Dynamics Of Natural Populations Research Articles

Viral exposure effects on life-history, flight-related traits, and wing melanisation in the Glanville fritillary butterfly

Infections represent a constant threat for organisms and can lead to substantial fitness losses. Understanding how individuals, especially from natural populations, respond towards infections is thus of great importance. Little is known about immunity in the Glanville fritillary butterfly (Melitaea cinxia). As the larvae live gregariously in family groups, vertical and horizontal transmission of infections could have tremendous effects on individuals and consequently impact population dynamics in nature. We used the Alphabaculovirus type strain Autographa californica multiple nucleopolyhedrovirus (AcMNPV) and demonstrated that positive concentration-dependent baculovirus exposure leads to prolonged developmental time and decreased survival during larval and pupal development, with no sex specific differences. Viral exposure did not influence relative thorax mass or wing morphometric traits often related to flight ability, yet melanisation of the wings increased with viral exposure, potentially influencing disease resistance or flight capacity via thermal regulation. Further research is needed to explore effects under sub-optimal conditions, determine effects on fitness-related traits, and investigate a potential adaptive response of increased melanisation in the wings due to baculovirus exposure.

Strong linkages between depth, longevity and demographic stability across marine sessile species

Understanding the role of the environment in shaping the evolution of life histories remains a major challenge in ecology and evolution. We synthesize longevity patterns of marine sessile species and find strong positive relationships between depth and maximum lifespan across multiple sessile marine taxa, including corals, bivalves, sponges and macroalgae. Using long-term demographic data on marine sessile and terrestrial plant species, we show that extreme longevity leads to strongly dampened population dynamics. We also used detailed analyses of Mediterranean red coral, with a maximum lifespan of 532 years, to explore the life-history patterns of long-lived taxa and the vulnerability to external mortality sources that these characteristics can create. Depth-related environmental gradients-including light, food availability, temperature and disturbance intensity-drive highly predictable distributions of life histories that, in turn, have predictable ecological consequences for the dynamics of natural populations.

Assessing the dynamics of natural populations by fitting individual‐based models with approximate Bayesian computation

Abstract Individual‐based models (IBMs) allow realistic and flexible modelling of ecological systems, but their parameterization with empirical data is statistically and computationally challenging. Approximate Bayesian computation (ABC) has been proposed as an efficient approach for inference with IBMs, but its applicability to data on natural populations has not been yet fully explored. We construct an IBM for the metapopulation dynamics of a species inhabiting a fragmented patch network, and develop an ABC method for parameterization of the model. We consider several scenarios of data availability from count data to combination of mark‐recapture and genetic data. We analyse both simulated and real data on white‐starred robin (Pogonocichla stellata), a passerine bird living in montane forest environment in Kenya, and assess how the amount and type of data affect the estimates of model parameters and indicators of population state. The indicators of the population state could be reliably estimated using the ABC method, but full parameterization was not achieved due to strong posterior correlations between model parameters. While the combination of the data types did not provide more accurate estimates for most of the indicators of population state or model parameters than the most informative data type (ringing data or genetic data) alone, the combined data allowed robust simultaneous estimation of all unknown quantities. Our results show that ABC methods provide a powerful and flexible technique for parameterizing complex IBMs with multiple data sources, and assessing the dynamics of the population in a robust manner.

Recent Activity in Expanding Populations and Purifying Selection Have Shaped Transposable Element Landscapes across Natural Accessions of the Mediterranean Grass Brachypodium distachyon.

Transposable element (TE) activity has emerged as a major cause of variation in genome size and structure among species. To what extent TEs contribute to genetic variation and divergence within species, however, is much less clear, mainly because population genomic data have so far only been available for the classical model organisms. In this study, we use the annual Mediterranean grass Brachypodium distachyon to investigate TE dynamics in natural populations. Using whole-genome sequencing data for 53 natural accessions, we identified more than 5,400 TE polymorphisms across the studied genomes. We found, first, that while population bottlenecks and expansions have shaped genetic diversity in B. distachyon, these events did not lead to lineage-specific activations of TE families, as observed in other species. Instead, the same families have been active across the species range and TE activity is homogeneous across populations, indicating the presence of conserved regulatory mechanisms. Second, almost half of the TE insertion polymorphisms are accession-specific, most likely because of recent activity in expanding populations and the action of purifying selection. And finally, although TE insertion polymorphisms are underrepresented in and around genes, more than 1,000 of them occur in genic regions and could thus contribute to functional divergence. Our study shows that while TEs in B. distachyon are “well-behaved” compared with TEs in other species with larger genomes, they are an abundant source of lineage-specific genetic variation and may play an important role in population divergence and adaptation.

Spatio-temporal ecological and evolutionary dynamics in natural butterfly populations

Long term studies of wild populations indicate that natural selection can cause rapid and dramatic changes in traits, with spatial and temporal variation in the strength of selection a critical driver of genetic variation in natural populations. In 2012, we began a long term study of genome-wide molecular evolution in populations of the butterfly Lycaeides ideas in the Greater Yellowstone Area (GYA). We aimed to quantify the role of environment-dependent selection on evolution in these populations. Building on previous work, in 2017 we collected new samples, incorporated distance sampling, and surveyed the insect community at each site. We also defined the habitat boundary at anew, eleventh site. Our preliminary analyses suggest that both genetic drift and selection are important drivers in this system.
 
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Geographic variation in forest composition and precipitation predict the synchrony of forest insect outbreaks

Evaluating the causes of spatial synchrony in population dynamics in nature is notoriously difficult due to a lack of data and appropriate statistical methods. Here, we use a recently developed method, a multivariate extension of the local indicators of spatial autocorrelation statistic, to map geographic variation in the synchrony of gypsy moth outbreaks. Regression analyses indicated that local synchrony of gypsy moth defoliation increased with the local synchrony of precipitation and the proportion of host tree density composed of oaks, especially those in the Lobatae (red oak) section. This may be the first study that demonstrates a relationship between defoliator population synchrony and host tree composition. More broadly, this study contributes to a small body of recent work that illustrates how mapping hotspots of unusually high or low synchrony facilitates an improved understanding of factors influencing spatially synchronous population dynamics generally, and triggers of pest insect outbreaks, more specifically.

Spatio-temporal variation in lifelong telomere dynamics in a long-term ecological study.

Understanding individual‐level variation in response to the environment is fundamental to understanding life‐history evolution and population dynamics. Telomeres, the protective caps at the ends of chromosomes, shorten in response to oxidative stress, and telomere shortening is correlated with reduced survival and life span. Investigating telomere dynamics may help us quantify individual variation in the costs experienced from social and ecological factors, and enhance our understanding of the dynamics of natural populations.Here, we study spatio‐temporal variation in lifelong telomere dynamics in the Seychelles warbler, Acrocephalus sechellensis. We combine long‐term life history and ecological data with a large longitudinal dataset of mean telomere lengths, consisting of 1,808 samples from 22 cohorts born between 1993 and 2014. We provide a detailed analysis of how telomere dynamics vary over individual life spans and cohorts, and with spatio‐temporal variation in the social and ecological environment.We found that telomere length decreases with cross‐sectional and longitudinal measures of age, and most rapidly very early in life. However, both cross‐sectional and longitudinal data suggested that against this overall pattern of shortening, bouts of telomere length increase occur in some individuals. Using a large number of repeated measurements we show statistically that these increases are unlikely to be explained solely by qPCR measurement error.Telomere length varied markedly among cohorts. Telomere length was positively associated with temporal variation in island‐wide insect abundance—a key resource for the insectivorous Seychelles warbler—suggesting that the costs associated with living in harsher environments can be studied by investigating telomere dynamics. We also found evidence for sex‐specific relationships between telomeres and tarsus length, potentially reflecting differential costs of growth.Our long‐term data show that in a natural population, telomere dynamics vary in a complex manner over individual life spans, and across space and time. Variance in telomere dynamics among individuals is the product of a wide array of genetic, parental and environmental factors. Explaining this variation more fully will require the integration of comprehensive long‐term ecological and genetic data from multiple populations and species.

Age-dependent associations between telomere length and environmental conditions in roe deer.

Telomere length (TL) represents a promising biomarker of overall physiological state and of past environmental experiences, which could help us understand the drivers of life-history variation in natural populations. A growing number of studies in birds suggest that environmental stress or poor environmental conditions are associated with shortened TL, but studies of such relationships in wild mammals are lacking. Here, we compare leucocyte TL from cross-sectional samples collected from two French populations of roe deer which experience different environmental conditions. We found that, as predicted, TL was shorter in the population experiencing poor environmental conditions but that this difference was only significant in older individuals and was independent of sex and body mass. Unexpectedly, the difference was underpinned by a significant increase in TL with age in the population experiencing good environmental conditions, while there was no detectable relationship with age in poor conditions. These results demonstrate both the environmental sensitivity and complexity of telomere dynamics in natural mammal populations, and highlight the importance of longitudinal data to disentangle the within- and among-individual processes that generate them.

Decadal-scale variation in diet forecasts persistently poor breeding under ocean warming in a tropical seabird.

Climate change effects on population dynamics of natural populations are well documented at higher latitudes, where relatively rapid warming illuminates cause-effect relationships, but not in the tropics and especially the marine tropics, where warming has been slow. Here we forecast the indirect effect of ocean warming on a top predator, Nazca boobies in the equatorial Galápagos Islands, where rising water temperature is expected to exceed the upper thermal tolerance of a key prey item in the future, severely reducing its availability within the boobies’ foraging envelope. From 1983 to 1997 boobies ate mostly sardines, a densely aggregated, highly nutritious food. From 1997 until the present, flying fish, a lower quality food, replaced sardines. Breeding success under the poor diet fell dramatically, causing the population growth rate to fall below 1, indicating a shrinking population. Population growth may not recover: rapid future warming is predicted around Galápagos, usually exceeding the upper lethal temperature and maximum spawning temperature of sardines within 100 years, displacing them permanently from the boobies’ island-constrained foraging range. This provides rare evidence of the effect of ocean warming on a tropical marine vertebrate.

Hybridization Associated with Cycles of Ecological Succession in a Passerine Bird.

Identifying the diversity of contexts that can lead to hybridization is important for understanding its prevalence and dynamics in natural populations. Despite the potential of ecological succession to dramatically alter species co-occurrence and abundances, it is unknown whether it directly promotes hybridization and, if so, has long-lasting consequences. Here, we summarize 30 years of survey data across 10 populations to show that in western and mountain bluebirds, heterospecific pairing occurs during repeatable and transient colonization events at the early stages of species turnover. Despite mixed pairing occurring only during early succession, genetic data showed presence of hybrids at both early and late successional stages. Moreover, hybrids showed novel patterns of variation in morphology and behavior, emphasizing that even ephemeral contexts for hybridization can have important evolutionary consequences. Our results suggest that because ecological succession often brings together closely related competitors in disparate numbers but lasts for only a brief period of time, it may be a widespread but underappreciated context for hybridization.

Study on natural population dynamics and spatial distribution pattern of Tyrophagus putrescentiae in stored flour

To understand the natural population dynamics and spatial distribution of Tyrophagus putrescentiae in storage flour, so as to provide an evidence for its prevention and control. The samples from five sampling points in Wuhu City were collected monthly from January to December, 2013, and examined and counted for T. putrescentiae. The dispersion pattern target, Iwao's m*- x̄; regression analysis and Taylor's lgS2-lg x̄; regression analysis were used for analyzing the spatial distribution pattern of T. putrescentiae in the storage flour. The peaks of population dynamics of T. putrescentiae were discovered in July and September. The indexes of dispersion were as follows：I > 0, CA > 0, m*/ x̄; > 1; and the linear regression equation of Iwao：m* = 3.740 3 + 1.017 5 x̄; (r = 0.995 8) and Taylor：lgS2 = 0.500 4 + 1.134 9 lg x̄; (r =0.832 8) showed that the spatial distribution pattern of T. putrescentiae in the storage flour was assembled. The peak of population dynamics of T. putrescentiae in the storage flour in Wuhu City is a double peak type, and the spatial distribution pattern of T. putrescentiae is assembled.

Impact of constant versus fluctuating temperatures on the development and life history parameters of Tetranychus urticae (Acari: Tetranychidae).

The impact of daily temperature fluctuations on arthropod life history parameters is inadequately studied compared with the ample amount of research that has been conducted on the effects of constant temperatures. Fluctuating temperatures are likely to be more realistic, as they are ecologically more similar to what these arthropods experience in nature. Here, we compared the impact of 11 constant temperatures that ranged from 10 to 35°C with fluctuating temperatures with the same corresponding mean temperature and an amplitude of 10°C between high (12h) and low (12h) temperatures on the development and life history parameters of Tetranychus urticae under continuous light conditions. No eggs hatched at constant 10°C, whereas 81.5% of eggs successfully completed development at fluctuating 10°C (15/5°C). Egg-to-female adult development was faster under fluctuating temperatures from 12.5 to 27.5°C than under constant temperatures, whereas the opposite trend was observed at >30°C. The lower thermal thresholds (T) were 11.63 and 8.63°C, and thermal constants (K) were 127.81 and 150.69 degree-days for egg-to-female adults at constant and fluctuating temperatures, respectively. The numbers of oviposition days were significantly higher at fluctuating 15°C than at the corresponding constant temperature, whereas the opposite trend was observed from 20 to 30°C. The intrinsic rate of increase (r) was higher at fluctuating than at constant 15°C. The net reproductive rate (R 0) was also higher at fluctuating than at constant 15 and 35°C, but showed an opposite trend at 20 and 25°C. We conclude that fluctuating temperatures should be considered to accurately predict spider mite population dynamics in nature.

Competition between influenza A virus subtypes through heterosubtypic immunity modulates re-infection and antibody dynamics in the mallard duck.

Our overall hypothesis is that host population immunity directed at multiple antigens will influence the prevalence, diversity and evolution of influenza A virus (IAV) in avian populations where the vast subtype diversity is maintained. To investigate how initial infection influences the outcome of later infections with homologous or heterologous IAV subtypes and how viruses interact through host immune responses, we carried out experimental infections in mallard ducks (Anas platyrhynchos). Mallards were pre-challenged with an H3N8 low-pathogenic IAV and were divided into six groups. At five weeks post H3N8 inoculation, each group was challenged with a different IAV subtype (H4N5, H10N7, H6N2, H12N5) or the same H3N8. Two additional pre-challenged groups were inoculated with the homologous H3N8 virus at weeks 11 and 15 after pre-challenge to evaluate the duration of protection. The results showed that mallards were still resistant to re-infection after 15 weeks. There was a significant reduction in shedding for all pre-challenged groups compared to controls and the outcome of the heterologous challenges varied according to hemagglutinin (HA) phylogenetic relatedness between the viruses used. There was a boost in the H3 antibody titer after re-infection with H4N5, which is consistent with original antigenic sin or antigenic seniority and suggest a putative strategy of virus evasion. These results imply competition between related subtypes that could regulate IAV subtype population dynamics in nature. Collectively, we provide new insights into within-host IAV complex interactions as drivers of IAV antigenic diversity that could allow the circulation of multiple subtypes in wild ducks.

Population Dynamics and Genetic Homogeneity in Natural Populations of Drosophila melanogaster from Faisalabad, Pakistan

Drosophila melanogaster has been considered an important model species to explore the patterns of diversity in natural populations. The current study was conducted to study population dynamics and genetic variability, gene flow and rate of migration in Faisalabad. The samples were collected from 17 different collection sites and cultured in the laboratory. The data for temperature and humidity were also recorded. It was observed that a decrease in temperature and increase in relative humidity caused an increase in population number and vice versa. Ten RAPD primers were used for PCR. Four primers were further selected on the basis of their efficiency and reproducibility. The number of amplification products varied from 4 to 10 with an average of 7.0 bands per primer. Mostly, all the samples showed monomorphic bands except for few samples from the south of the city. The allele and genotype frequencies were measured at each RAPD loci. Average observed heterozygosity (Ht 0.1886) and the genetic variation (G ST 0.129) showed that D. melanogaster natural populations had low level of genetic diversity. The dendrogram based on genetic similarities revealed three main groups of D. melanogaster populations. This pattern of genetic homogeneity due to low genetic variability in local populations was attributed to the gene flow with no genetic drift in D. melanogaster populations in Faisalabad.

A resource on latitudinal and altitudinal clines of ecologically relevant phenotypes of the Indian Drosophila

The unique geography of the Indian subcontinent has provided diverse natural environments for a variety of organisms. In this region, many ecological indices such as temperature and humidity vary predictably as a function of both latitude and altitude; these environmental parameters significantly affect fundamental dynamics of natural populations. Indian drosophilids are diverse in their geographic distribution and climate tolerance, possibly as a result of climatic adaptation. These associations with environmental parameters are further reflected in a large number of clines that have been reported for various fitness traits along these geographical ranges. This unique amalgamation of environmental variability and genetic diversity make the subcontinent an ecological laboratory for studying evolution in action. We assembled data collected over the last 20 years on the geographical clines for various phenotypic traits in several species of drosophilids and present a web-resource on Indian-Drosophila (http://www.indian-drosophila.org/). The clinal data on ecologically relevant phenotypes of Indian drosophilids will be useful in addressing questions related to future challenges in biodiversity and ecosystems in this region.

Cryptic chytridiomycosis linked to climate and genetic variation in amphibian populations of the southeastern United States.

North American amphibians have recently been impacted by two major emerging pathogens, the fungus Batrachochytrium dendrobatidis (Bd) and iridoviruses in the genus Ranavirus (Rv). Environmental factors and host genetics may play important roles in disease dynamics, but few studies incorporate both of these components into their analyses.Here, we investigated the role of environmental and genetic factors in driving Bd and Rv infection prevalence and severity in a biodiversity hot spot, the southeastern United States.We used quantitative PCR to characterize Bd and Rv dynamics in natural populations of three amphibian species: Notophthalmus perstriatus, Hyla squirella and Pseudacris ornata. We combined pathogen data, genetic diversity metrics generated from neutral markers, and environmental variables into general linear models to evaluate how these factors impact infectious disease dynamics. Occurrence, prevalence and intensity of Bd and Rv varied across species and populations, but only one species, Pseudacris ornata, harbored high Bd intensities in the majority of sampled populations. Genetic diversity and climate variables both predicted Bd prevalence, whereas climatic variables alone predicted infection intensity.We conclude that Bd is more abundant in the southeastern United States than previously thought and that genetic and environmental factors are both important for predicting amphibian pathogen dynamics. Incorporating both genetic and environmental information into conservation plans for amphibians is necessary for the development of more effective management strategies to mitigate the impact of emerging infectious diseases.

A SURVEY OF THE AVIFAUNA OF THE KOSTOMUKSHSKY STRICT NATURE RESERVE IN 2015 AND 2016

The last large-scope ornithological survey in the Kostomukshsky Strict Nature Reserve was conducted some 20 years ago by S. V. Sazonov. Inventory and diversity assessment of the avifauna in the then-planned national park Kalevalsky were also conducted by S. V. Sazonov in 1992 and 1995-1997. In 1997 he was joined by N. V. Medvedev, Y T. Khokhlova, N. V. Lapshin, and A. V. Artemyev. The findings from these surveys were published later. To investigate the current state of the avifauna and assess possible changes during past decades special surveys were conducted in the reserve in June 2015 and July 2016. The method consisted in a combination of transect surveys, partially duplicating the routes surveyed in the previous years, and examination of sample plots representing all the main types of local habitats. Overall, the surveys covered around 20 % of the nature reserve area, including the Kalevalsky National Park (now incorporated within the strict nature reserve). A part of the routes included lake sections (specialized waterfowl surveys). Several plots were established in the reserve's buffer zone and in the suburbs of the Town of Kostomuksha (territory under the reserve's authority). Current records from the surveyed area include 105 species of birds belonging to 33 families of 13 orders. It should be noted, that the list of species in our paper is shorter than the one compiled after the longer surveys conducted 20 years ago (in Sazonov's publication of 1997). First, the new list misses some rare and vagrant species, the registration of which is largely random in nature and is more likely during long-term studies. In addition, for some species the optimal time of observation when birds are more noticeable is spring (migration and active demonstrations), and not summer, when our investigations were conducted. A small share of species in the reserve is more common in winter. Thus, to obtain up-to-date data on birds of these categories and, in general, to provide a more complete analysis of the state of the avifauna in the reserve, further monitoring studies are needed in all existing types of landscapes and habitats in different seasons of a year. However, a slight increase in the species diversity was observed in data from our transects compared to the results of previous studies. The reasons for that may be associated with the redistribution of birds across the reserve, some successional changes, specifics of the seasons of 2015 and 2016, and natural population dynamics of different species. In general, according to data pooled from all the surveyed sites, we can conclude that the qualitative status of the avifauna in the reserve (species presence) has changed insignificantly over the past two decades, which is apparently due to the fact that most of the local habitats are in final stages of the succession, with communities close to climax. At the same time, some changes in the quantitative composition of the avifauna were noted: the share of typical boreal species has declined, whereas the proportion of species with wide distribution and species typical of southerner regions slightly increased. The reasons for these changes are not completely clear, but because such a situation has been observed in other boreal complexes as well, we can assume that this is an expression of global processes, of the natural population dynamics of species.

Sexual signals reflect telomere dynamics in a wild bird.

Telomere dynamics in natural populations have been linked to survival, reproduction, and energetic investment. Given their putative role in mediating life‐history trade‐offs, telomeres are also a likely candidate for maintaining honesty in sexually selected signals; few studies to date, however, have demonstrated a correlation between sexual signals and telomere dynamics. Here, we show that plumage coloration in male common yellowthroats (Geothlypis trichas) is correlated with both relative telomere length and with the rate of telomere loss between years. Elevated antioxidant capacity is also associated with reduced telomere loss, but only among older males. Previous work in this population has demonstrated that males with brighter plumage are in better condition, have higher reproductive success, and are more likely to survive over winter. Thus, the signal attribute associated with mate choice in this system also conveys reliable information about telomere dynamics. At present, it is unclear whether telomere maintenance plays a causal role in maintaining signal honesty or whether the correlation arises due to underlying variation in individual resources or genotypes. We suggest that subsequent work should consider the possibility that fundamental trade‐offs between signal investment and cell‐level processes that influence aging and reproductive senescence may provide a foundation for understanding the maintenance of sexual signal honesty.

Fine-Scale Genetic Structure ofZamia furfuracea: Variation with Life-Cycle Stages

Fine-scale spatial genetic structure (SGS) analysis has proved to be a useful tool to establish the distribution of genetic variability between individuals and how these patterns are affected by microenvironmental conditions, associations with pollinators and dispersers, and sex ratio. In this study, the correlation between the fine-scale SGS of a population of Zamia furfuracea L. fil. and its dependence on the patterns of spatial aggregation between categories of life cycle and the proportion of males and females was determined by using intersimple sequence repeat markers. Results showed an aggregation pattern dependent on reproductive adults of up to 10 m; however, dependence on sex was restricted to only 3 m, suggesting limited pollen and seed dispersal. Gene neighborhoods did not exceed 10 m, with three well-defined families within the population. The small size of the neighborhoods, high mortality rate of seedlings, and loss of genetic variability in the juvenile category suggest that this population is severely affected. Our results contribute to the understanding of genetic and spatial dynamics in natural populations of cycads. Such information should be considered for the implementation of ex situ population-management programs.

Deterministic chaоs and the problem of predictability in population dynamics

The studies of the processes that can significantly influence the predictability in population dynamics are reviewed and the results of mathematical simulations of population dynamics are compared to the time series obtained in field observations. Considerable attention is given to the chaotic changes in population abundance. Some methods of numerical analysis of chaoticity and predictability of the time series are considered. The importance of comparing the results of mathematical simulation and observation data is tightly linked to problems in detecting chaos in the dynamics of natural populations and estimating the prevalence of chaotic regimes in nature. Insight into these problems can allow identification of the functional role of chaotic regimes in population dynamics.