Using stable isotopes to investigate the dietary trophic level of fledgling songbirds

ABSTRACT Use of early successional habitat by mature forest birds during the postfledging period is well documented, but reasons for this habitat shift remain elusive. Although forest‐breeding songbirds are primarily insectivorous during the nestling and early fledgling periods due to high protein requirements, older fledglings may adopt a heavily frugivorous diet. Our objectives were to use stable isotopes to examine the dietary trophic level of juveniles of three species of mature forest songbirds to determine if juvenile songbirds heavily consume fruit resources during the postfledging period and to evaluate a possible link between diet and energetic condition. We collected the outer right rectrix and several body feathers from 34 Wood Thrushes (Hylocichla mustelina), 34 Ovenbirds (Seiurus aurocapilla), and 35 Scarlet Tanagers (Piranga olivacea) captured in regenerating clearcuts in southeastern Ohio in 2005 and 2006. We also collected fruit and arthropod samples from each clearcut. Isotopic values of body feathers were significantly higher (more enriched) than those of rectrices in all cases except values of δ¹³C for Ovenbirds where we found no difference between body and rectrix feathers. These results suggest that juvenile songbirds did not undergo a strong shift to frugivory during the postfledging period, and arthropods were the primary source of protein during the period when rectrix and body feathers were growing. In addition, the energetic condition of birds was not related to the isotopic signature of feathers. Although our results are inconsistent with the hypothesis that juveniles move into regenerating clearcuts enabling them to shift to a primarily frugivorous diet during the postfledging period, they may consume fruit for nonprotein requirements, such as lipids and carbohydrates.     

Joint generalized models for multidimensional outcomes: A case study of neuroscience data from multimodalities

This paper is motivated from the analysis of neuroscience data in a study of neural and muscular mechanisms of muscle fatigue. Multidimensional outcomes of different natures were obtained simultaneously from multiple modalities, including handgrip force, electromyography (EMG), and functional magnetic resonance imaging (fMRI). We first study individual modeling of the univariate response depending on its nature. A mixed‐effects beta model and a mixed‐effects simplex model are compared for modeling the force/EMG percentages. A mixed‐effects negative‐binomial model is proposed for modeling the fMRI counts. Then, I present a joint modeling approach to model the multidimensional outcomes together, which allows us to not only estimate the covariate effects but also to evaluate the strength of association among the multiple responses from different modalities. A simulation study is conducted to quantify the possible benefits by the new approaches in finite sample situations. Finally, the analysis of the fatigue data is illustrated with the use of the proposed methods.     

Reserve selection and persistence: complementing the existing Atlantic Forest reserve system

This study is an exercise to check the efficiency of the existing reserve system, and to show how systematic conservation planning—using information available and the complementarity concept—can improve the basis for decisions and minimize costs. We verified the performance, in number of cells and primate species representation, of the existing Atlantic Forest (Brazil) reserve network with a quarter-degree resolution grid, with 1,884 cells. We used occurrence data of 20 endemic primate species, and the maps of 237 existing reserves. Reserve networks were selected to represent primate species first considering no pre-existing reserves in Atlantic Forest, and then, considering the existing reserve system, taking into account the minimum area for viable population of the larger species (Northern muriqui Brachyteles hypoxanthus). Reserve selection was carried out using the complementarity concept implemented by a simulated annealing algorithm. Primate species representation (at least one occurrence in the network) could be achieved with 8% of the existing reserve system (nine cells in relation to the 120 in the existing reserve system). We found that today’s reserve system represents 89% of endemic primate species, excluding the species Coimbra Filho’s titi monkey (Callicebus coimbrai) and Marcgraf’s capuchin (Cebus flavius). The networks selected without considering existing reserves contained nine cells. The networks selected considering existing reserves (120 cells), had two new cells necessary to represent all the primates. This does not mean that a viable alternative is to start from zero (i.e., nonexistent reserves). Identifying critical supplementary areas using biodiversity information to fill the gaps and then starting “conservation in practice” in these areas should be priorities.     

Anonymous single‐copy nuclear DNA (scnDNA) markers for two endemic log‐dwelling beetles: Apasis puncticeps and Adelium calosomoides (Tenebrionidae: Lagriinae: Adeliini)

Three approaches — microsatellite library screening, consensus primer PCR (polymerase chain reaction) and sequencing with arbitrary primer pairs (SWAPP) — were used to develop single‐copy nuclear DNA (scnDNA) markers for log‐dwelling beetles Apasis puncticeps and Adelium calosomoides. We are unaware of other nuclear markers for Adeliini. We tested > 70 primer pairs per species, but despite exhaustive optimization, we obtained only five polymorphic markers. Nonetheless, the markers are valuable in detection of effects of habitat fragmentation.     

Cinnamic acid 4-hydroxylase from gherkin tissues

Homogenates from 4-day-old gherkin cotyledons and hypocotyls fractionated by sucrose density gradient centrifugation contain cinnamic acid 4-hydroxylase activity, the activity being highest in the endoplasmic reticulum fractions. These fractions also contain very low concentrations of cytochrome P₄₅₀. Hydroxylase activity is dependent on NADPH and on molecular oxygen, is optimal at pH 7.5 and is inhibited by carbon monoxide. The enzyme is very sensitive to inhibition by 2-mercaptoethanol, but it is not inhibited by the product, p-coumaric acid. Further, its responses to various potential inhibitors are fairly typical of mixed function oxidases from other sources.     

Point pattern analysis of different age-classes of Larix principis-rupprechtii in Luya Mountain Reserve, Shanxi Province, China

Larix principis-rupprechtii forest is an important vegetation formation and has a large distribution area in Luya Mountain Reserve, China. Spatial pattern analysis on individual trees in different age-classes of Larix principis-rupprechtii was made in this paper. Here, we employed the technique of point pattern analysis, which could analyze patterns under all scales along a gradient. It was based on spatial mapped points of individual distribution. The results of this study showed that the densities of the five age-classes varied in the order: age-class 3 > age-class 4 > age-class 5 > age-class 2 > age-class 1. Although age-classes 1 and 2 have much fewer individuals than other three age-classes do, the population was stable at present. However, it would be necessary to take some measures for improving population regeneration for a long-time view. The individuals of all age-classes focused on clumping distribution in space; however, their distribution pattern varied with the change of scale. This mainly depended on biological features of Larix principis-rupprechtii and forest environments, but it also meant that the scale was an important factor in controlling spatial distribution pattern of tree individuals. The feature of clumping distribution became more significant with the increase of age. The relationships between individuals in different age-classes were almost all significantly correlated with each other. These associations became more significant within the older age-classes. This suggested that the individuals of different age-classes were interdistributed, by which the population could get benefits in resource utilization. The technique of point pattern analysis is effective and easy to be used in species pattern study. Its results are more closer to the reality, especially for community structure. Translated from Acta Ecologica Sinica, 2004, 24(1): 35–40 [译自: 生态学报]     

格氏栲自然保护区常绿阔叶林群落的数量分类

基于对群落22个样地的调查,以群落样地中乔木层树种的重要值为指标,采用纸条排队法、群落相似系数分类法、最近邻体法和组平均法对格氏栲自然保护区常绿阔叶林群落进行数量分类。结果表明:4种分类结果基本相似,格氏栲自然保护区常绿阔叶林群落样地可分为格氏栲群系、米槠群系、甜槠群系、刨花楠群系、沉水樟群系、观光木群系和闽楠群系等7个群系,并论述了各群系的群落学特征,各群系基本处于稳定的顶极阶段。