Geographic variation in the population cycles and spatial synchrony of the mulberry tiger moth, Lemyra imparilis (Lepidoptera: Erebidae), in the Kansai region, western Japan

Ever since Elton, the 3–5 year density cycles in lemmings (and other microtines) in Fennoscandia have troubled scientists. Explanations have involved intrinsic regulation and trophic interactions. We have analysed yearly changes in fall abundances for lemmings over 25 years from two local mountain sites in South Norway. These time series appear to have an underlying nonlinear structure of order two. Fitting a piece-wise linear threshold model of maximum order two, the most parsimonious model was, however, of first order for both series. The resulting dynamics from this model is a limit cycle. Reformulating the model in terms of abundances yields a model which combines (delayed) density-dependent effects and the influence of the cyclic phase. The delayed density-dependence of one part of the model is consistent with an effect of specialist predators during the peak and crash phases of the cycle, although other trophic interactions cannot be excluded.

Annual variation in the testicular cycle of a population of stinkpot turtles, Sternotherus odoratus, from Virginia was found to occur in late stages of spermatogenesis but not in initiation of the cellular cycle or in the testis weight cycle. Seasonal variation in testis weight was generally concordant with variation in the spermatogenic cycle and followed the typical postnuptial pattern in which testicular growth and recrudescence begins in late spring, followed by peak weights and spermiogenesis in August, and regression in fall and winter. Minimum testis weights and onset of spermatogenesis were in May. The variables seminiferous tubule diameter, carapace length, and month accounted for 89.3% of the variation in testis weight; year accounted for 0.1%. Males in this population matured at the end of their second year at a minimum carapace length of 51 mm. Geographic variation in timing of spermatogenic events is discussed with reference to populations in Alabama and Michigan. Water temperature is the probable cue for initiation of spermatogenesis in stinkpots, and the variation in occurrence of later stages may be due to individual movement in the water column. Comparisons are made with the testicular cycle of a syntopic population of painted turtles, Chrysemys picta, studied concurrently.

This study reconstructs patterns of stress and phenotypic variation in prehistoric Japan. Greater evidence for stress is indicated by elevated enamel hypoplasia frequency among Jomon foragers from western compared to eastern Japan. Geographic variation in stress between Jomon people is related to plant-based diets and resource scarcity in western Japan. The hypothesis that Jomon people from western Japan had shorter stature than those from the east is, therefore, tested. Relationships between individual stature, geographic location, and enamel hypoplasia presence/absence are also explored. In addition, increased population density and reliance on plant foods are observed during the Late/Final Jomon period in western Japan. A second hypothesis proposing shorter stature for Late/Final Jomon people compared to those from the Middle Jomon period is tested. Statistically significant differences in stature between males and females from eastern and western Japan were not observed. Individual relationships between enamel hypoplasia and stature were rejected. Stature decreased significantly over time in western Japan. It is possible that stature between the eastern and western Jomon did not differ because the western Jomon experienced catch up growth after childhood stress episodes. It is also likely that variation in stress between the two groups was not severe enough to warrant stature reduction. Decreases in stature through time in western Japan are related to increased exposure to chronic infection and dietary stress. Overall, these results indicate that enamel hypoplasia frequencies provide an adequate index of general stress but may fail to predict the impact of stress on the human phenotype.

The Kansai region in Western Japan includes Osaka, the central city of Western Japan; Kyoto, a famous ancient capital; Nara, an ancient capital older than Kyoto; and Kobe, one of the first international ports in Japan. Tokyo has a history of approximately 400 years, whereas Kansai has a history of approximately 1,800 years. Each city in Kansai has its own traditional and unique culture, where new and innovative ideas are often conceived. In Kansai, some family physicians are attempting to establish Japanese family medicine as a specialty in their medical systems and context. Recently, a new era has begun in general practice in Japan. The Japan Primary Care Association, established in 2010 by the merger of the Japanese Academy of Primary Care Physicians, the Japanese Academy of Family Medicine, and the Japanese Society of General Medicine, has become the largest academic association of general practitioners in Japan. Members include practicing family physicians (primary care physicians), hospital-based general practitioners, and university-based general practitioners. Hospital-based general practitioners in Japan are interested in diagnosis-oriented medical practice. They focus on common symptoms in uncommon diseases and uncommon symptoms in common diseases. Some family physicians and university-based general practitioners in Japan have more advanced medical education; however, most of them teach only basic clinical skills and diagnosis-oriented medical practices rather than specialization in family medicine. Some family physicians who have studied in North America or Europe disconnect themselves from the Japanese style of practicing medicine. They seem to regard their way as the only correct way to practice medicine. According to them, their specialty is a combination of internal medicine, minor surgery, orthopedics, pediatrics, obstetrics, and gynecology, thus providing a patchwork of medical care. But a patchwork of medical care is only one side of family medicine, not a specialty. However some family physicians who have studied in North America or Europe insist that Japanese family physicians who have not studied abroad are not family physicians. Therefore, satisfactory answers as to what kind of specialty they should have can be difficult to find and hence, they often fall into identity crises. Unfortunately, some leave primary care and family medicine and move on to become alternative specialists. Due to such conditions, very few Japanese family physicians have pursued further education to become specialists of family medicine. Family medicine can be considered a specialty in itself. It can be defined as care that is accessible, comprehensive, coordinated, continuous, and accountable (ACCCA). Interestingly, the practices of some Japanese specialists who establish private clinics also provide this sort of care. Thus, ACCCA is not exclusively confined to family medicine in Japan. Then, how can we characterize family medicine, especially in Japan? Japanese patients tend to come to physicians in the early stages of their diseases because they are covered under a national health insurance system. Many patients are cured before severe symptoms develop. If the diagnosis is difficult, family physicians can consult hospital-based general practitioners. If patients may need palliative care, or they may have dementia, unexplained medical symptoms, and several other conditions, their diagnoses are easy, but solution is not. One of the roles of family physicians is to lead solutions by providing coordinated, multi-professional collaborative care to these patients. Some hospital- and university-based general practitioners are not interested in the care of such patients. Thus, family physicians are more interested in providing solutions through collaboration than in diagnosing. But solution does not mean expedient treatment, for example, administering iron to an anemic patient regardless of the cause or Scopolamine for abdominal pain regardless of the cause. They are not what family medicine is about. Family physicians should treat such cases with varied approaches as well as perseverance to achieve a definite solution. These medical practice based on solutions can be called medical practice, which is one of the essences of family medicine. Recognition of the solution-oriented approach is still uncommon. Appraisal of various medical practices and a commonly accepted definition of solution-oriented medical practice are necessary; this process should lead to a greater awareness of the true essence of family medicine in Japan, and help for many family physicians who suffer from an identity crisis.

Background: Transthyretin tetramer destabilizing variants accelerate hereditary transthyretin amyloidosis and shorten survival. The contribution of transthyretin tetramer destabilizing variants to prognosis in the general population, particularly in Asians, remains limited. Objective: To quantify nationwide prevalence of transthyretin tetramer destabilizing variants in Japanese population and evaluate its association with incident heart failure and cardiovascular mortality. Methods: Data were used from Biobank Japan, a hospital-based national biobank that enrolled participants between 2003 and 2007. After stringent sample and variant quality control, 7,949 individuals with complete survival information remained eligible for analysis. The entire TTR locus was interrogated using either targeted sequencing or whole-genome sequencing. A 1:1 age-matched subcohort (2,096 HF cases, 2,096 non-HF controls) served as validation. Longitudinal clinical data available in a nested observational subset were also examined and all time-to-event outcomes were ascertained from follow-up records. Results: Among 7,949 participants, the mean baseline age was 65 ± 13 years and 32.3 % were women. Sixty individuals (0.75 %) carried TTR variants. Prevalence was highest in Kanto region (eastern Japan, including Tokyo; 0.78 %) and in Kansai region (western Japan, including Osaka; 1.08 %). After adjusting for sex, body-mass index, smoking status, hypertension, diabetes, and dyslipidemia, carriage of the p.Asp119Asn variant was linked to a 39 % higher risk of incident heart failure (HR 1.39, 95 % CI 1.07–2.02; P = 0.042) and to more than a twofold increase in composite cardiovascular death ,defined as death from ischemic events or progressive heart failure (HR 2.41, 95 % CI 1.20–4.86; P = 0.014). This excess cardiovascular mortality persisted when the analysis was restricted to participants who developed heart failure. All-cause mortality did not differ (HR 1.20, 95 % CI 0.72–2.00; P = 0.48), and age-matched models yielded similar estimates. Conclusions: p.Asp119Asn is present in about 1 in 130 Japanese adults, a prevalence far higher than that of destabilizing TTR variants reported in Europeans. It independently accelerates heart failure onset and doubles cardiovascular mortality, supporting ancestry-tailored genetic screening and early therapeutic trials in East Asia.

The Japanese Archipelago consists of a series of isolated yet interconnected islands off the Eurasian continent. The linear topography of the archipelago presents a unique biogeographic context for the dispersal of organisms from the continent. In this study, mitochondrial DNA (mtDNA) and single-nucleotide polymorphism (SNP) variation were employed to elucidate the dispersal history of the Japanese clouded butterfly (Parnassius glacialis) across the Japanese Archipelago, including the northern island (Hokkaido), the main island (Honshu), and Shikoku Island. Network analysis of 1192bp of mtDNA (cytochrome oxidase I and II) regions revealed 49 haplotypes and three distinct haplotype groups, which correspond geographically to Eastern Japan, Western Japan, and Chugoku-Shikoku. The Chugoku-Shikoku group is the most ancient lineage. Divergence time estimates using whole-genome sequencing of mtDNA suggest that the Japanese lineage diverged from the continental P. glacialis approximately 3.08 million years ago (Ma). Subsequently, the Eastern Japan and Western Japan lineages diverged from the Chugoku-Shikoku lineage around 1.06Ma, with subsequent divergence of the Eastern and Western Japan lineages at approximately 0.62Ma. P. glacialis is estimated to have expanded its distribution via a land bridge that once connected China and the Japanese Archipelago. Population structure analysis based on 3067 SNP genotypes revealed five distinct genetic structures within the Japanese Archipelago, indicating geographical differentiation. Through mtDNA and SNP variation analyses, four primary genetic barriers were identified: between Hokkaido and Honshu, between Eastern and Central Japan, within the Kansai region, and in the Chugoku region. The first three barriers correspond to notable geographical features, the Blakiston Line, a line parallel to the Itoigawa-Shizuoka Tectonic Line, and a boundary crossing Lake Biwa. These findings suggest that Japanese P. glacialis diverged from the continental P. glacialis and expanded its range across the Japanese Archipelago via western routes, leading to its current distribution.

Geographical gradients in the stability of cyclic populations of herbivores and their predators may relate to the degree of specialization of predators. However, such changes are usually associated with transition from specialist to generalist predator species, rather than from geographical variation in dietary breadth of specialist predators. Canada lynx (Lynx canadensis) and snowshoe hare (Lepus americanus) populations undergo cyclic fluctuations in northern parts of their range, but cycles are either greatly attenuated or lost altogether in the southern boreal forest where prey diversity is higher. We tested the influence of prey specialization on population cycles by measuring the stable carbon and nitrogen isotope ratios in lynx and their prey, estimating the contribution of hares to lynx diet across their range, and correlating this degree of specialization to the strength of their population cycles. Hares dominated the lynx diet across their range, but specialization on hares decreased in southern and western populations. The degree of specialization correlated with cyclic signal strength indicated by spectral analysis of lynx harvest data, but overall variability of lynx harvest (the standard deviation of natural-log-transformed harvest numbers) did not change significantly with dietary specialization. Thus, as alternative prey became more important in the lynx diet, the fluctuations became decoupled from a regular cycle but did not become less variable. Our results support the hypothesis that alternative prey decrease population cycle regularity but emphasize that such changes may be driven by dietary shifts among dominant specialist predators rather than exclusively through changes in the predator community.

Selection mosaic theory explains observations of polymorphism in host-pathogen interactions in terms of spatially variable natural selection but does not account for population dynamics. In contrast, classical host-pathogen theory easily explains observations of population cycles, but does not explain the persistence of pathogen polymorphism. Here, we synthesize these two frameworks to understand the effects of population cycles on pathogen polymorphism. We show that geographic variation in the frequency of two morphotypes of a baculovirus that infects the Douglas-fir tussock moth (Orgyia pseudotsugata) depends on the frequency of Douglas-fir (Pseudotsuga menziesii), an important tussock moth host tree. The morphotype frequency data are best explained by host-pathogen models that combine a selection mosaic with population cycles. In our model, population cycles intensify pathogen competition across a selection mosaic, leading to a strong effect of Douglas-fir frequency on morphotype frequency that matches the data. Models without host-pathogen cycles or a selection mosaic project only weak effects of varying Douglas-fir frequency. Our model further projects that a biopesticide made up of both viral morphotypes would be more effective than the current single-morphotype biopesticide, demonstrating that our synthesis of selection mosaic theory and host-pathogen theory provides useful insights into pest management.

We investigated the geographic diversification of Plestiodon finitimus, which occurs in the central to northern parts of the Japanese Islands, based on a time-calibrated mitochondrial DNA (mtDNA) phylogeny and external morphological characters. The mtDNA phylogeny suggests that P. finitimus diverged from its sister species Plestiodon japonicus in western Japan 2.82-4.63 million years ago (MYA), which can be explained by geographic isolation due to the spread of sedimentary basins in the Pliocene. The primary intraspecific divergence was that between P. finitimus lineages in central and northeastern Japan 1.58-2.76 MYA, which could have been caused by the upliftings of major mountain ranges. In the northeastern lineage, mtDNA and morphological characters suggest a geographic differentiation between sub-lineages of the northwestern Tohoku District (α) and other areas (β). Although the sub-lineage β occurs in a disjunct geographic range, consisting of Hokkaido and the central to south of Tohoku, these areas are bridged by populations with intermediate characteristics along the Pacific side of northern Tohoku. Overall, the geographic variation in P. finitimus in northern Japan can be explained by an initial allopatric divergence of the sub-lineages α and β at 0.71-1.39 MYA, a recent northward expansion of the sub-lineage β, and subsequent secondary introgressive hybridization between the sub-lineages.

Adaptation to local pollination regimes and secondary contact of allopatrically differentiated populations with respect to pollination ecology may result in geographical variation in floral traits. We examined the contributions of these two processes in Isodon shikokianus, which showed remarkable geographical variation in corolla tube length in western Japan. Corolla tube length varied among 17 study populations located within a relatively narrow area, and covaried with altitude and distribution of two bumblebee pollinators with different tongue lengths: the longer corolla was found at lower altitudes where the long‐tongued pollinator was more abundant, and vice versa. Additionally, bumblebee species preferentially visited flowers that fit their tongue lengths. Population genetic analysis based on 11 microsatellite loci revealed that populations with long and short corolla tubes constituted genetically distinct groups. Migration rates were low between the groups, but high within each group. These results indicate that two genetically differentiated groups made secondary contact and hybridized, and gene flow between the groups was limited. Thus, the geographical variation in corolla tube length in I. shikokianus may be a result of past allopatric differentiation and subsequent secondary contact of populations with different corolla tube lengths. The variation in corolla tube length within a narrow area may be maintained by selection owing to the altitudinally structured pollinator assemblages. Altitudinal differences in relative abundance of two pollinators and their assortative visitation with respect to corolla tube length may contribute to reproductive isolation between the two groups.

Population cycles are fundamentally linked with spatial synchrony, the prevailing paradigm being that populations with cyclic dynamics are easily synchronised. That is, population cycles help give rise to spatial synchrony. Here we demonstrate this process can work in reverse, with synchrony causing population cycles. We show that timescale-specific environmental effects, by synchronising local population dynamics on certain timescales only, cause major population cycles over large areas in white-tailed deer. An important aspect of the new mechanism is specificity of synchronising effects to certain timescales, which causes local dynamics to sum across space to a substantial cycle on those timescales. We also demonstrate, to our knowledge for the first time, that synchrony can be transmitted not only from environmental drivers to populations (deer), but also from there to human systems (deer-vehicle collisions). Because synchrony of drivers may be altered by climate change, changes to population cycles may arise via our mechanism.

Many defoliating forest lepidopterans cause predictable periodic deforestation. Several of these species exhibit geographical variation in both the strength of periodic behavior and the frequency of cycles. The mathematical models used to describe the population dynamics of such species commonly predict that gradual variation in the underlying ecological mechanisms may lead to punctuated (subharmonic) variation in outbreak cycles through period-doubling cascades. Gypsy moth, Lymantria dispar, in its recently established range in the northeastern United States may represent an unusually clear natural manifestation of this phenomenon. In this study we introduce a new statistical spatial-smoothing method for estimating outbreak periodicity from space-time defoliation data collected with spatial error. The method statistically confirms the existence of subharmonic variation in cyclicity among different forest types. Some xeric forest types exhibit a statistical 4-5 year period in outbreak dynamics, some mesic forest types a 9-10 year period, and some intermediate forest types a dominant 9-10 year period with a 4-5 year subdominant superharmonic. We then use a theoretical model involving gypsy moth, pathogens, and predators to investigate the possible role of geographical variation in generalist predator populations as the cause of this variation in dynamics. The model predicts that the period of gypsy moth oscillations should be positively associated with predator carrying capacity and that variation in the carrying capacity provides a parsimonious explanation of previous reports of geographical variation in gypsy moth periodicity. Furthermore, a two-patch spatial extension of the model shows that, in the presence of spatial coupling, subharmonic attractors can coexist whereas nonharmonic attractors (i.e., where the cycle lengths are not integer multiples of one another) cannot.

The distribution of gene frequencies in the phosphoglucomutase-1 (PGM1) system was investigated in two Japanese populations from Yamaguchi (Western Japan) and Okinawa (Southern Japan) using an improved isoelectric focusing method permitting the successful detection of the most anodal variant PGM1 3+. PGM1*7+ occurred with a polymorphic frequency of 0.012-0.021. A difference in the gene frequency was observed between the two populations. In comparison with neighboring populations, the Yamaguchi population was similar to Mongolians and Koreans in North China, and Okinawa to Zhuang in South China.

Multiple introductions of a species are thought to enhance its invasion success by increasing genotypic diversity; this involves frequent crossing among different lineages. However, genetic diversity through crossing is less likely in autogamous species. To understand the impact of multiple introductions on the colonization success of autogamous species, we studied hairy bittercress, Cardamine hirsuta, which invaded Japan several decades ago. We detected temporal changes in its population structure using nine microsatellite markers amplified from leaf samples collected from 87 sites between 2009 and 2010, and herbarium specimens collected between 1988 and 2007. To examine whether the phenotypic variation corresponded with the genetic population structure, we also investigated the geographic variation in the lateral stamen number of this species across 49 sites. The present populations can be divided into three genetic groups, which are distributed in northern, eastern, and western Japan. This finding suggests that there are three invasive lineages (North, East, and West) in Japan. The geographic variation in lateral stamen number corresponded to the distributions of these lineages. The former distributions of the North and West lineages mostly corresponded to those found at present, but they were also historically found in eastern Japan. However, the East lineage has apparently expanded into eastern Japan, resulting in a change in dominant lineages over only a few decades. For the autogamous C. hirsuta, multiple introductions contributed toward colonization success over a wider range, which was associated with a local change in the dominant lineages.

Four highly variable microsatellite loci, Acs1*, Acs3*, Acs4* and Acs9*, were isolated and then used to investigate genetic diversity and population structure in black sea bream, Acanthopagrus schlegeli, collected from wild populations of six locations (western Japan and southern Korea), and hatchery stock and post-stock populations from Hiroshima Bay. When allelic segregation of each microsatellite locus was examined using the single spawning pair and their progeny, all loci were well fitted to the Mendelian manner of inheritance. The genetic variations at these loci in the eight populations revealed high levels of variability. In the wild populations the mean number of alleles per locus was 10.8-13.5, and the mean observed hetrozygosity was 0.755-0.828. In contrast, these values in hatchery stock population were 10.0 and 0.776, respectively. Genetic distance indicates the existence of geographic divergence between western Japan and south Korea, and little genetic differentiation among populations in western Japan.