Evidence of obligate female promiscuity in a socially monogamous passerine

Extrapair paternity in birds has been the focus of an increasing number of studies over the last decades. Nevertheless, there is little knowledge about extrapair copulation (EPC) behavior. In this study, we investigate whether female bluethroats (Luscinia s. svecica) with no extrapair offspring (EPO) in their broods really have been sexually monogamous or if they have copulated with extrapair males. We used an experimental approach to prevent transfer of sperm from the social male during copulation by fitting a rubber tube around the cloaca of randomly chosen males. If the females mated to these males do not participate in EPCs, they will produce infertile eggs, whereas females that copulate with extrapair males will only produce EPO. We found that 87% (n=15) of the experimental pairs compared to only 36% (n=51) of unmanipulated pairs produced EPO. Our result therefore suggests that females having no EPO may still have copulated with extrapair males and that promiscuity may be an obligate sexual strategy among bluethroat females.Communicated by S. Pruett-Jones     

Characterisation of cholinesterases and evaluation of the inhibitory potential of chlorpyrifos and dichlorvos to Artemia salina and Artemia parthenogenetica

In this study, the acute toxicity of the organophosphorous pesticides dichlorvos and chlorpyrifos to two different species of Artemia (A. salina and A. parthenogenetica) was evaluated. In addition, the in vivo effect of these two pesticides on cholinesterase (ChE) activity of both A. salina and A. parthenogenetica was also determined. The characterisation of the ChE, using different substrates and specific inhibitors, and the normal range of activity in non-exposed individuals were previously investigated for both species. The results obtained indicate that the ChE of A. salina is different from that of A. parthenogenetica and that both enzymes cannot be classified neither as acetylcholinesterase nor as butyrylcholinesterase since they show intermediary characteristics between the two vertebrate forms. The range of normal ChE activity was 2.65+/-0.15 U/mg protein for A. salina, and 3.69+/-0.17 U/mg protein for A. parthenogenetica. Significant in vivo effects of both pesticides on Artemia ChE activity were found, at concentrations between 5.38 and 9.30 mg/l for dichlorvos and between 1.85 and 3.19 mg/l for chlorpyrifos. Both Artemia species are resistant to these pesticides and they are able to survive with more than 80% ChE inhibition. However, A. parthenogenetica is more resistant than A. salina, with about a 95% reduction in its ChE activity respect to the control for nauplii exposed to the median lethal concentrations (LC50), without lethal effects after 24 h of exposure.     

Application of the quadratic entropy indices for diversity studies of drosophilid assemblages

Most diversity indices widely used in ecology (e.g. the Shannon-Wiener index and the Gini-Simpson index) do not reflect taxonomic or other differences among species. Quadratic entropy, proposed by C.R. Rao (1982), takes these differences into account. The aim of this paper is to demonstrate the application of this diversity index in investigations of drosophilid species diversity. Quadratic entropy and Simpson index values are also compared. The elements of the difference matrix in the quadratic form are taxonomic differences (distances) among the species. The difference is defined by the position of the lowest-ranking taxon containing both species. According to the results, the Gini-Simpson index and the taxonomic quadratic entropy are positively correlated. The observed differences are due to the fact that assemblages with greater taxonomic distances produce greater quadratic entropy. Drosophilid species can be assigned to specific life habit classes, more specifically to resource types. After postulating differences between the types, we used the quadratic entropy measure to analyse resource diversity. These kinds of examinations approximate to an operative association of species diversity and environmental diversity.     

Spatial scales and probability based sampling in determining levels of benthic community degradation in the Chesapeake Bay

The extent of degradation of benthic communities of the Chesapeake Bay was determined by applying a previously developed benthic index of biotic integrity at three spatial scales. Allocation of sampling was probability-based allowing areal estimates of degradation with known confidence intervals. The three spatial scales were: (1) the tidal Chesapeake Bay; (2) the Elizabeth River watershed; and (3) two small tidal creeks within the Southern Branch of the Elizabeth River that are part of a sediment contaminant remediation effort. The areas covered varied from 10^–1 to 10⁴ km² and all were sampled in 1999. The Chesapeake Bay was divided into ten strata, the Elizabeth River into five strata and each of the two tidal creeks was a single stratum. The determination of the number and size of strata was based upon consideration of both managerially useful units for restoration and limitations of funding. Within each stratum 25 random locations were sampled for benthic community condition. In 1999 the percent of the benthos with poor benthic community condition for the entire Chesapeake Bay was 47% and varied from 20% at the mouth of the Bay to 72% in the Potomac River. The estimated area of benthos with poor benthic community condition for the Elizabeth River was 64% and varied from 52–92%. Both small tidal creeks had estimates of 76% of poor benthic community condition. These kinds of estimates allow environmental managers to better direct restoration efforts and evaluate progress towards restoration. Patterns of benthic community condition at smaller spatial scales may not be correctly inferred from larger spatial scales. Comparisons of patterns in benthic community condition across spatial scales, and between combinations of strata, must be cautiously interpreted.     

Aggressive behavior of the male parent predicts brood sex ratio in a songbird

Brood sex ratio is often affected by parental or environmental quality, presumably in an adaptive manner that is the sex that confers higher fitness benefits to the mother is overproduced. So far, studies on the role of parental quality have focused on parental morphology and attractiveness. However, another aspect, the partner’s behavioral characteristics, may also be expected to play a role in brood sex ratio adjustment. To test this hypothesis, we investigated whether the proportion of sons in the brood is predicted by the level of territorial aggression displayed by the father, in the collared flycatcher (Ficedula albicollis). The proportion of sons in the brood was higher in early broods and increased with paternal tarsus length. When controlling for breeding date and body size, we found a higher proportion of sons in the brood of less aggressive fathers. Male nestlings are more sensitive to the rearing environment, and the behavior of courting males may often be used by females to assess their future parental activity. Therefore, adjusting brood sex ratio to the level of male aggression could be adaptive. Our results indicate that the behavior of the partner could indeed be a significant determinant in brood sex ratio adjustment, which should not be overlooked in future studies.     

Can household consumers save the wild fish? Lessons from a sustainable seafood advisory

Conservation organizations seeking to reduce over-fishing and promote better fishing practices have increasingly turned to market-based mechanisms such as environmental sustainability labels (eco-labels) in order to shift patterns of household consumption. This paper presents an analysis of consumer response to an advisory for sustainable seafood adopted by a regional supermarket in the United States. The advisory consisted of a label in which one of three traffic light colors was placed on each fresh seafood product to inform consumers about its relative environmental sustainability. Green meant “best” choice, yellow meant “proceed with caution,” and red meant “worst choice”. Using a unique product-level panel scanner data set of weekly sales and taking advantage of the random phase-in of the advisory by the retailer, we apply a difference-in-differences identification strategy to estimate the effect of the advisory on overall seafood sales as well as the heterogeneous impact of the advisory by label color and whether the seafood met additional health-related criteria. We find evidence that the advisory led to a statistically significant 15.3% decline in overall seafood sales, a statistically significant 34.9% decline in the sale of yellow labeled seafood, and a statistically significant 41.3% decline in the sale of yellow labeled seafood on a mercury safe list. We find no statistically significant difference in sales of green or red labeled seafood.     

Ecovalue08–A new valuation set for environmental systems analysis tools

In environmental systems analysis tools such as cost-benefit analysis (CBA), life-cycle assessment (LCA) and Environmental Management Systems (EMS), weighting is often used to aggregate results and compare different alternatives. There are several weighting sets available, but so far there is no set that consistently use monetary values based on actual or hypothetical market valuation of environmental degradation and depletion.In this paper, we develop a weighting set where the values are based on willingness-to-pay estimates for environmental quality, and market values for resource depletion. The weighting set is applied to three case studies and the outcome is compared with the outcomes from three other weighting sets, Ecotax02, Ecoindicator99 and EPS2000. We find that the different sets give different results in many cases. The reason for this is partly that they are based on different values and thus should give different results. However, the differences can also be explained by data gaps and different methodological choices. If weighting sets are used, it is also important to use several to reduce the risk of overlooking important impacts due to data gaps. It is also interesting to note that though Ecovalue08 and Ecotax02 give different absolute values, the results are very similar in relative terms. Thus the political and the individual willingness-to-pay estimates yield a similar ranking of the impacts.     

Weighting and valuation in selected environmental systems analysis tools – suggestions for further developments

In environmental systems analysis tools like Life Cycle Assessment, strategic environmental assessment, cost–benefit analysis and environmental management systems, results need to be presented in a comprehensible way to make alternatives easily comparable. One way of doing this is to aggregate results to a manageable set by using weighting methods. In this paper, we explore how weighting methods are used in some selected Environmental Systems Analysis Tools (ESATs), and suggest possible developments of their use. We examine the differences in current use patterns, discuss the reasons for and implications of such differences, and investigate whether observed differences in use are necessary. The result of our survey shows that weighting and valuation is broadly used in the examined ESATs. The use of weighting/valuation methods is different in different tools, but these differences are not always related to the application; rather, they are related to traditions and views on valuation and weighting. Also, although the requirements on the weights/values may differ between tools, there are intersections where they coincide. Monetary weights, using either endpoint or midpoint methods, are found to be useful in all the selected tools. Furthermore, the inventory shows that that there is a common need for generic sets of weights. There is a need for further research focusing on the development of consistent value sets derived with a wide range of methods. In parallel to the development of weighting methods it is important with critical evaluations of the weighting sets with regard to scientific quality, consistency and data gaps.