关键词： Brownian motion   character displacement   coexistence   competition   ecophylogenetics   environmental filtering   phylogenetic imbalance   Yotvata, Israel   BODY-SIZE   TRAIT EVOLUTION   ECOLOGICAL COMMUNITIES   ADAPTIVE RADIATIONS   SANTA-ROSALIA   DIVERSIFICATION   DISTRIBUTIONS   DYNAMICS   PATTERNS   BALANCE  

摘要： The distribution of traits within communities is thought to provide information on the evolutionary and ecological forces that structure community composition. Ecological character displacement (evolutionary divergence among populations of interacting species within a community), as well as community-wide character displacement (even dispersion of species traits within a community via species sorting), have been widely reported and are typically interpreted as evidence for interspecific competition. However, defining an appropriate null distribution with which to assess the observed distribution of traits within a community has proved controversial. Phylogenetic methods provide an alternative approach to evaluating community structure, but such methods also require an appropriate null and have typically overlooked the potential for evolutionary dynamics within communities. Here, we present a novel phylogenetic framework that uses evolutionary expectations to generate a simple null model of the expected distribution of traits among co-occurring species. Using a stochastic Brownian motion model of trait change, we illustrate that the expected community-wide dispersion of traits varies with phylogenetic tree shape. We then use data on body mass for mammals to evaluate the accuracy with which phylogeny can predict the empirical distribution of traits and find a strong correlation between predicted and observed trait distributions. We suggest that deviations from phylogenetic expectations may therefore provide a useful tool for evaluating the role of competition in shaping community structure. Finally, we demonstrate the utility of our approach using empirical data on body mass and a phylogeny for a small community of terrestrial mammals in Yotvata, Israel, and reveal evidence consistent with ecological and community-wide character displacement. Our method unites ecological and evolutionary approaches, and it provides a novel framework for exploring community structure.

关键词： elk   plant demography   snowpack   species interactions   Yellowstone   YELLOWSTONE-NATIONAL-PARK   POPULATION-DYNAMICS   TROPHIC CASCADES   ELK   ASPEN   RESPONSES   ECOSYSTEM   USA   SNOWPACK   WOLVES  

摘要： Altered species interactions are difficult to predict and yet may drive the response of ecological communities to climate change. We show that declining snowpack strengthens the impacts of a generalist herbivore, elk (Cervus elaphus), on a common tree species. Thick snowpack substantially reduces elk visitation to sites; aspen (Populus tremuloides) shoots in these areas experience lower browsing rates, higher survival and enhanced recruitment. Aspen inside herbivore exclosures have greatly increased recruitment, particularly at sites with thick snowpack. We suggest that long-term decreases in snowpack could help explain a widespread decline of aspen through previously unconsidered relationships. More generally, reduced snowpack across the Rocky Mountains, combined with rising elk populations, may remove the conditions needed for recruitment of this ecologically important tree species. These results highlight that herbivore behavioural responses to altered abiotic conditions are critical determinants of plant persistence. Predictions of climate change impacts must not overlook the crucial importance of species interactions.

关键词： capture-recapture   communal nesting   countryside   old-growth forest   population density   selectively logged forest   temperate rain forest   MONITO DEL MONTE   TEMPERATE RAIN-FORESTS   IXODES-NEUQUENENSIS RINGUELET   SMALL MAMMALS   SEED DISPERSAL   LIVING FOSSIL   ELEVATIONAL TRANSECT   MICOUREUS-DEMERARAE   UNDERSTORY BIRDS   ATLANTIC FOREST  

摘要： Populations of the endemic and threatened marsupial Dromiciops gliroides were studied in logged and unlogged forest patches and shrublands in a rural area of northern Chiloe Island (42 degrees S), Chile. We expected to find differences in abundance, with higher densities in unlogged, old-growth remnant forests. Individuals were livetrapped over 4 years (2005-2009) at the peak of their breeding (November) and nonbreeding (February) seasons. We estimated population densities using capture mark recapture procedures. Home range, diet (through fecal content), and health status (ectoparasite loads) were assessed for captured individuals. We estimated the length of the breeding season by the levels of reproductive hormones, whereas winter torpor was documented using artificial nest boxes. Population densities varied seasonally in accordance with breeding, with higher densities recorded during summer, and were similar in old-growth and in logged forests, but were considerable higher in forests than in shrublands. D. gliroides reproduced well in both unlogged and logged forests. Social torpor was documented for the 1st time and was fairly frequent (64%), especially among juveniles. Home ranges were 2 times larger for males than for females. We confirmed the omnivorous diet of D. gliroides, with predominant consumption of arthropods, and a higher consumption of fleshy fruits during summer. Habitat and animal age had significant effects on ectoparasite prevalence, with higher incidences among juveniles in logged forests. We conclude that D. gliroides is not a rare species in remnant forests in the rural landscape of Chiloe Island. This result is crucial for the assessment of its conservation status and offers clues for designing better conservation strategies for this living fossil in anthropogenic landscapes.

关键词： 后生动物   古生物学家   系统演化   研究员   化石生物   螺旋星系   系统树   仙女座  

摘要： 发现于华南贵州的一类5．8亿年前的化石让我们开始，怀疑已知的动物系统树。因为形体像极了螺旋星系仙女座。这类被命名为“八臂仙母虫”的化石生物，将重新排序生命系统树的最早期分支。相关论文在2011年9月21日美国出版的《进化和发育》杂志以封面文章形式发表。

关键词： 油桐饼(粕)   蛋白质   脱毒方法   畜牧生产  

摘要： 本文主要介绍油桐饼(粕)资源的特点、营养价值、脱毒方法及其在畜牧生产上的应用。

关键词： 墨尔本   澳大利亚   新西兰北岛   十字星   羊毛制品   生态游  

摘要： 2012年4月,民间环保组织绿家园组织了赴澳大利亚与新西兰的生态游。在这次生态游中,我看到了很多,也思考了很多。走进大树体内去拍照一到新西兰基督城,负责接待的当地华人殷晓雷就问我们:"要不要走进一棵大树去拍照?"走进大树?大树也能走进去吗?带着好奇,我们真的走进了大树。原来这棵树一

关键词： 动物化石   恐龙   科学家   古生物学家   古脊椎动物   美国科学院   研究所   古人类  

摘要： 古生物学家认为，鸟类是由恐龙进化来的，而且许多恐龙也是凶猛的肉食动物，那么，刚披上羽毛的恐龙能飞上树吗？近日，《美国科学院院刊》将在线发表中科院古脊椎动物与古人类研究所的最新发现：它们可以飞上树!因为它们能逮食树栖动物。

关键词： 雕塑   单簧管   北京   学习   田树民   石雕  

摘要： 田树民,1956年生,北京人,自幼随父学习绘画,尤喜动物与音乐,先拜解放军军乐团单簧管演奏家张进才学习单簧管,后从吾学习石雕。树民青年时期在北京动物园供职,与鸟兽虫鱼结下不解之缘。

关键词： 古脊椎动物   化石证据   树栖   恐龙   中国科学院   古生物学家   早白垩世   相对位置  

摘要： 中国科学院古脊椎动物与古人类研究所的周忠和发现：刚披上羽毛的恐龙可以飞上树．因为它们能逮食树栖动物。那是1.2亿年前的一只小盗龙，古生物学家在我国辽宁早白垩世的地层中发现了它的化石。在它的腹部，竟然保存了一件不完整的树栖动物残骸。从骨骼化石的保存特点和相对位置推测，该动物很可能是被小盗龙活捉了吞下肚子的。这件标本解开了一些谜团：这只已经成年的小动物残存下了两只脚，从脚趾看，属于典型的树栖类动物，