Although density regulates the abundance of most wild animal populations by influencing vital rates, such as fecundity and survival, the mechanisms responsible for generating negative density ...dependence are unclear for many species. Site dependence occurs when there is preferential filling of high-quality territories, which results in higher per capita vital rates at low densities because a larger proportion of occupied territories are of high quality. Using 41 yr of territory occupancy and demographic data, we investigated whether site dependence was a mechanism acting to influence fecundity and, by extension, regulate a population of Canada Jays in Algonquin Provincial Park, Ontario, Canada. As predicted by site dependence, the proportion of occupied territories that were of high quality was negatively correlated with population density and periods of vacancy were shorter for high-quality territories than for low-quality territories. We also found evidence that per capita fecundity was positively related to the proportion of occupied territories that were of high quality, but only when environmental conditions, which influence the entire population, were otherwise poor for breeding. Our results suggest that site dependence likely plays a role in regulating this population but that environmental conditions can modulate the strength of density dependence.
The greater wax moth (Galleria mellonella (Linnaeus)) is one of Asia’s most essential pests in honey beekeeping. Apart from being a pest, G. mellonella was also used as a test insect in several ...business fields. The needs of the population of G. mellonella encourage several areas of the business to cultivate it practically and economically. This study aimed to determine and examine the composition of food ingredients as an artificial diet that can affect the growth and development of G. mellonella. The test consisted of four different feed-modified formulas, namely P1 (corn flour, wheat, glycerol, and yeast), P2 (rice flour, wheat flour, wheat bran, glycerol, and yeast), P3 (wheat flour, wheat, glycerol, and yeast), and P4 (brown rice, glycerol, and yeast). The observation criteria were life cycle, mortality rate, fecundity, and egg fertility of the G. mellonella moth. Based on the study’s results, the life cycle development of G. mellonella was the shortest in the P3 treatment (71.5 ± 5.2 days) and the longest P4 treatment (84.2 ± 8.3 days). The highest mortality rate was in the P3 feed type at 13.12%, while the lowest occurred in the P4 treatment at 4.44%. Based on the fecundity of female imago, treatment P4 had the highest fecundity level of 527.7 eggs/female, while treatment P1 was the lowest (169.6 eggs/female). P4 treatment responded best to several biological aspects of the G. mellonella moth, such as larger body size, lower mortality, and high fecundity rates.
Is there tree senescence? The fecundity evidence Qiu, Tong; Aravena, Marie-Claire; Andrus, Robert ...
Proceedings of the National Academy of Sciences - PNAS,
08/2021, Letnik:
118, Številka:
34
Journal Article
Recenzirano
Odprti dostop
Despite its importance for forest regeneration, food webs, and human economies, changes in tree fecundity with tree size and age remain largely unknown. The allometric increase with tree diameter ...assumed in ecological models would substantially overestimate seed contributions from large trees if fecundity eventually declines with size. Current estimates are dominated by overrepresentation of small trees in regression models. We combined global fecundity data, including a substantial representation of large trees. We compared size-fecundity relationships against traditional allometric scaling with diameter and two models based on crown architecture. All allometric models fail to describe the declining rate of increase in fecundity with diameter found for 80% of 597 species in our analysis. The strong evidence of declining fecundity, beyond what can be explained by crown architectural change, is consistent with physiological decline. A downward revision of projected fecundity of large trees can improve the next generation of forest dynamic models.
Exposure to ambient fine particulate matter (PM2.5) has been associated with reduced human fecundity. However, the attributable burden has not been estimated for low- and middle-income countries ...(LMICs), where the exposure–response function between PM2.5 and the infertility rate has been insufficiently studied.
This study examined the associations between long-term exposure to PM2.5 and human fecundity indicators, namely the expected time to pregnancy (TTP) and 12-month infertility rate (IR), and then estimated PM2.5-attributable burden of infertility in LMICs.
We analyzed 164,593 eligible women from 100 Demographic and Health Surveys conducted in 49 LMICs between 1999 and 2021. We assessed PM2.5 exposures during the 12 months before a pregnancy attempt using the global satellite-derived PM2.5 estimates produced by Atmospheric Composition Analysis Group (ACAG). First, we created a series of pseudo-populations with balanced covariates, given different levels of PM2.5 exposure, using a matching approach based on the generalized propensity score. For each pseudo-population, we used 2-stage generalized Gamma models to derive TTP or IR from the probability distribution of the questionnaire-based duration time for the pregnancy attempt before the interview. Second, we used spline regressions to generate nonlinear PM2.5 exposure–response functions for each of the two fecundity indicators. Finally, we applied the exposure–response functions to estimate number of infertile couples attributable to PM2.5 exposure in 118 LMICs.
Based on the Gamma models, each 10 µg/m3 increment in PM2.5 exposure was associated with a TTP increase by 1.7 % (95 % confidence interval CI: -2.3 %–6.0 %) and an IR increase by 2.3 % (95 %CI: 0.6 %–3.9 %). The nonlinear exposure–response function suggested a robust effect of an increased IR for high-concentration PM2.5 exposure (>75 µg/m3). Based on the PM2.5-IR function, across the 118 LMICs, the number of infertile couples attributable to PM2.5 exposure exceeding 35 µg/m3 (the first-stage interim target recommended by the World Health Organization global air quality guidelines) was 0.66 million (95 %CI: 0.061–1.43), accounting for 2.25 % (95 %CI: 0.20 %–4.84 %) of all couples affected by infertility. Among the 0.66 million, 66.5 % were within the top 10 % high-exposure infertile couples, mainly from South Asia, East Asia, and West Africa.
PM2.5 contributes significantly to human infertility in places with high levels of air pollution. PM2.5-pollution control is imperative to protect human fecundity in LMICs.
ABSTRACT
Fitness results from an optimal balance between survival, mating success and fecundity. The interactions between these three components of fitness vary depending on the selective context, ...from positive covariation between them, to antagonistic pleiotropic relationships when fitness increases in one reduce the fitness of others. Therefore, elucidating the routes through which selection shapes life history and phenotypic adaptations via these fitness components is of primary significance to understanding ecological and evolutionary dynamics. However, while the fitness components mediated by natural (survival) and sexual (mating success) selection have been debated extensively from most possible perspectives, fecundity selection remains considerably less studied. Here, we review the theoretical basis, evidence and implications of fecundity selection as a driver of sex‐specific adaptive evolution. Based on accumulating literature on the life‐history, phenotypic and ecological aspects of fecundity, we (i) suggest a re‐arrangement of the concepts of fecundity, whereby we coin the term ‘transient fecundity’ to refer to brood size per reproductive episode, while ‘annual’ and ‘lifetime fecundity’ should not be used interchangeably with ‘transient fecundity’ as they represent different life‐history parameters; (ii) provide a generalized re‐definition of the concept of fecundity selection as a mechanism that encompasses any traits that influence fecundity in any direction (from high to low) and in either sex; (iii) review the (macro)ecological basis of fecundity selection (e.g. ecological pressures that influence predictable spatial variation in fecundity); (iv) suggest that most ecological theories of fecundity selection should be tested in organisms other than birds; (v) argue that the longstanding fecundity selection hypothesis of female‐biased sexual size dimorphism (SSD) has gained inconsistent support, that strong fecundity selection does not necessarily drive female‐biased SSD, and that this form of SSD can be driven by other selective pressures; and (vi) discuss cases in which fecundity selection operates on males. This conceptual analysis of the theory of fecundity selection promises to help illuminate one of the central components of fitness and its contribution to adaptive evolution.
This study reports the effects of bisphenol A (BPA) on the rotifer Brachionus plicatilis, focusing on growth performance, reproductive output, oxidative stress responses, and lipid metabolism genes. ...High BPA levels disrupted peak daily offspring production and led to oxidative stress and increased superoxide dismutase and catalase activity. The research identified distinctive monoacylglycerol O-acyltransferase (MGAT) and diacylglycerol O-acyltransferase (DGAT) genes in B. plicatilis, B. rotundiformis, and B. koreanus, enhancing understanding of lipid metabolism in these species. BPA exposure significantly altered MGAT and DGAT expression, and feeding status affected these regulatory patterns. When food was unavailable, BPA reduced DGAT2 and MGAT2a expression. However, under feeding conditions, DGAT2 and MGAT1 levels increased, indicating that nutritional status and BPA exposure interact to affect gene expression.
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•BPA delays offspring production in B. plicatilis.•Oxidative stress is increased by BPA in rotifers.•BPA reduces fatty acid, Nile red staining area•New MGAT and DGAT genes in Brachionus species were found.•Food availability impacts MGAT and DGAT gene expression.
The narrow-barred Spanish mackerel (Scomberomorus commerson) is an economically important fish species in Taiwan. Nevertheless, its reproductive biology in the region is poorly understood. This study ...provides the first information on the reproductive biology of this species in the central Taiwan Strait. In total, 1031 specimens were collected from January 2016 through August 2017, and the sex ratio (0.55) was significantly different from 0.5 (p = 0.0016). On the basis of progressive changes in ovary size, ovary histology, oocyte diameter, and gonadosomatic index, the spawning season was estimated to extend from March through August, peaking between March and May. The fecundity (F) and batch F (BF) were estimated to range from 193,212 to 9,810,450 and 91,117 to 2,077,581 eggs per fish, respectively. The relationships of F and BF to fork length (FL) were estimated as follows: F = 0.0247FL4.005 (r2 = 0.57, n = 110, p = 1.05 × 10−10) and BF = 0.00071FL3.999 (r2 = 0.514, n = 41, p = 0.0000149). Based on a logistic model, sizes at 50% of maturity were 68.0 and 68.4 cm in FL for female and male specimens, respectively. Hydrated and postovulatory oocytes were collected from March through June, suggesting that the Taiwan Strait is a spawning ground for S. commerson. The proportion of reproductively active female fish with postovulatory oocytes during the spawning season was 0.15, indicating that spawning occurs every 6.5 days on average. The parameters measured in this study, which provide useful information about S. commerson, can facilitate management, conservation, and sustainable fishing of this species in the region.
Life‐history trade‐offs are important coexistence mechanisms in plant communities. In particular, a trade‐off between seed quality and seed output may explain coexistence among species with a wide ...variety of seed sizes in heterogeneous landscapes with varying degrees of local stresses such as shade, drought and browsing.
Under spatially implicit formulations of the tolerance‐fecundity trade‐off, species diversity is only bounded by community size and environmental heterogeneity. However, these formulations leave unanswered the question of how dispersal limitation, an important aspect of real communities, impacts the ability of the tolerance‐fecundity trade‐off to support coexistence.
Here we show using stochastic cellular automata that coexistence under the tolerance‐fecundity trade‐off in a spatially structured landscape is strongly modulated by the interactions between the spatial scales of species dispersal and environmental variability. Specifically, coexistence in a patchy landscape is higher under short dispersal scales relative to the scale of environmental variation. These conditions allow species to segregate spatially and thus avoid interspecific competition.
In addition to dispersal limitation, coexistence under the tolerance‐fecundity trade‐off is promoted by a sharp drop in tolerance as local environmental stress increases, a high overall seed output across species, local homogeneity in environmental conditions and weak age structure in fertility. In particular, coexistence is much higher when species have full tolerance to stress levels below a threshold and zero tolerance above that threshold, with nothing in between. This steep gradient contributes to coexistence because it maximizes niche separation between similar species.
Synthesis. When plants compete for space, dispersal limitation and landscape spatial structure can conspire to boost coexistence and diversity. Our results show that the tolerance‐fecundity trade‐off is a strong niche differentiation mechanism when species experience a well‐defined distinction between suitable and unsuitable environments, and supports higher diversity when dispersal scales are shorter than the scales of variation in the environment. We conclude that the trade‐off is more likely to be a relevant coexistence mechanism in the context of large‐scale environmental variation, such as topography, than small‐scale variation, such as in litter cover and canopy shading.
When plants compete for space, dispersal limitation and landscape spatial structure can conspire to boost coexistence and diversity. Our results show that the tolerance‐fecundity trade‐off is a strong niche differentiation mechanism when species experience a well‐defined distinction between suitable and unsuitable environments, and supports higher diversity when dispersal scales are shorter than the scales of variation in the environment. We conclude that the trade‐off is more likely to be a relevant coexistence mechanism in the context of large‐scale environmental variation, such as topography, than small‐scale variation, such as in litter cover and canopy shading.
•Sown and natural cover crops reduced crop yield.•Grasses promoted higher content of sugars and phenols in berries.•Grass and natural cover crops reduced the development and reproduction of P. ficus.
...The influence of complete cover cropping (inter- and intra-row) on grapevine growth, yield and must quality was evaluated in a three-year field trial in a commercial vineyard in northwestern Sardinia (Italy). Effects on developmental and reproductive parameters of the vine mealybug, Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae), were also investigated. The cover crop treatments were: natural covering, legume mixture, grass mixture, and conventional soil tillage, which was included as the reference treatment. Relative to soil tillage, cover crops reduced grape production by modifying yield components in different ways: legume mixture reduced the cluster weight, whereas grass mixture led to a lower number of clusters per vine coupled with a lower cluster weight. Cover crops also altered the must qualities relative to soil tillage. Grass mixture increased the content of sugar, anthocyanins and polyphenols, whereas legume mixture and natural covering reduced total polyphenols and anthocyanin content, respectively. All the P. ficus biological parameters examined were affected by the floor management practices. Mealybugs reared on grapevines subjected to soil tillage and legume covering showed a faster development time and higher survival, fecundity and fertility than those developed on natural covering and grass plots. The vine mealybug showed a higher performance on grapevines with a higher nitrogen content and vigor. Effects of cover crop treatments appear to be mediated through nutrient availability and content in grape plants. Consequently, utilizing competitive cover crops, while reducing yields, would improve must quality and reduce pest development.
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