Speciation and long- and short-term molecular-level dynamics of soil organic sulfur studied by X-ray absorption near-edge structure spectroscopy

We investigated speciation, oxidative state changes, and long- and short-term molecular-level dynamics of organic S after 365 d of aerobic incubation with and without the addition of sugarcane residue using XANES spectroscopy. Soil samples were collected from the upper 15 cm of undisturbed grasslands since 1880, from undisturbed grasslands since 1931, and from cultivated fields since 1880 in the western United States. We found three distinct groups of organosulfur compounds in these grassland-derived soils: (i) strongly reduced (S to S) organic S that encompasses thiols, monosulfides, disulfides, polysulfides, and thiophenes; (ii) organic S in intermediate oxidation (S to S) states, which include sulfoxides and sulfonates; and (iii) strongly oxidized (S) organic S, which comprises ester-SO-S. The first two groups represent S directly linked to C and accounted for 80% of the total organic S detected by XANES from the undisturbed soils. Aerobic incubation without the addition of sugarcane residue led to a 21% decline in organanosulfur compounds directly linked to C and to up to an 82% increase inorganic S directly bonded to O. Among the C-bonded S compounds, low-valence thiols, sulfides, thiophenic S, and intermediate-valence sulfoxide S seem to be highly susceptible to microbial attack and may represent the most reactive components of organic S pool in these grassland soils. Sulfonate S exhibited a much lower short-term reactivity. The incorporation of sugarcane residue resulted in an increase in organosulfur compounds directly bonded to C at the early stage of incubation. However, similar to soils incubated without residue addition, the proportion of organic S directly linked to C continued to decline with increasing duration of aerobic incubation, whereas the proportion of organic S directly bonded to O showed a steady rise.     

Dominance rank,female reproductive synchrony,and male reproductive skew in wild Assamese macaques

In groups with multiple males, direct mate competition may select for the evolution of dominance hierarchies that sort males into a queue for access to fertile females. The priority-of-access (PoA) model proposed by Altmann in 1962 makes explicit predictions about the resulting paternity distribution based on an interaction between male dominance rank and the overlap of female receptive phases. Here, we investigated whether the logic of the PoA model predicted the distribution of paternity across ranks in a seasonal breeder with high reproductive synchrony over six consecutive mating seasons. We studied 18 males that resided in a group of wild Assamese macaques (Macaca assamensis) in their natural habitat at Phu Khieo Wildlife Sanctuary, Thailand, between 2006 and 2011 with 5 to 13 conceptions per season. We assessed whether mate guarding increased paternity success, described “short-term” deviations from predicted paternity distribution, and examined how these are related to the number of competitors and fertile females. We determined genetic paternity of 43 (93 %) offspring born into the study group and found reproductive skew to be relatively low with 29 % alpha male paternity in accordance with the high degree of female reproductive synchrony observed. Short-term deviations from expected paternity distribution over ranks were not explained by the number of resident males or the number of conceiving females or their interaction. Within the limits of this study, these results suggest that even if males cannot discern female fertile phases, if reproduction is seasonal, and if reproductive synchrony is high, males may also compete directly over access to females.     

Lignoid chemical defenses in the freshwater macrophyte Saururus cernuus

Summary. Chemical defense against herbivores has rarely been investigated for freshwater plants, possibly due to the common misconception that herbivory on aquatic macrophytes is low and would not select for chemical defenses. In previous work, the freshwater angiosperm Saururus cernuus was shown to be a low preference food for omnivorous crayfish despite its high nutrient value and relatively soft texture. We used feeding by the crayfish Procambarus clarkii to guide fractionation of the deterrent lipid-soluble extract of this plant, leading to the identification of seven deterrent lignoid metabolites, (–)-licarin A, (+)-saucernetin, (–)-dihydroguaiaretic acid, (–)-sauriols A and B, (–)-saucerneol, and (–)-saucerneol methyl ether. Lignans have been implicated in terrestrial plant chemical defenses as insect growth inhibitors, insect toxins, nematocides, antibacterial, and antifungal agents. However, these activities have rarely been demonstrated using ecologically relevant methodologies in terrestrial systems, and never before in freshwater systems. The widespread nature of lignans amongst very distantly related plants, along with their rich diversity of molecular structure, suggests that they could play a large role in mediating plant-herbivore interactions. In addition to the lignoid compounds we identified, there were other compounds present in low concentration or unstable compounds that were deterrent, that did not appear to be lignans, but that we were unable to identify. This plant thus appears to be defended by a complex mixture of natural products. Received 6 June 2000; revised 23 August 2000; accepted 2 September 2000     

Cryptic species within the commercially most important lobster in the tropical Atlantic, the spiny lobster Panulirus argus

Panulirus argus (Latreille in Ann Mus Hist Nat Paris 3:388–395, 1804) is the lobster of greatest economic importance throughout its distribution. In this study, mitochondrial (Cytochrome Oxidase I and 16S ribosomal genes) and nuclear (Adenine Nucleotide Transporter gene) sequences were used to evaluate the taxonomic status of P. argus sampled from five sites in the Caribbean Sea and nine sites in the Southwest Atlantic. Phylogenetic analyses indicate that lobsters from the two regions form two monophyletic groups with a molecular divergence similar to that observed between distinct congeneric lobster species and much larger than that found between conspecific lobster populations. Therefore, the Caribbean and the Southwest Atlantic lobster populations originally attributed to P. argus belong to different species, with an estimated time of isolation of around 16 Million years. An important consequence of these findings is that the fisheries of spiny lobsters from the Caribbean and the Southwest Atlantic species must be managed separately.     

Distributional patterns of adult male loggerhead sea turtles (<Emphasis Type="Italic">Caretta caretta</Emphasis>) in the vicinity of Cape Canaveral,Florida, USA during and after a major annual breeding aggregation

Satellite transmitters were attached to 25 reproductively active and four inactive adult male loggerhead sea turtles (86.6–107.0 cm SCLmin) captured from the Port Canaveral, FL, USA shipping channel to assess horizontal and vertical distributions. During the breeding period, male loggerheads aggregated (44% of 755 turtle days) in a 117.6 km² core area that encompassed the shipping channel. Median dive duration during the breeding period was 27 min (IQR = 15–42 min) and males spent 4% (IQR = 3–5%) of the time at the surface, with significantly shorter dives associated with reproductively active males. Migrant and resident males dispersed concurrently, with residents shifting > 30 km east across the continental shelf over a more protracted departure schedule than migrants. Dive duration and time spent at the surface increased through the fall. Cluster analysis revealed the strongest association for dive duration with sea state during and after the breeding period, with significantly longer dives during more turbulent conditions. In contrast, univariate associations with surface interval duration were not elucidated.     

Baboon loud calls advertise male quality: acoustic features and their relation to rank,age, and exhaustion

Free-ranging adult male baboons give loud two-syllable wahoo calls during dawn choruses, interactions between groups, when chasing females, and in aggressive interactions with other males. Previous research has shown that the rate and duration of these contest wahoos are correlated with a males competitive ability: high-ranking males call more often, call at faster rates, and call for longer bouts than do low-ranking males. Here we report that acoustic features of wahoos also reveal information about male competitive ability. High-ranking males give wahoos with higher fundamental frequencies (F0) and longer hoo syllables. Within-subject analyses revealed that, as males fall in rank, the hoo syllables tend to shorten within a period of months. As males age and continue to fall in rank, F0 declines, hoo syllables shorten, and formant dispersion decreases. Independent of age and rank, within bouts of calling F0 declines and hoo syllables become shorter. Because wahoos are often given while males are running or leaping through trees, variation in these acoustic features may function as an indicator of a males stamina. The acoustic features of contest wahoos thus potentially allow listeners to assess a males competitive ability.Communicated by C. Nunn     

Behavioural and metabolic adaptations of marine isopods to the rafting life style

Rafting on floating objects is a common dispersal mechanism for many marine invertebrates. In order to identify adaptations to the rafting life style, we compared behavioural and metabolic characteristics of two isopods, the obligate rafter Idotea metallica and the facultative rafter Idotea baltica. In laboratory experiments, I. metallica showed low locomotive activity and a tight association to the substratum. Idotea baltica, in contrast, was more active with more frequent excursions in the surrounding water column. Oxygen consumption rates were similar in both species. Idotea metallica fed on zooplankton making this species widely independent of autochthonous food resources of the raft. Feeding rates and digestive enzyme activities were low in I. metallica. Reduced egestion rates may indicate slow gut passage and, thus, efficient resorption of nutrients. Efficient food utilization and the ability to accumulate high amounts of storage products, i.e. lipids, indicate a possible adaptation of I. metallica to low food availability or starvation. The feeding behaviour of I. baltica, in contrast, was more herbivorous and appeared wasteful and inefficient. Low lipid contents in I. baltica also indicate poor storage reserves. Thus, I. baltica requires a permanent access to food.     

Using the polychaete Arenicola marina to determine toxicity and bioaccumulation of PAHS bound to sediments

Transportation system has contributed significantly to the development of human civilization; on the other hand it has an enormous impact on the ambient air quality in several ways. In this paper the air and noise pollution at selected sites along three sections of National Highway was monitored. Pakistan National Highway Authority has started a Highway Improvement program for rehabilitations and maintenance of National highways to improve the traffic flows, and would ultimately improve the air quality along highways. The ambient air quality and noise level was monitored at nine different locations along these sections of highways to quantify the air pollution. The duration of monitoring at individual location was 72 h. The most of the sampling points were near the urban or village population, schools or hospitals, in order to quantify the air pollution at most affected locations along these roads. A database consisting of information regarding the source of emission, local metrology and air quality may be created to assess the profile of air quality in the area.     

Role of Light Availability and Dispersal in Exotic Plant Invasion along Roads and Streams in the H. J. Andrews Experimental Forest, Oregon

Abstract: We examined the roles of dispersal mechanism, a biological barrier; light availability, an environmental barrier; and level of disturbance, a physical barrier, in explaining the spatial patterns of exotic plant species along road and stream segments in a forest landscape in the western Cascade Range of Oregon (U.S.A). The presence or absence of 21 selected exotic plant species and light levels were observed along 0.3- to 1.0-km transects within four habitat types. Each habitat represented a different level of disturbance: high-use roads, low-use roads, abandoned roads, and streams in the H. J. Andrews Experimental Forest. Nearly 300 50 × 2–m sampling units were surveyed along five transects in each habitat type. We used ordination (nonmetric multidimensional scaling) and logistic regression to analyze data. All of the nearly 200 sampling units along roads with high and low levels of vehicle traffic contained at least one exotic plant species, and some contained as many as 14. Streams that were most recently disturbed by floods 20–30 years ago and abandoned spur roads with no traffic for 20–40 years also had numerous exotic species. Roads and streams apparently serve multiple functions that enhance exotic species invasion in this landscape: they act as corridors or agents for dispersal, provide suitable habitat, and contain reservoirs of propagules for future episodes of invasion. Species-specific dispersal mechanisms, habitat characteristics, and disturbance history each explain some, but not all, of the patterns of exotic species invasion observed in this study.