Effects of Transient and Continuous Wheel Running Activity on the Upper and Lower Limits of Entrainment to Light‐Dark Cycles in Female Hamsters

The entrainment limits to light‐dark cycles can be modified by the experimental conditions under which they are tested. Among the factors that may influence entrainment is the amount of wheel running exerted by the animal. In the present work, the effects of transitory and continuous wheel running on entrainment to light‐dark cycles were tested using a range of T cycles at the entrainment limits. Four groups of female hamsters were submitted to 1 h stepwise changes in T cycles. Two groups were exposed to T cycles of which the period was shortened at the lower limit from T22 to T18, and the other two groups were exposed to cycles that lengthened at the upper limit from T27 to T32. One of the groups at the lower limit and one at the upper limit had continuous access to a running wheel, while the others had the wheel locked, except at certain T when a lack of period control by T cycle appeared. The study demonstrates that access to running wheel widens the limits of entrainment to LD cycles. Specifically, the following observations were made: the effects of wheel running for entrainment were more evident in the groups with continuous access to wheel, as they did entrain to T19 and T32; continuous access to a wheel produced aftereffects only after T19, but not under T32; and when animals without a wheel showed relative coordination, unlocking the wheel favored entrainment in all the animals at T31, but in only 1 out 6 at T19. All of these indicate a different effect of the wheel running on the upper and lower limits of entrainment.     

A forceful upper jaw facilitates picking-based prey capture: biomechanics of feeding in a butterflyfish,Chaetodon trichrous

Biomechanical models of feeding mechanisms elucidate how animals capture food in the wild, which, in turn, expands our understanding of their fundamental trophic niche. However, little attention has been given to modeling the protrusible upper jaw apparatus that characterizes many teleost species. We expanded existing biomechanical models to include upper jaw forces using a generalist butterflyfish, Chaetodon trichrous (Chaetodontidae) that produces substantial upper jaw protrusion when feeding on midwater and benthic prey. Laboratory feeding trials for C. trichrous were recorded using high-speed digital imaging; from these sequences we quantified feeding performance parameters to use as inputs for the biomechanical model. According to the model outputs, the upper jaw makes a substantial contribution to the overall forces produced during mouth closing in C. trichrous. Thus, biomechanical models that only consider lower jaw closing forces will underestimate total bite force for this and likely other teleost species. We also quantified and subsequently modeled feeding events for C. trichrous consuming prey from the water column versus picking attached prey from the substrate to investigate whether there is a functional trade-off between prey capture modes. We found that individuals of C. trichrous alter their feeding behavior when consuming different prey types by changing the timing and magnitude of upper and lower jaw movements and that this behavioral modification will affect the forces produced by the jaws during prey capture by dynamically altering the lever mechanics of the jaws. In fact, the slower, lower magnitude movements produced during picking-based prey capture should produce a more forceful bite, which will facilitate feeding on benthic attached prey items, such as corals. Similarities between butterflyfishes and other teleost lineages that also employ picking-based prey capture suggest that a suite of key behavioral and morphological innovations enhances feeding success for benthic attached prey items.     

Absolute fitness, relative fitness, and utility

It is well known that (1) natural selection typically favors an allele with both a large mean fitness and a small variance in fitness; and (2) investors typically prefer a portfolio with both a large mean return and a small variance in returns. In the case of investors, this mean-variance trade-off reflects risk aversion; in the case of evolution, the mathematics is straightforward but the result is harder to intuit. In particular, it is harder to understand where, in the mathematics of natural selection, risk aversion arises. Here I present a result that suggests a simple answer to this question. Although my answer is essentially identical to one offered previously, my path to it differs somewhat from previous approaches. Some may find this new approach easier to intuit.     

Bird eggs or wheat: Assessing the impact of an overabundant crow species in a landscape mosaic in the Negev desert of Israel

The intensification of land alterations promotes the spread of invasive and overabundant species. Yet, controlling such species is not always derived from extensive impact assessments. We explored the consequences of the Hooded Crow (Corvus cornix) expansion into the arid region of Israel on the local biota. Crow activities and their potential effects were examined in a nature reserve and its surrounding agricultural lands. We used line transect counts and Global Positioning System (GPS) tagging to assess crow habitat utilization patterns. To measure crow impact on the local community, we compared artificial nest predation rates between agrarian and natural land types. Compositional analysis of the GPS-tagged crows' home range indicated a preference for arable lands, with low utilization of natural areas, limited to the vicinity of the nature reserve edges. Accordingly, Hooded Crows were among the dominant nest predators, mainly in agricultural lands or near their borders. These findings suggest that crow impact on natural habitats is low and limited to highly exploratory individuals. As crow abundance is expected to continue increasing, we call for short and long-term management actions, including establishing agri-environmental schemes to boost the local community's resistance to overabundant and invasive species.     

SOD融合蛋白降低阿尔兹海默症小鼠脑内氧化水平及改善认知功能

摘要 目的：观察SOD融合蛋白对阿尔茨海默症（Alzheimer''s Disease,AD）小鼠学习记忆能力及大脑氧化应激水平影响,探究小鼠行为改变与脑内氧化应激水平之间的关系。方法：选用32只KM雄性小鼠,适应性饲养7天后,随机分为4组：假手术组（S组）,模型组（M组）,SOD干预模型组（SM组）和SOD融合蛋白干预模型组（PM组）。实验第8天进行Y迷宫和黑白箱测试,9-23天,通过小鼠连续腹腔内注射等量生理盐水（S和M组）、6 mg/kg SOD（SM组）或6 mg/kg SOD融合蛋白（PM组）进行预防干预。其中,实验第16天,通过5 μL微量注射器将生理盐水（S组,2 μL/只）及Aβ1-42寡聚体（M组、SM组及PM组,2 μL/只）注射于小鼠右侧脑室,制备AD动物模型。第24天及31天进行Y迷宫和黑白箱测试。行为学测试结束后,随机选取一侧大脑半球用ELISA法测定脑组织匀浆中的SOD和MDA水平。结果：1）行为学测试：第8天,各处理组间差异无统计学意义,第24及第31天,与S组相比,M组小鼠Y迷宫新颖臂探索距离、探索次数及探索时间及黑白箱测试白箱探索距离、探索次数及探索时间均明显增加（P<0.05）;与M组相比,PM组小鼠Y迷宫新颖臂探索距离、探索次数及探索时间及白箱探索距离、探索次数及探索时间均明显减少（P<0.05）;SM组与M组相比差异无统计学意义。2）小鼠脑组织匀浆中SOD和MDA测定：与S组相比,M组SOD活性明显下降而MDA表达明显升高（P<0.05）,与M组相比,PM组SOD活性明显增加而MDA表达明显下降（P<0.05）,SM组与M组相比差异无统计学意义。3）SOD活性与Y迷宫新颖臂探索距离、探索次数和探索时间以及黑白箱中白箱探索距离、探索次数和探索时间呈负相关,而MDA表达与Y迷宫新颖臂探索距离、探索次数和探索时间以及黑白箱中白箱探索距离、探索次数和探索时间呈正相关。结论：SOD融合蛋白腹腔内注射可明显减轻Aβ1-42诱导的氧化应激及改善AD小鼠的行为恶化。SOD融合蛋白的抗氧化功能可能是预防AD的有效方法。     

狭域还是广域：杂色山雀和 大山雀行为特征比较

动物行为是个体与社群适应内外环境变化（刺激）所作出的动态反应。动物的行为特征对其适合度以及进化有着重要意义,但关于鸟类行为特征对扩散以及分布的研究还较少,本文以杂色山雀（Sittiparus varius）和大山雀（Parus cinereus）这两种生活史策略相似、分布范围差异显著的雀形目鸟类为例,采用经典新环境测试法对两物种探索性、活跃性、冒险性三种行为进行比较。Mann-Whitney U-test结果显示,大山雀的探索性（Z =﹣2.582,P < 0.01）、活跃性（Z =﹣5.148,P < 0.001）、冒险性（Z =﹣2.046,P < 0.05）得分均显著高于杂色山雀,证明广域分布的大山雀探索性、活跃性及冒险性明显强于狭域分布的杂色山雀。我们由此猜想鸟类行为特征可能会与种群的分布范围相关;通过对鸟类行为特征的探究或许可以间接预测种群未来的发展方向,为种群的保护提供指导。     

Phylogenetic interpretation of ontogenetic change: sorting out the actual and artefactual in an empirical case study of centrarchid fishes

Hypothesized relationships between ontogenetic and phylogenetic change in morphological characters were empirically tested in centrarchid fishes by comparing observed patterns of character development with patterns of character evolution as inferred from a representative phylogenetic hypothesis. This phylogeny was based on 56–61 morphological characters that were polarized by outgroup comparison. Through these comparisons, evolutionary changes in character ontogeny were categorized in one of eight classes (terminal addition, terminal deletion, terminal substitution, non-terminal addition, non-terminal deletion, non-terminal substitution, ontogenetic reversal and substitution). The relative frequencies of each of these classes provided an empirical basis from which assumptions underlying hypothesized relationships between ontogeny and phylogeny were tested. In order to test hypothesized relationships between ontogeny and phylogeny that involve assumptions about the relative frequencies of terminal change (e.g. the use of ontogeny as a homology criterion), two additional phylogenies were generated in which terminal addition and terminal deletion were maximized and minimized for all characters. Character state change interpreted from these phylogenies thus represents the maxima and minima of the frequency range of terminal addition and terminal deletion for the 8.7 × 10³⁶ trees possible for centrarchids. It was found for these data that terminal change accounts for c. 75% of the character state change. This suggests either that early ontogeny is conserved in evolution or that interpretation and classification of evolutionary changes in ontogeny is biased in part by the way that characters are recognized, delimited and coded. It was found that ontogenetic interpretation is influenced by two levels of homology decision: an initial decision involving delimitation of the character (the ontogenetic sequence), and the subsequent recognition of homologous components of developmental sequences. Recognition of phylogenetic homology among individual components of developmental sequences is necessary for interpretation of evolutionary changes in ontogeny as either terminal or non-terminal. If development is the primary criterion applied in recognizing individual homologies among parts of ontogenetic sequences, the only possible interpretation of phylogenetic differences is that of terminal change. If homologies of the components cannot be ascertained, recognition of the homology of the developmental sequence as a whole will result in the interpretation of evolutionary differences as substitutions. Particularly when the objective of a study is to discover how ontogeny has evolved, criteria in addition to ontogeny must be used to recognize homology. Interpretation is also dependent upon delimitation within an ontogenetic sequence. This is in part a function of the way that an investigator ‘sees’ and codes characters. Binary and multistate characters influence interpretation differently and predictably. The use of ontogeny for determining phylogenetic polarity as previously proposed rests on the assumptions that ancestral ontogenies are conserved and that character evolution occurs predominantly through terminal addition. It was found for these data that terminal addition may comprise a maximum of 51.9% of the total character state change. It is concluded that the ontogenetic criterion is not a reliable indicator of phylogenetic polarity. Process and pattern data are collected simultaneously by those engaged in comparative morphological studies of development. The set of alternative explanatory processes is limited in the process of observing development. These form necessary starting points for the research of developmental biologists. Separating ‘empirical’ results from interpretational influences requires awareness of potential biases in the course of character selection, coding and interpretation. Consideration of the interpretational problems involved in identifying and classifying phylogenetic changes in ontogeny leads to a re-evaluation of the purpose, usefulness and information conveyed by the current classification system. It is recommended that alternative classification schemes be pursued.