Naegleria lovaniensis tarasca New Subspecies, and the Purepecha Strain, a Morphological Variant of N. I. lovaniensis, Isolated from Natural Thermal Waters in Mexico

Amoebae were isolated from a natural thermal water source in Michoacaan, Mexico, in September 1986. Two 500-ml samples were taken from pools with water at 45°C and 46°C and concentrated at 2,000 g for 15 min. The sediment was seeded on nonnutritive agar plates and incubated at 42°C. The isolates were axenized in bactocasitone-serum medium. The identification of the isolates was based on their morphology, total protein and isoenzyme patterns by agarose isoelectric focusing, serology, fine structure, agglutination with Concanavalin A, sensitivity to trimethoprim, capacity to kill mice, and their cytopathic effect in Vero cells. The results showed several morphophysiological, biochemical and serological differences between the isolates and the type strain Aq/9/1/ 45D of Naegleria lovaniensis. These remarkable differences provide sufficient evidence to consider one of the isolates a new subspecies, and the other one a morphological variant of N. l. lovaniensis, which can be differentiated from other Naegleriae by their morphology, biochemistry, serology and physiology. The authors propose the name tarasca for the subspecies and purepecha for the morphological variant.     

Lion density and population structure in the Selous Game Reserve: evaluation of hunting quotas and offtake

In 1992, tourist hunting in the Selous Game Reserve generated 1.28 million dollars for the Tanzanian government, of which 0·96 million dollars were returned to wildlife conservation. Lions ( Panthera leo ) are one of three critical species for tourist hunting, consistently generating 12%–13% of hunting revenue from 1988 to 1992. Because of their ecological and economic importance (and intrinsic value), it is important that lion quotas be set so that offtake is sustainable. The population density of lions in Selous ranges from 0·08 to 0·13 adults km⁻², comparable to unhunted ecosystems. The adult sex ratio (36–41% male) and the ratio of cubs to adults (29% cubs) are similar to those of unhunted populations. The ratio of lions to hyaenas is lower in heavily hunted areas (0·17 lions/hyena) than in unhunted areas (0·43 lions/hyena). Hunting levels between 1989 and 1994 took 2·7–4·3% of adult males annually, which is sustainable. The current quota is 10–16% of the adult male population, which exceeds natural mortality rates for male lions. To remain stable if the quota was filled, the population would have to compensate via increased fecundity, increased juvenile survival, or an altered sex‐ratio. Compensation occurs in Selous by producing (or raising) more male than female cubs (66–81% of juveniles are male). Only 28% of the Selous quota was filled in 1992. The percentage of quota filled (both in Selous and nationwide) has dropped since 1988 as quotas have increased. The current intensity of lion hunting in Selous is sustainable, but the quota cannot be filled sustainably.     

Assessment of soil calcium status in red spruce forests in the northeastern United States

Long-term changes in concentrations of available Ca in soils of redspruce forests have been documented, but remaining questions aboutthe magnitude and regional extent of these changes have precluded anassessment of the current and future status of soil Ca. To addressthis problem, soil samples were collected in 1992—93from 12 sites in New York, Vermont, New Hampshire, and Maine toprovide additional data necessary to synthesize all availableresearch results on soil Ca in red spruce forests. Sites werechosen to encompass the range of environmental conditionsexperienced by red spruce. Concentrations of exchangeableCa ranged from 2.13 to 21.6 cmol_ckg^–1 in the Oa horizon, and from 0.11 to 0.68cmol_c kg^–1 in the upper 10 cm of theB horizon. These measurements expanded the range of exchangeable Ca reported in the literature for both horizons in northeastern redspruce forests. Exchangeable Ca was the largest Ca fraction in theforest floor at most sites (92% ofacid-extractableCa), but mineral Ca was the largest fraction at the three sites that also had the highest mineral-matter concentrations. Theprimary factor causing variability in Ca concentrations among siteswas the mineralogy of parent material, but exchangeable concentrationsin the B horizon of all sites were probably reduced by acidicdeposition. Because the majority of Ca in the forest floor isin a readily leachable form, and Ca inputs to the forest floor from the mineral soil and atmospheric deposition have beendecreasing in recent decades, the previously documented decreasesin Ca concentrations in the forest floor over previous decades mayextend into the future.     

Embryonic responses to variation in oviductal oxygen in the lizard Sceloporus undulatus from New Jersey and South Carolina, USA

Viviparity in reptiles is hypothesized to evolve in cold climates at high latitudes and high elevations through selection for progressively longer periods of egg retention. Oxygen consumption of embryos increases during development and therefore longer periods of egg retention should be associated with maternal or embryonic features that enhance embryonic oxygen availability. We tested the hypotheses that embryos of the oviparous lizard Sceloporus undulatus from a high-latitude population in New Jersey are oviposited at more advanced developmental stages and have a higher growth rate at low oxygen partial pressures ( p O₂) than embryos from a low-latitude population in South Carolina. These hypotheses were rejected; embryos from the two populations did not differ in embryonic stage at oviposition, survival, rate of differentiation or growth in mass when incubated under simulated in utero conditions at low oxygen concentrations. We also estimated the effective p O₂ experienced by lizard embryos in utero . At an effective p O₂ of 8.6 kPa (9% O₂), development of S. undulatus embryos is arrested at Dufaure and Hubert stage 30 and at a dry mass of 0.8 mg. Physiological and morphological features of gravid females, embryos, or both, that facilitate oxygen uptake for developing embryos appear to be a critical early step during the evolution of reptilian viviparity. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 83 , 289–299.     

Variation in social rank acquisition influences lifetime reproductive success in black-capped chickadees

Dominance relationships structure many animal societies, yet the process of rank attainment is poorly understood. We investigated acquisition of social dominance in winter flocks and its fitness consequences in male black-capped chickadees (Poecile atricapillus) over a 10-year period. Age was the best predictor of rank, and paired comparisons showed high-ranked males to be older than their low-ranked flock-mates. When controlling for age, morphological variables did not predict male social rank, but high-ranked males were heavier, had lower fat scores and were in leaner condition than low-ranked males. Males that survived between years tended to increase in rank over time; however, the rate of rank advancement varied individually. Rank reversals between familiar contestants were rare, and changes in male social rank were associated with changes in flock membership. Average lifetime reproductive success (LRS) of males and females was variable and best predicted by lifespan. Male rank history also influenced realized reproductive success. Birds with higher average rank over their lifespan were more likely to reproduce successfully. However, among successful birds, average rank did not significantly predict LRS. Thus, birds that lived longer and attained high social rank earlier had higher fitness, but this effect was not manifested as fine-scale differences among successful individuals. Taken together, these findings demonstrate the importance of social factors influencing individual fitness.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 85–95.     

Effects of larval energetic resources on life history and adult allocation patterns in a caddisfly (Trichoptera: Phryganeidae)

Abstract 1. How populations respond to environmental change depends, in part, on the connection between environmental variance during early life stages and its effect on subsequent life‐history traits. For example, environmental variation during the larval stage can influence the life histories of organisms with complex life cycles by altering the amount of time spent in each stage of the life cycle as well as by altering allocation to life‐history traits during metamorphosis. 2. The effects of larval energetic resources on developmental timing, adult mass, fecundity, mating success, and allocation to adult body structures (thorax, abdomen, wings) were examined in an aquatic caddisfly (Agrypnia deflata Milne, Trichoptera: Phryganeidae). Larval energetic reserves were manipulated by removing larval cases just prior to pupation. In the first experiment, cases of all individuals were removed just prior to pupation; experimental individuals were required to build a new case whereas control individuals were allowed to re‐enter their case without building. In the second experiment, energy differences were maximised between the two treatments by supplementing the larval diet of the control group and removing cases and not supplementing the diet of the experimental group. 3. Male and female development time, adult mass, and female fecundity were not influenced by case removal or diet supplementation. In contrast, allocation to adult body parts indicated a trade‐off between abdominal and thoracic mass among case‐removal females, suggesting that, under larval resource stress, females adjust resource allocation during metamorphosis to alleviate potential negative impacts on clutch size. In addition, latency to copulation increased when cases were removed, indicating larval resource stress could influence male mating success. 4. This study suggests that, under larval energetic stress, the negative impacts on female reproduction might be mitigated by re‐allocating resources during metamorphosis, whereas male allocation strategies might not be as flexible as female strategies.     

Temporal response of stream benthic macroinvertebrate communities to the synergistic effects of anthropogenic acidification and natural drought events

1. We evaluated whether the surprisingly weak biological recovery associated with declines in acid deposition were related to drought‐induced re‐acidification of streams. We used test site analysis (TSA) to characterise temporal changes (1995–2003) in the degree and nature of impairments to stream benthic macroinvertebrate (BMI) communities influenced by acid deposition and drought. 2. The BMI communities in four historically impacted test streams were compared with communities in 30 minimally impacted reference streams. Six multivariate (e.g. ordination axes scores) and four traditional (e.g. % Diptera) summary metrics were used to describe BMI communities. Using all metrics simultaneously (i.e. Mahalanobis or generalised distance), the TSA provided a single probability that a test community was impaired. If a test community was significantly impaired, a further analysis was done to identify the metric(s) important in distinguishing the test community from reference condition. 3. Results of the TSAs indicated that the generalised distances between test communities and the reference condition were inversely related to stream water pH (n = 36). The TSAs also indicated ordination metrics based on BMI abundance were important in distinguishing significantly impaired communities from reference conditions. Temporal trends indicated that there has been short‐term recovery of these BMI communities, but that overall improvements have been hampered by acid or metal toxicity associated with drought‐induced re‐acidification of the streams. 4. Our use of a variety of summary metrics to obtain a single statistical test of significance within the context of the reference‐condition approach provided a simple and unambiguous framework for evaluating the biological condition of test sites.