In the Meiji era we had two serious Bruchid pests, Callosobruchus chinensis and Bruch us pisorum in Japan. In 1926 B. rulimanus was found in Kyushu. Urgent countermeasures were taken to meet the new pest: biology of and control measures against the weevil were studied extensively especially by Kamito. In 1937 the basis of classification of Bruchids in Japan was established by Chujo. Recently the introduction of C. maculatus was noticed. During and after World War II Ishii started his pioneering study on biochemical resistance to Bruchid attack in legume seeds. Also, Utida was carrying on his continuing study of experimental populations of C. chinensis. The range of his study was enlarged from density effect to interspecific competition, host-parasite relationship and phase dimorphism in Callosobruchus spp. The new pheromones of "oviposition marker" and "erectin" were identified and synthesized by Yamamoto and his school in the bean weevils. Some authors took a growing interest in the life history strategy of Bruchids, coevolution between bean and weevil, and evolution or domestication of the bean weevils. Dealing with the increase of imported beans from foreign countries into Japan, the techniques of bean fumigation with methyl bromide and phosphine for quarantine fumigation was developed. In the laboratories of Universities and the private laboratories of agricultural Chemicals Companies many investigations were carried on using the bean weevil as an experimental insect to develop new chemicals without environmental disruption.

Bruchids and Legumes: Economics, Ecology and Coevolution

The demographic genetics of a population of Liatris cylindracea were studied. The population has a nonstable age structure; there is a deficiency of young plants. Plants were divided into six age classes and the average heterozygosity of each age class measured at 27 allozyme loci. Average heterozygosity increases with increasing age class while FST, the standardized genetic variance, decreases. In addition, a positive relationship was found between individual heterozygosity and fecundity, longevity, and speed of development. Both age and reproductive potential are positively correlated with individual heterozygosity. The time of initial flowering is also related to heterozygosity; plants flowering after 2 seasons being more heterozygous than plants which do not flower. It is concluded that individual heterozygosity is being selected for.

The Demographic Genetics of Liatris cylindracea Michx. (Compositae)

Community selection, defined as the differential proliferation and/or extinction of communities, can bring about a response that may be qualitatively different from the response to selection acting at lower levels. This is because community selection can result in genetic changes in all of the species within the community by acting on the interaction among species. In the experiment presented here, a series of one generation assays were performed on the coevolved communities of two species of flour beetles, Tribolium castaneum and T. confusum, discussed by Goodnight (1990). Two community assays and one single-species assay were performed. Taken together, these provide insights into the genetic basis of the response to community selection. The first community assay involved measuring the selected traits on the original coevolved communities that had been subjected to community selection. This assay indicated that all of the selection treatments resulted in a significant response to selection in the original coevolved communities. The single-species assay involved separating the coevolved communities into their constituent single-species populations and again measuring the selected traits on these populations. None of the single-species populations exhibited a significant response to selection; thus the responses to community selection observed in the first community assay are expressed only in a community context. The second community assay again involved separating the coevolved communities into their constituent single-species populations; however, in this assay a competitor of the opposite species that had never been exposed to community selection was added to each population to form a "reconstructed" community. The results of this assay were that for two traits, emigration rate in T. castaneum and emigration rate in T. confusum, the genetic identity of the competing species did not affect the response to selection. This indicates that the competing species was acting like a nonevolving part of the environment. For the other two traits measured, population size in T. castaneum and population size in T. confusum, the results were very different. For these traits there was no detectable response to selection in the reconstructed communities. This indicates that for these traits the response to selection cannot be attributed to a genetic change in either species independently of the other species in the community. Rather it resides in the interaction between the two species.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1558-5646.1990.tb03851.x

Experimental studies of community evolution ii: the ecological basis of the response to community selection.

1Robert Taylor (University of Minnesota), D. A. Cawthon, Mrs. Joyce Reed, Mrs. Carol Mooney, Wayne Landerholm, and John Moy provided technical assistance at various times during the course of this study. I am grateful as well to Joseph Connell and William Murdoch (University of California, Santa Barbara), F. A. Lints (Catholic University of Louvain), Monte Lloyd and Thomas Park (University of Chicago), Richard Lewontin (Harvard University), William Heinze (University of Illinois Medical Center), Peter Frank (University of Oregon), J. S. F. Barker (University of Sydney), John Maynard Smith (University of Sussex), and George Sacher (Argonne National Laboratories) for discussions and advice during the conduct of the research and preparation of the manuscript. The manuscript benefited from critical readings by Thomas Park and Michael Wade (University of Chicago) and John Lussenhop (University of Illinois, Chicago Circle). This study was supported by National Science Foundation grants GB-7280, GB-17028, and GB-24818 and by a general research grant from the University of California, Santa Barbara. Medawar (1952) set forth an evolutionary theory of senescence based on concepts of adaptive demography; later, Hamilton (1966) and Charlesworth (1973) corrected and clarified mathematical aspects of Medawar's theory. Variants of the theory, based on similar demographic considerations but invoking different genetic explanations, have been proposed by Williams (1957, 1966), Edney and Gill (1968), and Guthrie (1969). The virtue of the approach used by all of these authors is that it views senescence not as a pathological condition but, rather, as just one component of an organism's life history. Insofar as life-history attributes are adaptive, senescence may be an integral part of an adapted constellation of characters.

Senescent Decline in Flour Beetle Strains Selected for Early Adult Fitness

Hypothesis.-Tribolium castaneum is a primary colonist. Adults of this species lead a nomadic existence in which dispersal is intensive and extensive, and highly responsive to density. T. confusum is a secondary colonist. By comparison with T. castaneum, dispersal of T. confusum adults is less intensive, and less responsive to the presence of other individuals. In both species of Tribolium the tendency to disperse persists throughout adulthood. Development of the hypothesis.-Beetles of the Tenebrionid subfamily Ulominae, to which Tribolium belong, are typically associated with rotting wood and the loose bark of trees (Good, 1933). T. castaneum is apparently found in this habitat in forests of the Indian subcontinent (Good, 1933), and Sinha (1968) notes that T. castaneum and T. confusum are occasionally found separately in Canadian forests. Feral populations of Tribolium have been observed in the nests of bees and birds, and in manure (Hinton, 1948; Lefkovitch in Mertz, 1971; Jones, 1967). The beetles, however, are most abundant in warehouses where they infest stored products. Such "domestic" populations of both species show a cosmopolitan distribution. The diets of T. castaneum and T. confusum overlap broadly, and include a bewildering array of plant and animal products (Good, 1933) which need only be sufficiently soft or small in size to be eaten. Immatures and adults of both species are also predaceous and cannibalistic (Park et al., 1965). These activities are modified according to the nutritional quality of their food (Sokoloff and Lerner, 1967). To be sure, comparative nutritional studies (Sokoloff et al., 1966a, 1966b; Sinha, 1966, 1972) have documented species differences in the suitability of specific foods for development and reproduction, but, on the whole, one is impressed with the opportunistic generality in the diets of both species. These and related aspects of the biology of Tribolium are comprehensively reviewed by Sokoloff ( 1974). Tribolium habitats are undoubtedly temporary. Whether a rotting log or a sack of flour, a Tribolium habitat can be expected to support a variable number of generations before it completely deteriorates. It is not unlikely, then, that Tribolium populations should alternate between short periods of rapid population growth and prolonged periods of decline. To this characteristic Mertz (1971) attributes much of the natural selection for long reproductive life (iteroparity) in Tribolium species. If breeding habitats are widely distributed in space, a long life span would give females time to search for them (cf. Cole, 1954). If we make the reasonable assumption that persistent habitats also arise infrequently, then it follows that iteroparity, which may have evolved in response to prolonged population decline within persistent local habitats, will also be adaptive when those habitats finally deteriorate. Tribolium females produce eggs continuously. They may lay them over a wide range of habitats, each with a low probability of successfully supporting their offspring to adulthood. Such temporal and spatial uncertainty in the survival of immatures will also promote the evolution of iteroparity (Murphy, 1968). Adaptive dispersal is an element of

Evolution of the migration response: emigration by tribolium and the influence of age.

Male and female flour beetles are described in terms of one mortality characteristic: adult age at death. Four strains of Triboliurn ccnfusum and four strains of Tribolium castaneum were studied. The actual data are reported in two Appendix tables. Death rates were found to depend upon the species, strain, sex, and age of the individuals concerned. Differences between the mortality patterns of the two sexes were especially striking and seemed to have a common character for all strains and both species.

W. J. Youden

Papers

Mortality Patterns in Eight Strains of Flour Beetles