Study On The Conservatism Of Climatic Niche During The Bird Range Expansion

Sustainable climate change is leading to species’ redistribution globally,but climate niche dynamics during the species’ redistribution are rarely studied.Ecological niche models(ENMs)have been widely applied for predicting species distribution changes,which basic theoretical hypothesis is the niche conservatism hypothesis(NCH).However,more and more evidence shows that some species have experienced shifts in climatic niche during the range changing.This challenges the basic theory of the ENMs’ applicability.On a global scale,this study of bird species with strong natural dispersal ability,and applied the niche dynamics framework to analyze the climatic niche dynamics of birds,testing the NCH;Further,on a regional scale,combining literature research and field work,this study explored the climatic niche dynamics between the expansion region of China and its natural origin,taking the Asian Openbill(Anastomus oscitans,hereafter referred to as the openbill).And we focused on analyzing the importance of predatory interaction factors in explaining niche conservatism during the species’ range changes.The main findings are as follows:We found that nearly 80% of birds have experienced climatic niche shifts by investigating the niche dynamics of 928 bird species during the range expansion,that is,the NCH has been denied.Passeriformes are a order of birds that have attracted more attention in range expansion research,with a high frequency of range changes and a high proportion of niche shifts.Besides,the niche dynamics of birds in different zoogeographical realms vary.Secondly,human activities dominated by pet trade have promoted the movement of species among different zoogeographical realms.And more than 60% of bird species are used for pet trade,and the proportion of niche shift among these trading birds is very high,accounting for over half of the total species.The study enables us to further understand the NCH and provide a scientific basis for developing species conservation strategies under climate change.As a key biological factor,predatory interactions have a vital role in predicting the openbill distributions.The main prey of the openbill include 136 snail species.We observed a realized climatic niche shift during the northward expansion of the openbill by considering only climates;however,the proportion of niche shift decreased by nearly50%,and niche conservatism was detected after incorporating their preferred prey.Secondly,ENMs including preferred snails also predicted the distributions of the Asian openbill better than climate-only models and models including nonpreferred snails or only habitat variables.The results of our study suggested the importance of incorporating preferred prey in evaluating the NCH and developing a framework for predicting the range shifts of both native and alien species in response to global climate change.