Variation In Fecundity Research Articles

Fecundity Variation of Labeo rohita (Hamilton, 1822) in Lentic Freshwater Systems in Purnea District, Bihar, India

Fecundity Variation of Labeo rohita (Hamilton, 1822) in Lentic Freshwater Systems in Purnea District, Bihar, India

Regional fertility predictors based on socioeconomic determinants in Slovakia

The study's primary purpose was to recognise the effects of determinants on the level of fertility and thereby explain the differences in trends in the regions of Slovakia. At the turn of the century, the differences in fertility in regions increased, but the total fertility rate decreased. Multivariate statistical methods clarified the regional effects of the level and nature of fertility. Initial regression surveys indicated weak effects between regions, which led to applying factor and cluster analysis to establish regional types. Comprehensive regression analysis was then applied. The strength and nature of regional relationships differed at the inter- and intra-regional levels. Research has demonstrated significant differences in fertility rates dependent on the socioeconomic environment, as regional types uniquely link to determinants. Moreover, each determinant has specific spatial patterns with unequal regression coefficients at different regional levels, which cannot be evaluated constantly. Knowing how spatial variation in fecundity occurs will enable future studies to elucidate the processes involved. Finally, fertility is vital for social assessment and policy formulation, the study’s findings could inform local decision-makers and planners in identifying the socioeconomic conditions underlying fertility at the regional level and planning appropriate intervention strategies.

The Impact of High-Temperature Stress on the Growth and Development of Tuta absoluta (Meyrick).

Insect life processes and reproductive behaviors are significantly affected by extremely high temperatures. This study focused on Tuta absoluta, which poses a severe threat to tomato cultivars. The effects of intense heat stress on the growth, development, oviposition, and longevity of T. absoluta were investigated. This investigation encompassed various developmental stages, including eggs, pupae, and adults. This study revealed that egg hatching and pupa emergence rates were significantly reduced at a temperature of 44 °C maintained for 6 h. The longevity of adults that emerged after the egg and pupal stages were exposed to 44 °C for 6 h was significantly reduced compared to the control. Notably, there was no significant variation in adult fecundity after egg-stage exposure to high temperatures. However, all treatments exhibited significantly reduced fecundity compared to the control after exposure to high temperatures during the pupal stage. Adult survival rates after exposure to 40 °C and 44 °C for 3 h were 74.29% and 22.40%, respectively, dramatically less than that of the control, which was 100%. However, no significant differences were noted in terms of longevity and egg production. These results offer a better understanding of the complex interactions between extreme temperatures and the life history traits of T. absoluta, thereby offering valuable insights for implementing management strategies to alleviate its impact on tomato crops in response to climate change.

Investigating structural variant, indel and single nucleotide polymorphism differentiation between locally adapted Atlantic salmon populations.

Genomic structural variants (SVs) are now recognized as an integral component of intraspecific polymorphism and are known to contribute to evolutionary processes in various organisms. However, they are inherently difficult to detect and genotype from readily available short-read sequencing data, and therefore remain poorly documented in wild populations. Salmonid species displaying strong interpopulation variability in both life history traits and habitat characteristics, such as Atlantic salmon (Salmo salar), offer a prime context for studying adaptive polymorphism, but the contribution of SVs to fine-scale local adaptation has yet to be explored. Here, we performed a comparative analysis of SVs, single nucleotide polymorphisms (SNPs) and small indels (<50 bp) segregating in the Romaine and Puyjalon salmon, two putatively locally adapted populations inhabiting neighboring rivers (Québec, Canada) and showing pronounced variation in life history traits, namely growth, fecundity, and age at maturity and smoltification. We first catalogued polymorphism using a hybrid SV characterization approach pairing both short- (16X) and long-read sequencing (20X) for variant discovery with graph-based genotyping of SVs across 60 salmon genomes, along with characterization of SNPs and small indels from short reads. We thus identified 115,907 SVs, 8,777,832 SNPs and 1,089,321 short indels, with SVs covering 4.8 times more base pairs than SNPs. All three variant types revealed a highly congruent population structure and similar patterns of F ST and density variation along the genome. Finally, we performed outlier detection and redundancy analysis (RDA) to identify variants of interest in the putative local adaptation of Romaine and Puyjalon salmon. Genes located near these variants were enriched for biological processes related to nervous system function, suggesting that observed variation in traits such as age at smoltification could arise from differences in neural development. This study therefore demonstrates the feasibility of large-scale SV characterization and highlights its relevance for salmonid population genomics.

Idiosyncratic effects of bacterial infection on female fecundity in Drosophila melanogaster

Existing theories make different predictions regarding the effect of a pathogenic infection on the host capacity to reproduce. Terminal investment theory suggests that due to the increased risk of mortality, and the associated risk of losing future opportunity to reproduce, infected individuals would increase their investment towards reproduction. Life-history theory posits that due to energetic and resource costs associated with mounting an immune defense, hosts would decrease their investment towards reproduction, and reallocate resources towards defense and survival. Additionally, Somatic damage incurred by the host due to the infection is also expected to compromise the host capacity to reproduce. We explored these possibilities in Drosophila melanogaster females experimentally infected with pathogenic bacteria. We tested if the effect of infection on female fecundity is pathogen specific, determined by infection outcome, and variable between individual infected females. We observed that the mean, population level change in post-infection female fecundity was pathogen specific, but not correlated with mortality risk. Furthermore, infection outcome, i.e., if the infected female died or survived the infection, had no effect on fecundity at this level. At individual resolution, females that died after infection exhibited greater variation in fecundity compared to ones that survived the infection. This increased variation was bidirectional, with some females reproducing in excess while others reproducing less compared to the controls. Altogether, our results suggest that post-infection female fecundity is unlikely to be driven by risk of mortality and is probably determined by the precise physiological changes that an infected female undergoes when infected by a specific pathogen.

Genetic and Phenotypic Consequences of Local Transitions between Sexual and Parthenogenetic Reproduction in the Wild.

AbstractTransitions from sexual to asexual reproduction have occurred in numerous lineages, but it remains unclear why asexual populations rarely persist. In facultatively parthenogenetic animals, all-female populations can arise when males are absent or become extinct, and such populations could help to understand the genetic and phenotypic changes that occur in the initial stages of transitions to asexuality. We investigated a naturally occurring spatial mosaic of mixed-sex and all-female populations of the facultatively parthenogenetic Australian phasmid Megacrania batesii. Analysis of single-nucleotide polymorphisms indicated multiple independent transitions between reproductive modes. All-female populations had much lower heterozygosity and allelic diversity than mixed-sex populations, but we found few consistent differences in fitness-related traits between population types. All-female populations exhibited more frequent and severe deformities in their (flight-incapable) wings but did not show higher rates of appendage loss. All-female populations also harbored more ectoparasites in swamp (but not beach) habitats. Reproductive mode explained little variation in female body size, fecundity, or egg hatch rate. Our results suggest that transitions to parthenogenetic reproduction can lead to dramatic genetic changes with little immediate effect on performance. All-female M. batesii populations appear to consist of high-fitness genotypes that might be able to thrive for many generations in relatively constant and benign environments but could be vulnerable to environmental challenges, such as increased parasite abundance.

A review on the effects of heavy metals on the development of blow flies (Diptera: Calliphoridae)

AbstractHeavy metals such as lead, cadmium, zinc, copper, mercury, and others, are naturally occurring non degradable elements which can accumulate in the environment and in living organisms and can have a significant impact on their physiological functions. Studies have shown that heavy metals can also influence the development and morphology of insects. Insects are the most abundant organisms on earth and play a major role in different ecosystems. They help in the dispersion of organic matter and are an important part of different ecological processes. Forensic entomology focuses on the use of arthropods in legal investigations. Shortly after death, a corpse is quickly colonized by several insect families; blow flies (Diptera: Calliphoridae) are among the first colonizers and are therefore often used for the estimation of the time of colonization (TOC) or minimum post‐mortem interval (mPMI). Since larvae feed on the corpse, any xenobiotic present in the remains, including heavy metals, can be ingested, and accumulated by them; these substances can influence their development and, in turn, can alter the estimation of the mPMI. We analyzed the literature on studies pertaining to the detection of heavy metals in blow flies and on their variations in developmental rate, mass, length, fecundity, morphology, immune system, and mortality rate.This article is categorized under: Forensic Biology &gt; Forensic Entomology Forensic Anthropology &gt; Time Since Death Estimation Forensic Biology &gt; Interpretation of Biological Evidence

Phytochemicals in Brassica juncea distressing developmental and reproductive biology of mustard aphid (Lipaphis erysimi)

The present study was carried out to decipher the variation in plant phytochemicals, and their effect on developmental, reproduction and survival of Lipaphis erysimi (Kalt.) on diverse Brassica juncea cultivars. These studies revealed significant differences in total nymphal, reproductive and developmental periods, fecundity and offspring survival of L. erysimi on the test B. juncea cultivars. Development period was significantly longer on DRMR 150-35, PM 26, RLC 3 and PM 25, while fecundity and survival were lower on PM 27, RLC 3, NRCHB 101, RH 749, Pusa Tarak, RH 0406 and PM 30, except in a few cases. Total proteins, antioxidants, tannins, phenols and FRAP were significantly higher, and sugars lower in DRMR 150-35, RLC 3, PM 26 and NRCHB 101 as compared to other B. juncea cultivars. Total proteins, total tannins and antioxidants exhibited a significant and positive, while total sugars showed negative correlation, and explained 86.1% variability in total developmental period of L. erysimi. Total sugars revealed a significantly positive and FRAP negative correlation, explaining 35.5% variability in fecundity of L. erysimi. Furthermore, total proteins and total antioxidants also showed significant and negative correlation with offspring survival, and total phenols and antioxidants explained 28.9% variability in offspring survival of L. erysimi on the test B. juncea genotypes. Present study suggests that DRMR 150-35, RLC 3, NRCHB 101 and PM 26 have greater amounts of antinutritional plant defense compounds which adversely affect the developmental and reproductive biology of L. erysimi, and thus could be used in Brassica improvement programme for sustainable crop production.

Estimating peak breeding season, size at first maturity and variation in fecundity and egg-size at different sizes of Hilsa (Tenualosa ilisha)

Hilsa shad, Tenualosa ilisha, has recently gained momentum due to its taste, nutrition and demand. Imposing ban at peak breeding and setting up a minimum capture size are two of the most effective tools for conservation and management of any fish species. Although, Bangladesh government has been imposing ban on a particular time and set the minimum legal size, there is still contradictory information on these two issues. That is why, a study was carried out to determine peak season of breeding and first maturity of Hilsa collected across the natural habitats in Bangladesh. Variation in fecundity and egg-size at different sizes were also investigated. Peak breeding season was identified observing gonadosomatic index of female Hilsa all the year round. First maturity was estimated with Probit analysis.Based on the gonadosomatic index of gravid females, peak breeding season was identified as late October to early November in this study. However, another minor peak was found in February–March. The highest GSI value (12.1) was observed in October–November, which indicates the peak time of spawning. The size at maturity (M50) of female Hilsa was estimated as 31 cm total length. A significant variation was observed in egg sizes between the left and right lobes of the fish (t (24) = 2.42, p = 0.02), and between the parts of the same lobe (p = 0.03). However, fish length and weight had no effect on egg size(for egg-size vs. fish length, r = -0.009, p = 0.966; and for egg size vs. body weight, r = 0.132 and p = 0.530). The average egg count from left lobe and right lobe were recorded as 0.375 ± 0.16 million, 0.371 ± 0.17 million. Total fecundity was counted as 0.745 ± 0.33 million. A significant positive correlation was noticed between length, weight, and total fecundity (r = 0.7 for total fecundity vs. body weight; r = 0.6 for of total fecundity vs. length). No significant variation was observed in fecundity between the left and right lobe (p = 0.6) and among three parts of a lobe (p = 0.3). The size of eggs varied between two lobes and among different parts of a lobe. The eggs from middle part were bigger in size than the other parts. The findings of our study will help conserve and manage the natural population of Hilsa (T. ilisha) in Bangladesh and contribute to the wider scientific community.

Size-dependent growth and fecundity variations of three land snails: implications for population management

ABSTRACT Size class dependent variations of growth and fecundity of three small land snails, Allopeas gracile (Hutton 1834) (Gastropoda: Subulinidae), Succinea daucina (Pfeiffer, 1855) (Gastropoda: Succineidae) and Glessula gemma (Reeve 1850) (Gastropoda: Subulinidae) were assessed in the laboratory condition. The field collected snails were segregated according to the size (shell length, in mm), and the frequency distribution of each size class was estimated. Subsequently, each size class was reared in the laboratory with continuous monitoring for the deposition of the eggs in the rearing terrarium for a period of six weeks using three replicates per size class. The growth rate of each species was highest in the smallest size class and declined gradually with the increment of shell length. The shell lengths of A. gracile and S. daucina at sexual maturity were 4–5 mm and 6–7 mm, respectively, and fecundity was positively linked with the size (shell length). G. gemma did not oviposit, except that the large size-class had given few small offspring. The results showed that growth and reproduction of three species varied significantly with size classes, which reflects the ability for these snails to colonize and establish in favourable habitats in short time period.

The effect of gene flow on frost tolerance in Scots pine – Latitudinal translocation of genetic material

Extensive gene flow can be detrimental to local adaptation and similarly, forestry seed sources such as seed orchards can be heavily influenced by external pollination, especially if the orchard material has been translocated a great distance. Here we conducted a coordinated genotyping-phenotyping study to examine how external pollination events and fecundity variation in a Pinus sylvestris seed orchard influence the genetic composition and the seed-lots’ autumn frost hardiness when genetic material had been translocated 630 km south. The results were then compared to those of a in situ established seed orchard. We genotyped and phenotype >1000 seedlings from these orchards, and constructed their pedigrees and scored their autumn frost tolerance in a controlled climate chamber environment. The hardiness scores were compared with a reference of nine natural stands along a latitudinal cline. We find substantial variation in fecundity and external pollination over crop years, thus unpredictable genetic composition because the contribution of some orchard clones is high in one crop but low in another. We observed that seedlings produced by mating among orchard genotypes were less hardy than expected (corresponding to an origin of −0.6°N) but the opposite in externally pollinated seedlings (+0.3 to +0.7°N). The freeze damage levels reflect the origin of parental genotypes, but to a smaller degree than expected (13% lower than expected damage levels for externally pollinate seedlings and 21% greater damage levels for internally pollinates seedlings). These results suggest that orchard parents’ origins, mating composition and orchard local environment could all affect the seed crops’ quality and their climate adaptation. Seed orchard crops are the key to realize the gain in forestry from breeding efforts. However, genetic monitoring of seed crops is necessary to improve the performance of seed orchards further and adjust deployment areas of seed crops in a timely manner for a more dynamic forestry, considering climate change and biodiversity demands.

Intraspecific variation for host immune activation by the spider mite Tetranychus evansi.

Many parasites can interfere with their host's defences to maximize their fitness. Here, we investigated if there is heritable variation in the spider mite Tetranychus evansi for traits associated with how they interact with their host plant. We also determined if this variation correlates with mite fecundity. Tetranychus evansi can interfere with jasmonate (JA) defences which are the main determinant of anti-herbivore immunity in plants. We investigated (i) variation in fecundity in the presence and absence of JA defences, making use of a wild-type tomato cultivar and a JA-deficient mutant (defenseless-1), and (ii) variation in the induction of JA defences, in four T. evansi field populations and 59 inbred lines created from an outbred population originating from controlled crosses of the four field populations. We observed a strong positive genetic correlation between fecundity in the presence (on wild-type) and the absence of JA defences (on defenseless-1). However, fecundity did not correlate with the magnitude of induced JA defences in wild-type plants. Our results suggest that the performance of the specialist T. evansi is not related to their ability to manipulate plant defences, either because all lines can adequately reduce levels of defences, or because they are resistant to them.

A simulation-based evaluation of methods for estimating census population size of terrestrial game species from genetically-identified parent-offspring pairs.

Estimates of wildlife population size are critical for conservation and management, but accurate estimates are difficult to obtain for many species. Several methods have recently been developed that estimate abundance using kinship relationships observed in genetic samples, particularly parent-offspring pairs. While these methods are similar to traditional Capture-Mark-Recapture, they do not need physical recapture, as individuals are considered recaptured if a sample contains one or more close relatives. This makes methods based on genetically-identified parent-offspring pairs particularly interesting for species for which releasing marked animals back into the population is not desirable or not possible (e.g., harvested fish or game species). However, while these methods have successfully been applied in commercially important fish species, in the absence of life-history data, they are making several assumptions unlikely to be met for harvested terrestrial species. They assume that a sample contains only one generation of parents and one generation of juveniles of the year, while more than two generations can coexist in the hunting bags of long-lived species, or that the sampling probability is the same for each individual, an assumption that is violated when fecundity and/or survival depend on sex or other individual traits. In order to assess the usefulness of kin-based methods to estimate population sizes of terrestrial game species, we simulated population pedigrees of two different species with contrasting demographic strategies (wild boar and red deer), applied four different methods and compared the accuracy and precision of their estimates. We also performed a sensitivity analysis, simulating population pedigrees with varying fecundity characteristics and various levels of harvesting to identify optimal conditions of applicability of each method. We showed that all these methods reached the required levels of accuracy and precision to be effective in wildlife management under simulated circumstances (i.e., for species within a given range of fecundity and for a given range of sampling intensity), while being robust to fecundity variation. Despite the potential usefulness of the methods for terrestrial game species, care is needed as several biases linked to hunting practices still need to be investigated (e.g., when hunting bags are biased toward a particular group of individuals).

Improved Quality Management of the Indian Meal Moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) for Enhanced Efficacy of the Sterile Insect Technique.

The sterile insect technique (SIT) is considered an environmentally friendly, autocidal control tactic to manage insect pests. This work dealt with the improvement of quality management of the Indian meal moth Plodia interpunctella (Hübner) for enhanced efficacy of the SIT. The results indicated that egg hatching of irradiated mature eggs of P. interpunctella was higher than that of younger eggs, indicating that mature eggs were significantly more tolerant than younger eggs. Moreover, our data revealed that a dose of 500 Gy completely prevented pupal formation in irradiated young and mature larvae. Crosses between irradiated and non-irradiated adults resulted in considerable variations in fecundity. The mating competitiveness index (CI) value was higher for a ratio of 5:1:1 (sterile male, fertile male, and fertile female, respectively) as compared with the ratio 1:1:1 for the irradiated individuals of all life stages. Low temperature (5 °C) maintenance of irradiated pupae significantly affected adult emergence. Using cylinders to assess flight ability, we found that the flight performance of adults that were developed from cold treated irradiated pupae was influenced by cylinder diameter, cylinder height and the number of hours the insects were in the cylinders. The percentage of DNA damage of the reproductive organs of adults developed from cold treated pupae that were irradiated with 100 and 150 Gy varied significantly. The results of this study should be used to implement pilot-scale field tests aiming at a sterile- to-fertile male ratio of 5 to 1.

Fecundity trends of Chinook salmon in the Pacific Northwest

AbstractFecundity is an important demographic parameter that contributes to the productivity of anadromous fish stock dynamics. Yet, studies on fecundity patterns in Pacific salmon (Oncorhynchusspp.) often only include a few years of data, limiting our ability to understand spatio‐temporal trends. Here, we used data on 43 hatchery Chinook salmon (O. tshawytscha, Salmonidae) populations in Washington State to evaluate whether average fecundity changed over the past three decades. We then used data from a subset of stocks (18) to evaluate the relationship between fecundity and body length. Our results revealed significant changes in fecundity across the 25‐year study period with most stocks showing declines in fecundity over the past decade. Results further showed that Chinook salmon have decreased in length over this same period and that annual variation in mean length explains a majority (62%) of annual variation in mean fecundity. Specifically, we estimated that a 1‐mm reduction in length results in 7.8 fewer eggs (95% CI = 6.6–8.9). Given that the majority of Pacific Northwest Chinook salmon in the environment and harvested in fisheries originate from hatchery releases and that nearby hatchery and wild populations generally have similar ocean distributions, these results likely reflect patterns for many populations not included. Combined, our results highlight the need to consider changes in body size and egg production when assessing the dynamics of anadromous fish populations and designing management or conservation plans, particularly for depressed populations.

NMπ 2.0: Software update to minimize the risk of false positives among determinants of reproductive success.

In plant populations, parentage analysis helps understand factors shaping individual reproductive success. However, estimating reproductive success determinants based on parentage counts requires decoupling the effects of individual fecundity and propagule dispersal. The neighbourhood model implemented in the NMπ software provides a standard solution for this problem based on the fixed-effects regression-like approach. Nonetheless, it has been recently shown that the method is prone to false discoveries when important fecundity determinants are omitted. To account for the unexplained variance in fecundity, the Bayesian approach was developed based on the new model (the hierarchical neighbourhood model; HNM). Here, I present the NMπ software update that allows the HNM approach to be used in the framework of a friendly interface. More importantly, the HNM approach is now made available for both dispersed (seedlings) and nondispersed (seeds with known mothers) progeny data. The Bayesian approach, among others, selects significant fecundity determinants, estimates the proportion of variance in reproductive potential explained by selected determinants (R2 ), and provides individual female and male fecundity values. Although the software was designed to handle microsatellite marker data, a solution is proposed for large sets of single nucleotide polymorphisms. The program can be run on Windows (using either a terminal or a graphical interface) as well as (using a terminal) on Linux, or macOS platforms. In any case, NMπ can utilize multicore processors to speed up the analysis. The updated package containing the code, the executable file, the user manual, and example data is available at https://www.ukw.edu.pl/pracownicy/plik/igor_chybicki/3694/.

A note on the modelling of MSY-related parameters when population dynamics are stochastic

A method is outlined for calculating the values for the parameters which determine MSYR and MSYL in the types of population dynamics models on which Implementation Simulation Trials and Evaluation Trials are based in the face of environmental variability in fecundity (birth rate) and survival. The method is illustrated using a minke whale-like biology in which MSYR is defined in terms of harvesting of the mature female component of the population. Results are shown for various levels of environmental variation in survival and fecundity

Response of the soft scale insect Parthenolecanium corni and its natural enemies on honeylocust trees to urban conditions

Urban habitats can alter tree physiology in ways that make trees more susceptible to insect pests. We examined how urban conditions (e.g., impervious surfaces and warming) affected the soft scale insect, European fruit lecanium, Parthenolecanium corni Bouché (Hemiptera: Coccidae) and the health of thornless honeylocust trees (Gleditsia tricanthos L. var. inermis) in Indianapolis, Indiana, USA. Hot and cool study sites were selected based on surface air temperatures obtained from thermal LANDSAT-8 images overlaid against a map of honeylocust tree locations. Based on temperature probe data, study trees located in hot sites had mean average daily temperatures up to 1.56 °C and 1.79 °C warmer than cool sites in 2019 and 2020, respectively. We hypothesized that abundance and fecundity of scale insects would be higher on trees in hot sites and those surrounded by more impervious surface cover within a 20 m radius. Although our data supported these hypotheses, impervious surface cover predicted more of the variation in abundance and fecundity of scale insects in hot sites compared to cool sites. Rates of parasitism were not affected by impervious surface cover or whether the site was from a hot or cool location. However, we found strong density dependence in parasitism of scale insects in both hot and cool sites when scale densities were at or below the levels present in cool sites. This suggests that lower densities of scale insects were associated with a positive numerical response of parasitoids, a necessary prerequisite for population regulation by top-down effects. In contrast, this numerical response was lacking at the higher densities of scales found on trees located in hot sites where, presumably bottom-up factors like water-stress increased the fecundity of scale insects. These findings add to a growing body of evidence linking rising global temperatures with increased pest abundance in ways that cannot be mitigated by local populations of natural enemies.

Territory and population attributes affect Florida scrub-jay fecundity in fire-adapted ecosystems.

Fecundity, the number of young produced by a breeding pair during a breeding season, is a primary component in evolutionary and ecological theory and applications. Fecundity can be influenced by many environmental factors and requires long-term study due to the range of variation in ecosystem dynamics. Fecundity data often include a large proportion of zeros when many pairs fail to produce any young during a breeding season due to nest failure or when all young die independently after fledging. We conducted color banding and monthly censuses of Florida scrub-jays (Aphelocoma coerulescens) across 31 years, 15 populations, and 761 territories along central Florida's Atlantic coast. We quantified how fecundity (juveniles/pair-year) was influenced by habitat quality, presence/absence of nonbreeders, population density, breeder experience, and rainfall, with a zero-inflated Bayesian hierarchical model including both a Bernoulli (e.g., brood success) and a Poisson (counts of young) submodel, and random effects for year, population, and territory. The results identified the importance of increasing "strong" quality habitat, which was a mid-successional state related to fire frequency and extent, because strong territories, and the proportion of strong territories in the overall population, influenced fecundity of breeding pairs. Populations subject to supplementary feeding also had greater fecundity. Territory size, population density, breeder experience, and rainfall surprisingly had no or small effects. Different mechanisms appeared to cause annual variation in fecundity, as estimates of random effects were not correlated between the success and count submodels. The increased fecundity for pairs with nonbreeders, compared to pairs without, identified empirical research needed to understand how the proportion of low-quality habitats influences population recovery and sustainability, because dispersal into low-quality habitats can drain nonbreeders from strong territories and decrease overall fecundity. We also describe how long-term study resulted in reversals in our understanding because of complications involving habitat quality, sociobiology, and population density.

Репродуктивные характеристики синца Ballerus ballerus (Linnaeus, 1758) Камского водохранилища

This paper presents the age and sex structure of the spawning part of the blue bream population in the Kama reservoir in 2019–2022. The age structure of the blue bream is characterized by a high number of older groups, which is associated with the peculiarity of fishing in the Kama reservoir. In comparison with earlier data on the reservoir, a reduction in the timing of fish puberty has been established, currently timed to the 5-year-old age for males, and to the 6-year-old age for females. It was revealed that the life expectancy of fish increased to 17 years of age. A study of fertility of blue bream was carried out on 87 females represented by 11 age groups. The limits of variation of individual absolute fecundity have been determined to exceed the earlier data, the minimum of individual absolute fecundity is 8.6 thousand eggs, the maximum of individual absolute fecundity is 78.8 thousand eggs. It is shown, that the reproductive ability of the females of the blue bream in the Kama reservoir remains at a high level and is characterized by increase in the average values of individual relative fertility up to 10 years of age, the maximum average values of relative fertility are observed in 15-year-old fish.