplanchna brightwelli.3.The results of the study on the effect of prey size on predator cannibalism showed that it was consistent with the experimental method of prey defense size mentioned above.The Brachionus calyciflorus was replaced by larval Brachionus calyciflorus Pallas and compared with adult Brachionus calyciflorus Pallas.The results showed that there was no significant difference between the experimental group and the control group in the remaining quantity of Brachionus calyciflorus Pallas,Asplanchna brightwelli and chewing apparatus.There was significant influence on the adult and young cannibalism in the experimental group,but not in the control group.The results showed that the defensive larval Brachionus calyciflorus Pallas had lower defensive ability than adult Brachionus calyciflorus Pallas and had no significant effect on the cannibalism behavior of Asplanchna brightwelli. |
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