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1.
Breeding adults and larvae of Macropetasma africanus were sampled over a two-year period in Algoa Bay, South Africa. Gonadal macro-and microscopic examination enabled classification of breeding females into four stages of development. Breeding females were present throughout the study with a summer peak of late maturing and mature females. Larvae were present in the plankton throughout the study with peak abundance in summer. Protozoea, mysis and post-larval stages were recorded with the mysis stage most abundant. Significantly higher numbers of the mysis and post-larval stages were taken at shallow stations (5 m) off sandy beaches than at the deeper stations (18 m). The presence of breeding females in the mature stage of ovarian development and the increase in larval abundance In summer indicates spawning throughout the year with peak intensity in summer.  相似文献   

2.
We determined for the first time the reproductive biology of Piabina argentea through macroscopic and microscopic analysis of ovaries and evaluated the morphological changes in hepatocytes. Two hundred and 46 specimens were collected, 204 females and 42 males, between March 2014 and February 2015. Biometrics data were obtained. From females, gonad and liver samples were conducted to histological, histochemical and immunohistochemical techniques. Mature ovaries were used to determine absolute and relative fecundity. Total length and body weight values indicated that females were larger than males. The estimated weight–length ratio showed negative allometric growth. The absolute fecundity average was 171.83 ± 59.89 oocytes per ovary. In addition, females spawning capable and regressing stages were found throughout the sampling period and the presence of all oocyte types in regressing stage ovaries indicated asynchronous oocyte development and multiple spawning. From regenerating to spawning capable stage the oocytes accumulated yolk in cytoplasm became bigger. While in the liver hepatocytes with a larger cell area during regenerating stage and proliferative activity in the spawning capable stage were observed. Thus, our results indicate that P. argentea had an opportunistic reproductive strategy and cyclic morphological changes of hepatocytes occurred during the oogenesis.  相似文献   

3.
Reproductive and life history patterns in reptiles are tightly related to the environmental conditions, so male reproductive cycles have been historically characterized as continuous, for tropical lizards, or seasonal, for temperate lizards. However, males of Liolaemus and Phymaturus lizards (Liolaemidae), from cold temperate climates of high altitudes or latitudes in Argentina and Chile, have developed a variety of reproductive cycles to coordinate with the short female reproductive season and to deal with the low frequency of reproductive females in the population. Using gonadal histology and morphological analysis, we describe the male reproductive biology, fat storage and sexual dimorphism of the viviparous lizards Liolaemus sarmientoi and Liolaemus magellanicus that inhabit an austral grass steppe at 51°S, in the southern limit of the American continent. Males of L. sarmientoi and L. magellanicus are reproductively available during the entire activity season of approximately 5 months. In addition, males of both species exhibit greater body sizes than females in morphological variables relevant in sexual selection. Meanwhile, females of both species exhibit larger inter‐limb length than conspecific males, which suggests fecundity selection to increase space for a larger litter size. The continuous sperm production throughout the activity season allows these liolaemids to mate at any time when females ovulate, representing a selective advantage to deal with the short activity season and the adversities of the cold environment they inhabit.  相似文献   

4.
Curimatella lepidura, commonly known as the manjuba, belongs to the Curimatidae family. To assess the reproductive activity of this species, fish were collected from three sections of the São Francisco River: section 1 = the Três Marias reservoir (TMR), section 2 = the SFR immediately downstream of the TMR, and section 3 = the SFR 54 km downstream from the TMR after the confluence of the SFR with the Abaeté River. Fish were collected bimonthly from January to December 2012. From this, the gonadosomatic index (GSI), Fulton condition factor (K), gonadal maturation stages in females and males, and diameters of vitellogenic follicles were determined. That is, this study employed histological and histometrical techniques to study the ovaries and testes of collected fish. The Fulton condition factor was statistically higher in section 1 than in the other sections, indicating that C. lepidura presents better health conditions in this section. Fish in the maturation/mature gonadal stage were collected in the November/December and January/February bimesters, coinciding with high temperatures, a long photoperiod, and abundant rainfall in this region. The mean vitellogenic follicle diameter was statistically lowest for sections 2 and 3, with a better impact on reproduction than in section 1. Overall, the results show that C. lepidura has reproductive success in lentic environments, such as in section 1, the TMR.  相似文献   

5.
Only one large yellowfish species occurs in the Hardap Dam, apparently closely related to Barbus kimberleyensis. Though smaller than this species in the Vaal River, it is nevertheless a valuable and abundant angling fish. After maturity, reached in females at 26 cm and in males at 18 cm fork length, females outnumber males by 9 :1 beyond 30 cm. Main spawnings occur between February and April, some four months later than in the Vaal River, being correlated with peak seasonal rains in both cases. A minor spawning later in the year is usual, with improved fry survival due to warmer weather conditions reducing the winter mortality of the earlier spawned young. Breeding sites are probably in lentic gravelly-bottomed areas within the dam. Egg production increases from 5-6 000 in 30 cm fish to ca 47 000 in 60 cm females, with strong relationship between cube of fish length and fecundity.  相似文献   

6.
Female Labeo umbratus reach sexual maturity at a larger size than males and dominate the population in fish over 450 mm in length. The gonads are large (up to 20% of total body mass) and they have a high fecundity which increases linearly with an increase in body mass. Successful spawning is dependent on suitable floods during the spawning season which extends from November to March or April. Spawning apparently occurred in the impoundment. All females did not spawn simultaneously and evidence suggests that individuals might spawn more than once during a particular season.  相似文献   

7.
Histological examination of gametogenesis revealed that the current staging criteria used to assess gonadal recrudescence of the redeye labeo, Labeo cylindricus, were adequate. Gametogenesis was qualitatively similar to thatof freshwater teleosts with a clearly defined seasonal reproductive cycle. L. cylindricus undergoes seasonal gross morphological and cytological gonadal changes with previtellogenesis dominating during the winter, vitellogenicdevelopment during spring and summer culminating in large-scale spawning at the end of summer. Post-spawning mass atresiaofoocytes was evident in autumn. The histological data presented support macroscopical evidence that L. cylindricus is a synchronous iteroparous spawner, reproducing over a short period each year throughout its life-span.  相似文献   

8.
ABSTRACT

1. The potential growth of feathers and feather-free body and their chemical components was measured in two commercial broiler strains.

2. A total of 200 chicks of each sex x strain were fed adequate amounts of dietary protein using a four-phase feeding programme. Ten birds per genotype were sampled at 14, 28, 42, 56, 70, 84, 98 and 112 d of age. They were weighed before and after being dry-plucked to determine the weight of feathers, and the feather-free body was then minced and analysed for water, protein and lipid.

3. Body weights and chemical composition of males of the two strains were similar throughout the trial. Females of the two strains differed only in their body lipid contents, with mature Cobb females being higher than Ross (1371 vs. 1210 g).

4. Mature body weights of males and females from both strains averaged 8420 g and 6650 g; mature body protein weights averaged 1555 g and 1030 g; and mature body lipid contents averaged 908 and 1290 g, respectively.

5. Rates of maturing per day of body weights of males and females of both strains averaged 0.0385 and 0.0368; feather-free body protein was 0.0316 and 0.0348 and body lipid was 0.0503 and 0.0375, respectively. The rates for body lipid differed between Cobb and Ross females (0.0352 vs. 0.0397/d). Separate equations were required for males and females to describe the allometric relationship between lipid and protein in the feather-free body.

6. The rate of maturing of feathers in females was higher than in males (0.0526 vs. 0398/d) and the mature weight was lower (205 vs. 266 g), respectively. Mature body weights of broilers in this trial were considerably higher than those measured using the same protocol 24 years ago, whereas rates of maturing remained the same.  相似文献   

9.
The fossa is an endangered, mongoose-like carnivore species endemic to Madagascar with a breeding season (BS) in the southern hemisphere spring. For the present study, faecal samples of captive fossas were collected for over 1 year for five males and four non-pregnant females, and for two pregnant animals during the reproductive period. The goal was to assess gonadal activity using non-invasive hormone measurements of faecal testosterone (T) and gestagen metabolites using assays previously established in our laboratory and further validated in this study. All study animals were housed in northern hemisphere zoos. In males, the seasonal T metabolite profile revealed a peak in spring (March). High performance liquid chromatography (HPLC) analysis was used to characterize the faecal hormone metabolite composition. The highest immunoreactivity was detected in the position of dihydrotestosterone, whereas native T was not detected. In the two pregnant females, gestagen metabolite concentrations increased 4–9 days after the initial matings and remained elevated throughout gestation with concentrations dramatically higher than those of the non-pregnant females during the BS. In these females, gestagen metabolite analyses did not reveal a seasonal pattern similar to the males. The HPLC-analysis revealed that the major proportion of immunoreactivity was associated with an unknown metabolite, whereas native progesterone was undetectable. The seasonal hormone pattern of male fossas gives proof of the reproductive seasonality of this species.
The elevated 5α-pregnan-3β-ol-20-one levels in pregnant animals allows for the characterization of pregnancy in the fossa based on analysis of faecal steroid metabolite concentrations.  相似文献   

10.
Effect of long‐term selection for improved growth on reproductive performance of giant freshwater prawn (GFP) Macrobrachium rosenbergii has not been reported in the literature. The present study aimed to measure correlated responses in reproductive traits and to estimate genetic parameters for these characters in a GFP population selected for high growth over ten generations from 2007 to 2016. A total of 959 breeding females (offspring of 515 sires and 810 dams) had measurements for seven reproductive traits (weight before spawn WBS; weight after spawn WAS; Fecundity FEC or number of larvae per female at hatching; first age to reach post‐larvae PLAGE; zoea (e) weight ZOEAWT; larval survival during hatchery phase SURV1 and survival from PL to tagging SURV2. The restricted maximum likelihood (REML) and mixed model analysis were used to estimate genetic parameters and evaluate selection responses for the seven traits studied. Our REML analysis showed that heritability for these traits ranged from 0.04 to 0.42 (SE: 0.19–0.28). Female body weight either before or after spawning had strong positive phenotypic correlations with fecundity (0.52–0.98). By contrast, the phenotypic correlations of WBS/WAS with larval and fry survivals were not significant (?0.08–0.05). Genetic correlations among fecundity‐related traits studied were not different from zero due to their high standard errors. Correlated responses in reproductive traits were measured by comparing least squares means of the selection line and control group. Females of the selected line for high growth had significantly greater weight before or after spawning than that of the control group. There were, however, no statistical differences between the two lines in the other traits. It is concluded that selection for high growth did not have detrimental impact on reproductive performance of breeding females in the present population of GFP.  相似文献   

11.
Gonadal cycle of the crowned plover Vanellus coronatus at two inland airports. The gonadal cycle of 474 crowned plovers Vanellus coronatus collected from two inland airports during 1986/87 was investigated. Judged by the ovarian mass and the diameter of the largest visible follicle, a prominent activity peak occurs in the ovarian cycle of females during early summer. Judged by the mass, volume, histological development stages and diameter jof the seminiferous tubules of the testes, a corresponding but longer activity peak also occurs among males. Although the testes of immature males are generally smaller than those of adults, some individuals are potentially capable of reproduction within their first year of life. Evidently the breeding cycle of the crowned plover is influenced to a greater extent by the relative availability of food than by environmental factors such as day length, temperature or rainfall.  相似文献   

12.
The aim of this study was to assess monthly testicular development in the cultured breeding stock of sterlet, Acipenser ruthenus, using histological and serum sex steroid changes. Testicular development in the adult male was examined monthly and showed four distinct phases including resting, pre‐spawning, spawning and post‐spawning. Also, seasonal changes of the testes were described according to its variations in gonadosomatic index (GSI) during different phases of testicular development. Using histology, we identified continuous spermatogenesis and asynchronous gonad development pattern in the testes of male sterlet, which shows that regulation of annual gonadal cycle is influenced by season. Results also showed variation in the GSI value and number of spermatogenic cells according to each season during annual cycle of gonad, as the highest value of GSI was recorded during spawning phase (spring; March‐May). Hormonal profiles of 11‐ketotestosterone (11‐KT) showed peak, which indicated a seasonal pattern of gonadal development. The 11‐KT concentration increased considerably during the spermatogenesis (pre‐spawning phase) and remained quite high throughout the pre‐spermiation period. In the final phase of testicular development (spawning phase), the 11‐KT markedly dropped. This study undertook an examination of complete reproductive development in cultured sterlet sturgeon to provide a valuable guide for the future sterlet studies, and allows comparison of reproductive development between sturgeon species.  相似文献   

13.
《African Zoology》2013,48(2):151-164
Copadichromis chrysonotus is a zooplanktivorous cichlid member of the diverse fish community inhabiting Lake Malawi’s rocky, littoral habitat. Like most Lake Malawi cichlids, this species’ reproductive strategy is based on maternal mouthbrooding, but it is the only littoral species known to spawn in the open water without a substrate-based territory. This studyinvestigated length at maturity, sexual dimorphism, spawning behaviour, breeding seasonality, fecundity, fertility, egg size, and brooding habits of C. chrysonotus in southern Lake Malawi. Males in breeding colouration aggregated in sheltered areas at least several metres deep, and each male defended a mobile breeding territory near the surface while attempting toattract females. Breeding was mostly continuous from August to May, with peaks in August–September and January–March. A major lull in breeding activity occurred in May and June. Mean fecundity and fertility increased significantly with female total length, while mean egg length, mean egg mass and gonadosomatic index did not increase significantly with female totallength. Females brooded their young up to 15–16 mm total length before abandoning them. Open-water spawning by C. chrysonotus may be an adaptation to reduce both egg predation during spawning and competition for substrate-based breeding territories.  相似文献   

14.
Burchell's redfin, Barbus burchelli is endemic to the Breede River and adjacent smaller river systems in the Cape Province. Negative human influences have led to a drastic decline in numbers of this medium-sized minnow, especially agricultural demand on the water resource and the introduction of exotic predatory fish. The breeding season is extended, from September to February, with a peak in December. The absolute fecundity of a 123 mm FL specimen was 10 678, which includes both mature and recruitment ova. Females grow larger (123 mm FL), and live longer (6 +years), than males (113 mm FL and 4 + years). 8. burchelli grow rapidly in their first year attaining a length of between 40 and 50 mm FL. Pronounced conical tubercles of sexually mature males erupt in spring, begin to show signs of wear in November and by March are worn or sloughed off. The survival of this species is dependent upon proper management of the Breede River system.  相似文献   

15.
《African Zoology》2013,48(1):38-44
We examined 170 museum specimens of the southern African gekkonid lizard Homopholis wahlbergii, to quantify sexual dimorphism, male and female reproductive cycles and diet. The largest male and female we recorded were 116 and 119 mm snout–vent length (SVL) respectively. We compared SVL, tail length, head length, head width and eye diameter and found no evidence of sexual dimorphism in any of these characters. The smallest female with thickened muscular oviducts and follicles, indicating sexual maturity, was 59 mm SVL, but the smallest female we found with fully developed eggs was 85mmSVL. Virtually all females larger than 59 mm appeared to be in some stage of reproduction, suggesting that females reproduce every year once they reach sexual maturity. Egg size ranged from 17–19mm long. Egg size was not correlated with maternal SVL. We found adult females with ready-to-lay eggs during the warmer months of the year, but not during winter and spring. The smallest sexually mature male was 72 mm SVL. Virtually all males larger than this size displayed at least semi-turgid testes and most adult male testes were at least semi-turgid for much of the year. The only significant decrease in testicular activity was in mid-winter (June–August), thus, spermatogenesis is closely tied to female follicular development and ovulation. Velvet geckos are largely insectivorous (92%) and feed on a broad spectrum of prey. Their diet was dominated both numerically (34%) and volumetrically (22%) by beetles. Lepidoptera were the next most important prey category, suggesting that they exploit both terrestrial and flying invertebrates. They are unusual among lizards because they feed on millipedes. Males and females had very similar diets which may be explained by their lack of sexual dimorphism, although females tended to eat a greater volume of prey. Interestingly, less than half (37%) of the lizards examined contained prey items, suggesting that most individuals were not in positive energy balance. We also found evidence of prey size selection as a function of gape size, such that larger geckos took advantage of larger prey items.  相似文献   

16.
The cost of reproduction is the core driver of life history evolution in animals. This paper demonstrates that the cumulative distance moved and the duration of movement of sexually immature abalones, Haliotis discus hannai, kept in various male and female groups, were significantly higher than those of sexually mature individuals, except when kept in mixed cultures of mature males and females. After mixed-culture, sexually mature males moved significantly further and for a longer duration than mature female abalones, and even more so than mature male abalones of any other group. Examination of the LC-MS metabolomics of mature males cultured with sexually mature females (AM) and those cultured with sexually immature females (JM) showed that cyclic adenosine monophosphate (cAMP) acted as a differential metabolic biomarker. After 24-h uninterrupted sampling, the concentration of 5-HT and the expression levels of the 5-HT2 and 5-HT6 receptors in AM were significantly higher than those in JM. After further injection of 5-HT2 and 5-HT6 receptor antagonists, the concentrations of cAMP and PKA rose again, but the cumulative movement duration and distance of male abalones decreased significantly, showing that 5-HT was involved in the regulation of movement behavior of male abalones through the 5-HT2 and 5-HT6 receptor-activated cAMP-PKA pathways. The results demonstrated a significant increase in the movement endurance of mature male abalones cultured with mature females, providing a theoretical basis for understanding the adaptive life history strategies of abalones and suggesting ways to protect diverse benthic resources for abalones during the reproductive stage.  相似文献   

17.
The aim of the study was to evaluate the use of laparoscopy for the assessment of the reproductive tract and stage of gonadal development of the tench (Tinca tinca). Laparoscopy was carried out from February to March 2009, on 30 anesthetized tenchs, 15 males and 15 females, of approximately 250 g bodyweight and 30 cm length, using a 1.9‐mm rigid cystoscope. Male and female gonads, attached to the swim bladder, were visualized. Testes were orange with a striped appearance. Mature ovaries were cluster‐shaped and whitish. Histological samples were collected, from the reproductive organs of both the sexes, with a forceps and showed the presence of gametes at different stages of maturity. The application of this minimally invasive diagnostic imaging technique could clinically be used as a powerful tool to evaluate the gender and to establish the reproductive status of tench and other fish.  相似文献   

18.
Seasonal modulation in antibody production in relation to the state of lymphoid tissue development was studied in the ovoviviparous fish, S. marmoratus. Animals were kept in tanks with running seawater at 23 +/- 1 degrees C for a minimum 2 week acclimatization period and then immunized three times at 2 day intervals with 20% SRBC (5 microliters/g body weight) intraperitoneally. Immunized fish were bled 2 weeks after the first injection at the time of peak response and plasma were analyzed for titration. The thymus and pronephros were weighed and the number of leukocytes counted in the cell suspension. Antibody levels in fish immunized in summer were higher than those in fish immunized in winter, even if the environmental temperature was held constant. Furthermore, the reactivity of mature females to SRBC was lower than that of males or immature females in the spawning season (winter). The antibody titre was inversely related to the weight of the thymus with the exception of females during the spawning season, while the weight of the pronephros did not show any significant change throughout the year. In addition, the thymus of pregnant, and especially post-spawning females, was entirely involuted, showing a marked decrease in the number of lymphocytes in both the cortex and medulla. Preliminary experiments to examine the effect of photoperiod on antibody production indicated a slight increase in titre among adult fish under a long photoperiod regimen. The present data show that both the season and stage of sexual maturity affect the humoral immune response and lymphoid tissues, and suggest that the thymus might have a function other than that concerned with immunity.  相似文献   

19.
Age structure and seasonality influence the population fluctuations of small rodents. Age determines body weight and social experience, while seasonality regulates the duration of the breeding season and onset of sexual maturity in newborn offspring. Therefore, reproductive success and skew usually occur in different age groups. Brandt's vole (Lasiopodomys brandtii) is a social, short‐lived and seasonal breeding small rodent with a dramatic seasonal population fluctuation, but reproductive skew is not fully understood in this species. In the present study, we determined kinship in semi‐natural enclosure populations using microsatellite markers based on genotyping, analyzed the reproductive skew between sexes and between overwintered and newborn voles, and monitored variation in male reproductive activity by testing fecal testosterone levels throughout the year. Overwintered voles had the most reproductive success along with a striking increase in the population size in the enclosures, with all biological fathers and 77.8% of biological mothers, which had 100% and 87% of the total offspring, respectively. Compared to overwintered voles, reproductive skews were significantly higher in potential overwintered and newborn parents, implying the possible reproductive suppression of newborn voles by dominant overwintered voles. Moreover, both heavier body weight and higher testosterone levels in overwintered males supported their potential social status in the population. Our study provided new evidence for reproductive skew and differentiation of postnatal gonadal development patterns of different age groups in Brandt's vole.  相似文献   

20.
Wild common carp (Cyprinus carpio carpio) is a native valuable but threatened species from the south‐eastern Caspian Sea in which the endocrine control of its reproduction has not been studied. The objectives of this research were to study the reproductive strategy and changes in steroid hormones during ovarian development. From October 2009 to June 2010, 65 adult females were caught from the Golestan coast (Iran) and the ovarian histology, and gonadosomatic and hepatosomatic indices (GSI and HSI) were studied. Also, the plasma profiles of steroid hormones including testosterone (T), 17β‐estradiol (E2) and 17α‐, 20β‐dihydroxyprogesterone (DHP) were measured by radioimmunoassay. The GSI increased gradually during sampling times and reached maximum value at the peak of reproduction season, but the HSI decreased during spawning season. All stages of ovarian development, except the stage of Balbiani bodies, were recorded macro‐ and microscopically. Spent fish were caught at six of nine sampling times. The peaks of spawning were at late winter and early spring. The results of this study showed that the majority of wild carp collected during the sampling period displayed asynchronous oocyte development. Plasma T showed no significant differences during sampling times or at different stages of ovarian development. The level of E2 decreased gradually during sampling times reached minimum value at the spawning season, and highest value was recorded at tertiary vitellogenesis stage. The plasma levels of DHP during late winter and early spring were significantly higher than those of other sampling periods and its maximum level associated with oocyte maturation stage.  相似文献   

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