Regulation of population numbers in the <Emphasis Type="Italic">Rana arvalis</Emphasis> frog according to the results of long-term observations on the same population

An analysis of the results of long-term stationary studies (1987–1996) on a Rana arvalis population showed that the mean body length and reproductive parameters of females increased with age. Significant interannual changes in body length and egg size (but not in fecundity and reproductive effort) were also accounted for by conditions of the warm season preceding the breeding season. The dependence of egg diameter and reproductive effort on the female body length weakened with age, and only the relationship between body length and fecundity was characterized by positive allometry. The survival rate of mature females depended on the premetamorphic survival rate and, therefore, was higher in earlier generations, in which the aquatic phase proceeded under more favorable conditions. The rate of reproduction (R ₀) decreased and, therefore, further population growth slowed down only after the initial abundance of the generation had reached a relatively high level. An increase in the initial abundance of the generation exerts a strong influence on R ₀ via a decrease in the survival of premetamorphic animals and, to a lesser extent, via a decrease in the body length and fecundity of tree-and four-year-old females. Changes in the annual abundance of breeding females in R. arvalis were more abrupt and less prolonged than those in the sympatric R. temporaria population. The holding capacity of the environment for the aquatic phase of the R. arvalis life cycle was higher than that for R. temporaria. Therefore, the population abundance of R. arvalis, compared to R. temporaria, was not subject to stringent negative feedback regulation dependent on the initial number of animals.     

Assessment of Maturity,Reproduction and Reproductive Potentials of Torpedo Scad, <Emphasis Type="Italic">Megalaspis cordyla</Emphasis> (Linnaeus, 1758) from Northern Arabian Sea Coast of Pakistan

Port landing specimens of torpedo scad, Megalaspis cordyla were collected at monthly intervals from August 2013 to June 2014 from the northern Arabian Sea coast of Pakistan. The life history characteristics revealed that torpedo scad has a prolonged breeding season which occurred with two peaks: from May to June and from November to February. The spawning seasonality was also validated with microscopic gonad examination.The highest GSI value was noted in May and January whereas the lowest in November was recorded for both sexes. The age at which individuals of both sexes become 50% mature (t₅₀) was estimated as 2.44 year. Life span (t_max) calculated as 3.96 years for male and females. The size of 270 and 265 mm at which 50% individuals attained sexual maturity (L₅₀) was determined for males and females respectively. The reproductive potential (fecundity)was made from ten ripe females ranged from 29–43.8 cm TL and weighing 220–540 g of IV–V developmental stage was enumerated as 32306–236677 eggs (CV = 2.135) with an average number of eggs 86544 counted per ripe female/season. This study contains fundamental data of an important fish species in the northern Arabian Sea coast of Pakistan. It provides vital information to the fisheries managers for implementation on sustainable use of the resource during spawning season.     

Gametogenesis and fecundity of <Emphasis Type="Italic">Acropora tenella</Emphasis> (Brook 1892) in a mesophotic coral ecosystem in Okinawa,Japan

Mesophotic coral ecosystems (below 30–40 m depth) host a large diversity of zooxanthellate coral communities and may play an important role in the ecology and conservation of coral reefs. Investigating the reproductive biology of mesophotic corals is important to understand their life history traits. Despite an increase in research on mesophotic corals in the last decade, their reproductive biology is still poorly understood. Here, gametogenesis and fecundity of the Indo-Pacific mesophotic coral, Acropora tenella, were examined in an upper mesophotic reef (40 m depth) in Okinawa, Japan for the first time. Acropora tenella is a hermaphrodite with a single annual gametogenic cycle, and both oogenesis and spermatogenesis occurring for 11–12 and 5–6 months, respectively. Timing of spawning of this species was similar to other shallow Acropora spp. in the region. However, colonies had longer gametogenic cycles and less synchronous gamete maturation compared to shallow acroporids with spawning extended over consecutive months. Both the polyp fecundity (number of eggs per polyp) and gonad index (defined as the number of eggs per square centimeter) of A. tenella were lower than most acroporids. Our findings contribute to understanding of the life history of corals on mesophotic reefs and suggest that the reproductive biology of upper mesophotic corals is similar to that of shallow-water corals.     

Life history of <Emphasis Type="Italic">Gymnotus refugio</Emphasis> (Gymnotiformes; Gymnotidae): an endangered species of weakly electric fish

The present study describes the life history of Gymnotus refugio, a species classified as Endangered in the last published list of threatened species of the Brazilian fauna. The study was conducted at a conservation unity that protect one of the last remaining semideciduous forests in the region. The reproductive period was estimated as occurring from the end of winter to the last summer months. Gymnotus refugio exibited fractional spawning, the lowest relative fecundity registered among the Gymnotifomes species studied at the present, and male parental care behavior. The analyses showed a seasonal pattern on the species diet, associating different food categories to winter, autumn, and spring. According to food items analysis and estimated intestinal quotient, G. refugio was classified as invertivorous, feeding mainly on autochthonous insects. The results obtained herein suggest that the position of G. refugio as an Endangered species might be influenced by its territoriality, habitat specificity, parental care behavior, and low fecundity, reinforcing the importance of swampy forest environment conservation as the only means of the species maintenance.     

Features of the reproductive cycle in females of the beaked redfish <Emphasis Type="Italic">Sebastes mentella</Emphasis> (Sebastidae)

The reproductive status of some categories of females of the beaked redfish Sebastes mentella has been determined as a result of the histological analysis. The histological characteristic of gonads of large nonreproductive females of redfish is presented for the first time. Gonads of mature females that skip spawning are studied. The cytomorphological characteristic of ovaries after larvae extrusion is specified. A broadened maturity scale for gonads of females of S. mentella supplemented with stages that characterize fish that skip spawning and large nonreproductive females is proposed.     

Divergent life history strategies in congeneric hyperparasitoids

Life histories can reveal important information on the performance of individuals within their environment and how that affects evolutionary change. Major trait changes, such as trait decay or loss, may lead to pronounced differences in life history strategies when tight correlations between traits exist. Here, we show that three congeneric hyperparasitoids (Gelis agilis, Gelis acarorum and Gelis areator) that have diverged in wing development and reproductive mode employ markedly different life history strategies. Potential fecundity of Gelis sp. varied, with the wingless G. acarorum maturing a much higher number of eggs throughout life compared with the other two species. Realized lifetime fecundity, in terms of total offspring number was, however, highest for the winged G. areator. The parthenogenic G. agilis invests its resources solely in females, whilst the sexually reproducing species both invested heavily in males to reduce competitive pressures for their female offspring. Longevity also differed between species, as did the direction of the reproduction-longevity trade-off, where reproduction is heavily traded off against longevity only in the asexual G. agilis. Resting metabolic rates also differed between the winged and wingless species, with the highest metabolic rate observed in the winged G. areator. Overall, these geline hyperparasitoids showed considerable divergence in life history strategies, both in terms of timing and investment patterns. Major trait changes observed between closely related species, such as the loss of wings and sexual reproduction, may contribute to the divergence in key life history traits.     

Age,growth and reproduction of the Iranian goby, <Emphasis Type="Italic">Ponticola iranicus</Emphasis> (Perciformes: Gobiidae) from the southern Caspian Sea basin

To estimate reproductive biology of Ponticola iranicus Vasil’eva et al., 2015, in Sefidroud River in the southern Caspian Sea basin age, sex ratio, fecundity, oocytes diameter, gonadosomatic, modified gonadosomatic and dobriyal indices were measured. Regression analyses were used to find relations between fecundity and fish size (length and weight), gonad weight, and age. Mature females and males were longer than 46 and 49 mm in total length, +1 in age. The Von Bertalanffy growth models were L _∞ = 23.00 cm (TL), K = 0.21, t ₀ =–0.25 for all specimens. Sex ratio was 1: 1.32 in favor of males. The average egg diameter was 0.96 mm. The spawning period extended from late February to late April. The averages of absolute and relative fecundity were calculated as 536.9 and 81.3, respectively. The absolute fecundity was significantly related to the body length and weight, as well as gonad weight.     

Fecundity of the tropical catadromous eels <Emphasis Type="Italic">Anguilla bicolor bicolor</Emphasis>, <Emphasis Type="Italic">A. bengalensis bengalensis</Emphasis> and <Emphasis Type="Italic">A. marmorata</Emphasis>

Maturation is one of the most important ontogenetic transitions in an individual’s life. However, the reproductive ecology of the tropical anguillid eel genus Anguilla at the onset of oceanic spawning migration is poorly understood. To understand the reproductive ecology, the fecundity of the tropical eels Anguilla bicolor bicolor, A. bengalensis bengalensis and A. marmorata was examined using advanced migrating silver eels (Stage IV and V). A close linear relationship was found between total length and fecundity in A. bengalensis bengalensis. The fecundities of A. bicolor bicolor (0.55 to 4.96 × 10⁶), A. bengalensis bengalensis (0.33–1.72 × 10⁶) and A. marmorata (0.99 × 10⁶) were within the range of those observed in temperate eels.     

Does simultaneous and sympatric reproduction between two native spined loaches lead to reproductive interference and local extinction?

Reproductive interference occurs when fitness of females of one species decreases because of misdirected courtship behaviors by males of another species. Reproductive interference strongly excludes either species in the interaction but it does not persist for long on an evolutionary time scale. Therefore, reproductive interference between a pair of co-evolved native species is difficult to observe because exclusion ends the interaction even if even the potential for reproductive interference still exists. However, anthropogenic environmental changes can bring about secondary contact between two species and trigger reproductive interference, leading to local species extinction. We demonstrated this phenomenon with two native spined loaches: Cobitis magnostriata (Cmag) and C. minamorii oumiensis (Cmio). In 2015 and 2016, we investigated the spatiotemporal dynamics of adults and juveniles of both species to estimate the effects of the relative abundance of adults on reproductive success. Additionally, we surveyed the distribution of juveniles and investigated the proportion of gravid females which failed to reproduce at the end of the spawning season. In 2016, Cmio juveniles were fewer than in 2015, although the abundances of Cmio adults were similarly low in both years and the Cmag adults were more abundant in 2016 than in 2015. The juveniles of the two species exhibited similar spatiotemporal dynamics. At the end of the spawning season, Cmag males were abundant and most Cmio females failed to reproduce. These results suggest that the two species share spawning habitats and seasons and that Cmag males exert reproductive interference on Cmio females. This report is the first of a study suggesting that anthropogenic environmental changes triggered reproductive interference between native species in the field.     

Complex effects of Ayurvedic formulation: <Emphasis Type="Italic">Guduchi</Emphasis> and <Emphasis Type="Italic">Madhuyashti</Emphasis> on different components of life history may elude the elixir effect

Formulations from the traditional Indian medicine, Ayurveda, have long been considered to have potent life-style-enhancing effects, possibly by their effect(s) on key life-history attributes. Although several studies have reported beneficial effects of these formulations on different components of life history, few have investigated their concurrent influence on various life-history traits. Here, we report the results of an investigation showing the effect of two well-known Ayurvedic formulations, Guduchi and Madhuyashti, on fecundity and longevity of Drosophila melanogaster. Flies were either grown (i.e., larval exposure) and/or maintained (i.e., adult exposure) on standard food supplemented with 0.5% Guduchi or 0.5% Madhuyashti. It was observed that the longevity of adult flies of both sexes was not affected on feeding Guduchi food, but fecundity of the females was greatly enhanced. Fecundity was also found to be affected by the adult food and whether their mates were grown on Guduchi or normal food. Madhuyashti, on the other hand, significantly reduced mean longevity and had a stimulatory effect on female fecundity. This fecundity enhancing effect however seemed to be mediated through its effect on the males. Interestingly, much of these effects interacted with age in a complex way, making it difficult to generalize the overall effect of these formulations on the reproductive output of the flies. Our study underlines the importance of evaluating the interacting effects of these (and similar) formulations on a range of life-history traits in a holistic way to understand their utility better.     

Reproductive biology and management of two commercially important groupers in the SW Atlantic

The reproductive biology of Epinephelus morio (red grouper) and Mycteroperca bonaci (black grouper) were evaluated based on 533 specimens collected from artisanal fisheries landings in the Abrolhos Bank, Brazil, between May 2005 and September 2012. Sex ratio for the black grouper was 1:14 (n = 155 females and 11 males; 26.1–147 cm TL) and 1:10 for the red grouper (n = 334 females and 33 males; 15.0–96.0 cm TL). For both species, highest values of the gonadosomatic index (GSI) for females were recorded between July and October, indicating spawning during the austral winter. The length at first maturity (L₅₀) for females was estimated at 62.0 and 47.0 cm TL for the black and red grouper, respectively. Batch fecundity based on TL and TW ranged from 2 to 15.4^?10⁶ and 1.5 to 13.7^?10⁶ for the black and red grouper, respectively. Interviews with experienced fishers revealed that spawning seasons of both groupers are largely unrecognized. Results demonstrate a positive relationship between GSI peaks, lower temperatures and stronger winds. The information provided herein may help decision-making regarding fisheries management and conservation for E. morio and M. bonaci at various levels of governance in the Abrolhos Bank, the region with the largest and richest coralline reefs in the South Atlantic.     

Reproductive features of <Emphasis Type="Italic">Upeneus margarethae</Emphasis> (Mullidae), a species recorded in the coastal zone of Vietnam for the first time

The species Upeneus margarethae described recently from the western Indian Ocean is recorded in the coastal zone of Vietnam for the first time. The reproductive features of the representatives of the species from southern Central Vietnam (Nha Trang Bay), Central Vietnam (Da Nang), and North Vietnam (Ha Long Bay) are studied. Based on the analysis of maturity stages of female’s ovaries and gonadosomatic index, the fishes spawn over the entire year in Central Vietnam, but the spawning interruption is observed in North Vietnam during a winter season. In Nha Trang Bay, 50% of females reach sexual maturity at the body length (FL) 9.8 cm. Based on histological structure of ovaries and frequency distribution of oocyte diameter before the spawning, the oogenesis is continuous. Anomalous oocyte structure is registered in 20% of the females. Egg morphology is described for 3 h after activation of ovulated oocytes. A comparison of reproductive parameters in U. margarethae and U. tragula is conducted.     

Life history strategies of the Scotia Sea icefish, <Emphasis Type="Italic">Chaenocephalus aceratus</Emphasis>, along the Southern Scotia Ridge

Reproductive capacity can influence distribution and abundance over large spatial scales through larval dispersal, even when adult stages remain isolated following settlement. We examined size distribution, reproductive traits and age structure in Scotia Sea icefish, Chaenocephalus aceratus, an abundant benthic species with a long larval pelagic phase found on continental shelves along the Southern Scotia Ridge. In particular, we compared life history strategies between fish caught during surveys undertaken off the South Orkney Islands (SOI) and South Shetland Islands (SSI). Results corroborated regional separation after settlement and suggested distinct life history strategies, in which fish from SOI invested much less in reproduction, and somewhat more in somatic growth earlier in their life history. Compared to SSI, body weight increased faster with length and absolute fecundity was 46 % lower and increased more slowly with size for SOI population. In addition, the proportion of spawning cohorts and L _∞ was lower and k higher for SOI. The differences appeared to be a phenotypic response to environmental conditions related to regional hydrography. Lower reproductive capacity around the SOI, and strong eastward flow in the large-scale circulation, suggests that the SSI may be more important in influencing distributions and abundance of icefish along the Southern Scotia Ridge.     

Some issues related to reproduction of Pacific cod <Emphasis Type="Italic">Gadus macrocephalus</Emphasis> in waters of the eastern coast of the northern Kuril Islands and the southern extremity of Kamchatka

The analysis of data collected in December 1996 and 1998 on the reproduction of cod Gadus macrocephalus in Pacific waters of the northern Kuril Islands and the southern part of Kamchatka was performed. It was shown that the individual absolute fecundity of the cod varies within 0.197–9.729 million eggs and the relative fecundity, in the range of 24-1386 eggs. The fecundity of 1000 mature females comprises 2179–2449 million eggs. The low individual fecundity of fish is related to pseudobranchial tumor growth. The main role in cod reproduction is played by females of two-three size groups characterized by the highest numbers of mature females. It is suggested that different fecundity within the range of Pacific cod is related to environmental conditions, in particular, water temperature in the spawning grounds during spawning rather than to the habitation latitude.     

A comparative gametogenesis and biochemical differentiation of goatfish (Family: Mullidae) from the Red Sea

Comparative study between few species of goatfishes (Mullidae), locally called Sultan Ibrahim, has been investigated from Jeddah coast. The present study compares gonad structure, oogenesis and spermatogenesis in three species of goatfish. The various stages are similar in the different species, but differ in time of spawning. The reproductive biology of three goatfishes, Mulloidichthys flavolineatus (1 black blotch), Mulloidichthys flavolineatus (3 black blotches), Mulloidichthys vanicolensis, were examined. A macroscopic and histological examination of the gonads demonstrated that all the three species are typically gonochoristic. Species-specific reproductive parameters including male stages, changes in gonado-somatic index (GSI), classification of oocyte stages were analyzed for each of the three targeted species. All three species have asynchronous ovary. The spawning season for the three studied species differ from one species to another i.e., the spawning season for M. vanicolensis females and males from April to July; M. flavolineatus, (1 black blotches) for both sexes from May until December; for M. flavolineatus (3 black blotches) showed a peak in May to early October for both sexes. Ultrastructurally the mature spermatozoon’s head shape appears like a computermouse, the tiny mid-piece consist two mitochondria and a flagellum. The chromatin, within the nucleus is electron-dense and homogenous in M. flavolineatus (with one black blotch), while the chromatin is granular in (M. vanicolensis and M. flavolineatus (3 black blotches)). The posterior region of the nucleus is deeply penetrated by the nuclear fossa which contains, the basal part of flagellum and centriolar complex. The ultrastructure of the eggs of the three Mullidae species is circular in shape and contains a simple, circular micropyle. The ovarian follicular epithelium of the three Mullidae species consists of two layers, an outer theca layer and an inner granulosa layer with zona radiata under them. Zona radiata consists of 2 layer-interna and externa. Zona radiata interna is thicker than zona radiata externa. Differences in protein patterns of muscles and gonads were observed in the present study.     

Life History of <Emphasis Type="Italic">Cochliomyia macellaria</Emphasis> (Fabricius, 1775) (Diptera,Calliphoridae), a Blowfly of Medical and Forensic Importance

The life history traits of blow fly Cochliomyia macellaria (Fabricius, 1775) was studied under semi-controlled laboratory conditions at 29.14°C temperature, 72.53% relative humidity, and 12-h photoperiod. The raw data were analyzed based on the age-stage, two-sex life table, considering the development rates among individuals of both sexes. Cochliomyia macellaria survival rate was 0.43 (♂) and 0.40 (♀), while life expectancy was 17.9 (♂) and 20.9 (♀) days, for adult males and females, respectively. The total fecundity was 681.15 eggs/female, with an average of 3.65 batches/female and 199 eggs/batch. The intrinsic rate of increase (r) was 0.327 days^?1, the finite rate of population increase (λ) was 3.35 days^?1, the mean generation time (T) was 17.15 days, and the net reproduction rate (R ₀ ) was 272.46 offspring/individual. The population parameters found here corroborates that C. macellaria population act as a r selected species under laboratory conditions. Additionally, development data and accumulated degree days (ADD) for each stage of C. macellaria are provided and its implications for the forensic use are discussed.     

Reproductive biology of <Emphasis Type="Italic">Astyanax lacustris</Emphasis> (Characiformes: Characidae) in the southern Pantanal floodplain,upper Paraguay River basin,Brazil

We studied the reproductive biology of Astyanax lacustris in the southern Pantanal, Brazil. A total of 382 fish were analyzed from February 2009 to January 2011. The sex ratio differed significantly from 1:1, with a larger proportion of females (χ² = 27.24; p < 0.001). Females achieve higher standard length than males (mean 72.30 mm and 56.51 mm, respectively), and possess negative allometric growth while males have positive allometric growth. Size at first maturation did not differ between sexes. The greatest reproductive activity occurred during the rainy season, when temperatures were highest (November to February). Total fecundity was significantly correlated with standard length (r_s = 0.74; p = 0.01), and spawn type was total. Then, the life history traits of A. lacustris are adjusted to seasonal variation in the Southern Pantanal.     

Ontogenetic and gender-related variation in the isotopic niche within and between three species of fur seals (genus <Emphasis Type="Italic">Arctocephalus</Emphasis>)

Differences in aggressiveness when competing for environmental resources are the main factor leading to social hierarchy in group living fish. Social status acquired is related to changes in physiological parameters, as metabolic rate. Habitat variation can interfere with aggressive behaviour and promote changes in physiological parameters associated with social status. The primary goal of our study was to investigate how differences in habitat complexity affect the relationship between resting metabolic rate (RMR) and social status in the Amazonian dwarf cichlid Apistogramma agassizii. We compared agonistic interactions between pairs of males in aquaria with different habitat enrichment levels, manipulated by adding shelters. RMR was measured before and after hierarchy establishment. Habitat enrichment promotes changes in aggressive behaviour and influences differences in metabolic rate between dominant and subordinate fish. We observed an increase in biting by dominant fish at high enrichment habitat, which could be related to the increase in territory value. We observed an increase in metabolic rate in dominant fish after hierarchy establishment. However, it occurs only in enriched habitats. We concluded that habitat structure interfere with behavioural characteristics in social hierarchies, as aggressiveness, and changes in aggressive interactions affect metabolic rate in different social ranks in the dwarf cichlid Apistogramma agassizii.     

Sublethal effects of abamectin on the biological performance of the predatory mite, <Emphasis Type="Italic">Phytoseius plumifer</Emphasis> (Acari: Phytoseiidae)

Traditionally estimating pesticide effects by measuring only lethal effect may underestimate the total negative effect on beneficial arthropods and sublethal effects should be assessed to estimate the total effect of their applications. In this study, sublethal effect of the acaricide abamectin (Vermectin^® 1.8% EC, Giah, Iran) on the predatory mite Phytoseius plumifer (Canestrini &; Fanzago) (Acari: Phytoseiidae) fed on Tetranychus urticae Koch was assessed in laboratory conditions. The adult predators were exposed to the residues of the acaricide on fig leaves and the LC₅₀ value was determined based on a concentration–response analysis. The results showed that sublethal concentrations (LC₁₀, LC₂₀ and LC₃₀) of abamectin severely affected the fecundity and longevity of the treated females of P. plumifer. Furthermore, reproductive and life table parameters of the subsequent generation were affected. The results indicated that adverse effects of abamectin on population growth of P. plumifer were significant, so the results from this study can be used to develop approximate guidelines for the use of abamectin in order to minimize their impact on P. plumifer and related natural enemies.     

Reproductive Biology of <Emphasis Type="Italic">Leptocybe invasa</Emphasis> Fisher &amp; La Salle (Hymenoptera: Eulophidae)

Leptocybe invasa Fisher & La Salle (Hymenoptera: Eulophidae) is an invasive pest in Eucalyptus plantations around the world. The successful colonization of L. invasa is possibly related to its reproductive biology. The objective of this study was to examine the reproductive biology of L. invasa. In Guangxi Province, the sex ratio (proportion of female, 0.99) of L. invasa was female-dominant throughout the year based on natural and artificial infestation. This result was similar to the ratios observed for other geographic populations in China, including those in Fujian (0.99), Guangdong (0.98), Hainan (0.95), Jiangxi (0.96), and Sichuan (0.99). The offspring sex ratio favored females. A large number of females emerged from the galls produced by females, with few males found. Galls on the petioles and midribs of Eucalyptus plants could be caused by newly emerged females with mature eggs. The lengths of the ovariole, spermatheca, common oviduct, and reproductive glands did not differ among L. invasa females, but their lateral oviducts showed differences from 0 to 42 h after emergence, indicating that this insect is proovigenic. These results could explain why L. invasa populations can rapidly increase in invaded areas.