Mating patterns of woolly spider monkeys,Brachyteles arachnoides: implications for female choice

Summary Woolly spider monkeys show a promiscuous, polygynous mating system in which a receptive female mates with several males, often in rapid succession. Copulation is prolonged with an average duration of 4.1±1.5 (SD) min. Coitus consists of a stationary phase with the male in intromission, followed by stercotypic behaviours of the female which appear to cue and/or accompany male climax and ejaculation. Subadult and adult males show different association patterns with individual females. Subadult males form long-term consortships with particular females while adult males appear strongly attracted to a particular female only when the is receptive. These different behavior patterns of males are viewed as age-specific mating tactics. Males in a mating aggregation show little intermale aggression for sexual access to a receptive female. Large testis size in this species suggests that much intermale competition for reproductive success may be carried out at a postcopulatory level, perhaps by sperm competition. The copulatory pattern of woolly spider monkeys may function primarily as a mechanism of female choice, aiding a female in assessing the quality of males in hei mating aggregation while helping to ensure that maximal high quality spermatozoa will be available at the proper time for fertilization.     

Size-selective harvesting alters life histories of a temperate sex-changing fish.

Selective mortality, whether caused naturally by predation or through the influence of harvest practices, initiates changes within populations when individuals possessing certain heritable traits have increased fitness. Theory predicts that increased mortality rates will select for changes in a number of different life history characteristics. For example, fishing often targets larger individuals and has been shown repeatedly to alter population size structure and growth rates, and the timing of maturation. For sex-changing species, selective fishing practices can affect additional traits such as the mature population sex ratio and the timing of sexual transformation. Using historical comparisons, we examined the effects of exploitation on life history characteristics of California sheephead, Semicossyphus pulcher, a temperate protogynous (female-male sex changer) labrid that inhabits nearshore rocky environments from central California, USA, to southern Baja California, Mexico. Recreational fishing intensified and an unregulated commercial live-fish fishery developed rapidly in southern California between the historical and current studies. Collections of S. pulcher from three locations (Bahia Tortugas, Catalina Island, and San Nicolas Island) in 1998 were compared with data collected 20-30 years previously to ascertain fishery-induced changes in life history traits. At Bahia Tortugas, where fishing by the artisanal community remained light and annual survivorship stayed high, we observed no changes in size structure or shifts in the timing of maturation or the timing of sex change. In contrast, where recreational (Catalina) and commercial (San Nicolas) fishing intensified and annual survivorship correspondingly declined, males and females shifted significantly to smaller body sizes, females matured earlier and changed sex into males at both smaller sizes and younger ages and appeared to have a reduced maximum lifespan. Mature sex ratios (female:male) increased at San Nicolas, despite a twofold reduction in the mean time spent as a mature female. Proper fisheries management requires measures to prevent sex ratio skew, sperm limitation, and reproductive failure because populations of sequential hermaphrodites are more sensitive to size-selective harvest than separate-sex species. This is especially true for S. pulcher, where different segments of the fishery (commercial vs. recreational) selectively target distinct sizes and therefore sexes in different locations.     

A MATHEMATICAL MODEL FOR EVALUATING THE POTENTIAL OF DESALTING1

ABSTRACT The Office of Saline Water, which has federal responsibility for developing low-cost, saline sources of fresh water, has recognized the need for an improved method of forecasting the future potential of desalting in this country. The magnitude of the role of desalting will influence the plans of federal, state, and local water resource agencies and the research and development programs of manufacturers. A dynamic simulation model has been developed by Arthur D. Little, Inc. under contract by OSW to translate relevant factors of water supply and demand into a forecast of desalting potential. The model projects the needs for desalting in 20 hydrologic regions of the U.S. Model performance has thus far been demonstrated by the development of a forecast and a battery of related sensitivity tests. Current results indicate the following potential desalting capacities: 225 MGD in 1980; 2,250 MGD in 2000; and 7,000 MGD in 2020. Significant improvements in desalting economics promise to increase these potentials by a factor of four or five by 2000-2020. Model inputs and results are continuing to be refined. When completed, OSW will have a dynamic tool with which to guide its R&D program.     

Potassium, phosphorus, or nitrogen limit root allocation, tree growth, or litter production in a lowland tropical forest

We maintained a factorial nitrogen (N), phosphorus (P), and potassium (K) addition experiment for 11 years in a humid lowland forest growing on a relatively fertile soil in Panama to evaluate potential nutrient limitation of tree growth rates, fine-litter production, and fine-root biomass. We replicated the eight factorial treatments four times using 32 plots of 40 x 40 m each. The addition of K was associated with significant decreases in stand-level fine-root biomass and, in a companion study of seedlings, decreases in allocation to roots and increases in height growth rates. The addition of K and N together was associated with significant increases in growth rates of saplings and poles (1-10 cm in diameter at breast height) and a further marginally significant decrease in stand-level fine-root biomass. The addition of P was associated with a marginally significant (P = 0.058) increase in fine-litter production that was consistent across all litter fractions. Our experiment provides evidence that N, P, and K all limit forest plants growing on a relatively fertile soil in the lowland tropics, with the strongest evidence for limitation by K among seedlings, saplings, and poles.     

The Determination of Formaldehyde,Acrolein, and Low Molecular Weight Aldehydes in Industrial Emissions on a Single Collection Sample

Formaldehyde, acrolein, and low molecular weight aldehydes are collected in 1% NaHSO₃ solution in Greenberg-Smith or midget impingers from industrial effluents. Efficiency of collection is excellent when two impingers are used in series. Formaldehyde is measured in an aliquot of the collection medium by the chromo-tropic acid procedure, acrolein by a modified mercuric-chloride-hexylresorcinol procedure, and C₂-C₅ aldehydes by a gas chromatographic procedure. The method permits the analysis of all C₁-C₅ aldehydes on a single collection sample. Data on aldehyde concentrations from a variety of effluents are presented.     

Gas chromatographic analysis of organic marker compounds in fine particulate matter using solid-phase microextraction

A gas chromatographic method that uses solid-phase microextraction for analysis of organic marker compounds in fine particulate matter (PM2.5) is reported. The target marker compounds were selected for specificity toward emission from wood smoke, diesel or gasoline combustion, or meat cooking. Temperature-programmed volatilization analysis was used to characterize the thermal stabilities and volatile properties of the compounds of interest. The compounds were thermally evaporated from a quartz filter, sorbed to a solid phase microextraction (SPME) fiber, and thermally desorbed at 280 degrees C in a gas chromatograph injection port connected via a DB 1701 capillary separating column. Various experimental parameters (fiber type, time, and temperature of sorption) were optimized. It was found that high extraction yield could be achieved using a polyacrylate fiber for polar substances, such as levoglucosan, and a 7-microm polydimethylsiloxane (PDMS)-coated fiber for nonpolar compounds, such as hopanes and polyaromatic hydrocarbon. A compromise was made by selecting a carboxen/PDMS fiber, which can simultaneously extract all of the analytes of interest with moderate-to-high efficiency at 180 degrees C within a 30-min accumulation period. The optimized method was applied to the determination of levoglucosan in pine wood combustion emissions. The simplicity, rapidity, and selectivity of sample collection with a polymer-coated SPME coupled to capillary gas chromatography (GC) made this method potentially useful for atmospheric chemistry studies.