Significance of two different ranking methods for studying fish fauna:a case study on the fish fauna from upper and middle portions from Mekong River

摘要

Studies onfish fauna should not only focus onfish composition and the comparison offish composition among the study region and adjacent regions,but should also explore the origin and uniqueness of different taxa as well as the substitution of genera and species.In this study,the value offloristic presence method was modified and renamed the value offish fauna presence(VFFP)method.The specific steps of the VFFP method and the traditionalfish fauna analysis(TFFA)method were refined and standardized.Then,the VFFP and TFFA methods were applied to study thefish fauna of the upper and middle portions of the Mekong River basin.The results indicate that the TFFA method reflects the families(subfamilies)and genera that constitute the main body offish in the studied river basin.The results of the VFFP method show which families(subfamilies)and genera are representative for the basin.Therefore,combining the TFFA and VFFP methods to analyze the composition offish fauna can reflect the characteristics offish fauna from different perspectives.The case study shows that thefish fauna of the Mekong River is a part of thefish fauna of Southeast Asia.Although it shows some similarities to the composition of South Asianfish fauna,it does not belong to the South Asianfish fauna as a whole,and is essentially different from the East Asianfish fauna.This study provides an objective,quantitative,and verifiable method for studyingfish fauna.