| Climate change and human activities can increase extinction risk by limiting and segmenting species distributions and reducing effective population size.However,it is difficult to quantify the extent to which species are declining due to climate change,human activity or a combination of the two.Human disturbance is believed to be a key factor in population decline and species extinction,and climate is another major culprit in the range shift and local extinction of animals in their prime habitat.By extracting original records from official or formally recorded history(e.g.,Twenty-four Histories,Tongjian and Zhizhi Tongjian),Wen Rongsheng has compiled compendiums of the historical distribution of some endangered mammal species and local Chronicles(provincial,county and district Chronicles),providing an opportunity to reconstruct the local extinctions of these mammals over the past millennium.Wan [1] et al.based on the original recorded mammalian data that Wenbansheng extracted from formally recorded history,using elephants(Elephas maximus),rhinos(Dicerorhinus sumatrensis),Historical records of 11 large and medium mammal species including Ailuropoda melanoleuca in China from 905 BC to 2006 AD indicate that anthropogenic and climatic pressures are uniquely associated with local extinctions of these mammals.All plants and animals on Earth went through the Quaternary ice Age,which began two million years ago and led to the extinction of a large number of large mammals.Based on the whole genome sequence information of this species,we infer the changes of its Effective population size(Ne)in the past long period of time,and study the extinction degree of the species in the past long period of time through modern biological information means.I used historical records of 15 large and medium-sized mammals to calculate the spatial extinction rate.Based on the climate factor data extracted from the longitude and latitude data of species distribution,the data of forest land,cultivated land,acres,land reclamation and population density were obtained from the global historical environmental database.The random forest model was used to analyze the effects of climate and human factors on the extinction of mammals.In this study,we comprehensively analyzed the temporal and spatial extinction rates of species and the influencing factors of species extinction.In addition,we also explored whether the characteristics of species affected their extinction rates.We get the following results:(1)Based on PSMC(Pairwise Sequentially Markovian Coalescent)and SMC++(sequkovian Coalescent)Samples)showed that the population size of elephants,giant pandas and other species was declining about 10,000 years ago,and this population size decrease was consistent with the period of the Quaternary Glacial period(1.1 to 3million years).Elephant numbers,for example,fell from 400,000 two million years ago to around 2,000 10,000 years ago.Large reductions in the effective population size of species indicate very large extinction rates over long time scales.(2)From the historical records of species,the extinction rate of species in spatial distribution is also very large.For example,the extinction rate of elephant is 0.95.(3)Among the environmental factors and human disturbance factors,temperature is an important factor to explain the change of latitude distribution range of species,population density is an important factor to explain the change of longitude distribution range of species,and the area of cultivated land and grazing land are also important factors.(4)Body weight,body length,sexual maturity time and generation length were positively correlated with extinction rate.This paper analyzes the factors affecting species extinction from the two dimensions of time and space,providing a new perspective for the study of the driving process of species extinction,which is of great significance for biodiversity conservation under the accelerated global change. |
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