Group histories and offspring sex ratios in ringtailed lemurs (Lemur catta)

Birth sex ratios were examined for ringtailed lemurs (Lemur catta) at the Duke University Primate Center. This population provides a long-term database of births under a variety of demographic and management conditions, including two semi-freeranging groups between which males transfer freely and females defend stable territorial boundaries. We examined three hypotheses usually considered in studies of primate sex ratio bias. The Trivers-Willard hypothesis predicts that dominant females produce males, local resource competition at the population level (LRC-population) predicts that the dispersing sex (males) will be overproduced in dense populations, and local resource competition among individuals (LRC-individual) predicts that dominant females overproduce the philopatric sex (females). We also examined a fourth hypothesis, local resource enhancement (LRE), which is usually subsumed under LRC-individual in studies of primate sex ratio evolution. LRE predicts that under certain conditions, females will produce the sex that provides later cooperative benefits, such as alliance support for within- or between-group competition. Our data provide support for LRE: females overproduce daughters given prospects of new group formation, either through group fission or threatened expulsion of young mothers. Behavioral data from Duke and also wild populations show that daughters serve mothers as important allies in this context and LRE effects also have been documented in other mammals that experience similar group histories. Nonsignificant trends in the data supported the LRC-population hypothesis, and we suggest that LRC interacts with LRE to explain offspring sex ratios in ringtailed lemurs. Received: 27 August 1999 / Received in revised form: 6 March 2000 / Accepted: 18 March 2000     

Restoring River Connectivity: Prioritizing Passage Improvements for Diadromous Fishes and Lampreys

Physical obstructions are becoming increasingly recognized as major factors influencing the migrations, population structures, spawning success and recruitment of freshwater organisms. This paper presents a simple but effective method, intended for use by environmental managers, government agencies and conservation bodies, of rapidly assessing and prioritizing barriers to the migrations of diadromous fishes and lampreys for passage improvements. A prioritization matrix was developed using information on fish stock status, the passage efficiency of fishes at individual structures, the distance from the tidal limit and the passability of downstream barriers, and the quantity and quality of habitat upstream of each structure. Importantly, the 'Likelihood of access' was incorporated into the matrix to account for passage efficiency at downstream barriers. Barriers ranked as the highest priority for passage improvements were those characterized by poor fish stocks upstream, low passage efficiency, easy passage from downstream, and a large quantity and high quality of habitat upstream. Prioritization of migration barriers should ensure that access improvements are targeted to achieve optimum benefits.     

Comparative tests of reproductive skew in male primates: the roles of demographic factors and incomplete control

Reproductive skew models have been proposed as a unifying framework for understanding animal social systems, but few studies have investigated reproductive skew in a broad evolutionary context. We compiled data on the distribution of mating among males for 31 species of primates and calculated skew indices for each study. We analyzed the determinants of mating skew with phylogenetic comparative methods to investigate two models from reproductive skew theory, the concession model and the tug-of-war model. Mating skew decreased as the number of males increased in multimale groups, suggesting that monopolization of females becomes more difficult when there are more rivals, and therefore supporting the tug-of-war model. We predicted that single males are unable to monopolize receptive females as overlap in female receptivity increases (estrous synchrony) and, as a result, that mating skew decreases. However, we did not find any evidence for a link between female estrous synchrony and male mating skew. Finally, the concession model predicts high skew in male philopatric species relative to species in which males disperse, yet our measures of mating skew showed no significant associations with qualitative scores of male dispersal. More definitive tests of the concession model will require more quantitative measures of relatedness, which are presently unavailable for most primate species in our study. Overall, our results provide support for the tug-of-war model in primates, and the approach developed here can be applied to study comparative patterns of skew in other biological systems.Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible to authorized users.     

Coastal issues for oceanic islands: implications for human futures

Compared to continental areas, most islands have exceptionally long coastlines relative to their total land area. For this reason, islands are uncommonly vulnerable to problems associated with coasts. The future of the human inhabitants of many island states depends intrinsically on the sustainable management of their coasts, a challenge which grows more pressing as island populations increase and the associated demands on island coastlines change and grow. These issues are presented and discussed in this article. The mechanics of the sustainable management of island coasts is itself an important issue. At the national or local level, management is plagued by problems of insufficient and/or imprecise data and understanding that may lead to inappropriate solutions that even exacerbate the problems they are intended to solve. At an inter-governmental or international level, problems associated with the understanding of island environments need to be resolved before optimal management strategies can be developed. This article presents a brief explanation of the nature of coastal vulnerability on oceanic islands, followed by a discussion of several key problems associated with their sustainable development and the role of human and non-human factors in recent environmental change. It discusses the future of oceanic island coasts in the face of both internal and external threats to their sustainable management. It concludes with a blueprint for their survival.     

A molecular approach for the identification of meiofaunal turbellarians (Platyhelminthes,Turbellaria)

In the absence of reliable morphological characters, or in conjunction with morphology-based identifications, meiofaunal turbellarians may also be identified using the nucleotide sequence of a portion of the large subunit of the ribosomal RNA (26/28S rRNA). A 284 base pair-long region of the 26/28S rRNA has been identified by isolating genomic DNA from ten species of turbellarians belonging to four orders, namely, the Proseriata, Macrostomida, Prolecithophora and Acoela. The proseriates had been collected from localities in Europe and Israel and were preserved in ethanol. The remaining turbellarians were isolated from intertidal sediment samples collected from two sites on the Maine and New Hampshire coast, USA in 1992. Amplification of the genomic DNA was carried out using two primers designed to match the nucleotide sequence of a portion of the 26/28S rDNA gene of the terrestrial nematode,Caenorhabditis elegans (Maupas 1900). This area consists of a highly variable, about 150 base pair-long region, called the D3 expansion segment, followed by a very conserved stretch of sequence. When folded into its secondary structure, the conserved region will form stem structures that correspond to helices 15 to 18 of theC. elegans structural model. The sequence alignment program PILEUP was used to perform a cluster analysis (unweighted pair group method using arthmetic averages, UPGMA) on the sequences. This analysis revealed that the helices allow for the classification of the turbellarians at the level of families and above, whereas if the D3 expansion segment itself was included in the analysis, intrageneric and intraspecific groupings could be established.     

Do male "long-distance calls" function in mate defense? A comparative study of long-distance calls in primates

Long-distance calls produced by males are common among vertebrate species. Several hypotheses have been proposed to explain features of male long-distance calls and their phylogenetic distribution in primates, but the putative functions of male long-distance calls have yet to be tested comprehensively. We used phylogenetic comparative methods to investigate hypotheses for the function of male long-distance calls. We focused on the mate defense hypothesis, which states that male long-distance calls function in intra-sexual competition for mates, but we also examined factors involving resource defense, mate attraction, and habitat. Phylogenetic reconstruction of male long-distance calls in 158 primate species indicates that the presence of male long-distance calls is the ancestral state. The carrying distance of male long-distance calls is correlated with the size of the home range, which is consistent with the role of male long-distance calls in defending mates, attracting mates, and defending resources. However, measures of male intra-sexual competition were not associated with the evolution of male long-distance calls. Evolutionary transitions were only partly correlated with factors related to mate attraction. Instead, the strongest correlates of male long-distance calls were activity period, body mass, home range, habitat and some measures of resource defense. Our results are consistent with long-distance call production as a costly signal, but detailed study within species is required to assess these costs and the functions of long-distance calls in individual cases. Electronic Supplementary Material is available if you access this article at http://dx.doi.org/10.1007/.     

Bromo- and bromochloro-dibenzo-p-dioxins and dibenzofurans in the environment

At least 36 million pounds of brominated flame retardants are used in the U.S. annually. Most if not all of these materials enter the waste stream via landfilled plastic waste, municipal incinerator fly ash, or automotive fluff waste. Analytical methodology is summarized which is suitable for environmental monitoring of these wastes, and the significance of the analytical results is discussed.     

Comparison of ozone uptake and sensitivity between a phytotron study with young beech and a field experiment with adult beech (Fagus sylvatica)

Chamber experiments on juvenile trees have resulted in severe injury and accelerated loss of leaves along with reduced biomass production under chronically enhanced O3 levels. In contrast, the few studies conducted on adult forest trees in the field have reported low O3 sensitivity. In the present study, young beech in phytotrons was more sensitive to O3 than adult beech in the field, although employed O3 regimes were similar. The hypotheses tested were that: (1) differences in O3 uptake were caused by the ontogenetically higher stomatal conductance of young compared to adult trees, (2) the experimental settings in the phytotrons enhanced O3 uptake compared to field conditions, and (3) a low detoxification capacity contributes to the higher O3 sensitivity of the young trees. The higher O3 sensitivity of juvenile beech in the phytotrons is demonstrated to relate to both the experimental conditions and the physiological responsiveness inherent to tree age.     

Enhanced ozone strongly reduces carbon sink strength of adult beech (Fagus sylvatica) - Resume from the free-air fumigation study at Kranzberg Forest

Ground-level ozone (O₃) has gained awareness as an agent of climate change. In this respect, key results are comprehended from a unique 8-year free-air O₃-fumigation experiment, conducted on adult beech (Fagus sylvatica) at Kranzberg Forest (Germany). A novel canopy O₃ exposure methodology was employed that allowed whole-tree assessment in situ under twice-ambient O₃ levels. Elevated O₃ significantly weakened the C sink strength of the tree-soil system as evidenced by lowered photosynthesis and 44% reduction in whole-stem growth, but increased soil respiration. Associated effects in leaves and roots at the gene, cell and organ level varied from year to year, with drought being a crucial determinant of O₃ responsiveness. Regarding adult individuals of a late-successional tree species, empirical proof is provided first time in relation to recent modelling predictions that enhanced ground-level O₃ can substantially mitigate the C sequestration of forests in view of climate change.