| Mutualism is an important behavior and relationship between two organisms which increase their survival rate in the ecosystem.Mutual relationship or mutualism is a fundamental element in aphid-ant communities and behavior through co-evolutionary adaptation.Mutualistic interactions of aphids and ants evaluate the role of different members of the species community of ants in the formation of mutualistic associations and also influence on species composition of aphids.Aphids and ants are common insect groups on the Earth.The aphids are abundant in temperate and ants are abundant in tropical regions,and both of them present relatively high diversity in subtropical regions.Considering the large-scale species diversity patterns of these two insect groups,it is supposed that they have more chance to interact with each other and present higher diversity of associated species pairs in subtropical areas.In our knowledge,no study has been done on the species diversity of associated aphids and ants in subtropical regions.The objectives of this study were to(1)explore the diversity of aphidant species pairs in a subtropical region,(2)evaluate the phylogenetic patterns of the aphid-ant associations,(3)investigate the role of dominant ant species in shaping regional aphid-ant associations.Based on all available data gathered from published articles and databases about aphids and ants in association with each other,the evolutionary and geographical patterns were analyzed.We found 284 species and 84 genera of eight aphid subfamilies were associated with 193 species and 39 genera of four subfamilies of ants.According to this study,the maximum aphid-ant species pairs were found from subtropical areas.On the basis of this information we conducted our experiment in subtropical areas of Fujian province,southern China.All collected aphid and ant species associated samples were identified morphologically first.A total of 48 species,30 genera belonging to eight subfamilies of aphids,while in ants,55 species,24 genera belonging to 3 subfamilies have been identified.The maximum interactions were recorded in aphid subfamily Aphidinae and ant subfamily Myrmicinae.Moreover,molecular analyses were conducted to confirm and delimit the morph-species by using the mitochondrial COI gene and ABGD,bPTP and GMYC approaches.Most of the species delimitation results matched with our morphological identification.Some variation in the results of ABGD,bPTP,and GMYC were observed.In the aphid species,ABGD,bPTP and GMYC delimitation methods produced 55,61,and 56 MOTUs,respectively.While in ants,ABGD and bPTP constructed 40 MOTUs,and GMYC produced 49 MOTUs.All extra produced MOTUs showed higher genetic distances.In aphids,all of the ABGD,bPTP and GMYC supported that Aphis gossypii,Aphis spiraecola,Matsumuraja rubifoliae,Aphis aurantii,Trichosiphonaphis lonicerae,Mollitrichosiphum tenuicorpus,and Chaitoregma tattakana are cryptic species,having >3% intraspecific genetic distances.Whereas in ants,C.vagula,T.bicarinatum and T.albipes,are cryptic species having >5% intraspecific genetic distances.Two ant species(T.erraticum and N.pubens)were first time reported from China,and the COI sequences for 10 ant species were newly added in GenBank.Overall,154 aphid-ant species pairs involving 44 aphid species and 38 ant species were described.A library of mutualistic aphid-ant species also provided for a subtropical regions of southern China.DNA Barcoding is not only useful for species delimitation,but also is able to produce sequence data,which can be used to build the phylogenetic tree of aphids and ants.Based on these phylogenetic trees,a hypothesis that whether close aphid species are usually tended by close ant species were tested.Overall the species of aphids feeding on same plants were clustered together at a subfamily level.Especially species of subfamily Hormaphidinae in current study only exhibit on the Bambusa genus,which is mostly associated with species of genus Crematogaster.Moreover,in ants,most of the species were found associated with species of the tribe Aphidini.Some patterns were found mostly at subfamily and tribal level.All ant subfamilies were mainly attending the aphid subfamily Aphidinae.Moreover,one ant species Formica japonica showed association only with Aphidinae.Three ant Crematogaster egidyi,Pristomyrmex punctatus and Pheidole noda were observed dominantly associated with aphids.Overall,the hypothesized pattern that close aphid species are tended by close ant species are not clear among associated aphids and ants in this study,but some ecological patterns(related to factors such as host plant and dominant species)do exist.Moreover,the role of dominant ant species in shaping regional aphidant associations was explored.Different dominant ant species associated with aphids in different localities were recorded.Overall three dominant species Crematogaster egidyi(14.46%,),Pristomyrmex punctatus(12.35%)and Pheidole noda(8.73%)were recorded from three localities mainly associated with 17,17 and 13 aphid species,respectively.The species dominance varied locality wise,such as from Wuyishan,Fuzhou and Shouning having 6,4 and 3 dominant aphid-associated ant species,correspondingly.Maximum species diversity was found in Wuyishan with 28 species(45.18%)(H=1.624,d=0.4551)having six dominate species.While,Fuzhou contained 25 species(28.61%)(H=1.146,d=0.286),having four dominant species among them only C.egidyi was the most dominant regarding aphid association and sample numbers.Moreover,Shouning contained 25 species(25%)(H=1.003,d=0.250)having three species were mainly associated with aphids.This thesis presents a first comprehensive study on aphid-ant associations in a subtropical region,which also provides DNA barcodes of identified species of trophobiotic aphids and ants.It seems reasonable that aphid-ant interactions are highest in subtropical regions.Moreover,at community level,the aphid-ant associations may be largely determined by regional dominant ant species. |
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