|
P1 Panda, Ailu-ropoda melaleuca, one of the most widelyrecognized and cherished Yet enigmatic →Disagreement in taxonomicplacement: with bears in the familyUrsidac, raccoons in the family Procyonidae or in family, the Ailuropodidac. The author: the riddleof the panda's ancestry has now been solved. P2 Controversy PAD: Ursus melanoleucus AME: giant panda wasmore closely related to the lesser or red panda, Ailurus fulgens （原因）bearlike appearance of the giant panda was a holdover fromthe past, a reflection of its descent from an ancestor common to both bears andraccoons P3 no clear-cutconsensus was reached on the subject of the giant panda's ancestry - D. DD: panda was a member of the bear family - DM and R. F. Ewer: giant panda belonged in the raccoon family. - J F. Eisenberg and G B. Schaller: giant panda be placed inits own family, the Ailuropodidac (endorsed by Chinese scientists) P4 Difficultiesencountered by systematists: whether a character is homologous to a similarcharacter in another species or whether it is merely analogous Homologous character: allthe species possessing the same trait have descended from a common ancestore.g. Mammalia Conclu: The degree of evolutionaryrelationship is determined by the number of homologous characteristicsshared by different species P5 Difficulty inidentifying a homologous character: genetic basis is rarely understood - small morphological change→extensive reorganization of multiplegenes - an apparently major structural change→small genetic changes P6 Analogous character(convergence):a trait possessed by two or more species in response to the same environment but not sharing a common descent. e.g. the wings of birdsand insects, as well as the case of Giant panda | 
[复制链接]
京公网安备11010202008513号 京ICP证101109号 京ICP备12012021号
发表于 2023-3-6 17:23:51
