Sex ratio manipulation in response to maternal condition in pigeons: evidence for pre-ovulatory follicle selection

A number of recent reports have documented offspring sex ratio biases in birds. However, to date the potential mechanisms that have been put forward to explain the proximate basis for these deviations are entirely speculative. Using a captive population of domestic pigeons (Columba livia domestica), I tested the hypothesis that mothers in relatively poor physical condition should overproduce daughters by manipulating maternal body condition around the time of egg laying by continuous egg removal and differing feeding regimes. During treatment, females were fed a controlled quantity of food. This, combined with the high energetic costs of repeated egg production caused a significant reduction in maternal body weight. In contrast, during control when food was available ad libitum, maternal body weight did not decline, despite repeated egg production. No significant deviation from parity was evident in the sex ratio of either the first or second eggs during control, whereas during treatment a significant female bias was evident in not only the first egg, but also in the second egg. The absence of single-egg clutches, the rarity of infertile eggs and the lack of laying delays between eggs strongly suggests that the mechanism of sex ratio adjustment in pigeons occurs prior to ovulation. The highly skewed sex-distribution within the two-egg clutches and the unexpectedly large amount of variation in the yolk weight of eggs produced during treatment (but not control) are consistent with the expectations of pre-ovulatory selective resorption of wrong sex ovarian follicles.     

An analysis of UK waste minimization clubs: key requirements for future cost effective developments

The UK waste strategy is based upon use of the best practicable environmental option (BPEO), by those making waste management decisions. BPEO is supported by the use of the waste hierarchy, with its range of preferable options for dealing with waste, and the proximity principle, where waste is treated/disposed of as close to its point of origin as possible. The national waste strategy emphasizes the key role of waste minimization and encourages industry, commerce and the public to move towards sustainable waste management practice for economic and environmental reasons. Waste minimization clubs have been used, since the early 1990s, to demonstrate to industry/commerce that reducing waste production can lead to significant financial savings. There have been around 75 such clubs in the UK and they receive support from a wide range of agencies, including the Environmental Technology Best Practice Program. The early Demonstration Clubs had significant savings to cost ratios, e.g. Aire and Calder at 8.4, but had very high costs, e.g. Aire and Calder at 400,000 pounds. It is acknowledged that the number of clubs will have to be approximately doubled in the next few years so as to have an adequate coverage of the UK. There are at present, marked regional variations in club development and cognizance needs to be taken, by facilitators, of the need for extensive coverage of the UK. Future clubs will probably have to operate in a financially constrained climate and they need to be designed to deliver significant savings and waste reduction at low cost. To aid future club design, final reports of all projects should report in a standard manner so that cost benefit analysis can be used to inform facilitators about the most effective club type. rights reserved.     

Estimating survival rates of uncatchable animals: the myth of high juvenile mortality in reptiles

Survival rates of juvenile reptiles are critical population parameters but are difficult to obtain through mark-recapture programs because these small, secretive animals are rarely caught. This scarcity has encouraged speculation that survival rates of juveniles are very low, and we test this prediction by estimating juvenile survival rates indirectly. A simple mathematical model calculates the annual juvenile survival rate needed to maintain a stable population size, using published data on adult survival rates, reproductive output, and ages at maturity in 109 reptile populations encompassing 57 species. Counter to prediction, estimated juvenile survival rates were relatively high (on average, only about 13% less than those of conspecific adults) and highly correlated with adult survival rates. Overall, survival rates during both juvenile and adult life were higher in turtles than in snakes, and higher in snakes than in lizards. As predicted from life history theory, rates of juvenile survival were higher in species that produce large offspring, and higher in viviparous squamates than in oviparous species. Our analyses challenge the widely held belief that juvenile reptiles have low rates of annual survival and suggest instead that sampling problems and the elusive biology of juvenile reptiles have misled researchers in this respect.     

Plutonium in groundwater at the 100K-Area of the U.S. DOE Hanford Site

We examined the concentration, size distribution, redox state and isotopic composition of plutonium (Pu) in groundwater at the 100K-Area at the U.S. Department of Energy's (DOE) Hanford Site. Total concentrations of Pu isotopes were extremely low (10(-4) to 10(-6) pCi/kg, approximately 10(4) to 10(6) atoms/kg) but measurable for the first time in the 100K-Area wells using mass spectrometric analyses that are much more sensitive than alpha spectroscopy methods used previously. Size fractionation data from two wells suggest that 7-29% of the Pu is associated with colloids, operationally defined here as particles between 1 kDa-0.2 microm in size. These colloids were collected using a 1 kDa cross-flow ultrafiltration (CFF) system developed specifically for groundwater actinide studies to include careful controls both in the field and during processing to ensure in situ geochemical conditions are maintained and size separations can be well characterized. Pu in this colloidal fraction was exclusively in the more reduced Pu(III/IV) form, consistent with the higher affinity of Pu in the lower oxidation states for particle surfaces. While the overall concentrations of Pu were low, the Pu isotopic composition suggests at least two local sources of groundwater Pu, namely, local Hanford reactor operations at the 100K-Area and spent nuclear fuel from the N-reactor, which was stored in concrete pools at this site. Differences between this site and the Savannah River Site (SRS) are noted, since groundwater Pu at the F-Area seepage basin at SRS has been found using these same methods, to be characterized by lower colloidal abundances and higher oxidation states. This difference is not directly attributable to groundwater redox potential or geochemical conditions, but rather the physical-chemical difference in Pu sources, which at SRS appear to be dominated downstream from the seepage basins by decay of 244Cm, resulting in more oxidized forms of 240Pu. There is no clear evidence for colloid facilitated transport of Pu in groundwater at the Hanford Site, since downstream wells have both an order of magnitude lower concentrations of Pu and a lower fractional colloidal distribution.     

Genetic structure of rhinoceros auklets,Cerorhinca monocerata,breeding in British Columbia,Alaska, and Japan

Data from eight microsatellite markers screened in 246 rhinoceros auklets (Cerorhinca monocerata) from across the North Pacific revealed multiple genetic groups. The east (North America) to west (Japan) split was clearly evident in all analyses. Within the eastern Pacific, a minimum of three genetic groups are present. Surprisingly, rhinoceros auklets from Triangle Island, British Columbia, were genetically isolated from other nearby populations, including the breeding colony on Pine Island (~100 km to the east). A fourth genetic cluster (Chowiet Is) was detected using principal coordinate’s analysis; however, sample sizes were limited. Patterns of differentiation correspond to nonbreeding distributions with the eastern and western Pacific birds spending time off the west coast of North America and Japan, respectively, and may represent historical isolation in separate refugia during the Pleistocene glaciations. The patterns of genetic structure result from a combination of historical and contemporary factors influencing dispersal of rhinoceros auklets.     

Possible future trade-offs between agriculture, energy production, and biodiversity conservation in North Dakota

In this study, we describe a spatially explicit scenario analysis of global change effects on the potential future trade-offs and conflicts between agriculture, energy generation, and grassland and wetland conservation in North Dakota (ND), USA. Integrated scenarios combining global policy, oil security, and climate change were applied to North Dakota using a spatial multi-criteria analysis shell. Spatial data describing climate changes and grassland, wetland, cropland, and energy distributions were used to characterize the geographical environment. The final multi-criteria framework examined the potential trade-offs between climate change, agricultural expansion, and energy generation resulting from global change scenarios on one hand, and the current footprint of wetlands and grasslands for six regions of ND that capture the major climate gradients and differences in land use. The results suggest that the tension between regional climate changes that may limit agricultural expansion, and global changes in food and energy security and commodity prices that favor agricultural expansion, may focus a zone of potential pressure on grasslands and wetland conversion in central ND and the Prairie Pothole Region. The balance between conservation programs, commodity prices, and land parcel productivity may determine grassland conversion, while wetland outcomes may almost totally depend upon regional climate change.     

Drinking water supply – a backward look into the future

An adequate supply of pure and wholesome water, together with effective main drainage and treatment of wastewater, before returning it to the aquatic environment, are arguably the most beneficial public health measures which can be taken by a community. When properly managed, their success derives from breaking cycles of transmissible disease. History has repeatedly shown that good process engineering – even at the simplest level – must be accompanied by effective management and responsibility at all levels, in order to protect public health. Conversely, even seemingly minor breakdowns in vigilance and the managerial chain, can result in sudden outbreaks of disease. Experiences over two millennia are cited in support. As a new millennium is about to commence, it is natural and prudent to ask what future problems of waterborne diseases might emerge. Candidates might be chosen, and vigilance cannot be relaxed, but experiences of the past enable make it possible to conclude that potential concerns are generically, those which render existing barriers to transmission of infection inoperative and, those which alter or impede existing patterns of communication between and within organisations and individuals responsible for water quality.