Preferred step frequency during downhill running may be determined by muscle activity

It is well established that metabolic cost is minimized at an individual’s running preferred step frequency (PSF). It has been proposed that the metabolic minimum at PSF is due to a tradeoff between mechanical factors, however, this ignores muscle activity, the primary consumer of energy. Thus, we hypothesized that during downhill running, total muscle activity would be greater with deviations from PSF. Specifically, we predicted that slow step frequencies would have greater stance activity while fast step frequencies would have greater swing activity. We collected metabolic cost and leg muscle activity data while 10 healthy young adults ran at 3.0 m/s for 5 min at level and downhill at PSF and ±15% PSF. In support of our hypothesis, there was a significant main effect for step frequency for both metabolic cost and total muscle activity. In addition, there was greater muscle activity in the stance phase during the slower step frequency while muscle activity was greater in the swing phase during the fast step frequency. This suggests that PSF is partially determined by the tradeoff between the greater cost of muscle activity in the swing phase and lower cost in the stance phase with faster step frequency.     

The coevolution of long‐term pair bonds and cooperation

The evolution of social traits may not only depend on but also change the social structure of the population. In particular, the evolution of pairwise cooperation, such as biparental care, depends on the pair‐matching distribution of the population, and the latter often emerges as a collective outcome of individual pair‐bonding traits, which are also under selection. Here, we develop an analytical model and individual‐based simulations to study the coevolution of long‐term pair bonds and cooperation in parental care, where partners play a Snowdrift game in each breeding season. We illustrate that long‐term pair bonds may coevolve with cooperation when bonding cost is below a threshold. As long‐term pair bonds lead to assortative interactions through pair‐matching dynamics, they may promote the prevalence of cooperation. In addition to the pay‐off matrix of a single game, the evolutionarily stable equilibrium also depends on bonding cost and accidental divorce rate, and it is determined by a form of balancing selection because the benefit from pair‐bond maintenance diminishes as the frequency of cooperators increases. Our findings highlight the importance of ecological factors affecting social bonding cost and stability in understanding the coevolution of social behaviour and social structures, which may lead to the diversity of biological social systems.     

张家界武陵源风景区自然景观价值评估

自然景观提供给人们观赏、娱乐和休闲的效用和价值,长期以来,人们对自然景观的价值忽略并低估,导致在开发利用自然资源过程中出现资源浪费和生态破坏的问题.如果赋予自然景观合适的经济价值,能为其开发利用提供决策支持.为评价张家界武陵源风景区的景观价值,构建了相应的指标体系.自然景观价值乃使用价值与非使用价值之和,并对这两种价值分别运用旅行费用法和条件价值法进行评估.结果表明:2011年武陵源风景区的自然景观价值为89.01亿元,其中使用价值为79.30亿元,非使用价值为9.71亿元.分析表明,武陵源风景区的自然景观价值要远高于以往的研究及近年的旅游收入,建议景区当局全面认识其景观价值,在旅游人次不断攀升的形势下,全力保护该地生态环境,探究武陵源风景区的可持续发展道路.     

Longevity costs of same‐sex interactions: first evidence from a parasitic wasp

Costs of sexual interactions play a key role in life‐history evolution. Although the costs of reproduction have been investigated in both sexes of many insects, the costs of same‐sex interactions have been examined in few species. In parasitic wasps, very little has been reported about the longevity costs of heterosexual interactions, and nothing is known about longevity costs of same‐sex interactions. In this study, the effects of heterosexual and homosexual activities on longevity were evaluated in Psyttalia concolor (Hymenoptera: Braconidae), a synovigenic koinobiont larval‐pupal endoparasitoid of tephritid flies. When compared with individually housed virgin wasps, male longevity was strongly reduced both in males kept with females, and in males kept with other males. When females were kept with males, their longevity was reduced compared with the virgin females and females kept with other females. Overall, the costs of male–female interactions were considerable in both sexes of P. concolor, while same‐sex activities were found to be costly only among males, suggesting that they may have implications for the evolution of the P. concolor mating system.     

Fermentation of cashew apple juice to produce high added value products

The use of agriculture substrates in industrial biotechnological processes has been increasing because of its low cost. Cashew apples are considered an agriculture low cost product in the Brazilian Northeast because the cashew cultivation is done mainly to produce cashew nuts. About 90% of the cashew apples production is lost in the field after removing the nut. In this work, the use of clarified cashew apple juice as substrate for microbial cultivation was investigated. The results showed that cashew apple juice is a good source of reducing sugars and can be used to grow Leuconostoc mesenteroides to produce high added value products such as dextran, lactic acid, mannitol and oligosaccharides.     

What is the Value of a Good Map? An Example Using High Spatial Resolution Imagery to Aid Riparian Restoration

Riparian areas contain structurally diverse habitats that are challenging to monitor routinely and accurately over broad areas. As the structural variability within riparian areas is often indiscernible using moderate-scale satellite imagery, new mapping techniques are needed. We used high spatial resolution satellite imagery from the QuickBird satellite to map harvested and intact forests in coastal British Columbia, Canada. We distinguished forest structural classes used in riparian restoration planning, each with different restoration costs. To assess the accuracy of high spatial resolution imagery relative to coarser imagery, we coarsened the pixel resolution of the image, repeated the classifications, and compared results. Accuracy assessments produced individual class accuracies ranging from 70 to 90% for most classes; whilst accuracies obtained using coarser scale imagery were lower. We also examined the implications of map error on riparian restoration budgets derived from our classified maps. To do so, we modified the confusion matrix to create a cost error matrix quantifying costs associated with misclassification. High spatial resolution satellite imagery can be useful for riparian mapping; however, errors in restoration budgets attributable to misclassification error can be significant, even when using highly accurate maps. As the spatial resolution of imagery increases, it will be used more routinely in ecosystem ecology. Thus, our ability to evaluate map accuracy in practical, meaningful ways must develop further. The cost error matrix is one method that can be adapted for conservation and planning decisions in many ecosystems.     

The reproduction potentials of four entomopathogenic nematode strains related to cost-effective production for biological control

Bioassays to evaluate the mortality, virulence and reproduction potentials of four indigenous EPN strains, S-PQ16, S-BM12, H-KT3987 and H-CB3452 on insect larvae of mealworm (Tenebrio molitor) and greater wax moth (Galleria mellonella) revealed the highest mortality rates of two insect larvae at the highest inoculation dose of 100 IJs to range from 89 to 100 percent and 94.3–100 percent at 48 h after inoculation, respectively. Virulence was high for all nematode strains, with LC₅₀ values between 29.6 and 47.3 IJs/insect host. The highest IJ yields were different between nematode strains and insect host, from 66.8 × 10³ IJs (S-PQ16) to 118.6 × 10³ IJs (H-KT3987) on T. molitor, and from 54.2 × 10³ IJs (S-BM12) to 163.3 × 10³ IJs (H-KT3987) on G. mellonella. The culturing cost in terms of food expenditure for rearing insect larvae varied between insect larvae and nematode strains, from 6.76 to 26.63 USD per billion IJs for nematode strains cultured on T. molitor larvae and from 3.54 to 7.81 USD per billion IJs for nematode strains cultured on G. mellonella larvae. The full cost for a nematode product of 2.5 × 10⁹ IJs per hectare, produced through in vivo mass culturing, of the most efficient nematode strain, H-KT3987, was 191.3 USD, slightly cheaper than 199.4 USD for the same nematode product produced through in vitro mass culturing.