Defining honeybee subspecies in an evolutionary context warrants strategized conservation

Despite the urgent need for conservation consideration,strategic action plans for the preservation of the Asian honeybee,Apis cerana Fabricius,1793,remain lacking.Both the convergent and divergent adaptations of this widespread insect have led to confusing phenotypical traits and inconsistent infraspecific taxonomy.Unclear subspecies boundaries pose a significant challenge to honeybee conservation efforts,as it is difficult to effectively prioritize conservation targets without a clear understanding of subspecies identities.Here,we investigated genome variations in 362 worker bees representing almost all populations of mainland A.cerana to understand how evolution has shaped its population structure.Whole-genome single nucleotide polymorphisms(SNPs)based on nuclear sequences revealed eight putative subspecies,with all seven peripheral subspecies exhibiting mutually exclusive monophyly and distinct genetic divergence from the widespread central subspecies.Our results demonstrated that most classic morphological traits,including body size,were related to the climatic variables of the local habitats and did not reflect the true evolutionary history of the organism.Thus,such morphological traits were not suitable for subspecific delineation.Conversely,wing vein characters showed relative independence to the environment and supported the subspecies boundaries inferred from nuclear genomes.Mitochondrial phylogeny further indicated that the present subspecies structure was a result of multiple waves of population divergence from a common ancestor.Based on our findings,we propose that criteria for subspecies delineation should be based on evolutionary independence,trait distinction,and geographic isolation.We formally defined and described eight subspecies of mainland A.cerana.Elucidation of the evolutionary history and subspecies boundaries enables a customized conservation strategy for both widespread and endemic honeybee conservation units,guiding colony introduction and breeding.

Do Geographically Isolated Grasslands Follow the Principle of Island Biogeography in a Landscape Scale? Taking Poyang Lake Grassland as an Example

As one of the basic theories of biodiversity conservation,island biogeography has been widely accepted in the past decades.Originally,island biogeography was put forward and applied in oceanic environments.But later on,it was found out that the application was not only limited to oceanic islands,but also in terrestrial environments with relatively isolated conditions.In terms of biodiversity level,island biogeography generally focuses on a small scale,such as species diversity and genetic diversity.The studies of biodiversity on a large-scale based on island biogeography,such as ecosystem and landscape scales,were seldomly conducted.Taking Poyang Lake,the largest fresh water lake in China as case study area,30 grasslands were randomly selected to study whether island biogeography can be applied to grasslands at a landscape level from three island attributes(area,distance and shape),and the most important ecological variable(flooding)in Poyang Lake.The results showed that in general,grasslands have the property of an island,and follow the basic principle of island biogeography.We found the area and flooding duration were the two most important determinants of landscape diversity.There was a significant positive correlation between the grassland area and the landscape diversity,which could be well expressed by logarithmic function model(R2=0.73).There was a negative correlation between flooding duration and landscape diversity,which could be described by an inverse model(R2=0.206).The distance to mainland and the shape of grassland were correlated with landscape diversity,but the fitting result of the models was not as good as expected.The possible reason could be that Poyang Lake is a seasonal lake,the water level varies with hydrological conditions,so that the grasslands are not strongly isolated and their shape is not stable enough required by island biogeography.Furthermore,it indicates that besides area,distance and shape attributes,flooding strongly affects the biodiversity of grassland vegetation,and should not be ignored when applying island biogeography theory to Poyang Lake.This study is expected to be a supplement for island biogeography in terrestrial environments,and the results are expected to benefit for the biodiversity conservation in Poyang Lake.

Silencing of Transposable Elements by piRNAs in Drosophila:An Evolutionary Perspective

Transposable elements （TEs） are DNA sequences that can move within the genome. TEs have greatly shaped the genomes, transcriptomes, and proteomes of the host organisms through a variety of mechanisms. However, TEs generally disrupt genes and destabilize the host genomes, which substantially reduce fitness of the host organisms. Understanding the genomic distribution and evolutionary dynamics of TEs will greatly deepen our understanding of the TE-mediated bio- logical processes. Most TE insertions are highly polymorphic in Drosophila melanogaster, providing us a good system to investigate the evolution of TEs at the population level. Decades of theoretical and experimental studies have well established ＂transposition-selection＂ population genetics model, which assumes that the equilibrium between TE replication and purifying selection determines the copy number of TEs in the genome. In the last decade, P-element-induced wimpy testis （PIW1）- interacting RNAs （piRNAs） were demonstrated to be master repressors of TE activities in Droso- phila, The discovery of piRNAs revolutionized our understanding of TE repression, because it reveals that the host organisms have evolved an adaptive mechanism to defend against TE invasion. Tremendous progress has been made to understand the molecular mechanisms by which piRNAs repress active TEs, although many details in this process remain to be further explored. The inter- action between piRNAs and TEs well explains the molecular mechanisms underlying hybrid dysge- nesis for the IoR and P-M systems in Drosophila, which have puzzled evolutionary biologists for decades. The piRNA repression pathway provides us an unparalleled system to study the co-evolutionary process between parasites and host organisms.

Emergency irradiation of 3.4Gy/2f in pineal gland germinoma patients with symptomatic hydrocephalus

Surgical interventions including ventriculostomy and ventriculo-peritoneal shunt were usually administrated in pineal germ cell tumor patients with symptomatic hydrocephalus. Considering higher sensitivity of germinoma to anti-tumor therapy, we explored emergency irradiation as non-invasive measure in this situation. Methods: Data of 35 germinoma patients with symptomatic hydrocephalus who received emergency irradiation of 3. 4 Gy/2f were studied retrospectively. The maximum width of frontal horn and the minimum width of trunk of corpus cal osum (TCC) were measured to evaluate hydrocephalus changing. Besides, mean deviation (MD) of Humphrey perimetry was employed to evaluate visual field defect. Correlations between hydrocephalus changing and clinical factors, including age, percentage of tumor regression, radiographic re-evaluation interval, and serum beta-human chorionic gonadotropin (β-HCG) level, were analyzed. Results: The median maximum diameter and volume of pineal lesions was 27 mm (range 10–55 mm) and 6.5cm3 (range 0.4–74.1 cm3), respectively. At median 8 days after irradiation, the median percentage of tumor remission was 55% (range 10–100%). The median maximum width of FN and the median minimum width of TCC were 11.6 mm and 39.0 mm, and 8.0 mm and 31.4 mm, before and after irradiation, respectively. The improvement of both parameters reached significant level (p < 0.001). However, none clinical factor was found to have correlation with their improvement. In 14 patients with paired data of pre- and post-irradiation MD, its change did not reach the significant level for both eyes. Al patients successful y received subsequent chemoradiotherapy without surgical intervention. Conclusions: Emergency irradiation of 3.4 Gy/2f was an effective non-invasive measure to relief hydrocephalus in pineal germinoma patients.