The evolution of primate communities and societies in Madagascar

During their 120 to 165 million years of isolation, the flora and fauna of Madagascar evolved, to a large extent, independently of the African mainland.¹ In contrast to other oceanic islands, Madagascar is large enough to house the major components of tropical ecosystems, allowing tests of evolutionary hypotheses on the level of complete communities. Taking lemurs, the primates of Madagascar, as an example, evolutionary hypotheses correctly predict the organization of their community structure with respect to ecological correlates. Lemur social systems and their morphological correlates, on the other hand, deviate in some respects from those of other primates. Apparently, lemur social systems are influenced by several selection pressures that are weak or rare in other primates. These include variable activity patterns and avoidance of infanticide. The interspecific variation in lemur social systems therefore offers a unique opportunity for a comprehensive study of the determinants of primate social systems.     

Blockage errors in studies of the effect of wind on thermoregulatory responses

1. 1.The presence of an animal in a wind tunnel increases the effective wind velocity, and so increases heat transfer rates.

2. 2.Potentially significant errors in thermal conductance and thermoregulatory metabolism measurements may result.

3. 3.In a given wind tunnel metabolism chamber, these errors are size dependent and thus may lead to invalid allometric or adaptive interpretations of data.

4. 4.The errors are also sensitive to the shape, orientation, and characteristics of the fur or feather insulation of the animal. Thus, only approximate guidelines can be given for choosing correction factors.

长江安庆新洲水域鱼类群落结构及多样性

沙洲水域环境良好,饵料资源丰富,栖息生境多样,为鱼类的生长繁殖提供了优良的生存环境。为了解长江安庆新洲水域鱼类群落结构特征,于2017年4月、7月、10月和12月对安庆江段新洲水域鱼类群落进行季节性调查。共采集鱼类64种,分属5目11科48属,其中62.5%为鲤科鱼类。以物种数和多样性指数分析群落多样性特征,结果表明新洲水域鱼类种类多样性水平较高。单因素方差分析表明,该群落多样性季节差异显著(P0.05),空间差异不明显。新洲水域鱼类群落优势种为鳊(Parabramis pekinensis Basilewsky, 1855)、鲤(Cyprinus carpio Linnaeus, 1758)、贝氏■(Hemiculter bleekeri Warpachowsky, 1887)、银鮈(Squalidus argentatus Sauvage et Dabry, 1874)和似鳊(Pseudobrama simoni Bleeker, 1864)。4种摄食功能群中,杂食性(42.19%)和肉食性(35.94%)鱼类物种数比例较高;3种生态类群中,淡水定居性鱼类占绝对优势(84.37%);3种栖息水层类型中,底层鱼类物种数比例较高,占37.50%。大型经济鱼类占总渔获物比例低(0.01%),但个体较大,因而相对重要性指数(IRI)高。总体上,新洲鱼类群落多样性和丰富度指数较高,均匀度指数偏低,个体小型化趋势明显。捕捞强度过大、水利工程建设导致的江湖阻隔及外来物种入侵是新洲水域渔业资源衰退的主要因素。由此,建议持续开展长江渔业资源监测,加强长江干流沙洲水域渔业资源保护。     

The dynamics of freshwater phytoplankton stability in the Naroch Lakes (Belarus)

The phytoplankton community of the Belarus Lakes Naroch, Myastro and Batorino, which have a Trophic State Index of 42.3, 60.7 and 66.8, respectively, underwent drastic changes to their structure during the period between 1968 and 2012. Thanks to an extensive monitoring program, these changes were well-documented and were qualitatively interpreted as signs of the community destabilization. The main objective of this study was the quantification of the ecological stability of the phytoplankton community in the Naroch Lakes. The approach to the quantification of ecological stability was based on defining the stability index as an inverse of the Euclidean Distance between the current and the reference states of the algal community (EuD-approach). The stability of the phytoplankton community was characterized by two indices: a “combined” index (SI[Comb]), and a “total community” index (SI[TotB]). SI[Comb] was calculated based on the individual taxonomic group biomasses and thus characterizes the stability of a community structure. SI[TotB] was calculated based on the values of the total algal biomass. Analyses of the results of this study extended the plausibility of the EuD-approach for the quantification of lake phytoplankton stability and allowed us to identify the dynamics of the stability of the Naroch Lakes phytoplankton. For the Naroch Lakes, we observed relatively larger SI[TotB] values in comparison with the SI[Comb] values. The results enabled us to examine the relationship between the lake trophic status and the stability of the phytoplankton community.     

Growth and maintenance respiration in leaves of northern red oak seedlings and mature trees after 3 years of ozone exposure

A two-component model of growth and maintenance respiration is used to study the response of northern red oak (Quercus rubra L.) seedlings and 32-year-old trees to sub-ambient (10 μmol h; cumulative dose based on 7 h daily mean), ambient (43 μmol h), and twice-ambient (85 μmolh) ozone. The relative growth rates (RGR) of leaves sampled from seedlings and trees were similar across treatments, as were specific leaf respiration rates (SRR). Growth coefficients estimated from the SRR versus RGR relationship averaged 25-3 mol CO2 kg^?1 leaf dry mass produced for seedlings and 21-5 mol kg^?1 for trees. Maintenance coefficients ranged from 0-89 to 1-07 mol CO₂ kg^?1 leaf dry mass d^?1 for seedlings and from 0-64 to 0-84 mol kg-1 d^?1 for trees. Neither coefficient was affected by ozone. Leaves sampled throughout the growing season also showed little response of respiration to ozone. This occurred despite a 30% reduction in net photosynthesis for trees grown at twice-ambient ozone. These results suggest that growth and maintenance respiration in young northern red oak leaves are not affected by ozone and that in older leaves injury can occur without a parallel increase in so-called ‘maintenance’ respiration.     

Experiments with artificial nests provide evidence for ant community stratification and nest site limitation in a tropical forest

Ants are dominant in tropical forests and many species nest in hollow cavities. The manner in which species are vertically stratified in these complex habitats is not known, with lack of nest sites being proposed to limit ant populations. Here, we assess ant community stratification and nest site limitation in a lowland rainforest in New Guinea using experimental addition of artificial bamboo nests of two cavity sizes (small: ~12 mm large: ~32 mm diameter) placed at ground level, in the understorey, and in the canopy. We also conducted a pilot experiment to test the utility of nest translocation. Nests were checked for occupancy after 10 weeks and half of the occupied nests were then translocated between forest plots, while keeping same vertical position. Occupancy of small nests was much higher in the understorey and canopy than at ground level (~75% vs. ~25%). Translocation was successful, as a majority of nests was inhabited by the same species before and after translocation and there was no impact of translocation to a different plot compared to the control, except for a reduction in colony size at ground level. Our experiment demonstrates a vertical stratification in community composition of ants nesting in hollow dead cavities and shows that these ants are more nest site limited in the higher strata than at ground level. Use of small artificial cavities has great potential for future experimental studies, especially for those focused on arboreal ants, as occupancy is high and translocation does not negatively affect their colony size. Abstract in Tok Pisin is available with online material.     

Ribosomal Tag Pyrosequencing of DNA and RNA Reveals “Rare” Taxa with High Protein Synthesis Potential in the Sediment of a Hypersaline Lake in Western Australia

Little is known about the potential activity of microbial communities in hypersaline sediment ecosystems. Ribosomal tag libraries of DNA and RNA extracted from the sediment of Lake Strawbridge (Western Australia) revealed bacterial and archaeal operational taxonomic units (OTUs) with high RNA/DNA ratios providing evidence for the presence of ‘rare’ but potentially “active” taxa. Among the ‘rare’ bacterial taxa Halomonas, Salinivibrio and Idiomarina showed the highest protein synthesis potential. Rare but ‘active’ archaeal OTUs were related to the KTK 4A cluster and the Marine-Benthic-Groups B and D. We present the first molecular analysis of the microbial diversity and protein synthesis potential of rare microbial taxa in a hypersaline sediment ecosystem.