Shifting effects of physiological integration on performance of a clonal plant during submergence and de-submergence

Background and Aims

Submergence and de-submergence are common phenomena encountered by riparian plants due to water level fluctuations, but little is known about the role of physiological integration in clonal plants (resource sharing between interconnected ramets) in their adaptation to such events. Using Alternanthera philoxeroides (alligator weed) as an example, this study tested the hypotheses that physiological integration will improve growth and photosynthetic capacity of submerged ramets during submergence and will promote their recovery following de-submergence.

Methods

Connected clones of A. philoxeroides, each consisting of two ramet systems and a stolon internode connecting them, were grown under control (both ramet systems untreated), half-submerged (one ramet system submerged and the other not submerged), fully submerged (both ramet systems submerged), half-shaded (one ramet system shaded and the other not shaded) and full-shaded (both ramet systems shaded) conditions for 30 d and then de-submerged/de-shaded for 20 d. The submerged plants were also shaded to very low light intensities, mimicking typical conditions in turbid floodwater.

Key Results

After 30 d of submergence, connections between submerged and non-submerged ramets significantly increased growth and carbohydrate accumulation of the submerged ramets, but decreased the growth of the non-submerged ramets. After 20 d of de-submergence, connections did not significantly affect the growth of either de-submerged or non-submerged ramets, but de-submerged ramets had high soluble sugar concentrations, suggesting high metabolic activities. The shift from significant effects of integration on both submerged and non-submerged ramets during the submergence period to little effect during the de-submergence period was due to the quick recovery of growth and photosynthesis. The effects of physiological integration were not found to be any stronger under submergence/de-submergence than under shading/de-shading.

Conclusions

The results indicate that it is not just the beneficial effects of physiological integration that are crucial to the survival of riparian clonal plants during periods of submergence, but also the ability to recover growth and photosynthesis rapidly after de-submergence, which thus allows them to spread.     

利益相关主体医疗风险分担机制的探讨

随着科技的快速发展和信息的扁平化,人类社会的各种风险在不断扩大,个体承担风险的程度是有限的,利益相关主体的合理化分担是保证风险化解的基础。医学作为一门不精确的科学,接近真理和无法穷尽真理是客观事实,作为探索医学真理的利益相关主体的患者、医疗工作者、医院和政府,单一分担医疗风险是不合理的,只有按照相关的规则共同分担,才能保证医学科学的进步和发展。     

Divergence in social foraging among morphs of the three‐spined stickleback,Gasterosteus aculeatus

Foraging in social groups has a number of benefits but can also increase the risk of exploitation. High tendency to shoal may be correlated with groups foraging, although facultatively social fish adjust both shoaling decisions and food resource defence based on intrinsic and extrinsic factors. The main aim of this study was to examine the relationships between shoaling, solitary foraging and aggression, forager tolerance of conspecifics joining at a discovered food patch and forager exploitation of resources discovered by others. We used two intra‐lacustrine three‐spined stickleback morph pairs, lava and mud, and monomorphic morphs from each of lava and mud habitats. The lava morph formed less cohesive shoals, was bolder during solitary foraging, approached and entered an occupied food patch less frequently than the mud morph, suggesting a link between shoaling and the propensity for social foraging. However, shoaling tendency and joiner tolerance were not correlated at a population level. Intralacustrine lava and mud morphs differed more markedly in joiner tolerance than morphs from single habitat lakes, whereas the opposite was true for shoaling tendency. We conclude that, in addition to differentiation in shoaling tendency, the lava and mud morphs differ in social foraging and these variations may act to promote population divergence. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 194–203.     

A Genetic Crossword

Simple models clarify lung and thorax structure and function for 14-19-year-olds     

GENETIC SIMILARITY BETWEEN PARENTS PREDICTS HATCHING FAILURE: NONINCESTUOUS INBREEDING IN THE GREAT REED WARBLER?

The DNA-fingerprinting technique was used to find the true pedigrees and to detect the overall genetic similarity between mates of great reed warblers (Acrocephalus arundinaceus) at an isolated breeding site in Sweden. The study covered 4 yr preceded by 3 yr when almost all adults and nestlings in the study area had been banded. DNA fingerprinting revealed that the putative father had sired 97% of the young (N = 455). The mate's genetic similarity, revealed as the proportion of bands shared in restriction fragment length polymorphism (RFLP) patterns, was high compared with other species of wild birds. Also, band sharing was higher between mates native to the area than between pairs in which the female was experimentally introduced from a distant breeding site. Hatching success of eggs was negatively correlated with the degree of genetic similarity between the mates, whereas pedigree data, up to the level of great-grandparents, clearly demonstrated an absence of close inbreeding. These are the first data showing a significant fitness cost associated with the choice of a mate that has high genetic similarity, even if it is not a close kin. This cost might be caused by generalized negative consequences of genomewide inbreeding in the present study, possibly accentuated by recent population bottlenecks.     

Use of fragment–sharing estimates from DNA fingerprinting to determine relatedness in a tropical wren

We assessed the usefulness of DNA fragment–sharing scores from DNA fingerprints for assigning relatedness to unknown pairs of individuals in a population of stripe–backed wrens (Campylorhynchus nuchalis). Preliminary investigation of scoring biases revealed consistency both within and between scorers in relative band–sharing scores, but a tendency for scores to be inflated and for inter–scorer agreement to decline as distance between lanes on an autoradiograph increased. Distributions of band–sharing values matched expected distributions well, which suggests that variability in scores is mostly inherent and not a result of errors in scoring. Confidence intervals based on band–sharing scores or means of scores across enzymes, probes and scorers revealed that unrelated (r= 0) and first–order dyads (r=Vi) could be distinguished on the basis of single band–sharing scores from the best combination of enzyme and probe (HaeIII/33.15) and that first– and second–order dyads could be distinguished when confidence intervals were based on means of band–sharing scores across two enzymes, two probes and two scorers.     

Our better nature: Does resource stress predict beyond-household sharing?

Food sharing and (to a lesser extent) labor sharing play central roles in the evolution of cooperation literature. One popular explanation for sharing beyond the family is that it reduces the likelihood of shortages by pooling risk across households. However, the frequency and scope of sharing have never been systematically documented across nonindustrial societies, and the literature is driven by theoretical models, experimental games, and case studies among a few extensively-studied populations. Here we explore the cross-cultural context, frequency, and scope of food and labor sharing customs in relation to resource stress. Using ethnographic data from a worldwide sample of 98 societies in the Standard Cross-Cultural Sample (SCCS), we test the following hypotheses: 1) customary sharing of food and labor beyond the household are cultural universals, 2) societies subject to more resource stress (including unpredictable food-destroying natural hazards) will share more frequently, and 3) the more frequent the resource stress, the broader the geographic and social scope of sharing customs. Hypotheses 1 and 2 are generally supported and are consistent with the theory that extensive beyond-household sharing is adaptive in societies that are subject to more resource stress. Hypothesis 3 was not supported and, contrary to our predictions, there is suggestive evidence that sharing beyond-relatives may be attenuated when resource stress is high. In light of these findings, we consider how resource stress may constitute an important selection pressure for maintaining extensive cooperation and help to explain the ubiquity of beyond-household sharing.     

Ecobat: An online resource to facilitate transparent,evidence‐based interpretation of bat activity data

Acoustic surveys of bats are one of the techniques most commonly used by ecological practitioners. The results are used in Ecological Impact Assessments to assess the likely impacts of future developments on species that are widely protected in law, and to monitor developments’ postconstruction. However, there is no standardized methodology for analyzing or interpreting these data, which can make the assessment of the ecological value of a site very subjective. Comparisons of sites and projects are therefore difficult for ecologists and decision‐makers, for example, when trying to identify the best location for a new road based on relative bat activity levels along alternative routes. Here, we present a new web‐based, data‐driven tool, Ecobat, which addresses the need for a more robust way of interpreting ecological data. Ecobat offers users an easy, standardized, and objective method for analyzing bat activity data. It allows ecological practitioners to compare bat activity data at regional and national scales and to generate a numerical indicator of the relative importance of a night's worth of bat activity. The tool is free and open‐source; because the underlying algorithms are already developed, it could easily be expanded to new geographical regions and species. Data donation is required to ensure the robustness of the analyses; we use a positive feedback mechanism to encourage ecological practitioners to share data by providing in return high quality, contextualized data analysis, and graphical visualizations for direct use in ecological reports.     

Selfish long-term benefits of hoarding in the Siberian jay

We followed the consumption of cached food in Siberian jay flocksduring winter. Siberian jay flocks contain kin associationscomposed of parents in company with mature offspring. Further,flocks often contain immigrants not closely related to the groupmembers. We studied the extent to which Siberian jay offspringkept caches to themselves or whether they showed a kin biasand shared cached food mutualistically with relatives (parents/siblings)thus making an inclusive fitness gain. We recorded the retrievalof cached food using radio-ptilochronology, a technique thatdetects the consumption of a radioactively labeled food itemin the growth bar laid down in a growing feather the day ofconsumption. Food caching entailed a selfish benefit to thehoarder. The hoarding bird showed a substantial "recovery advantage"and retrieved its own cached food seven times as often as anyof its flock mates. There was no evidence for mutualistic sharingof caches among relatives. This selfish benefit persisted throughoutthe 7-week period for which we could follow the consumptionof labeled food.