Are flies kind to kin? The role of intra- and inter-sexual relatedness in mediating reproductive conflict.

As individual success often comes at the expense of others, interactions between the members of a species are frequently antagonistic, especially in the context of reproduction. In theory, this conflict may be reduced in magnitude when kin interact, as cooperative behaviour between relatives can result in increased inclusive fitness. Recent tests of the potential role of cooperative behaviour between brothers in Drosophila melanogaster have proved to be both exciting and controversial. We set out to replicate these experiments, which have profound implications for the study of kin selection and sexual conflict, and to expand upon them by also examining the potential role of kinship between males and females in reproductive interactions. While we did observe reduced fighting and courtship effort between competing brothers, contrary to previous studies we did not detect any fitness benefit to females as a result of the modification of male antagonistic behaviours. Furthermore, we did not observe any differential treatment of females by their brothers, as would be expected if the intensity of sexual conflict was mediated by kin selection. In the light of these results, we propose an alternative explanation for observed differences in male-male conflict and provide preliminary empirical support for this hypothesis.

Spring-harvested game birds from the western James Bay region of northern Ontario, Canada: organochlorine concentrations in breast muscle.

Although studies have assessed organochlorine concentration in breast tissue (pectoral muscle) of fall-harvested game birds in Canada, data for spring-harvested game birds are limited, especially for remote sub-arctic areas. Taking into account that most traditional Aboriginal diets include a large number of spring-harvested game birds, there is a need to assess organochlorine concentration in spring-harvested water birds with respect to suitability for human consumption. We examined organochlorine concentrations in breasts of 20 mallard ducks (Anas platyrhynchos), 20 northern pintails (A. acuta), 21 Canada geese (Branta canadensis interior), and 20 lesser snow geese (Chen caerulescens caerulescens) harvested in the spring; summer-harvested shorebirds (godwits; Limosa spp.) were also assessed as these water birds are an important part of the game bird harvest for First Nation Cree of the western James Bay region of Ontario, Canada. The most frequently detected organochlorines in striated (pectoral) muscle were SigmaPCBs (sum of 14 congeners [CBs]) and SigmaDDT (sum of DDE and DDT) followed by SigmaCHL (sum of oxy-chlordane, cis- and trans-nonachlor) and hexachlorobenzene with beta-hexachlorocyclohexane being the least frequently detected. For organochlorines that had < or =70% of the samples with detectable concentrations of an organochlorine (i.e., CBs 105, 128, 156, 170, 180, 183, cis-nonachlor, DDT, and mirex), log-linear contingency modelling revealed that the dabbling ducks had significantly more than expected detectable concentrations of most organochlorines; by contrast, geese and shorebirds had significantly less than expected detectable concentrations of most organochlorines. ANOVA for organochlorines with frequency of detection > or =70% (i.e., Aroclor 1260, SigmaPCBs, CBs 118, 138, 153, 187, DDE, hexachlorobenzene, oxy-chlordane and trans-nonachlor) revealed significant differences between bird species: Breast tissue in snow geese contained significantly less organochlorines than Canada geese (Aroclor 1260, CBs 118, 138, and 153) and godwits (Aroclor 1260, CBs 138, 153); mallards had significantly higher concentrations compared to godwits (DDE, trans-nonachlor, and SigmaCHLs), Canada geese (oxy-chlordane and SigmaCHLs), and snow geese (oxy-chlordane, trans-nonachlor, SigmaCHLs); and pintails had elevated levels compared to snow geese (CB 153, oxy-chlordane, trans-nonachlor, and SigmaCHLs) and Canada geese (oxy-chlordane). However, none of the samples analyzed in the present study exceeded the consumption guideline for organochlorines in fish or poultry with most samples being orders of magnitude less than the consumption guideline even when compared to maxima. Thus, the present spring-harvested-game bird study supports previous studies of fall-harvested game birds that contend that pectoral muscle portions are safe to eat. Nevertheless, skin and fat associated with the breast muscle may be another matter.

Spring-harvested game birds in the Western James Bay region of Northern Ontario, Canada: the amount of organochlorines in matched samples of breast muscle, skin, and abdominal fat.

We examined matched-tissue samples (the right pectoral muscle plus the associated skin and fat was considered a breast portion) of 81 spring-harvested waterfowl and 19 summer-harvested godwits (Limosa spp.) to assess the potential of these water birds contributing to the body burden of PCBs and DDT noted in First Nation people of the western James Bay region, northern Ontario, Canada. In general, the dabbling ducks (mallard duck, Anas platyrhynchos; and northern pintail, A. acuta) had significantly lower percent lipid (gravimetrically determined) values in skin tissue, fat tissue, and breast muscle compared to the goose species (Canada goose, Branta canadensis; lesser snow goose, Chen caerulescens); godwits had percent lipid values not significantly different than ducks and geese. Also, the percent lipid values in skin for all species of birds examined approached those found in fat tissue. Organochlorine data were expressed as the amount (microg) of each contaminant per breast portion to show contaminant consumption in terms of typical and easily recognizable dietary portions; direct comparisons were made to acceptable daily intake (ADI) or tolerable daily intake (TDI) values as recommended by Health Canada. Significant differences in the amount of organochlorines between bird species for skin, fat tissue, and breast muscle samples were found. In general, breast portions from snow geese contained the least amount of organochlorines, followed by godwits (except for mirex) and then Canada geese; the dabbling ducks had the greatest amount of organochlorines on a breast portion basis. However, on average, no 60 kg person would exceed the calculated organochlorine ADI/TDI values consuming one breast portion (i.e., breast + associated skin and fat), but the maximum value of SigmaPCBs for skin tissue alone in male mallards (47 microg) was more than twice the ADI/TDI (18 microg/day); while, that in fat tissue alone (17 microg) approached the ADI/TDI. Thus, the consumption of dabbling ducks by children is an issue that should be explored further, if tissue other than breast muscle is eaten. Lastly, the consumption of waterfowl was a source of PCBs for people of Fort Albany and Kashechewan, but not DDT, as this organochlorine was infrequently detected.