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A widespread and popular belief posits that humans possess a cognitive capacity that is limited to keeping track of and maintaining stable relationships with approximately 150 people. This influential number, ‘Dunbar''s number’, originates from an extrapolation of a regression line describing the relationship between relative neocortex size and group size in primates. Here, we test if there is statistical support for this idea. Our analyses on complementary datasets using different methods yield wildly different numbers. Bayesian and generalized least-squares phylogenetic methods generate approximations of average group sizes between 69–109 and 16–42, respectively. However, enormous 95% confidence intervals (4–520 and 2–336, respectively) imply that specifying any one number is futile. A cognitive limit on human group size cannot be derived in this manner. 相似文献
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Lindell Bromham 《Biology letters》2009,5(3):391-393
Bioinformatic analyses have grown rapidly in sophistication and efficiency to accommodate the vast increase in available data. One of the major challenges has been to incorporate the growing appreciation of the complexity of molecular evolution into new analytical methods. As the reliance on molecular data in biology and medicine increases, we need to be confident that these methods adequately reflect the underlying processes of genome change. This special issue focuses on the way that patterns and processes of molecular evolution are influenced by features of populations of whole organisms, such as selection pressure, population size and life history. The advantage of this approach to molecular evolution is that it views genomic change not simply as a biochemical or stochastic process, but as the result of a complex series of interactions that shape the kinds of genomic changes that can and do happen. 相似文献
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香菇‘申香1644’是以传统优质栽培品种‘申香215’为亲本,采用多孢自交育种技术选育的新品种。其菌盖纵切面呈凸形,菌盖直径(6.15±0.38) cm,菌盖厚度(2.27±0.42) cm,菇型圆整,菇质紧实,产量高,生物学转化率95%以上。与亲本相比,‘申香1644’在分子标记和栽培性状上均具有明显差异性,其菌盖为浅黄褐色,颜色较亲本浅;菌龄100-105 d,较亲本缩短5-10 d。‘申香1644’菌丝生长适宜温度为22-26 ℃,原基发育适宜温度为16-22 ℃,可在全国范围内进行代料栽培。 相似文献
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Addmore Shonhai 《Biophysical reviews》2021,13(2):167
It gives me great pleasure to have the opportunity to introduce myself to the readers of Biophysical Reviews as part of the ‘meet the editors’ series. What follows is a mini-autobiography of my life as it relates to my scientific career and research. 相似文献
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Eric R Beyerle Mohammadhasan Dinpajooh Huiying Ji Peter H von
Hippel Andrew H Marcus Marina G Guenza 《Nucleic acids research》2021,49(4):1872
Regulatory protein access to the DNA duplex ‘interior’ depends on local DNA ‘breathing’ fluctuations, and the most fundamental of these are thermally-driven base stacking-unstacking interactions. The smallest DNA unit that can undergo such transitions is the dinucleotide, whose structural and dynamic properties are dominated by stacking, while the ion condensation, cooperative stacking and inter-base hydrogen-bonding present in duplex DNA are not involved. We use dApdA to study stacking-unstacking at the dinucleotide level because the fluctuations observed are likely to resemble those of larger DNA molecules, but in the absence of constraints introduced by cooperativity are likely to be more pronounced, and thus more accessible to measurement. We study these fluctuations with a combination of Molecular Dynamics simulations on the microsecond timescale and Markov State Model analyses, and validate our results by calculations of circular dichroism (CD) spectra, with results that agree well with the experimental spectra. Our analyses show that the CD spectrum of dApdA is defined by two distinct chiral conformations that correspond, respectively, to a Watson–Crick form and a hybrid form with one base in a Hoogsteen configuration. We find also that ionic structure and water orientation around dApdA play important roles in controlling its breathing fluctuations. 相似文献
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