| For animals who live in groups,the recogniton between individuals or groups often promote the transmission and sharing of information,which is conducive to the survival and reproduction of the animals themselves.Recognition is also the premise that almost all animal community behaviors can occur.Animals can use vision,olfaction,hearing and so on to identify.For most vocal animals,acoustic signals often mediate a series of life history events such as foraging and courtship,which is the key to maintaining animal survival and social stability.Therefore,the study on the recognition ability of animal acoustic signals will help to deeply understand the function of acoustic signals and their adaptive evolution under selective pressure,as well as how animals use acoustic signals to maintain social stability,and provide a certain scientific basis for the protection of animal diversity from the acoustic level.As the only truly flying mammal,bats occupy a unique ecological niche in the night sky.Most species have weak vision and rely mainly on acoustic signals for spatial navigation and intraspecific communication,making them an ideal group for acoustic studies.In this dissertation,by recording and analyzing acoustic signals and combining with behavioral and molecular approaches,I explore the intraspecific acoustic recognition ability of in greater horseshoe bat(Rhinolophus ferrumequinum)who emits echolocation calls containing long constant-frequency(CF)components and Asian parti-colored bat(Vespertilio sinensis)who emits frequency-modulated(FM)echolocation calls.Firstly,echolocation calls of different geographic populations of the same species of R.ferrumequinum were recorded,compared the differences in acoustic parameters between sexes,ages and individuals.Then habituation-discrimination playback experiments were conducted to verify the recognition ability of echolocation calls in different geographical populations of the same species.The results showed that there were significant differences in acoustic parameters between sexes,ages and individuals in the echolocation calls of the R.ferrumequinum(binomial test: all P <0.01).When transformed to acoustic stimuli different from habituated acoustic waves,there were significant differences in the number of nodding,ear movements,body movements and echolocation pulses in R.ferrumequinum(Kruskal-Wallis H test: all P < 0.05).The results suggest that the echolocation calls of the bats have a communicative function and carry information related to sex,age and individuals.The echolocation calls may be used to identify sex,age and individuals in different geographical populations of the same species.Secondly,by recording the social calls of R.ferrumequinum under distress condition,the types and numbers of vocalized syllables were counted in this paper,and it was found that NB-DFM(noise burst to downward frequency modulation)calls accounted for the largest proportion(40.13%).The support vector machine(SVM)in the machine learning method was used to classify the NB-DFM calls by sex,age and individual.The model well classified the calls into sex,age and individual.After that,habituation-dishabituation playback experiments were conducted to verify the recognition ability of social calls in R.ferrumequinum.The results showed that Rhinolophus ferrumequinum were able to recognize NB-DFM calls under distress of different sexes,ages and individuals(binomial test: all P < 0.01).Thirdly,the frequency modulated V.sinensis were taken as the research object to explore whether the acoustic recognition between females and pups was unidirectional or bidirectional.Thirdly,I recorded the isolation calls of pups and the echolocation calls of mothers during mother-infant reunion,and conducted playback experiments to verify the acoustic signals recognition ability between mothers and pups in V.sinensis.This is the first study to investigate the acoustic recognition ability of pups by two-choice acoustic signals playback for different day-age groups.In this study,firstly,I analyzed whether the echolocation calls of mothers and isolation calls of pups had individual characteristics in statistics.Then,two-choice playback experiments to test whether the mothers and pups of V.sinensis could recognize each other by acoustic signals.The results showed that the isolation calls of pups had individual characteristics,and the frequency of female bats choosing the calls of their biological pups was significantly higher than that of non-biological pups(Exact binomial tests: P < 0.01,N = 20),indicating that female bats could identify their offspring by isolation calls.The echolocation calls of females were also individually labeled.For young bats aged 2-12 days,there was no significant difference in the frequency of selecting biological female bats,non-biological female bats and staying in the adaptation area(Exact binomial tests: P > 0.05,N = 30),indicating that pups before the age of 12 days could not recognize the echolocation calls of female bats.However,after 14 days of age,pups selected the calls of biological females significantly more frequently than non-biological females(Exact binomial tests: P <0.01,N = 30),indicating that the young bats could recognize the echolocation calls of the mothers after 14 days of age.Finally,this paper explores the potential molecular basis of recognition ability in V.sinensis pups based on the ability to recognize the calls from females.The brain and cochlea tissues from different acoustic treatment groups(isolated group who were never exposed to mother bat’s sound waves and they have no acoustic recognition ability;playback group who were playbacked mother’s sound waves and they have acoustic recognition ability of their mothers)were collected and conducted transcriptome sequencing to clarify the differences in gene expression in brain and cochlea of different treatment groups,so as to reveal the potential molecular basis of sound wave recognition ability of pups at the transcriptome level.The results showed that,compared with the isolated group,the differentially expressed genes in the brain and cochlea tissues of V.sinensis pups in the playback group were significantly enriched in neurologically related pathways,including cholinergic synapses and retrograde endocannabinoid signaling pathways,which may be the potential molecular basis for the acoustic recognition ability of juvenile bats.In summary,this disseration combines behavioral,machine learning models and molecular biology to conduct the intraspecies acoustic signal recognition in constant frequency and frequency modulated bats.The communication function of echolocation calls in R.ferrumequinum was verified and the ecological function of social calls recognition ability under distress was revealed.In this paper,I proved for the first time that the acoustic recognition ability of V.sinensis pups increased with age,and revealed the molecular basis of the acoustic recognition ability of pups.This study can improve the in-depth understanding of bat acoustic signal function and adaptive evolution,enrich the relevant content of bat acoustic research,and provide a scientific basis for bat diversity protection from the acoustic level. |
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