Interannual Abundance Fluctuations of Two Oceanic Squids in the Pacific Ocean Can Be Evaluated Through Their Habitat Temperature Variabilities

Neon flying squid (Ommastrephes bartramii) and jumbo flying squid (Dosidicus gigas) are two commercially essential oceanic squids in the Pacific Ocean. An in-depth understanding of the mechanisms of their annual and interannual abundance fluctuations under environmental and climate variabilities can ensure ration and suitable management. Thus, the annual and interannual abundance fluctuations of the stock of the western winter-spring cohort of O. bartramii and D. gigas off Peru Exclusive Economic Zone (PEEZ) waters and their association with habitat temperature variabilities are explored in this study based on the historical Chinese Squid-jigging fishery data from 2003 to 2020. The habitat temperature variabilities were defined as the effective principal components of the SST at the squids’ two important habitats (spawning and feeding ground) through life histories according to the principal component analysis. The Hodrick—Prescott filter analysis was conducted to quantify the annual and interannual fluctuations of abundance and habitat temperature variabilities. Furthermore, the generalized additive model (GAM) was employed to investigate their associations. The results demonstrated different but not synchronous trends of abundance for O. bartramii and D. gigas. Regarding O. bartramii, the interannual abundance first decreased (2003∼2013) and then increased (after 2014). For D. gigas, the interannual abundance kept decreasing within 2003∼2020. Their annual trends have presented large fluctuations over years. The results of GAM indicated that using habitat temperature variabilities only can trace the abundance trend of O. bartramii and D. gigas at an interannual but not annual scale. Further studies verified that Pacific Decadal Oscillation (PDO) is a crucial factor affecting the interannual abundance trend of these two squids through the habitat temperature variabilities. However, this study indicates that the habitat temperature variabilities not only are related to other large-scale factors, which are not investigated currently at an interannual scale, but also, are combined with other small- or middle-scale factors at an annual scale on their impacts to the abundance fluctuations of these two squids. Therefore, in order to better explain the mechanisms of annual and interannual abundance fluctuations of O. bartramii and D. gigas under environmental and climate variabilities, the importance of combining other potential factors into consideration is highlighted.

Cyclic abundance fluctuations in a completely isolated population of Euphydryas maturna

A highly isolated and the last autochthonous Czech Republic population of the endangered Euphydryas maturna (Lepidoptera: Nymphalidae) is monitored since 2001 by larval nests counts. The 20 years` time series displays remarkable abundance fluctuations with peak-to-peak period 11 years, peak numbers >150 and bust numbers <15 larval nests (arithmetic and harmonic means: 92.6 and 36.3). Establishment of more favourable management of the site probably heightened and prolonged the boom phase but did not alter the overall pattern. We attribute the cycling to pressures of natural enemies. Climatically unfavourable years appear deepening the bust phase. Species displaying such fluctuations cannot be conserved within a single site, which is being addressed by ex-situ breeding of the Czech stock and recent reestablishment of two additional populations, with the aim to achieve asynchronous dynamics of the local populations and eventually stabilise the regional metapopulation.

Ecological Stability Emerges at the Level of Strains in the Human Gut Microbiome

The human gut microbiome is a complex community that harbors substantial ecological diversity at the species level, as well as at the strain level within species. In healthy hosts, species abundance fluctuations in the microbiome community are thought to be stable, and these fluctuations can be described by macroecological laws. However, it is less clear how strain abundances change over time. An open question is whether individual strains behave like species themselves, exhibiting stability and following the macroecological relationships known to hold at the species level, or whether strains have different dynamics, perhaps due to the relatively close phylogenetic relatedness of co-colonizing lineages. In this study, we sought to characterize the typical strain-level dynamics of the healthy human gut microbiome on timescales ranging from days to years. We show that genetic diversity within almost all species is stationary, tending towards a long-term typical value within hosts over time scales of several years, despite fluctuations on shorter timescales. Moreover, the abundance fluctuations of strains can be sufficiently described by a stochastic logistic model (SLM), a model previously used to describe abundance fluctuations among species around a fixed carrying capacity, in the vast majority of cases, suggesting that strains are dynamically stable. Lastly, we find that strain abundances follow the same macroecological laws known to hold at the species level. Together, our results suggest that macroecological properties of the human gut microbiome, including its stability, emerge at the level of strains.

Microhabitats Utilization by Solitary Parasitoids and Predatory Insects as Indicators of Oil Palm Agroecosystem’s Capacity to Support Insect Species Diversity

Microhabitats capacity to support insect species diversity and persistence were evaluated implementing solitary parasitoids and predatory insects according to different phases of herbicide and chemical fertilizer applications. Two species of the genus Xanthopimpla (Ichneumonidae) and one species of the genus Pompilus (Pompilidae) showed relationships on vegetation-type microhabitats, notably natural weeds, leguminous cover crops, and the beneficial plant Turnera subulata, while two species of the genus Evania (Evaniidae) showed relationships with chipped oil palm trunks. One species from the genus Odontomachus (Formicidae) as an exclusive predatory ant was related to both chipped oil palm trunks and the beneficial plant T. subulata. Xanthopimpla parasitoids exhibited abundance fluctuations difference around natural weeds during herbicide application phases between three- and six-years old oil palm stands, with decreased and increased abundance patterns of the former and the latter, respectively. 18 years old oil palm stand showed increased abundance patterns only along with the different phases of chemical fertilizer applications. The importance of natural weeds diversity, restrictions of leguminous cover crops, frequency of herbicide applications, and the arrangements between beneficial plants and wood-based microhabitats that benefited insect parasitoids and predators were discussed.

Rodent host population dynamics drive zoonotic Lyme Borreliosis and Orthohantavirus infections in humans in Northern Europe

Zoonotic diseases, caused by pathogens transmitted between other vertebrate animals and humans, pose a major risk to human health. Rodents are important reservoir hosts for many zoonotic pathogens, and rodent population dynamics affect the infection dynamics of rodent-borne diseases, such as diseases caused by hantaviruses. However, the role of rodent population dynamics in determining the infection dynamics of rodent-associated tick-borne diseases, such as Lyme borreliosis (LB), caused by Borrelia burgdorferi sensu lato bacteria, have gained limited attention in Northern Europe, despite the multiannual abundance fluctuations, the so-called vole cycles, that characterise rodent population dynamics in the region. Here, we quantify the associations between rodent abundance and LB human cases and Puumala Orthohantavirus (PUUV) infections by using two time series (25-year and 9-year) in Finland. Both bank vole (Myodes glareolus) abundance as well as LB and PUUV infection incidence in humans showed approximately 3-year cycles. Without vector transmitted PUUV infections followed the bank vole host abundance fluctuations with two-month time lag, whereas tick-transmitted LB was associated with bank vole abundance ca. 12 and 24 months earlier. However, the strength of association between LB incidence and bank vole abundance ca. 12 months before varied over the study years. This study highlights that the human risk to acquire rodent-borne pathogens, as well as rodent-associated tick-borne pathogens is associated with the vole cycles in Northern Fennoscandia, yet with complex time lags.