Female Size Research Articles

Larval diet and temperature alter mosquito immunity and development: using body size and developmental traits to track carry-over effects on longevity

BackgroundEstimating arbovirus transmission potential requires a mechanistic understanding of how environmental factors influence the expression of adult mosquito traits. While preimaginal exposure to environmental factors can have profound effects on adult traits, tracking and predicting these effects remains challenging.MethodsUsing Aedes albopictus and a structural equation modeling approach, we explored how larval nutrition and temperature jointly affect development rate and success, female body size, and whether these metrics capture carry-over effects on adult female longevity. Additionally, we investigated how larval diet and temperature affect the baseline expression of 10 immune genes.ResultsWe found that larval development success was primarily determined by diet, while temperature and diet both affected development rate and female body size. Under a low larval diet, pupal wet weight and wing length both declined with increasing temperature. In contrast, responses of the two morphometric measures to rearing temperature diverged when females were provided higher larval nutrition, with pupal wet weight increasing and wing length decreasing at higher temperatures. Our analyses also revealed opposing relationships between adult female lifespan and the two morphometric measures, with wing length having a positive association with longevity and pupal weight a negative association. Larval diet indirectly affected adult longevity, and the time to pupation was negatively correlated with longevity. The expression of eight immune genes from the toll, JAK-STAT and Imd pathways was enhanced in mosquitoes with higher nutrition.ConclusionsOur results highlight deficiencies from using a single body size measure to capture carry-over effects on adult traits. Further studies of larval development rate under varying environmental conditions and its potential for tracking carry-over effects on vectorial capacity are warranted.Graphical

Phenotypic, endocrinological, and metabolic effects of zearalenone exposure and additive effect of heat stress in prepubertal female pigs

Independently, both heat stress (HS) and zearalenone (ZEN) compromise female reproduction, thus the hypothesis that ZEN would affect phenotypic, endocrine, and metabolic parameters in pigs with a synergistic and/or additive impact of HS was investigated. Prepubertal gilts (n = 6–7) were assigned to: thermoneutral (TN) vehicle control (TC; n = 6); TN ZEN (40 μg/kg; TZ; n = 6); pair-fed (PF; n = 6) vehicle control (PC; n = 6); PF ZEN (40 μg/kg; PZ; n = 6); HS vehicle control (HC; n = 7); and HS ZEN (40 μg/kg; HZ; n = 7) and experienced either constant 21.0 ± 0.10 °C (TN and PF) or 35.0 ± 0.2 °C (12 h) and 32.2 ± 0.1 °C (12 h) to induce HS for 7 d. Elevated rectal temperature (P < 0.01) and respiration rate (P < 0.01) confirmed induction of HS. Rectal temperature was decreased (P = 0.03) by ZEN. Heat stress decreased (P < 0.01) feed intake, body weight, and average daily gain, with absence of a ZEN effect (P > 0.22). White blood cells, hematocrit, and lymphocytes decreased (P < 0.04) with HS. Prolactin increased (P < 0.01) in PC and PZ and increased in HZ females (P < 0.01). 17β-estradiol reduced (P < 0.01) in HC and increased in TZ females (P = 0.03). Serum metabolites were altered by both HS and ZEN. Neither HS nor ZEN impacted ovary weight, uterus weight, teat size or vulva area in TN and PF treatments, although ZEN increased vulva area (P = 0.02) in HS females. Thus, ZEN and HS, independently and additively, altered blood composition, impacted the serum endocrine and metabolic profile and increased vulva size in prepubertal females, potentially contributing to infertility.

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.

FEMALE BROODSTOCK SIZE AND MATERNAL EFFECTS ON PROGENY OF Clarias gariepinus (BURCHELL 1822)

Catfish farmers have been enduring having to spawn with very big females at high cost avoiding medium and small sizes. The relationship between female broodstock weight and the growth rate of progeny has been a major concern among catfish producers. To examine the impact of different female broodstock sizes on the reaction to growth of the fish seed, induced breeding of the study fish was done. The experiment was designed a completely randomized design (CRD) made of three treatments replicated three times. The treatment were three categories of weight of broodstocks as Treatment I (1000g (Treatment I or Small size), Treatment II (1500g or Medium size) and Treatment III (2500g or Large size). There was no significant fluctuation in the physico-chemical parameters of the water. There was no significant difference in the fry survival among Treatments (P&gt;0.05). The maternal effect on growth of the study fish was 10.5 weeks of culture as Treatment 11 fingerlings then grew fastest. At the end of 40 weeks culture period there was significant difference (P&lt;0.05) in the final weight of the table fish (1231.67 g, 1156.67g, and 1006.67g, for Treatment 11, Treatment 111, and Treatment 1, respectively). Overall, the results of these growth evaluations showed that the selected group had improved growth performance. Medium sized female broodstock can therefore deliver substantial genetic improvements in induced breeding of the study fish.&#x0D;

Shifting incubation rhythms in response to predation risk and the length of the response in mountain bluebirds

Abstract Parent birds may alter incubation rhythms in response to predation risk but few studies have examined the recovery time immediately after exposure to a predator. Here, we examined incubation rhythms in mountain bluebirds (Sialia currucoides) in response to a simulated nest predator, a taxidermy-mounted squirrel. We used data loggers (iButtons) to measure the recess (off-bout) length, recess rate, and constancy of incubation and found no relationship between incubation rhythms and female age, body size and aggressiveness. Incubating females reacted to the predator by reducing nest visitation rates and increasing recess length but did not change incubation constancy. Instead, constancy was negatively associated with ambient temperature. Changes in incubation behaviour lasted about 48 h before returning to pre-exposure patterns. Our results suggest that modifying incubation rhythms is costly for female birds and the demand to regulate egg temperature efficiently limits the length of behavioural responses to the threat of nest predation.

Incidence of early onset puberty in two-year-old female sea bass, Dicentrarchus labrax L.

The incidence of early onset puberty in female aquaculture fish species is less well known than in males and, it merits to be taken into account in order to properly address its outcomes. The goal of this study was to compare the growth performance and reproductive physiology between 2-year-old female sea bass with early or late onset puberty. Fish from seven fertilized egg cohorts of sea bass were considered. Animals were individually tagged and histologically identified when terminally sampled over the first and second year of life. Ovaries from 1-year-old females were in the chromatin nucleolus (CN) or perinucleolar stage (PN), whereas 2-year-old females showed oocytes in the PN stage and early vitellogenesis (EV) (GSI < 0.7%) or late vitellogenesis (LV) (GSI of 4.45 ± 0.55%). Accordingly, 2-year-old females with less advanced reproductive development were considered as fish with late onset puberty (PN, EV), in contrast to their counterparts that were considered to be fish with early onset puberty (LV). Non-spawning females with early onset puberty were observed. The early onset puberty occurred in 18.1 ± 6.4% of fish in the population, although it was variable among the cohorts. Body size of early pubertal females was usually larger than that of fish with late onset puberty (28.7% heavier in weight and 7.9% greater in fork length). Differences in circulating levels of the insulin-like growth factor-1 (Igf-1) and those of 17-beta estradiol (E2), follicle-stimulating hormone (Fsh) and vitellogenin (Vtg) one year before spawning, significantly contributed to explaining the total variance associated with the early onset puberty in this species. This study provides valuable information on the interplay that these factors might have at the onset of early puberty in fish and, in turn, its potential use as key indicators of this trait in the female sea bass.

Using advances in technology to develop sizing methodology for women’s sports compression garments

ABSTRACT The aim of this study was to evaluate the suitability of current sizing systems adopted by brands, for an athletic female population and try to identify areas of improvement in current sizing and grading methods used. This information can be used to engineer accurately fitting lower-body sports compression leggings for the target demographic. Size and shape data of sixty-three athletic females was collected using 3D body scanning. The data was compared to size charts of three commercially available sports compression leggings manufactured by different brands as well as Alvanon's UK sizing and grading standards. Results show that athletic females are not catered for by current products. 28 women (44.44%) fell between sizes for at least one measurement across the three brands. Participant's measurements indicate differing body shapes to the standard ‘hourglass’ shape presented by the Alvanon UK sizing standards, used by companies as a basis for their sizing systems.

Assessment of biomass culturing effectiveness of Artemia in tarpaulin tank in Ho Chi Minh City

The study was carried out to determine the suitable stocking densities and harvesting methods, and to evaluate the economic efficiency of Artemia biomass culturing in tarpaulin tanks in Ho Chi Minh City. The experiment consisted of 8 treatments arranged in a completely randomized block design with 3 replicates of 2 stocking densities (M1: 1,500 &amp; M2: 2,000 individuals/L) and 4 harvesting frequencies (T1: 1 day/time - 10%, T3: 3 days/time - 30%, T5: 5 days/time - 50% and T14: 14 days collecting 100% amount of Artemia biomass in the tank). The study results showed that the average size of males and females ranged from 9.12 - 9.55 mm and 9.84 - 11.01 mm, respectively. At day 14, the survival rate at a density of 1,500 individuals/L accounted for 63.68 ± 2.50% which was statistically significant (P &lt; 0.05) compared to the density of 2,000 individuals/L (60.95 ± 1.39%). The mean fecundity of female Artemia ranged from 70 to 72 embryos/female and tended to increase gradually from 92 to 101 embryos/female. The harvesting frequency affected Artemia population composition, density and biomass yield. After 29 days, the T3M1 treatment yielded the highest biomass (3.33 ± 0.39 kg/m3) and the most optimal profit with 225.53 ± 9.08 thousand VND/kg. The treatment DCM2 gave the lowest yield (1,22 ± 0.27 kg/m3) with a profit of 78.04 ± 58.58 thousand VND/kg.

New insight into drivers of mammalian litter size from individual‐level traits

The digitization and open availability of life history traits measured directly from individuals provide a key means of linking organismal function to environmental and ecological contexts at fine resolution. These linkages play a critical role in understanding trait‐mediated response to global change, with particular need to resolve them for taxa that are secretive and hard to monitor, like most mammals. In this study, we use digitized museum specimen and census data to document how climate and body size each shape a key life history trait – litter size – in 39 small mammals across North America. We employ mixed models to test associations between litter size, climate and body size, with a focus on joint estimation of inter‐ and intraspecific trends. Among species, no single climate predictor explained a large amount of litter size variation. Instead, interactions between temperature‐related (continentality, solar irradiation) and moisture‐related (annual precipitation, relative humidity) indices, along with body size, exert a stronger influence on litter size. We observed maximal litter sizes for species inhabiting seasonal or xeric regions under conditions of increased moisture availability, or conversely, mesic or aseasonal regions under conditions of reduced moisture availability. These patterns are consistent with primary productivity as a mechanistic driver of litter size. At the intraspecific level, litter size responds to continentality and temperature‐related indices experienced by populations, but is most strongly shaped by body size of individual females. We also find evidence of phylogenetic covariation in these intraspecific trends. Our study demonstrates how life history traits assembled from individual‐level biodiversity records improve precision and granularity of ecological studies, help to parse among‐ and within‐species trends, and foster improved understanding of tradeoffs between energetic supply and demand (e.g. reproduction) in wild mammals.

Comparison of home range size, habitat use and the influence of resource variations between two species of greater gliders (Petauroides minor and Petauroides volans).

Knowledge of the spatial requirements of a species is fundamental to understanding its environmental requirements. However, this can be challenging as the size of a species' home range can be influenced by ecological factors such as diet and size-dependent metabolic demands, as well as factors related to the quality of their habitat such as the density and distribution of resources needed for food and shelter. Until recently, the genus Petauroides was thought to include only a single species with a widespread distribution across eastern Australia. However, a recent study has provided genetic and morphological evidence supporting Petauroides minor as a distinct northern species. Previous studies have focused on the ecology of P. volans, but there has been inadequate research on P. minor. Data on home range and habitat use were obtained for both species using a combination of techniques including GPS collar locations, radiotelemetry, and spotlighting and comparisons were made using consistent methodology. Home range sizes of P. minor (4.79 ha ± 0.97 s.d., KUD .95) were significantly larger than those of P. volans (2.0 ha ± 0.42 s.d., KUD .95). There were no significant differences between male and female home range sizes in either species. Both species showed site-specific preferences for tree species and for larger diameter trees for both forage and shelter. Tree size and biomass/ha were significantly greater in the P. volans study sites than the P. minor study sites and there was a negative correlation between home range size and eucalypt biomass. Larger home range size is likely driven by the substantial differences in biomass between northern (tropical) and southern (temperate) eucalypt-dominated habitats affecting the quality and quantity of resources for food and shelter. Understanding landscape use and habitat requirements within each species of Petauroides can provide important information regarding limiting factors and in directing conservation and management planning.

Cortical growth from infancy to adolescence in preterm and term-born children.

Early life experiences can exert a significant influence on cortical and cognitive development. Very preterm birth exposes infants to several adverse environmental factors during hospital admission, which affect cortical architecture. However, the subsequent consequence of very preterm birth on cortical growth from infancy to adolescence has never been defined; despite knowledge of critical periods during childhood for establishment of cortical networks. Our aims were to: chart typical longitudinal cortical development and sex differences in cortical development from birth to adolescence in healthy term-born children; estimate differences in cortical development between children born at term and very preterm; and estimate differences in cortical development between children with normal and impaired cognition in adolescence. This longitudinal cohort study included children born at term (≥37 weeks' gestation) and very preterm (<30 weeks' gestation) with MRI scans at ages 0, 7 and 13 years (n = 66 term-born participants comprising 34 with one scan, 18 with two scans and 14 with three scans; n = 201 very preterm participants comprising 56 with one scan, 88 with two scans and 57 with three scans). Cognitive assessments were performed at age 13 years. Cortical surface reconstruction and parcellation were performed with state-of-the-art, equivalent MRI analysis pipelines for all time points, resulting in longitudinal cortical volume, surface area and thickness measurements for 62 cortical regions. Developmental trajectories for each region were modelled in term-born children, contrasted between children born at term and very preterm, and contrasted between all children with normal and impaired cognition. In typically developing term-born children, we documented anticipated patterns of rapidly increasing cortical volume, area and thickness in early childhood, followed by more subtle changes in later childhood, with smaller cortical size in females than males. In contrast, children born very preterm exhibited increasingly reduced cortical volumes, relative to term-born children, particularly during ages 0-7 years in temporal cortical regions. This reduction in cortical volume in children born very preterm was largely driven by increasingly reduced cortical thickness rather than area. This resulted in amplified cortical volume and thickness reductions by age 13 years in individuals born very preterm. Alterations in cortical thickness development were found in children with impaired language and memory. This study shows that the neurobiological impact of very preterm birth on cortical growth is amplified from infancy to adolescence. These data further inform the long-lasting impact on cortical development from very preterm birth, providing broader insights into neurodevelopmental consequences of early life experiences.

Negative effects of high-temperature stress on gametophyte performance and their consequences for seed reproduction in wild plants

(1) Plant regeneration by seeds is highly sensitive to temperature stress, particularly in the gametophyte stage. However, most of the existing research has focused on one single stage of gametophyte development and/or conducted using cultivated or a very few model species. Thus, it is unclear whether the results of such studies can be applied to natural populations. (2) To fill this gap, we investigated a) the effects of chronic heat stress (CHS; 17 days) at 35/30 °C (moderate stress) and 40/35 °C (severe stress) on gametophyte performance, and b) how these effects translated into seed quantity and quality. We measured six traits related to male (anther length, pollen production and size) and female (ovary length, ovule production, and size) gametophyte performance and leaf chlorophyll fluorescence (Fv/Fm) in four wild Silene species. The ripe seeds of the treated plants were used to measure seed mass and seed production; the seed germination was characterized in terms of germination percentage, speed, and synchrony. (3) Fv/Fm decreased significantly in both heat treatments, confirming a negative effect of CHS on overall plant performance. All male gametophyte traits decreased significantly in both CHS treatments compared to the control. The length and size of the ovary were significantly smaller in the 40/35 °C treatment than in the 35/30 °C treatment and the control, while ovule production decreased significantly in both CHS treatments compared to the control. The negative effects on gametophyte performance translated into significantly fewer seeds in the 35/30 °C and 40/35 °C treatments compared to the control. CHS treatments did not affect the seed mass. The final germination percentage differed weakly significantly between the severe treatment and the control but did not show any negative impacts by heat stress, whereas seed germination was significantly faster in the treated plants, both moderate and severe. Germination synchrony was not affected by heat treatments. (4) The high sensitivity of gametophytes in vascular plants to high-temperature stress implies that climate change-associated heat waves can significantly impact seed reproduction in wild plants. The altered seed quantity could have potential consequences for the long-term survival of the wild plant populations and the performance of the granivores.

Early origin and diverse phenotypic implementation of iridescent UV patterns for sexual signaling in pierid butterflies.

Iridescent ultraviolet (IUV) patterns on pierid butterfly wings are phenotypic adaptations commonly used as sexual signals, generated by scales with ultrastructural modifications. Pierid IUV patterns are sexually dichromatic, with reduced size in females, where conspicuous sexual signaling balances courtship against ecological predation. There have been no phylogenetic reconstructions of IUV within Pieridae and little morphological characterization of phenotypic diversity. Our genus-wide characterization of IUV revealed the uniform similarity of stacked lamellar ridges on the dorsal surface of cover scales. We tested a hypothesis of single versus multiple origins by reconstructing a phylogeny of 534 species (~43.2% described species), with all genera represented, and a trait matrix of 734 species (~59.4%) screened for IUV. A single, early dimorphic origin of IUV followed by several losses and gains received strong support, concluding that IUV patterns and structural coloration are old traits. Collectively, these results support the homology of IUV scales and patterns that diversified within several lineages, suggesting an interplay between female-mediated sexual selection and ecological predatory selection.

Increased offspring provisioning by large female fish and consequences for reproductive efficiency.

Contemporary fisheries research and management have highlighted the need to protect size and age structures of fish populations. Many studies particularly emphasize a disproportionate contribution of populations' largest, oldest female fish to population-level recruitment through maternal effects: non-genetic effects of females on performance of their offspring including through energetic provisioning of eggs. Our study synthesized the effects of increasing female size on offspring performance using a meta-analysis approach. In a stepwise fashion, we conducted three separate meta-analyses to estimate the broad-scale patterns of maternal effects in fish. We synthesized relationships between female size and egg size, egg size and offspring size, and egg size and offspring survival. We tested maternal effects across numerous taxonomic orders and system types including freshwater, diadromous, and saltwater species. We also compared the effects of increasing egg size on offspring performance at different experimental durations. These three meta-analyses all supported the paradigm that larger females render individual benefits to offspring performance. However, females have finite gonadal energy and space for egg provisioning and must trade off between egg size and fecundity. For the largest females to contribute disproportionately to population recruitment (relative to their gonadal investment), they must utilize their gonadal investment more efficiently than their smaller conspecifics. Using example studies in published literature, we demonstrated how established maternal effects on egg provisioning do not necessarily support greater reproductive efficiency in larger females. Therefore, while larger females do produce larger eggs, which promote offspring growth and survival, we concluded these benefits may not always outweigh relative fecundity costs of larger eggs.

Sex-specific trait architecture in a spider with sexual size dimorphism.

Sexual dimorphism, or sex-specific trait expression, may evolve when selection favours different optima for the same trait between sexes, that is, under antagonistic selection. Intra-locus sexual conflict exists when the sexually dimorphic trait under antagonistic selection is based on genes shared between sexes. A common assumption is that the presence of sexual-size dimorphism (SSD) indicates that sexual conflict has been, at least partly, resolved via decoupling of the trait architecture between sexes. However, whether and how decoupling of the trait architecture between sexes has been realized often remains unknown. We tested for differences in architecture of adult body size between sexes in a species with extreme SSD, the African hermit spider (Nephilingis cruentata), where adult female body size greatly exceeds that of males. Specifically, we estimated the sex-specific importance of genetic and maternal effects on adult body size among individuals that we laboratory-reared for up to eight generations. Quantitative genetic model estimates indicated that size variation in females is to a larger extent explained by direct genetic effects than by maternal effects, but in males to a larger extent by maternal than by genetic effects. We conclude that this sex-specific body-size architecture enables body-size evolution to proceed much more independently than under a common architecture to both sexes.

Drop dead! Female mate avoidance in an explosively breeding frog.

Males' and females' reproductive strategies may differ, potentially leading to sexual conflict. Increased efforts by males (harassment, forced copulation, intimidation) to gain access to females could even negatively affect female survival and thus lead to reproductive failure for both individuals. In anurans, a higher mortality risk of mating females has been reported in explosive breeding species. During these mating events, several males cling to a female, which are mostly unable to get rid of the unwanted males. This can lead to the female's death. From the literature, it seems that females of explosive breeding frogs have no means to reject unwanted males. Here we describe female mate avoidance behaviours in the European common frog. We observed three female avoidance behaviours, namely 'rotation', 'release call(s)' and tonic immobility (death feigning). These behaviours were significantly associated with smaller female body size, and smaller females were more successful in escaping amplexus. Tonic immobility as a tactic to avoid mating or male harassment has only been observed in a handful of species and only in one other amphibian. Our observations show that females in explosive breeding frogs may not be as passive and helpless as previously thought.

Sex Ratio, Sexual Dimorphism, and Wing Geometric Morphometrics in Species of Trypoxylon Latreille, 1796 (Hymenoptera: Crabronidae).

Studying the nesting biology of wasp and bee species provides valuable insights into the ecology and evolution of these insects, shedding light on their ecological significance and aiding in their conservation efforts. Trypoxylon Latreille, 1796 is a genus of spider-hunting wasps that provisions their brood with paralyzed preys. This study focuses on aspects of nesting biology of Trypoxylon (Trypargilum) species such as sex ratio, sexual dimorphism, and morphometric variation at both inter- and intraspecific levels. The secondary sex ratio (SR) exhibited variation among species and populations. Males predominantly emerged from the first brood cells and from trap nests with smaller diameters. In comparison, females showed significantly larger body mass and linear wing measurements than males. Procrustes ANOVA values for centroid size (CS) and wing shape (SH) indicated significant differences in both wing size and shape among the five analyzed Trypoxylon species. Sexual dimorphism indices (SDI) derived from centroid size were found to be similar to those obtained from linear measurements, while SDI values based on body mass were significantly higher. Nests containing a greater number of cells tended to produce a larger number of higher-quality males and females. This observation, along with the lower coefficient of variation for female body size and high heritability, suggests that this trait may be subject to natural selection. Further studies that estimate the size of parents and their respective offspring are necessary to confirm the fitness advantage associated with larger female sizes in Trypoxylon species.

Phenotypic variation of protandrous hermaphrodite fish Eleutheronema tetradactylum (Shaw, 1804) from Thailand coastal waters

This study was conducted to investigate the intraspecific variation of Eleutheronema tetradactylum (Shaw, 1804) using traditional morphometric measurements. In total, 136 samples were collected from four fishing areas across Thailand coastal waters. Raw data were standardized and then evaluated with univariate analysis of variance, canonical discriminant function analysis, and dendrogram of cluster analysis regarding to site, size, and sex. Result from ANOVA test exhibited that all morphological characters were significantly different among sites (P < 0.05). Nevertheless, forty-one morphometric characters were significantly different among size of male and female fish (P < 0.05) except for pre-orbital length, pupil diameter, eye diameter, and depth of maxilla for male fish. Forty-four morphometric characters were significantly different (P < 0.05) except of fork length among sex. From CDFA, E. tetradactylum showed phenotypic heterogeneity and two distinct stocks in the four selected fishing areas. Phenotypic variation on sites was determined by six morphological characters (MnFL, DFAF, DOM, HW, PeBFL and ED) for males, while eight characters for females (PrOL, AFSL, PeBFL, DOM, UJL, PD, AFRL and ED) in decreasing order. Differentiations between fish size classes, relied on PrDFL2, BD and UCFL in males and PrOL, PrePeFL and DFAF in females. Among sexes, PeFAF, PrDFL2, MxFL, MnFL, PrePeFL, HSDF and PrePFL were highly influential. Discriminate functions (DF1) clarified that 83.60% and 94.10% of the total variance were found among the sites of males and females, and 99.20% and 93.20% of the total variance were found among the sizes of males and females, respectively. and 73% of the total variance were found among the sexes. In the confusion matrix of CDFA, the overall assignments of individuals into their correctly classified original population were 98.68% and 100% for males and females based on site and size, and 75.74% of sex groups, respectively. Our study highlighted that the hermaphroditism of E. tetradactylum showed that three distinct stocks of males and two stocks of females inhabited Thai coastal waters.

Dependence of fecundity on body length of the invasive species Gmelinoides fasciatus (Crustacea; Amphipoda) in Lake Onega

For the first time in Lake Onega, the reproduction features of the alien amphipod Gmelinoides fasciatus (Stebbing, 1899) were studied based on research in 2010–2011. The period of reproduction in the conditions of the reservoir (May–September) were established, the body length ranges of egg-bearing females, the average and maximum sizes of breeding individuals, as well as fertility were determined. During the study period, a decrease in the average size of females from May–June to August–September was noted, which is associated with the beginning of reproduction of females of the summer generation and the continued reproduction of females of the last year's generation. Equations were calculated that make it possible to predict the fecundity of females by body length, which indicates similar patterns of generative growth of G. fasciatus on the littoral in the northern bays of Lake Onega. Generally, the fecundity of the amphipod is higher in Lake Onega compared to the fecundity of the same species in Lake Ladoga, Neva Bay, Lake Arakhley and the Bratsk Reservoir. This phenomenon is probably associated with the geographical location of Lake Onega, a higher latitude and a longer photoperiod.

Different demographic responses of three species of container Aedes (Diptera: Culicidae) larvae to timing of extrinsic mortality.

Mortality imposed on a population can interact with negatively density-dependent mortality to produce overcompensation, wherein added mortality results in more survivors. Experimental mortality can cause overcompensation in mosquito larvae, which would be counterproductive if it resulted from mosquito control in nature. We tested for different demographic responses to mortality among 3 container Aedes species when impacted by density dependence. We imposed 48.2% mortality on cohorts of larvae 2, 6, or 8 days after hatching and compared adult production, development times, and female size to those variables for controls without mortality. Mortality significantly increased adult production compared to controls, but the 3 species varied in the details of that response. Aedes albopictus (Skuse) produced more adults with mortality on day 2 primarily because of greater production of males. Aedes triseriatus (Say) yielded more adults with mortality on day 2 primarily because of greater production of females. Aedes aegypti (L.) adult production was not significantly affected by mortality, but development times for both sexes were significantly shorter with mortality on day 8. There were no effects of mortality on female wing length. None of our mortality treatments yielded significant reductions of adults for any species. These species responses to mortality are not the same, despite their similar ecologies and life histories. Thus, we cannot assume that killing almost half the larvae present in a dense population will reduce adult production, nor can we assume that different Aedes species will respond to mortality in the same way.