Limb regeneration and subsequent asymmetry in a male secondary sexual character influences sexual selection in wolf spiders

Males of the brush-legged wolf spider Schizocosa ocreata (Hentz) have conspicuously decorated forelegs used in courtship and agonistic displays. Approximately one in five juvenile males has a missing or regenerating foreleg, and regeneration of a leg lost during development usually results in the absence of a decorative tuft on that leg. The subsequent asymmetry in this male secondary character significantly decreases success in both courtship of females and male-male agonistic interactions. Experimental removal of tufts from one leg of previously successful symmetric males produces similar results. As a test for concomitant behavioral effects, female spiders were shown video images of a courting male with symmetric tufts and the same video image altered to have asymmetric tufts. Female receptivity to the asymmetric video image was lower. In contrast to fluctuating asymmetry resulting from developmental instability, leg tuft asymmetry in S. ocreata most likely arises from a single event during ontogeny – possibly leg loss from an aggressive or predator encounter  – and may serve as a quality indicator in female mate choice. Received: 27 July 1995/ Accepted after revision: 19 November 1995     

Integrating economic costs into the analysis of flexible conservation management strategies.

Flexible conservation management, where measures (e.g., mowing of meadows, removing invasive species) are selected in each decision period depending on the current state of the ecological system, is generally perceived as superior to fixed management, where the same measure is applied in each decision period independent of the current state of the system. In past comparisons of fixed and flexible conservation strategies the additional costs that arise only in flexible strategies have usually been ignored. In this paper, we present a framework to integrate costs of flexible management into the evaluation of flexible conservation strategies. Using the example of an endangered butterfly species we demonstrate that the costs of flexible management may reverse the rank order of flexible and fixed conservation strategies, such that fixed strategies may lead to better ecological results than flexible ones for the same financial budget.     

Effect of water pH and total dissolved solids on the species diversity of pelagic zooplankton in lakes: A statistical analysis

Statistical analysis of the combined influence of lake surface area (S), water pH, and total dissolved solids (TDS) on the formation of zooplankton communities in lakes has been made on the basis of available data on the number of species (N _sp ) of pelagic zooplankton in 256 lakes of the temperate zone of Europe, Asia, and North America. Graphic analysis and analysis of variance have shown that extremely high or extremely low values of pH and TDS inhibit lake zooplankton. If the value of one of these factors is extremely high, any increase in the other factor is favorable for the inhibited zooplankton, and this second factor determines the value of N _sp .     

The Spatiotemporal Structure of Rodent Populations in the Steppe Zone of Western Siberia

The spatial structure of populations has been studied in two rodent species inhabiting the subzone of meadow steppes of the steppe zone of Omsk oblast: the narrow-sculled vole (Microtus gregalis Pall.) and steppe lemming (Lagurus lagurus Pall.). Their populations are represented by combinations of territorial family groups whose structure and spatial distribution vary by season depending on population density, the phase of the population cycle, and the status of their members in the population. In the areas cohabited by M. gregalis and L. lagurus, the pattern of territory use and the rhythm of animal activity during the day depend primarily on their total density: under conditions of low density, the population groups of both species are spatially separated; at increased density, they are distributed with respect to the pattern of daily activity. Both species jointly use part of the territory but at different times of day: M. gregalis, mainly at night and in the morning; L. lagurus, in the daytime.     

Conservation of biodiversity in western India

Director of environmental studies at the Indira Gandhi Centre for Human Ecology, Environmental and Population Studies at the University of Rajasthan. This paper describes the biodiversity in the north-western Indian State of Rajasthan, its relationship with the environment and the existing human and livestock populations. As the biodiversity is depleting in this area due to zoogenic and anthropogenic reasons, certain pragmatic conservation strategies are advocated. The north-western part of India is occupied by a desert ecosystem, the Thar Desert. Animal husbandry is the major livelihood in the region, followed by agriculture. The vegetation, which is predominantly xerophytic and quite sparse, occurs in great variety. Six hundred and eighty-two plant species and 390 animal species have been identified from the Thar Desert. Many plant and animal species have become endangered due to zoogenic and anthropogenic activities. Plants such as Calligonum polygonoides, Tecomella undulata and Prosopis cineraria urgently require conservation.     

An assessment of endocrine disrupting activity changes during wastewater treatment through the use of bioassays and chemical measurements.

The objective of this study was to assess the removal efficiencies of secondary wastewater treatment processes for compounds causing endocrine disrupting activity. The study used bioassays and chemical measurements, such as gas chromatography with mass spectrometry and enzyme immunosorbent assays. A total of seven full-scale water reclamation facilities using different unit operations and two pilot-scale membrane bioreactors were examined. Findings of this study imply that estrogenic disrupting activity in primary effluent is mainly caused by two steroidal hormones (17beta-estradiol and estriol) and, to a lesser extent, by synthetic chemicals, such as bisphenol A, 4-nonylphenol, and 4-tert-octylphenol. During secondary treatment, steroidal hormones were removed to a higher degree than nonylphenol and bisphenol A. The total estrogenic activity was removed by an average of 96%. The remaining concentrations of targeted steroids in secondary effluents, except for estriol, still had the potential to elicit a positive response in the human breast cell cancer assay. For the majority of facilities, the remaining activity was likely attributed to residual concentrations of two steroidal hormones (17beta-estradiol and estriol).     

The use of volcanic soil as mineral landfill liner--I. Physicochemical characterization and comparison with zeolites.

The main physicochemical characteristics of the volcanic soil of Southern Chile, with allophane as the main pedogenic mineral phase were analysed and compared with common zeolites (clinoptilolite) of the European market. The ultimate goal of this study was to test volcanic soil for the use as mineral landfill liner. The main results indicated that the clay and silt fractions together of the volcanic soil were between 38 and 54%. The buffering capacity of the volcanic soil was higher compared with the studied zeolites, whereas the cationic exchange capacity of the volcanic soil (between 5.2 and 6.5 cmol + kg(-1)) is of the same order of magnitude of the studied zeolites (between 9.7 and 11.4 cmol + kg(-1)). Moreover, the anionic exchange capacity of the volcanic soil was higher compared to the zeolites analysed. The hydraulic conductivity of the volcanic soil, measured in the laboratory at maximum proctor density, ranges between 5.16 x 10(-9) and 6.48 x 10(-9) m s(-1), a range that is comparable to the value of 4.51 x 10(-9) m s(-1) of the studied zeolite. The Proctor densities of the volcanic soil are in a lower range (between 1.11 and 1.15 g ml(-1)) compared with zeolites (between 1.19 and 1.34 g ml(-1)). The volcanic soil physicochemical characteristics are comparable to all the requirements established in the Austrian landfill directive (DVO, 2000). Therefore, the use as mineral landfill basal sealing of the analysed volcanic soil appears reasonable, having a pollutant adsorption capacity comparable to zeolites. It is of special interest for Southern Chile, because there are no alternative mineral raw materials for basal liners of landfills.