Impact Population Dynamics Research Articles

OBSTETRIC OUTCOMES OF DELIVERY IN WOMEN WITH A HISTORY OF REPRODUCTIVE LOSS

Relevance. The protection of women's reproductive health holds significant medical and social importance in Ukraine, especially in light of the declining birth rate, which adversely impacts population dynamics. This issue has become even more critical since the onset of the full-scale invasion of Ukraine. Currently, Ukraine faces one of the most challenging demographic situations in Europe. According to the Institute of Demography of the National Academy of Sciences of Ukraine, the country’s total population is projected to decrease to 36 million by 2026 and to 34.8 million by 2050. This decline is largely attributed to low fertility rates, which are closely linked to reproductive losses, particularly during pregnancies up to 22 weeks. Given the forecasted population decline, addressing the preservation and enhancement of reproductive health and increasing birth rates must become a priority in demographic policy. Therefore, implementing strategies to reduce pregnancy loss is critical for improving Ukraine's demographic future. Aim: to assess the obstetric outcomes of childbirth in women with a history of reproductive loss. Materials and Methods. A prospective study was conducted involving 75 pregnant women with a history of one reproductive loss. The participants were divided into two groups: the main group comprised 38 pregnant women who enrolled in a women's consultation regarding pregnancy and began their participation in the study after the onset of the full-scale war in Ukraine; the comparison group included 37 women who registered for pregnancy before the war began. The control group involved 30 women without a history of reproductive losses. 44.7% of pregnant women had the status of an internally displaced person. All women underwent an analysis of the course of childbirth and the postpartum period according to the histories of pregnancy and childbirth (form No. 096/o). Management of pregnancy and delivery of women in the research groups was carried out in accordance with the current Orders of the Ministry of Health of Ukraine. Variational and statistical processing of the results was carried out using the “STATISTICA 13” program. Results. Analysis of childbirth outcomes revealed that the highest percentage of premature births occurred in the main group, accounting for 5.3%. Women with a history of reproductive loss demonstrated a significantly higher rate of operative deliveries—21.05% in the main group versus 13.51% in the comparison group. The primary indication for operative delivery in both groups was fetal distress during labor (in the first and second stages). Moreover, birth trauma was more frequent in the main and comparison groups compared to the control group. Newborns with low birth weight were reported in 7.9% of cases in the main group and 2.7% in the comparison group, while no such cases were observed in the control group. The incidence of macrosomia was 10.7% among women with a history of reproductive loss, compared to 3.3% in women without such a history. Conclusions. The findings highlight a high risk of obstetric complications among pregnant women with a history of one reproductive loss, particularly those monitored during martial law in Ukraine. These women experienced a significantly higher incidence of complications, including premature birth, fetal distress during labor, and labor anomalies, which directly contributed to an increased rate of operative deliveries.

High Incubation Attendance and Nesting Site Constraints of the Sclater's Monal in an Alpine Environment in Southwestern China.

Breeding in alpine environments poses significant challenges to birds, requiring specific adaptations for survival. The Sclater's monal (Lophophorus sclateri), a regionally threatened, typical alpine pheasant species, is restricted to high-elevation habitat from the East Himalayas to the mountains of west Yunnan, China. Due to its low population density and the difficulty of accessing its habitats, the breeding ecology of this species is understudied. Therefore, we aimed to understand the breeding behavior, nest site use, and life-history traits that allow this monal species to cope with the alpine environment. During our fieldwork from March to June 2015 and 2016 in the Gaoligong Mountains in western Yunnan, China, we found six cliff nesting sites ranging from 3535 m to 3892 m. Three sites were active, with one being used in both years, and the remaining three were inactive but had been used in prior years. The clutch size was 2.75 ± 0.5 (2 or 3 eggs; n = 4 nests at three nesting sites), and all 11 eggs were successfully hatched. The female solely performed incubation, spending 97.2% of its time in incubating with an average duration of 25.69 ± 13.79 h (n = 43 bouts across three females) per on-bout which indicates the female bird invested more time than other pheasants. High incubation attendance by females highlights the importance of increased parental care in ensuring reproductive success. These findings highlight that the Sclater monal exhibits specific breeding behaviors and nesting strategies that reflect adaption to harsh environments. Additionally, our observations of intense male-male interactions and reuse of nesting sites suggest that suitable nesting sites are limited, which could significantly impact population dynamics. Together, these insights are crucial for conserving this regionally threatened pheasant.

Population dynamics and its relationship with functional traits in different succession stages of temperate mixed coniferous broad-leaved forest in Northeast China.

Functional traits regulate plant response to environmental changes, with consequences on population dynamics. However, how plant functional traits impact population dynamics, including growth, mortality, and recruitment, remains elusive in temperate forests across different successional stages. In this study, we compiled data on population dynamics and eight functional traits, encompassing hydraulic, wood, and leaf traits, from 35 species commonly found in a secondary poplar-birch forest and a broad-leaved Korean pine forest in Northeast China. We quantified the intrinsic relationships between plant population dynamics and assessed how plant functional traits influenced these dynamics. The results demonstrated a gradual increase in the correlation among population dynamics as forest succession progressed. In the secondary forest, tree growth rate and mortality rate were negatively correlated, while growth-death rate and growth-recruitment rate were not related. Conversely, in the broad-leaved Korean pine forest, there was a significant negative correlation between tree growth rate and mortality rate, as well as between growth rate and recruitment rate, while tree mortality rate positively correlated with recruitment rate. Additionally, functional traits effectively predicted population dynamics, but the predictive ability varied across successional stages. Functional traits, particularly xylem hydraulic traits (e.g., Huber value) and anatomical traits (e.g., mean xylem conduit diameter), were stronger predictors of tree growth, mortality, and recruitment rates at the late successional stage compared with the early stage. These findings indicated that population dynamics and functional traits exhibited strong regularity in the late successional stage of broad-leaved Korean pine forests.

Embrace the Past and Forge Ahead: The China Report on the 30th Anniversary of the International Conference on Population and Development (ICPD)

Since the International Conference on Population and Development (ICPD) in 1994, global initiatives like the Millennium Development Goals (MDGs) and Sustainable Development Goals (SDGs) have evolved from simple population control to a comprehensive focus on human rights, social justice, and sustainable development, emphasizing social equity, gender equality, sustainability, and global cooperation. This paper reviews China’s response to these initiatives, focusing on the ICPD Program of Action and SDGs, and assesses how its demographic transformation over the past 30 years has influenced global population trends and other development areas. We find that China has actively embraced these global principles, integrating them into its national strategy through improved fertility policies, population structure optimization, and addressing population aging. These measures have significantly reshaped China’s demographic landscape and impacted global population dynamics. The paper also highlights China’s substantial progress in health and well-being, life expectancy, gender equality, social equity, and climate action. To address its rapid population aging, China has developed robust social security systems, particularly in pensions and health insurance. China’s experience in urbanization and economic growth has provided valuable insights for global development. Additionally, China's efforts have advanced education, improved women's rights, and supported disadvantaged groups, contributing to the undertaking of global sustainable development. We conclude that China's efforts in implementing international action plans since the ICPD have laid a strong foundation for achieving global SDGs, that China has become a role model for the international community in the domain of population and development, and that China will continuously contribute significantly to global development agendas in the years to come.

Global dynamics and spatiotemporal patterns of a two‐species chemotaxis system with chemical signaling loop and Lotka–Volterra competition

AbstractThis paper considers a two‐species chemotaxis system with chemical signaling loop and Lotka–Volterra competition kinetics under the homogeneous Newman boundary condition in smooth bounded domains. The global existence and boundedness of solutions for the parabolic–elliptic/parabolic–parabolic system are established. In the strong competition case, the global stability of the semitrivial constant steady state is obtained under certain parameter conditions. Linear analyzes and numerical simulations demonstrate that chemical signaling loop can significantly impact population dynamics, and admit the coexistence in the exclusion competitive case, including nonconstant steady states, chaos, and spatially inhomogeneous time‐periodic types.

A stage-based life cycle implementation for individual-based population viability analyses of grey wolves (Canis lupus) in Europe

Population viability analyses (PVA) are important tools for decision-making and planning of adaptive wildlife management actions. While earlier approaches on individual based PVAs have often been age-based, analyses of species with strong social structure might benefit from a stage-based model approach. In this study, we designed an individual-based and stage-based PVA within the software Vortex. As a case study, we applied our model to the German part of the European wolf population, making use of comprehensive data sets originating from the German monitoring regime including individual genotypes. Genetic diversity and inbreeding were important considerations in our analysis, as they could greatly impact population dynamics. We aimed to assess the population's trajectory, extinction risk, and genetic integrity under different scenarios while analyzing factors that could affect its survival. We found that mortality rates at different life cycle stages had varying effects on population growth. Higher mortality rates among pups and dispersers led to negative growth and increased the risk of extinction. In comparison, higher mortality rates among yearlings and subdominant wolves still resulted in positive growth but at a slower rate. Mortality among the breeding individuals within the pack (territorials) had the highest impact on population trajectory. Although the German wolves represent a rather recently founded population, our simulations predicted generally good genetic diversity as long as the population was not held at artificially low numbers.Ultimately, we present a generic, easy-to-use-and-adapt model built within the Vortex environment, that after appropriate modification, calibration and testing could be used within conservation practice and management in collaboration with scientific research. Our study highlights the importance of stage-based modeling for understanding the demographic traits of social species like wolves.

Sensitivity of amphibian embryos to timing and magnitude of present and future thermal extremes.

Ongoing climate change is increasing the frequency and intensity of extreme temperature events. Unlike the gradual increase on average environmental temperatures, these short-term and unpredictable temperature extremes impact population dynamics of ectotherms through their effect on individual survival. While previous research has predominantly focused on the survival rate of terrestrial embryos under acute heat stress, less attention has been dedicated to the nonlethal effects of ecologically realistic timing and magnitude of temperature extremes on aquatic embryos. In this study, we investigated the influence of the timing and magnitude of current and projected temperature extremes on embryonic life history traits and hatchling behavior in the alpine newt, Ichthyosaura alpestris. Using a factorial experiment under controlled laboratory conditions, we exposed 3- or 10-day-old embryos to different regimes of extreme temperatures for 3 days. Our results show that exposure to different extreme temperature regimes led to a shortened embryonic development time and an increase in hatchling length, while not significantly affecting embryonic survival. The duration of development was sensitive to the timing of temperature extremes, as early exposure accelerated embryo development. Exposure to temperature extremes during embryonic development heightened the exploratory activity of hatched larvae. We conclude that the timing and magnitude of ecologically realistic temperature extremes during embryogenesis have nonlethal effects on life history and behavioral traits. This suggests that species' vulnerability to climate change might be determined by other ecophysiological traits beyond embryonic thermal tolerance in temperate pond-breeding amphibians.

Infectious and parasitic diseases in European hares (Lepus europaeus Pall.) from the Lublin Upland detected by macroscopic autopsy

The European hare (Lepus europaeus), commonly known as the gray hare, belongs to the Leporidae family. Widely distributed throughout Poland, it exhibits higher population density in the eastern regions. However, Europe has witnessed a significant decline in hare populations over the past 50 years, a trend also observed in most Polish areas. Contributing factors include intensified agriculture, habitat loss, urbanization, pollution (water, air, and soil), and climate change, all impacting population dynamics, including reproduction. Increased predation by foxes, raccoons, and birds of prey, along with poaching and hunting-related damage, further affect hare populations. Infectious and parasitic diseases play a crucial role in hare health, often leading to mortality. These animals constantly interact with various pathogens and vectors due to their natural environment. The objective of this study was to assess the health of the European hare population in the Lublin Upland based on macroscopic findings during autopsies. The research involved 85 hares from two hunting districts in the western part of the Lublin Upland. These animals were necropsied, and material was collected for laboratory tests. Macroscopic examinations revealed the presence of several diseases, including brucellosis (6 cases), rodentiosis (11 cases), tularemia (3 cases), echinococcosis (5 cases), and cysticercosis (11 cases). Most of these diseases are classified as dangerous zoonotic infections. The detection of multiple diseases underscores the gray hare’s role as a reservoir in the natural environment. These confirmed diseases pose significant risks, often proving fatal for both hares and their predators. As a game species, European hares also pose a threat to hunters who handle infected animals. Moreover, meat from sick hares jeopardizes consumer health and safety. This research holds substantial importance for veterinary medicine and public health, aiding in early diagnosis and effective disease prevention strategies.

Two distinct mechanisms lead to either oocyte or spermatocyte decrease in C. elegans after whole developmental exposure to γ-rays.

Wildlife is subject to various sources of pollution, including ionizing radiation. Adverse effects can impact the survival, growth, or reproduction of organisms, later affecting population dynamics. In invertebrates, reproduction, which directly impacts population dynamics, has been found to be the most radiosensitive endpoint. Understanding the underlying molecular pathways inducing this reproduction decrease can help to comprehend species-specific differences in radiosensitivity. From our previous studies, we found that decrease in reproduction is life stage dependent in the roundworm Caenorhabditis elegans, possibly resulting from an accumulation of damages during germ cell development and gamete differentiation. To go further, we used the same experimental design to assess more precisely the molecular determinants of reproductive toxicity, primarily decreases in gamete number. As before, worms were chronically exposed to 50 mGy·h-1 external gamma ionizing radiation throughout different developmental periods (namely embryogenesis, gametogenesis, and full development). To enable cross species extrapolation, conserved molecular pathways across invertebrates and vertebrates were analysed: apoptosis and MAP kinase Ras/ERK (MPK-1), both involved in reproduction and stress responses. Our results showed that these pathways are life-stage dependent, resulting from an accumulation of damages upon chronic exposure to IR throughout the life development. The Ras/ERK pathway was activated in our conditions in the pachytene region of the gonad where it regulates cell fate including apoptosis, but not in the ovulation zone, where it controls oocyte maturation and ovulation. Additionally, assessment of germ cell proliferation via Ras/ERK pathway showed no effect. Finally, a functional analysis of apoptosis revealed that while the decrease of the ovulation rate is caused by DNA-damaged induced apoptosis, this process does not occur in spermatocytes. Thus, sperm decrease seems to be mediated via another mechanism, probably a decrease in germ cell proliferation speed that needs further investigation to better characterize sex-specific responses to IR exposure. These results are of main importance to describe radio-induced reprotoxic effects and contribute as weight of evidence for the AOP #396 "Deposition of ionizing energy leads to population decline via impaired meiosis".

Effects of conventional vs. organic farming practices on raptor nestling health: Neither black nor white

Agricultural intensification is one of the main threats to biodiversity. Farmland bird specialists such as Montagu’s harrier, Circus pygargus, are particularly at risk and declining. Conventional farming (CF) production systems usually involve landscape homogenisation, mechanisation, and the use of synthetic pesticides that may have direct and indirect effects on individuals. By contrast, organic farming (OF) systems typically promote agro-ecosystem health, which benefits biodiversity and the reproductive success of birds. However, the potential effects of agricultural systems on life history traits of Montagu’s harrier chicks have not been investigated. Still, altered life history traits could impair chick survival and future reproductive success, which may in turn impact population dynamics. Here, we investigated the effects of OF (measured as a percentage around nests at different buffer sizes from 100 m to 2000 m) on a set of life history traits covering the behaviour, physiology (haematological, immune and nervous systems) and body condition of 380 chicks from 137 nests monitored between 2016 and 2021. At a local scale (<2000 m), only the H/L ratio (indicative of physiological stress) and carotenoid-based ornaments were clearly related to OF percentage. At 600 m around the nest, a higher OF percentage increased the H/L ratio, suggesting that chicks experienced greater stress due to either increased human disturbance or higher intra-/interspecific negative interactions around OF crop plots. Carotenoid-based ornaments were more strongly coloured with increasing OF around the nest at 1500 m. Considering the role of carotenoids in both detoxification processes and expression of secondary sexual traits, this result may indicate that CF would lead either to a difference in nestlings’ diet and/or to a trade-off between organism’s maintenance and sexual characters. These findings suggest that farming practices at a local scale surrounding nest locations may have subtle effects on chick development, but also on trade-offs between important physiological functions. This study highlights the importance of a multi-trait approach when assessing adverse and beneficial effects of both OF and CF on individuals.

Nutrients and flow shape the cyclic dominance games between Escherichia coli strains.

Evolutionary game theory has provided various models to explain the coexistence of competing strategies, one of which is the rock-paper-scissors (RPS) game. A system of three Escherichia coli strains-a toxin-producer, a resistant and a sensitive-has become a classic experimental model for studying RPS games. Previous experimental and theoretical studies, however, often ignored the influence of ecological factors such as nutrients and toxin dynamics on the evolutionary game dynamics. In this work, we combine experiments and modelling to study how these factors affect competition dynamics. Using three-dimensional printed mini-bioreactors, we tracked the frequency of the three strains in different culturing media and under different flow regimes. Although our experimental system fulfilled the requirements of cyclic dominance, we did not observe clear cycles or long-term coexistence between strains. We found that both nutrients and flow rates strongly impacted population dynamics. In our simulations, we explicitly modelled the release, removal and diffusion of toxin. We showed that the amount of toxin that is retained in the system is a simple indicator that can predict competition outcomes across broad parameter space. Moreover, our simulation results suggest that high rates of toxin diffusion might have prevented cyclic patterns from emerging in our experimental system. This article is part of the theme issue 'Half a century of evolutionary games: a synthesis of theory, application and future directions'.

Habitat fragmentation reduces survival and drives source-sink dynamics for a large carnivore.

Rigorous understanding of how environmental conditions impact population dynamics is essential for species conservation, especially in mixed-use landscapes where source-sink dynamics may be at play. Conservation of large carnivore populations in fragmented, human-dominated landscapes is critical for their long-term persistence. However, living in human-dominated landscapes comes with myriad costs, including direct anthropogenic mortality and sublethal energetic costs. How these costs impact individual fitness and population dynamics are not fully understood, partly due to the difficulty in collecting long-term demographic data for these species. Here, we analyzed an 11-year dataset on puma (Puma concolor) space use, mortality, and reproduction in the Santa Cruz Mountains, California, USA, to quantify how living in a fragmented landscape impacts individual survival and population dynamics. Long-term exposure to housing density drove mortality risk for female pumas, resulting in an 18-percentage-point reduction in annual survival for females in exurban versus remote areas. While the overall population growth rate appeared stable, reduced female survival in more developed areas resulted in source-sink dynamics across the study area, with 42.1% of the Santa Cruz Mountains exhibiting estimated population growth rates <1. Since habitat selection is often used as a proxy for habitat quality, we also assessed whether puma habitat selection predicted source and sink areas. Patterns of daytime puma habitat selection predicted source areas, while time-of-day-independent habitat selection performed less well as a proxy. These results illuminate the individual- and population-level consequences of habitat fragmentation for large carnivores, illustrating that habitat fragmentation can produce source-sink dynamics that may not be apparent from other metrics of habitat quality. Locally, conserving high-quality source habitat within the Santa Cruz Mountains is necessary to support long-term puma population persistence. More broadly, source-sink dynamics may at play for other carnivore populations in similar fragmented systems, and linking landscape conditions to population dynamics is essential for effective conservation. Caution should be used in inferring habitat quality from habitat selection alone, but these results shed light on metrics of selection that may be better or worse proxies to identify source areas for large carnivores.

Long and Short Duration Exposures to the Selective Serotonin Reuptake Inhibitors (SSRIs) Fluoxetine, Paroxetine and Sertraline at Environmentally Relevant Concentrations Lead to Adverse Effects on Zebrafish Behaviour and Reproduction

Selective serotonin reuptake inhibitors (SSRIs) are currently the most prescribed class of psychotropic medications. Their increased global manufacture and use have become growing concerns for aquatic toxicologists and environmental biologists, who assess both the direct and indirect effects of substances on the environment and on human health. In order to assess the potential impact of environmentally relevant levels of SSRIs on fish development, behaviour and reproduction, we exposed juvenile and adult zebrafish to a select group of SSRIs using two separate exposure paradigms. In the first paradigm, juvenile zebrafish were exposed to Fluoxetine (Prozac), Paroxetine (Paxil), Sertraline (Zoloft) or a mixture of the three beginning at environmentally relevant levels (10 µg/L) for 135 days (long-term exposure) beginning at 5 days post fertilization (dpf). In the second paradigm, adult zebrafish were exposed to matching concentrations of the same SSRIs for 35 days (short-term exposure). The long-term exposure paradigm proved to have little to no overt effect on growth or development at sub-lethal concentrations (10 and 100 µg/L). However, both the stress/anxiety response (novel tank tests) and reproduction (fecundity and fertility) were dramatically reduced. Importantly, the short-term exposure of reproductively mature fish led to similar adverse effects on both the stress response and reproduction. Following both the short and long duration exposure paradigms, a 2-week washout period led to a small reduction in the adverse effects. These findings highlight the potential for SSRIs to negatively impact population dynamics in zebrafish and may be of particular value should they be found in other fish species in the environment.

Validation of a microwave energy meter to non-lethally estimate energetic reserves in adult sturgeon.

Whole-body (WB) energetic reserves influence fish survival, growth, and reproduction but are typically quantified using lethal methods (i.e. proximate analyses) or interpreted through body condition indices. Energetic reserves can impact population dynamics through influences on growth rates, age-at-first-reproductive-maturity, and spawning periodicity at the individual-fish level, especially in long-lived sturgeon species. Therefore, a non-lethal tool to track the energetic reserves of endangered sturgeon populations could inform adaptive management and further our understanding of the sturgeon's biology. The Distell Fatmeter is a microwave energy meter that has been validated to non-lethally estimate energetic reserves in some fish species, but never successfully for sturgeon. Here, stepwise linear regressions were applied to test commonly monitored body metrics and Fatmeter measurements at nine different anatomical sites on captive adult pallid sturgeon (Scaphirhynchus albus; total length of 790-1015mm; WB lipid of 13.9-33.3%) compared with WB lipid and energy content determined by proximate analyses. Fatmeter measurements alone explained approximately 70% of the variation in WB energetic reserves, which outperformed models considering body metrics alone by a margin of approximately 20%. The top-ranked models based on AICc score (second-order Akaike Information Criterion) included a combination of body metrics and Fatmeter measurements and accounted for up to 76% of the variation in WB lipid and energy. We recommend the incorporation of Fatmeter measurements at a single site located dorsally to the lateral scutes at the posterior end of the fish above the pelvic fins (U-P) into conservation monitoring programs for adult pallid sturgeon (total length [TL] ≥ 790mm; fork length [FL] ≥ 715mm) and the cautious application of Fatmeter measurements for sturgeon between 435 and 790mm TL (375-715mm FL). Measurements at this U-P site combined with body mass explained approximately 75% of the variation in WB lipid and energy.

Estimating reproductive costs in marine mammal bioenergetic models: a review of current knowledge and data availability.

Reproductive costs represent a significant proportion of a mammalian female's energy budget. Estimates of reproductive costs are needed for understanding how alterations to energy budgets, such as those from environmental variation or human activities, impact maternal body condition, vital rates and population dynamics. Such questions are increasingly important for marine mammals, as many populations are faced with rapidly changing and increasingly disturbed environments. Here we review the different energetic costs that marine mammals incur during gestation and lactation and how those costs are typically estimated in bioenergetic models. We compiled data availability on key model parameters for each species across all six marine mammal taxonomic groups (mysticetes, odontocetes, pinnipeds, sirenians, mustelids and ursids). Pinnipeds were the best-represented group regarding data availability, including estimates of milk intake, milk composition, lactation duration, birth mass, body composition at birth and growth. There were still considerable data gaps, particularly for polar species, and good data were only available across all parameters in 45% of pinniped species. Cetaceans and sirenians were comparatively data-poor, with some species having little or no data for any parameters, particularly beaked whales. Even for species with moderate data coverage, many parameter estimates were tentative or based on indirect approaches, necessitating reevaluation of these estimates. We discuss mechanisms and factors that affect maternal energy investment or prey requirements during reproduction, such as prey supplementation by offspring, metabolic compensation, environmental conditions and maternal characteristics. Filling the existing data gaps highlighted in this review, particularly for parameters that are influential on bioenergetic model outputs, will help refine reproductive costs estimated from bioenergetic models and better address how and when energy imbalances are likely to affect marine mammal populations.

Do Jaw Deformities Adversely Affect Largemouth Bass?

Abstract Largemouth Bass Micropterus nigricans anglers have mainly adopted catch-and-release practices with limited direct fishing mortality. However, catch-and-release angling could cause delayed mortality and nonlethal effects that could potentially affect population dynamics. For instance, hooking can result in jaw deformities, with unknown subsequent effects on vulnerability to angling, condition, growth, and mortality. Our objectives were to assess the prevalence of Largemouth Bass jaw deformities and test for differences in angling vulnerability, growth, condition, size structure, and mortality of fish with and without jaw deformities. Largemouth Bass were captured by electrofishing and by anglers at 41 tournaments at Brushy Creek Lake, Iowa, between April and August 2015. Jaw deformities were observed in 7.0% of fish caught at tournaments and 3.3% caught while electrofishing (5.8% overall). Angling recapture rates of tagged fish with (78.9%) and without (76.8%) jaw deformities were similar. Condition, growth, size structure, and mortality of fish with and without jaw deformities were also similar. Our results indicate jaw deformities have little effect on Largemouth Bass angling vulnerability, condition, growth, or survival; however, we still recommend careful handling of fish to minimize injuries that may occur during angling.

The trade-off between condition and growth shapes juveniles’ survival of harvested demersal fish of the Mediterranean sea

Fish body condition and growth are two interrelated traits closely associated with species life history and fitness, whose trade-off can ultimately impact population dynamics albeit seldom empirically demonstrated. They can intricately affect survival rates, which are particularly relevant for species under exploitation. Using individual spatiotemporal information in Northwestern Mediterranean, we document for the first time the existence of a trade-off between condition and growth in regulating survival dynamics in two important fish species for the Mediterranean fisheries that are characterized by contrasting life histories. For the European hake (Merluccius merluccius), a benthopelagic species, juveniles’ body condition was detected to be positively linked to survival and negatively associated with the growth of this age group. For the red mullet (Mullus barbatus), the same pattern was observed for young adults. We also show that the observed patterns on a regional level have a clear spatial dependence as we found that observed body condition over a local scale had a broad effect on the population dynamics of the whole region, with the Ebro delta area emerging as the demographic engine of the two species. We discuss our results in the context of fisheries management and underline the importance of improving current stock assessment models and spatially based fishery management towards incorporating body condition and growth due to their influence on important parameters such as survival.

Prediction of Potential Habitats of Zanthoxylum armatum DC. and Their Changes under Climate Change

Climate change poses a severe threat to biodiversity. Greenhouse gas emissions have accelerated climate warming and significantly impacted species distribution and population dynamics. Zanthoxylum armatum DC. is an ecologically, medicinally, and economically important plant; it is cultivated as an economic crop at large scales in China, and is a valuable medicinal plant in India, Nepal, etc. A precise prediction of the potential distribution areas of Z. armatum will contribute to its protection and determination of its planting areas. In this paper, based on 433 distribution points and 19 climate factors, the MaxEnt model was used to analyze the spatial distribution pattern of Z. armatum between 1970 and 2000, predict its spatial distribution pattern in 2040–2060 (the 2050s) and 2081–2100 (the 2090s), and comprehensively assess the critical climate factors limiting its geographical distribution. The findings are as follows: (1) in the 1970–2000 scenario, the potential suitable distribution areas of Z. armatum include the subtropical monsoon climate regions of Japan, the Korean Peninsula, the south of the Qinling–Huaihe Line of China, and the regions along the southern foot of the Himalayas (India, Bhutan, Nepal, etc.), with an area of 330.54 × 104 km2; (2) the critical climate factors affecting the potential distribution of Z. armatum include temperature (mean diurnal temperature range, mean temperature of the coldest quarter, and temperature seasonality) and annual precipitation; (3) the distribution areas of Z. armatum will shift to higher latitudes and shrink under the three climate change scenarios in the 2050s and 2090s. In the 2090s–SSP585 scenario, the total area of suitable habitat will decrease most markedly, and the decrease rate of the highly suitable areas will reach up to 97.61%; only the region near Delong Town, Nanshan District, Chongqing City, will remain a highly suitable habitat, covering an area of merely 0.08 × 104 km2. These findings suggest that Z. armatum is susceptible to climate change. The border area between Guizhou Province and Chongqing City and the southwest district of Leshan City, Sichuan Province, will be a stable and moderately high potential suitable habitat for Z. armatum in the future. The above regions are recommended to be managed as key protected areas.

Competitive Plant-Mediated and Intraguild Predation Interactions of the Invasive Spodoptera frugiperda and Resident Stemborers Busseola fusca and Chilo partellus in Maize Cropping Systems in Kenya.

Simple SummaryInvasion of fall armyworm led to co-inhabitation with resident stemborers in maize cropping systems in Kenya. As a result, exploitative and interference intraguild interactions occur between these lepidopteran pests. However, mechanistic insights into these interactions are poorly understood. These interspecific interactions may impact population dynamics and niche displacement of these pests in maize crops. Fall armyworm dominates resident stemborers in maize crops where they co-exist. This is due to plant-mediated and predation competitive advantages exhibited by fall armyworm over stemborers. Understanding such interactions provides crucial information for designing pest management strategies for these lepidopteran pests.Following its recent invasion of African countries, fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae), now co-exists with resident stemborers such as Busseola fusca (Lepidoptera: Noctuidae) and Chilo partellus (Lepidoptera: Crambidae) causing severe damage to maize crops. Due to niche overlap, interspecific interactions occur among the three species, but the mechanisms and degree remain unclear. In this study, we assessed plant-mediated intraspecific and interspecific interactions, predation in laboratory and semi-field settings, and larval field occurrence of S. frugiperda and the two stemborer species. Larval feeding assays to evaluate competitive plant-mediated interactions demonstrated that initial S. frugiperda feeding negatively affected subsequent stemborer larval feeding and survival, suggesting induction of herbivore-induced mechanisms by S. frugiperda, which deters establishment and survival of competing species. Predation assays showed that, at different developmental larval stages, second–sixth instars of S. frugiperda preyed on larvae of both B. fusca and C. partellus. Predation rates of S. frugiperda on stemborers was significantly higher than cannibalism of S. frugiperda and its conspecifics (p < 0.001). Cannibalism of S. frugiperda in the presence of stemborers was significantly lower than in the presence of conspecifics (p = 0.04). Field surveys showed a significantly higher number of S. frugiperda larvae than stemborers across three altitudinally different agroecological zones (p < 0.001). In conclusion, this study showed that the invasive S. frugiperda exhibited a clear competitive advantage over resident stemborers within maize cropping systems in Kenya. Our findings reveal some of the possible mechanisms employed by S. frugiperda to outcompete resident stemborers and provide crucial information for developing pest management strategies for these lepidopteran pests.

A comparison of non-surgical methods for sexing young gopher tortoises (Gopherus polyphemus).

Many turtle species have temperature-dependent sex determination (TSD), raising the prospect that climate change could impact population dynamics by altering sex ratios. Understanding how climate change will affect populations of animals with TSD requires a reliable and minimally invasive method of identifying the sexes of young individuals. This determination is challenging in many turtles, which often lack conspicuous external sexual dimorphism until years after hatching. Here, we explore four alternatives for sexing three age classes of captive-reared young gopher tortoises (Gopherus polyphemus), a terrestrial turtle of conservation concern native to the southeastern United States: (1) naive testosterone levels, (2) testosterone levels following a follicle stimulating hormone (FSH) challenge, (3) linear morphological measurements, and (4) geometric morphometrics. Unlike some other turtle species, male and female neonatal gopher tortoises have overlapping naive testosterone concentration distributions, justifying more complicated methods. We found that sex of neonates (<7 days old) is best predicted by a “random forest” machine learning model with naive testosterone levels and morphological measurements (8% out-of-bag error). Sex of hatchlings (4–8 months old) was predicted with 11% error using a simple threshold on naive testosterone levels, or with 4% error using a simple threshold on post-FSH testosterone levels. Sex of juveniles (approximately 3.5 years old) was perfectly predicted using a simple threshold on naive testosterone levels. Sexing hatchlings at >4 months of age is the easiest and most reliable non-surgical method for sex identification. Given access to a rearing facility and equipment to perform hormone assays, these methods have the potential to supplant laparoscopic surgery as the method of choice for sexing young gopher tortoises.