Whose feather is that? A cross-views between a naturalist and a molecular biologist
Identifyingthespeciesorsexofabirdbasedonafeatherfoundinnatureisoftenchallenging,evenwith the help of reference books. However, determining the presence of a rare species in a habitat using an indirectpresenceindicator,suchasafeather,canhelpinimplementingspecificmeasuresforpreserving the species. The aim of this study is to investigate whether DNAgenotyping is better than specialized books when identifying bird feathers. Toanswerthisquestion,Icollectedfeathersinthewildand,withthehelpoftwobooks,triedtoidentify theirspeciesandsex.Then,assistedbyDrGwenaëlJacob(UNIFR),Iisolatedtwogenesinnineselected feathers. The investigated genes were the CHD gene for sexing and the COI gene for species identification.Todothis,theDNAwasfirstextractedfromthefeathers,purified,andamplifiedbyPCR. Subsequently,anelectrophoresis wasperformedtosexthe samples andcheckthatthe PCRamplification hadworkedproperly.Finally,thesamplesweresequencedbytheMicrosynthlaboratory(St-Gall),and the obtained sequences were entered into the NCBI database. Acomparisonoftheresultsobtainedwitheachofthetwodifferentmethodsshowsthattheidentification with specialized books was fairly successful. 56% of the species identification made with the books were indeed confirmed by genotyping. DNAanalysis provided a different result only for feather #16. However,33%ofgeneticidentificationfailed,eitherduetogeneticmaterialqualityorlaboratoryerrors. Asitwaspossibletoidentifythesexofonlyonesample(feather#14)withthebooks,itwasnotpossible tomakeatruecomparisonofthetwoapproaches.However,asgeneticsexingworkedwell(onefailure, feather #28), it can be inferred that genetic sexing is more effective than using books. This work demonstrated that DNAis not infallible and that sometimes books are equally effective in identifyingbirdspeciesfromafeather.However,insexingbird,DNAremainsmoreefficient.Thus,one can conclude that DNAgenotyping is not superior but rather complementary to specialized books for identifying bird feathers.
果蠅緯度相關晝夜節律特徵:穩定性、活動量分佈與演化意義
Latitude-Dependent Circadian Traits in Drosophila: Stability, Activity Peaks, and Evolutionary Implications
生物時鐘可對生物體的行為與生理造成影響,在探討晝夜節律特徵的差異時,過去研究常侷限於北美大陸的品系,缺少赤道及南半球品系的晝夜節律特徵探討。有鑒於黑腹果蠅在全球各大洲的廣泛分佈,因此我們以黑腹果蠅(近赤道與中高緯度品系)為材料,研究果蠅是否因緯度而有相異的晝夜節律特徵?結果顯示不同緯度的果蠅品系展現出相異的晝夜節律特徵。赤報品系在全暗狀態下仍維持原本光暗12小時的穩定節律,而南北半球的中高緯度品系則具有相似節律特徵,即在全暗狀態下的節律不對齊原本正常光源的穩定節律,其他如活動量、週期、及節律強度等皆有著品系間的差異。更進一步比對實驗中各個品系基因序列,研究發現per和tim在調控區段有許多SNP變異,顯示其與晝夜節律特徵的關係,有助於後續尋找更多造成晝夜節律特徵差異的可能遺傳變異並探討。