Study On The Relationship Between Beetle Morphological Diversity And Species Richness

Coleoptera,commonly known as beetles,is the largest order of the insecta,which has a large population,extensive distribution,complex living environment,and diverse morphological structures.Therefore,it has become a hot research topic for scholars to study insect diversity.Conducting sample site diversity surveys targeting specific regions can help promote the progress of diversity mapping in China.The investigation of insect diversity includes the collection and identification of insect samples.In China,the most common method for collecting insect samples is active collection method.However,this method is not effective and far from achieving ideal collection results.Therefore,passive collection methods have gradually emerged in people’s vision.Through these methods,long-term monitoring and collection of insects in the sample area can be achieved.Moreover,the collected insects have the advantages of high repeatability,large quantity,high diversity and traceable samples.Consequently,passive collection methods have been widely used by scholars both domestically and internationally.As to insect identification and classification,traditional taxonomy has always been the most commonly used method.By classifying the insects,describing the discontinuous morphological characteristics(length and width of body,etc.),and compiling a key table,the purpose of insect identification and classification can be achieved.However,the traditional classification method is largely affected by the subjective experience of scholars.The inability to find simple and clear morphological characteristics for distinguishing some related species has led to continuous changes in insect classification levels,slow progress in identification work,and difficulty in quantifying insect morphological characteristics.Continuity characteristics(pronotum,elytron,epipharynx etc.)widely exist in all kinds of insects.However,it is difficult to describe and compare them through traditional taxonomy,so the related biodiversity assessment work has not made substantive progress.This article uses geometric morphometrics method to quantitatively study the continuity features of the pronotum and elytron.The beetles were obtained from different collection methods.By obtaining beetles’ morphological diversity,the morphological differences of beetles through different collection methods are analyzed.And the relationships between beetles’ morphological diversity and species richness are explored,in order to evaluate the application value of continuity characteristics in beetles’ advanced level classification.Besides,the relationships between beetle morphological changes,species composition,and geographical environment are also discussed.This study selects 10 sample sites from the northwest inland to the southeast coast,namely Helan Mountain in Ningxia,Jintong Mountain in Hunan,and three large sample sites in Hong Kong.Hong Kong was further divided into 8 small sample sites.The beetles’ pronotums and elytrons are analyzed through geometric morphometrics.Principal component analysis shows that the beetles’ pronotums show higher morphological differences,with an overall degree of variation higher than elytrons.However,when using the Spearman correlation coefficient to explore the relationship between beetles’ morphological diversity and species richness,the pronotums with greater variability shows a low correlation(r=0.344,p=0.068>0.05),and the elytrons shows a highly significant positive correlation(r=0.611,p=0.001<0.01),proving that elytron is more suitable as a classification feature of beetles.In addition,the beetles’ morphological diversity and species richness are compared,which are collected through three passive collection methods.As a result,FIT has the best collection effect in all sample sites,MT comes second,and the last is PT.Otherwise,the above results combined with geographical differences show that the morphological diversity and species richness of beetles in Hong Kong were slightly higher than those in Jintong Mountain which located in Hunan,and far higher than those in Helan Mountain which located in Ningxia.