The Simulium vernum group (Diptera: Simuliidae) in Europe: multiple character sets for assessing species status

The value of using characters from multiple sources – chromosomes, ecology, gene sequences, and morphology – to evaluate the species status of closely related black flies is demonstrated for three European members of the Simulium vernum group: Simulium crenobium (Knoz, 1961), Simulium juxtacrenobium Bass & Brockhouse, 1990, and Simulium vernum s.s. Macquart, 1826. Simulium juxtacrenobium is a chromosomally, molecularly, and morphologically distinct species that diverged from S. crenobium and S. vernum s.s. about 2 Mya. It is specialized for intermittent streams, is univoltine, and is recorded for the first time from northern Europe, based on collections from Finland and Sweden, representing a range extension of about 1800 km. In contrast, S. crenobium, although confirmed as a distinct species, differs from S. vernum s.s. by only a few larval and chromosomal characters, and by a breeding habitat restricted to mountain spring brooks. Whereas all four character sets independently support the specific distinctness of S. juxtacrenobium and S. vernum s.s., multiple character sets are required to establish the specific validity of S. crenobium.     

The rarity concept and the commonness of rarity in freshwater zooplankton

1. Regional distribution, frequency of occurrence and relative abundance were scored in 2467 Norwegian lakes for all the recorded 130 species of crustacean zooplankton. The majority of species were rare in the sense that 65% of species were recorded in fewer than 10% of localities. Only six species were recorded in more than 50% of localities, and the median number of species in a given locality was 14 (i.e. 10% of the total species pool). 2. Abundances of all species were scored according to the fraction of lakes in which they were recorded, their geographical range of distribution, and their numerical abundance. Typically the most rare species were rare by all three criteria, and vice versa for the common species, pointing to rarity as an inherent property of some species. For some species this rarity reflects being on the edge of their distributional range, while for others rarity seems to be a consequence of their life cycle strategies. 3. Some of the truly rare species have high dispersal rates and high colonization abilities, but are rapidly replaced by other species. Others are confined to specific habitats, often highly eutrophic, pointing to highly specialized niche adaptations. 4. A major cause for the few truly common species seems to be the limited number of species that are able to coexist within a given locality, reflecting ‘the ghost of competition past’ and predation pressure. 5. While species composition and species richness may reflect colonization abilities and stochastic events, the presence or absence of species is not only a random lottery but also a consequence of species‐specific attributes.     

Molecular evolution modeled as a fractal Poisson process in agreement with mammalian sequence comparisons

The fractal doubly stochastic Poisson process (FDSPP) model of molecular evolution, like other doubly stochastic Poisson models, agrees with the high estimates for the index of dispersion found from sequence comparisons. Unlike certain previous models, the FDSPP also predicts a positive geometric correlation between the index of dispersion and the mean number of substitutions. Such a relationship is statistically proven herein using comparisons between 49 mammalian genes. There is no characteristic rate associated with molecular evolution according to this model, but there is a scaling relationship in rates according to a fractal dimension of evolution. The FDSPP is a suitable replacement for the homogeneous Poisson process in tests of the lineage dependence of rates and in estimating confidence intervals for divergence times. As opposed to other fractal models, this model can be interpreted in terms of Darwinian selection and drift.      

Protective actions of green tea polyphenols and alfacalcidol on bone microstructure in female rats with chronic inflammation

This study investigated the effects of green tea polyphenols (GTP) and alfacalcidol on bone microstructure and strength along with possible mechanisms in rats with chronic inflammation. A 12-week study using a 2 (no GTP vs. 0.5%, w/v GTP in drinking water)×2 (no alfacalcidol vs. 0.05 μg/kg alfacalcidol orally, 5×/week) factorial design was employed in lipopolysaccharide (LPS)-administered female rats. A group receiving placebo administration was used to compare with a group receiving LPS administration only to evaluate the effect of LPS. Changes in tibial and femoral microarchitecture and strength of femur were evaluated. Difference in expression of tumor necrosis factor-α (TNF-α) in proximal tibia using immunohistochemistry was examined. Compared to the placebo group, the LPS-administered-only group had significantly lower femoral mass, trabecular volume, thickness and number in proximal tibia and femur, and lower periosteal bone formation rate in tibial shafts but had significantly higher trabecular separation and osteoclast number in proximal tibia and eroded surface in endocortical tibial shafts. Both GTP and alfacalcidol reversed these LPS-induced detrimental changes in femur, proximal tibia and endocortical tibial shaft. Both GTP and alfacalcidol also significantly improved femoral strength, while significantly suppressed TNF-α expression in proximal tibia. There were significant interactions in femoral mass and strength, trabecular separation, osteoclast number and TNF-α expression in proximal tibia. A combination of both showed to sustain bone microarchitecture and strength. We conclude that a protective impact of GTP and alfacalcidol in bone microarchitecture during chronic inflammation may be due to a suppression of TNF-α.     

Termite cohabitation: the relative effect of biotic and abiotic factors on mound biodiversity

1. Termites are important ecosystem engineers that improve primary productivity in trees and animal diversity outside their mounds. However, their ecological relationship with the species nesting inside their mounds is poorly understood. 2. The presence of termite cohabitant colonies inside 145 Cornitermes cumulans mounds of known size and location was recorded. Using network‐theoretical methods in conjunction with a suite of statistical analyses, the relative influence of biotic and abiotic drivers of termite within‐mound diversity on the composition and species richness of the termite community was investigated, specifically builder presence and physical aspects of the mound. 3. We found that richness inside the mound increases with mound size, and the species similarity between mounds decreases with distance. The physical attributes (abiotic drivers) of termite mounds (size and relative distance to other mounds) are the strongest predictors of termite species richness and composition. The biotic driver (presence of a builder colony) has an important, though smaller, negative effect on within‐mound termite species richness. 4. The findings suggest that the termites' physical manipulation of their environment is an important driver of within‐mound community diversity. More generally, the approach taken here, using a combination of statistical and network‐theoretical methods, can be used to determine the relative importance of abiotic and biotic drivers of diversity in a wide range of communities of interacting species.     

Genetic polymorphism in Gymnodinium galatheanum chloroplast DNA sequences and development of a molecular detection assay

Nuclear and chloroplast-encoded small subunit ribosomal DNA sequences were obtained from several strains of the toxic dinoflagellate Gymnodinium galatheanum. Phylogenetic analyses and comparison of sequences indicate that the chloroplast sequences show a higher degree of sequence divergence than the nuclear homologue. The chloroplast sequences were chosen as targets for the development of a 5'--3' exonuclease assay for detection of the organism. The assay has a very high degree of specificity and has been used to screen environmental water samples from a fish farm where the presence of this dinoflagellate species has previously been associated with fish kills. Various hypotheses for the derived nature of the chloroplast sequences are discussed, as well as what is known about the toxicity of the species.     

Temperature,predator–prey interaction strength and population stability

Warming could strongly stabilize or destabilize populations and food webs by changing the interaction strengths between predators and their prey. Predicting the consequences of warming requires understanding how temperature affects ingestion (energy gain) and metabolism (energy loss). Here, we studied the temperature dependence of metabolism and ingestion in laboratory experiments with terrestrial arthropods (beetles and spiders). From this data, we calculated ingestion efficiencies (ingestion/metabolism) and per capita interaction strengths in the short and long term. Additionally, we investigated if and how body mass changes these temperature dependencies. For both predator groups, warming increased metabolic rates substantially, whereas temperature effects on ingestion rates were weak. Accordingly, the ingestion efficiency (the ratio of ingestion to metabolism) decreased in all treatments. This result has two possible consequences: on the one hand, it suggests that warming of natural ecosystems could increase intrinsic population stability, meaning less fluctuations in population density; on the other hand, decreasing ingestion efficiencies may also lead to higher extinction risks because of starvation. Additionally, predicted long‐term per capita interaction strengths decreased with warming, which suggests an increase in perturbation stability of populations, i.e., a higher probability of returning to the same equilibrium density after a small perturbation. Together, these results suggest that warming has complex and potentially profound effects on predator–prey interactions and food‐web stability.     

Effects of Hunting on Response Behaviors of Wild Reindeer

ABSTRACT Because wild reindeer (Rangifer tarandus) are hunted in southern Norway, reindeer may perceive all recreationists as threats. Potential adverse effects of hunting on reindeer behavior may be exacerbated by other forms of recreation because the number of skiers and hikers in areas inhabited by reindeer has also increased. The Norefjell-Reinsjøfjell wild reindeer area is used extensively for recreation and tourism. Reindeer hunting was introduced in the area in 1992, and harvest rate has been stable at about 38% of winter herd size. We recorded behavioral responses of reindeer to a person approaching directly on foot or skis during 1992 and again in 2002–2006. Compared to 1992, flight-initiation distance increased and fewer groups assessed the observer before taking flight during 2002–2006. In winter, when reindeer are usually comparably more vigilant than in other seasons, flight-initiation distance increased from only 60 m to 115 m and escape distance decreased from 400 m to 210 m. Neither alert distance, calf carcass weights (23.6 ± 0.7 [SE] kg to 22.4 ± 0.2 kg), nor reindeer herd size (661 ± 73 to 579 ± 15) changed during the 15 years of our study. Reindeer appeared to habituate to the observer because they initiated flight at shorter distances as the number of approaches on the same day increased. In Norefjell-Reinsjøfjell, encounters with a person on foot or skis did not result in behavioral responses likely to entail substantial energy costs for reindeer; therefore, hunting at current levels appears compatible with other recreational activities.