The dynamics of genetic variation in susceptibility to insecticides within a natural population of Drosophila melanogaster (Meigen) at Katsunuma (Yamanashi Prefecture, Japan) was examined. Two resistance factors for t...The dynamics of genetic variation in susceptibility to insecticides within a natural population of Drosophila melanogaster (Meigen) at Katsunuma (Yamanashi Prefecture, Japan) was examined. Two resistance factors for three organophosphate insecticides (OPs), a resistant-type acetylcholinesterase (AChE) and a cytochrome P450 monooxygenase (cytochrome P450), have already been suggested to be involved within the Katsunuma population. In this study, genetic variances were estimated for susceptibility to other classes of chemicals than OPs, permethrin (a pyrethroid) and dichloro-diphenyl-trichloroethane (DDT;an organo-chlorine), which existed simultaneously with genetic variances for susceptibility to OPs. Analyses of variance for susceptibility to permethrin and DDT showed highly significant variation among isofemale lines from the Katsunuma population, and the genetic variances for susceptibility to each insecticide fluctuated differently during this period. The impacts of fluctuations of genetic variation in susceptibility to one class of insecticides on genetic variation in susceptibility to other classes of insecticides existing simultaneously within the natural population were discussed.展开更多
From the standpoint of evolution, caring for old parents may be maladaptive, because they have ceased reproduction, so that the benefit for inclusive fitness may not be expected. Then why do we care for old parents? I...From the standpoint of evolution, caring for old parents may be maladaptive, because they have ceased reproduction, so that the benefit for inclusive fitness may not be expected. Then why do we care for old parents? In this study, the evolution of care for the elderly was examined, by using an evolutionary genetic model, in which pleiotropic constraints between behaviors expressed in different social contexts among family members were assumed. It was suggested that establishing a solid relationship with parents during infancy should be selectively favorable, even though old parents have to be cared for in the future, but that caring for old parents may be excluded from the population if this behavior imposes high costs on reproduction of the younger generation. Despite the diminishing numbers of individuals within the population, care for the elderly may not be readily selected against, but at the same time this may not contribute to the rate of increase in population size. The significance of discussing the behavior of elderly caring from the standpoint of evolutionary genetics was emphasized.展开更多
In order to gain insights into the seasonal dynamics of genetic variation in insecticide resistance within a natural population of Drosophila melanogaster during population growth, which we considered the most importa...In order to gain insights into the seasonal dynamics of genetic variation in insecticide resistance within a natural population of Drosophila melanogaster during population growth, which we considered the most important ecological factor there, we conducted a series of genetic analyses of resistance factors involved in that population and compared individual-based intrinsic rates of natural increase among resistance genotypes. However, some researchers have argued that it is a misconception to apply the intrinsic rate of natural increase to individuals, because it is a population parameter. We consider that their criticisms were incorrect. In this article, I described our research briefly and set forth the reasons why we conducted these studies.展开更多
文摘The dynamics of genetic variation in susceptibility to insecticides within a natural population of Drosophila melanogaster (Meigen) at Katsunuma (Yamanashi Prefecture, Japan) was examined. Two resistance factors for three organophosphate insecticides (OPs), a resistant-type acetylcholinesterase (AChE) and a cytochrome P450 monooxygenase (cytochrome P450), have already been suggested to be involved within the Katsunuma population. In this study, genetic variances were estimated for susceptibility to other classes of chemicals than OPs, permethrin (a pyrethroid) and dichloro-diphenyl-trichloroethane (DDT;an organo-chlorine), which existed simultaneously with genetic variances for susceptibility to OPs. Analyses of variance for susceptibility to permethrin and DDT showed highly significant variation among isofemale lines from the Katsunuma population, and the genetic variances for susceptibility to each insecticide fluctuated differently during this period. The impacts of fluctuations of genetic variation in susceptibility to one class of insecticides on genetic variation in susceptibility to other classes of insecticides existing simultaneously within the natural population were discussed.
文摘From the standpoint of evolution, caring for old parents may be maladaptive, because they have ceased reproduction, so that the benefit for inclusive fitness may not be expected. Then why do we care for old parents? In this study, the evolution of care for the elderly was examined, by using an evolutionary genetic model, in which pleiotropic constraints between behaviors expressed in different social contexts among family members were assumed. It was suggested that establishing a solid relationship with parents during infancy should be selectively favorable, even though old parents have to be cared for in the future, but that caring for old parents may be excluded from the population if this behavior imposes high costs on reproduction of the younger generation. Despite the diminishing numbers of individuals within the population, care for the elderly may not be readily selected against, but at the same time this may not contribute to the rate of increase in population size. The significance of discussing the behavior of elderly caring from the standpoint of evolutionary genetics was emphasized.
文摘In order to gain insights into the seasonal dynamics of genetic variation in insecticide resistance within a natural population of Drosophila melanogaster during population growth, which we considered the most important ecological factor there, we conducted a series of genetic analyses of resistance factors involved in that population and compared individual-based intrinsic rates of natural increase among resistance genotypes. However, some researchers have argued that it is a misconception to apply the intrinsic rate of natural increase to individuals, because it is a population parameter. We consider that their criticisms were incorrect. In this article, I described our research briefly and set forth the reasons why we conducted these studies.
