Hot spots become cold spots: coevolution in variable temperature environments

Antagonistic coevolution between hosts and parasites is a key process in the genesis and maintenance of biological diversity. Whereas coevolutionary dynamics show distinct patterns under favourable environmental conditions, the effects of more realistic, variable conditions are largely unknown. We investigated the impact of a fluctuating environment on antagonistic coevolution in experimental microcosms of Pseudomonas fluorescens SBW25 and lytic phage SBWΦ2. High‐frequency temperature fluctuations caused no deviations from typical coevolutionary arms race dynamics. However, coevolution was stalled during periods of high temperature under intermediate‐ and low‐frequency fluctuations, generating temporary coevolutionary cold spots. Temperature variation affected population density, providing evidence that eco‐evolutionary feedbacks act through variable bacteria–phage encounter rates. Our study shows that environmental fluctuations can drive antagonistic species interactions into and out of coevolutionary cold and hot spots. Whether coevolution persists or stalls depends on the frequency of change and the environmental optima of both interacting players.     

The 'spiteful' origins of human cooperation

We analyse generosity, second-party ('spiteful') punishment (2PP), and third-party ('altruistic') punishment (3PP) in a cross-cultural experimental economics project. We show that smaller societies are less generous in the Dictator Game but no less prone to 2PP in the Ultimatum Game. We might assume people everywhere would be more willing to punish someone who hurt them directly (2PP) than someone who hurt an anonymous third person (3PP). While this is true of small societies, people in large societies are actually more likely to engage in 3PP than 2PP. Strong reciprocity, including generous offers and 3PP, exists mostly in large, complex societies that face numerous challenging collective action problems. We argue that 'spiteful' 2PP, motivated by the basic emotion of anger, is more universal than 3PP and sufficient to explain the origins of human cooperation.     

原生质体融合构建高效产脂肽工程菌

芽孢杆菌因其可产生多种生理活性物质,在环境污染修复、生物防治、微生物采油等领域具有广阔的应用前景。莫哈韦芽孢杆菌Bacillus mojavensis JF-2和解淀粉芽孢杆菌B. amyloliquefaciens BQ-6是从油田筛选出的产脂肽类表面活性剂菌株, 但在微生物采油实际应用中受到氧气浓度、盐度及pH的限制。原生质体融合是改变微生物代谢功能的一种简便有效的方法,以上述两株芽孢杆菌为对象,利用4因素3水平正交试验来探索菌龄、溶菌酶浓度、酶解温度和酶解时间对原生体制备、再生的影响。此外,对两菌株进行了双亲灭活原生质体融合,通过筛选得到了一株工程菌HY-4,并对其进行了初步的评价。结果表明:菌龄、溶菌酶浓度和酶解时间显著影响芽孢杆菌原生质体制备率及再生率(P<0.05),且在溶菌酶处理前用生理盐水多次洗涤菌体细胞,可提高制备率。两种芽孢杆菌原生质体制备及再生的最优条件均为:菌龄7 h、溶菌酶浓度2.5 mg/ml、酶解时间30 min、酶解温度42 ℃。融合子HY-4的最高耐盐度为15%,可耐50 ℃高温,代谢产脂肽的pH范围为4.0~9.5,且在好氧及厌氧条件下均能够代谢产脂肽,在厌氧条件下生长迅猛(细胞干重>1.6 g/L)。综上所述,融合子HY-4具有较大的应用潜力,该研究为芽孢杆菌的遗传育种打下了方法学基础,并对驱油微生物菌种的选育具有指导意义。     

Adaptation to simultaneous warming and acidification carries a thermal tolerance cost in a marine copepod

The ocean is undergoing warming and acidification. Thermal tolerance is affected both by evolutionary adaptation and developmental plasticity. Yet, thermal tolerance in animals adapted to simultaneous warming and acidification is unknown. We experimentally evolved the ubiquitous copepod Acartia tonsa to future combined ocean warming and acidification conditions (OWA approx. 22°C, 2000 µatm CO₂) and then compared its thermal tolerance relative to ambient conditions (AM approx. 18°C, 400 µatm CO₂). The OWA and AM treatments were reciprocally transplanted after 65 generations to assess effects of developmental conditions on thermal tolerance and potential costs of adaptation. Treatments transplanted from OWA to AM conditions were assessed at the F1 and F9 generations following transplant. Adaptation to warming and acidification, paradoxically, reduces both thermal tolerance and phenotypic plasticity. These costs of adaptation to combined warming and acidification may limit future population resilience.     

Calculation of impingement-free combined cup and stem alignments based on the patient-specific pelvic tilt

Proper cup alignment is crucial in total hip arthroplasty for reducing impingement risks, dislocations and wear. The Lewinnek “safe zone” is often used in clinical routine. This safe zone does not consider functional aspects and dislocation can occur even when the cup is oriented within the safe zone. Functional safe zones based on the hip range of motion (ROM) were introduced but are not commonly used in clinical routine. The reason might be that these methods are time-consuming due to complex simulations. A relatively fast method based on analytical mathematical formulas was proposed, but it is difficult to consider arbitrary motion. This work introduces an efficient algorithm for calculating a patient-specific target zone based on the target ROM which can consider any set of motions. The method is based on matrix transformations and trigonometric formulas. The resulting target zone which contains all impingement-free cup orientations is dependent on the patient-specific pelvic tilt, the 3D angular neck and stem orientation within the femur, and the technical prosthesis ROM. This method could be integrated into computer-assisted preoperative planning and intra-operative navigation tools. As pelvic tilt and stem orientation influence the optimal cup orientation they need to be acquired from the patient to derive a patient-specific ROM-based target zone.     

Landscape ecology planning principles in Korean Feng-Shui, Bi-bo woodlands and ponds

The purpose of this study is to suggest practical planning principles, which are absent in landscape ecology planning, according to which the spatial completeness of the watershed is derived from native Korean Feng-Shui (). Landscape ecology planning principles are used widely in contemporary planning projects in terms of patch, corridor, matrix and network of landscape pattern. However, landscape indices for planning principles are complicated and constrained, and so are limited to applications for site and eco-village plannings. Native Korean Feng-Shui is different from Chinese Feng-Shui in that it is aimed at theoretical completeness in terms of aspect and topographical shape, based on the concept of ideal Myung-dang () to complete the space, according to local conditions in the physiognomy of the watershed. The complementary method is called Bi-bo () in native Korean Feng-Shui. These principles have been applied in traditional Korean villages, leading to consistent location choices and fractal patterns in land use. Furthermore, Bi-bo woodlands and ponds have been introduced to achieve spatial completeness in the landscape structure of the village.     

The influence of marking upon bee behaviour in circle tube experiments with a methodological comparison among studies

Summary. Circle tubes were used to investigate the influence of marking upon the behavioural profiles of two halictid species; one, Penapis toroi Rozen, putatively solitary, the other, Corynura chloris (Spinola) thought to be semisocial. Previous studies have shown that solitary bees tend to exhibit avoidance behaviour and those with a reproductive division of labour tend to behave aggressively within circle tube arenas. Marked pairs of C. chloris were significantly more cooperative than unmarked pairs and marked P. toroi showed significantly increased aggression and decreased cooperation. These findings suggest that marking bees may reduce behavioural differences among taxa with different types of social organization. Recommendations are made on how to use the circle tube apparatus to detect bee populations that might be worth more detailed studies of social organization and also for standardization in the way results of these studies are presented. Further experiments are suggested to clarify the effects of certain variables upon bee behaviour using this apparatus. The data presented here are the first for any member of the subfamily Rophitinae and the first for any bee thought to be primarily semisocial. A narrower range of behaviours were observed in the Rophitine, Penapis toroi Rozen, in comparison to species from other subfamilies of Halictidae and Corynura chloris Spinola had a behavioural profile similar to that of eusocial species.Received 15 December 2003; revised 12 September 2004; accepted 15 October 2004.     

Alternative parasite development in transmission strategies: how time flies!

Among parasitic platyhelminths with complex life cycles, it has been well documented that transmission opportunities are the main forces shaping the diversity of life‐history traits and parasite developmental strategies. While deviations in the development pathway usually involve shortening of life cycles, their extension may also occur following perception of remaining time by parasites. Polystoma gallieni, the monogenean parasite of Hyla meridionalis, is able to trigger two alternative developmental strategies depending on the physiological stage of the tadpoles upon which larvae attach. The distribution and reproductive outputs of both resulting phenotypes were surveyed to address questions about the dynamics of transmission in natural environments. Because modifications in the completion of life cycles can have drawbacks which may perturb the dynamic equilibrium of the resulting host–parasite systems, experimental infestations were also performed to assess parasite–parasite interactions. Our results suggest that the bladder adult phenotype, which involves transmission between frogs and tadpoles, is supplied secondarily by the branchial phenotype which involves transmission between tadpoles and metamorphs. They also support the occurrence of finely tuned trade‐offs between hosts and parasites and highlight positive trends behind the extension of direct life cycles, in which host‐derived signals account for the remaining time to achieve parasitic transmission.