Population genomic analysis reveals distinct demographics and recent adaptation in the black flying fox(Pteropus alecto)

As the only mammalian group capable of powered flight,bats have many unique biological traits.Previous comparative genomic studies in bats have focused on long-term evolution.However,the microevolutionary processes driving recent evolution are largely under-explored.Using resequencing data from 50 black flying foxes(Pteropus alecto),one of the model species for bats,we find that black flying fox has much higher genetic diversity and lower levels of linkage disequilibrium than most of the mammalian species.Demographic inference reveals strong population fluctuations(>100 fold)coinciding with multiple historical events including the last glacial change and Toba super eruption,suggesting that the black flying fox is a very resilient species with strong recovery abilities.While long-term adaptation in the black flying fox is enriched in metabolic genes,recent adaptation in the black flying fox has a unique landscape where recently selected genes are not strongly enriched in any functional category.The demographic history and mode of adaptation suggest that black flying fox might be a well-adapted species with strong evolutionary resilience.Taken together,this study unravels a vibrant landscape of recent evolution for the black flying fox and sheds light on several unique evolutionary processes for bats comparing to other mammalian groups.

Apoptotic and nonapoptotic function of caspase 7 in spermatogenesis

Recent studies have reported that caspase 7 has an apoptotic and nonapoptotic function. However, the relationship between caspase 7 and spermatogenesis remains unknown. This study aimed to investigate the possible function of caspase 7 during normal and abnormal spermatogenesis. The cleaved form of caspase 7 was detected in testis tissues at different postpartum times （5-14 weeks） by qRT-PCR, Western blot and immunohistochemistry （IHC）. Then, the mice models of spermatogenic dysfunction were obtained by busulfan （30 mg kg-1） to further evaluate the potential function and mechanism of caspase 7. qRT-PCR and Western blot results showed that caspase 7 expression was gradually elevated from 5 to 14 weeks, which was not connected with apoptosis. IHC results revealed that caspase 7 was mainly located in spermatogenic cells and Leydig cells. In addition, spermatogenic dysfunction induced by busulfan gradually enhanced the apoptosis and elevated the expression of caspase 3, caspase 6, and caspase 9, but decreased the expression of caspase 7 in spermatogenic cells. However, when spermatogenic cells were mostly disappeared at the fourth week after busulfan treatment, caspase 7 expression in Leydig cells was significantly increased and positively correlated with the expression of caspase 3, caspase 6, and caspase 9. Therefore, these results indicate that caspase 7 has a nonapoptic function that participates in normal spermatogenesis, but also displays apoptotic function in spermatogenic dysfunction.

The position of tree shrews in the mammalian tree:Comparing multi-gene analyses with phylogenomic results leaves monophyly of Euarchonta doubtful

The well-accepted Euarchonta grandorder is a pruned version of Archonta nested within the Euarchontoglires(or Supraprimates)clade.At present,it includes tree shrews(Scandentia),flying lemurs(Dermoptera)and primates(Primates).Here,a phylogenomic dataset containing 1912 exons from 22 representative mammals was compiled to investigate the phylogenetic relationships within this group.Phylogenetic analyses and hypothesis testing suggested that tree shrews can be classified as a sister group to Primates or to Glires or even as a basal clade within Euarchontoglires.Further analyses of both modified and original previously published datasets found that the phylogenetic position of tree shrews is unstable.We also found that two of three exonic indels reported as synapomorphies of Euarchonta in a previous study do not unambiguously support the monophyly of such a clade.Therefore,the monophyly of both Euarchonta and Sundatheria(Dermoptera+Scandentia)are suspect.Molecular dating and divergence rate analyses suggested that the ancestor of Euarchontoglires experienced a rapid divergence,which may cause the unresolved position of tree shrews even using the whole genomic data.

A joint call for actions to advance taxonomy in China

Taxonomy plays an important role in understanding the origin, evolution, and ecological functionality of biodiversity. There are large number of unknown species yet to be described by taxonomists, which together with their ecosystem services cannot be effectively protected prior to description. Despite this, taxonomy has been increasingly underrated insufficient funds and permanent positions to retain young talents. Further, the impact factordriven evaluation systems in China exacerbate this downward trend, so alternative evaluation metrics are urgently necessary. When the current generation of outstanding taxonomists retires,there will be too few remaining taxonomists left to train the next generation. In light of these challenges, all co-authors worked together on this paper to analyze the current situation of taxonomy and put out a joint call for immediate actions to advance taxonomy in China.

Comprehensive Knowledge of Reservoir Hosts is Key to Mitigating Future Pandemics

Coronavirus disease 2019(COVID-19)and other epidemics(such as severe acute respiratory syndrome[SARS],Ebola,and H1N1)are stark reminders that knowledge of animal behavior and ecosystem health are key to controlling the spread of zoonotic diseases early in their onset.However,we have very limited information about the set of behavioral and ecological factors that promote viral spillover and the effects that has on ecosystem health and disease transmission.Thus,expanding our current knowledge of reservoir hosts and pandemics represents an urgent and critical tool in ecological epidemiology.We also propose to create an integrative database that ranks animal species in terms of their likelihood as hosts for specific infectious diseases.We call for a global and cooperative effort of field and laboratory scientists to create,maintain,and update this information in order to reduce the severity of future pandemics.