Number Of Clutches Research Articles

Nomographs for synthesis of epicyclic-type automatic transmissions

This paper presents a MATLAB optimization technique for the determination of the gear ratios of epicyclic-type transmission mechanisms for a given set of velocity ratios. First, all of the feasible clutching sequences are enumerated directly without using complicated techniques. Then, for the transmission mechanism with the associated clutching sequence graph, the overall velocity ratios are derived and expressed in terms of the gear ratios of all the mating gears. Next, following the general trend of increased shift stages and a wider range of velocity ratios, the numbers of teeth of all gears are estimated by MATLAB optimization technique in a single run. Ravigneaux gear mechanisms are used as design examples. The methodology can be applied to any transmission mechanism depending on its kinematic and geometric constraints. New five- and six-velocity automatic transmissions are enumerated from the Ravigneaux gear mechanism. It is a major breakthrough to design a completely satisfactory six-speed automatic transmission from the Ravigneaux gear mechanism since it has only eight links. The new design makes use of the benefits of the Ravigneaux gear train and overcomes the previous art difficulties. This structural design has realized a six-speed automatic transmission, while having minimal number of clutches, and brakes. It is also low cost due to adoption of the conventional available Ravigneaux gear train.

Better in the dark: two Mediterranean amphibians synchronize reproduction with moonlit nights

Abstract. In Amphibians, both positive and negative correlations between activity and full moon phase have been observed. In this study, we present data for two anuran species (Hyla intermedia and Rana dalmatina) studied in a hilly Mediterranean area of central Italy. We analysed, in a two-year survey, the relationships between the number of egg clutches laid each night and the moon phases by means of circular statistics. Moreover, the studied species exhibited clear oviposition site selection behaviour influenced, at least in H. intermedia, by moon phases. We observed the occurrence of an avoidance effect by amphibians for oviposition and specific egg-laying behaviour during moon phases around the full moon. This apparent lunar phobia was evident in both species when yearly data were pooled. On the other hand, while this pattern continued to be also evident in H. intermedia when single years were considered, in R. dalmatina it stood just in one year of study. Nonetheless, during cloudy nights, when moonlight arriving on the ground was low, the frogs' behaviour was similar to that observed in new moon phases. We interpreted the observed pattern as an anti-predatory strategy. Overall, comparisons between our own study and previous research suggest that there was insufficient evidence to establish any unequivocal patterns and that further research in this regard is needed.

Adoption of Improved Strain of Backyard Poultry

Backyard poultry plays a major role in alleviating malnutrition in developing countries like India. The present study was undertaken among 120 backyard poultry farmers in Karaikal region of Puducherry an aim to assess the extent of adoption of improved strain of backyard poultry in Karaikal region, a backward area in Puducherry Union Territory. Majority of the respondents were middle aged with primary school level of education belonging to small family group with 6-15 years of experience in backyard poultry rearing. Nearly one third of the respondents had 1-5 birds in their backyard. Majority of the farmers reared desi birds followed by Giriraja strain. The average number of eggs per clutch and the average number of clutches per year were 16 and 6 respectively. Majority of the respondents were aware of the improved strains of backyard poultry. Most of them had discontinued rearing improved strain of backyard poultry mainly due to susceptibility to diseases and attack by predators.

Egg-laying pattern of Hyposidra talaca (Lepidoptera: Geometridae) in Northeastern Indian tea plantations: implications for pest management

Hyposidra talaca (Walker) is a recent host range-expanded major insect pest of tea in Northeastern India. We studied the egg-laying pattern of H. talaca in tea plantations with an aim to take suitable measures to disrupt egg hatching and to manage the pest. Egg clutch distribution in different heights (0–8 m) of 49 shade trees of seven species was studied. Stems and foliage of a total of 400 tea plants growing close to the shade trees were also subjected to the survey. Female moths deposited eggs underneath the scales of shade tree bark, lichen cover and the root mantles of parasitic plants that are growing on all shade tree plants, except Melia azaderach L. The shade tree bark of M. azaderach and tea plants had no egg deposits. Overall, 1785 egg clutches, comprising 84–302 eggs/clutch (average 258 eggs), were located. An average of 45.77 ( ± 7.06 SD, range 0–183) egg clutches was found per tree. The mean number of egg clutches was high in Acacia lenticularis Buch.-Ham. (95.4 ± 24.78 SD, range 40–183), and was low in Lagerstroemia speciosa (L.) Pers. (23 ± 6.42 SD, range 4–46). Overall, the number of egg clutches reduced with the height of shade trees. This study suggests that the oviposition of H. talaca is typical for an outbreak species and that the management of shade trees, including the choice of species, has an important role in controlling the pest in tea plantations.

Development of a captive breeding program for the Florida apple snail, Pomacea paludosa: Relaxation and sex ratio recommendations

Stock enhancement of the Florida apple snail, Pomacea paludosa, is a potential management strategy for the conservation of the endangered snail kite which is dependent upon the snail as its predominant food source. Reliable culture techniques that provide high growth and survival rates for juvenile snails have been established; however, additional research is needed to improve breeding in captivity. The goals of this study were to efficiently relax the snails to identify the sex in order to conduct a study to understand the effect of different sex ratios on reproductive output. Of the seven chemical solutions used to relax the snails, benzocaine mixed in methanol was the most effective. To examine the effect of sex ratio, 10 snails were stocked into 75L tanks within a recirculating aquaculture system at the ratios of 3F:7M, 5F:5M, 7F:3M, and 8F:2M for 8weeks. There was a significant positive relationship between the number of egg clutches produced and a higher number of females in the tank. However, there were no significant differences in the number of eggs per clutch, egg diameter, percent hatch rates, female production (egg clutches per female per week), or the number of juvenile snails produced per female. The number of copulations was observed for the first three weeks of the experiment. When standardized to the number of copulations per male snails, no significant differences between treatments were detected. Our results suggest that a female-biased sex ratio may prove optimal and cost effective for large-scale captive breeding production. Future studies should determine the minimal proportion of males needed to limit the loss of genetic diversity in a female-biased stock enhancement program.

The effect of stocking density on the reproductive output of hatchery-reared Florida apple snails, Pomacea paludosa

The effect of stocking density on the reproductive output of Florida apple snails was investigated with the goal of developing a captive breeding program that would sustain year-round production and yield a high number of juvenile snails. We examined stocking densities of 50, 100, and 150 snails/m2 to determine the threshold at which density negatively affects reproduction. Adult snails were added to tanks in a recirculating aquaculture system at a 1:1 sex ratio and reproductive output was followed for 8weeks. The total number of clutches per tank and the number of eggs per clutch were recorded daily. The number of egg clutches produced in each tank was standardized per female to assess among treatment differences. Once hatched, the juveniles were counted and the percent hatch rates were determined for each clutch. The findings of the study demonstrated that density affected the mean number of clutches laid per female per week with snails in the 50 snails/m2 treatment having higher egg production than snails stocked at 100 and 150 snails/m2 treatments. Similarly, the number of juveniles produced per female was also higher in the lowest density treatment. There were no significant differences between treatments for egg characteristics (number of eggs per clutch and percent hatch rate). Based on these results, it is recommended that adult snails be stocked at 50 snails/m2 to yield optimum egg production per female, attain the highest number of juveniles, and to sustain production for a reliable captive breeding program.

Activity Predicts Male Reproductive Success in a Polygynous Lizard

Activity patterns and social interactions play a key role in determining reproductive success, although this is poorly understood for species that lack overt social behaviour. We used genetic paternity analysis to quantify both multiple paternity and the relative roles of activity and social behaviour in determining reproductive success in a nondescript Australian lizard. During the breeding season we intensively followed and recorded the behaviour of a group of seven males and 13 females in a naturalistic outdoor enclosure to examine the relative roles of body size, activity and social interactions in determining male fertilization success. We found multiple paternity in 42% of clutches. No single behaviour was a significant predictor of male fertilization success in isolation, but male-female association, interactions and courtship explained 41% of the variation in male fertilization success. Males with the highest number of offspring sired invested heavily in interacting with females but spent very little time in interactions with males. These same males also sired offspring from more clutches. When taken collectively, an index of overall male activity, including locomotion and all social interactions, significantly explained 81% of the variation in the total number of offspring sired and 90% of the variation in the number of clutches in which males sired offspring. We suggest that the most successful male strategy is a form of endurance rivalry in which active mate searching and interactions with females have the greatest fitness benefits.

Podisus nigrispinus (Heteroptera: Pentatomidae) and IAC-24 Soybean Cultivar Are Compatible

<p>The main tactics of soybean integrated pest management combine plant resistance and biological control. The impact of insect resistant IAC-24 soybean cultivar [caterpillars of <em>Anticarsia gemmatalis</em> Hübner (Lepidoptera: Noctuidae) in UFVS-2006 soybean cultivar susceptible to insects and water compared to <em>A. gemmatalis</em> in IAC-24 soybean cultivar resistant to insects and water] on the nymphal and adult stages of the predator <em>Podisus nigrispinus</em> Dallas (Heteroptera: Pentatomidae) was evaluated. The duration and survival of the instars and nymphal stage and the body mass of nymphs, males and females of this predator were similar between treatments. The periods of pre-oviposition, oviposition, post-oviposition and egg incubation; interval between egg clutch; number of egg clutch per female, eggs per egg clutch, eggs per female, nymphs per female, nymphs per egg clutch and percentage of nymph eclosion and male and female longevity were also similar between treatments. The use of insect resistant IAC-24 soybean cultivar on <em>P. nigrispinus</em> was found to be safe because that legume did not have any deleterious effects on the referred predator.</p>

Olive Ridley Mass Nesting Ecology and Egg Harvest at Ostional Beach, Costa Rica

The olive ridley sea turtle (Lepidochelys olivacea), a species listed by the International Union for Conservation of Nature as vulnerable, is characterized by its mass-nesting behavior, also known as arribada. For decades, this phenomenon has facilitated the utilization of this species by coastal communities, much of it illegally. At Ostional beach, Costa Rica, a community-based egg-harvest program operates legally to generate important income for the community while promoting the protection of the ridley nesting assemblage. However, to date, no analysis exists that indicates the long-term viability of the egg harvest program as a sound management tool. To address this void, we generated baseline abundance data of the major arribada events that occurred in the period 2006–2010, as well as egg harvest data, along with preliminary hatching success. Arribadas ranged between 3564 and 476,550 egg-laying females, which indicated a large variability in the magnitude of the mass nesting events. Estimated mean egg harvest was 4746.4 and ranged from 1527 to 8138 total clutches. In relation to the estimated number of clutches laid, the estimated mean of clutches harvested was 21.2%, ranging from 1.5% to 102.4%. Estimated monthly mean hatching rates ranged from 0.0% to 32.6%. It is not clear whether arribadas underwent a significant change in abundance during the study period, although the number of years covered is too short to establish a long-term trend. However, when compared with historical data, the population appears to have declined. Based on our data, we present various management recommendations aimed at increasing hatching rates.

Manipulation of Life-History Decisions Using Leptin in a Wild Passerine

Seasonal timing of reproduction and the number of clutches produced per season are two key avian life-history traits with major fitness consequences. Female condition may play an important role in these decisions. In mammals, body condition and leptin levels are correlated. In birds, the role of leptin remains unclear. We did two experiments where we implanted female great tits with a pellet releasing leptin evenly for 14 days, to manipulate their perceived body condition, or a placebo pellet. In the first experiment where females were implanted when feeding their first brood offspring we found, surprisingly, that placebo treated females were more likely to initiate a second brood compared to leptin treated females. Only one second brood fledged two chicks while five were deserted late in the incubation stage or when the first egg hatched. No difference was found in female or male return rate or in recruitment rate of fledglings of the first brood, possibly due to the desertion of the second broods. In our study population, where there is selection for early egg laying, earlier timing of reproduction might be hampered by food availability and thus nutritional state of the female before egg laying. We therefore implanted similar leptin pellets three weeks before the expected start of egg laying in an attempt to manipulate the laying dates of first clutches. However, leptin treated females did not initiate egg laying earlier compared to placebo treated females, suggesting that other variables than the perceived body condition play a major role in the timing of reproduction. Also, leptin treatment did not affect body mass, basal metabolic rate or feeding rates in captive females. Manipulating life history decisions using experimental protocols which do not alter individuals' energy balance are crucial in understanding the trade-off between costs and benefits of life history decisions.

The Interactive Effects of Ammonia and Microcystin on Life-History Traits of the Cladoceran Daphnia magna: Synergistic or Antagonistic?

The occurrence of Microcystis blooms is a worldwide concern that has caused numerous adverse effects on water quality and lake ecology. Elevated ammonia and microcystin concentrations co-occur during the degradation of Microcystis blooms and are toxic to aquatic organisms; we studied the relative and combined effects of these on the life history of the model organism Daphnia magna. Ammonia and microcystin-LR treatments were: 0, 0.366, 0.581 mg L−1 and 0, 10, 30, 100 µg L−1, respectively. Experiments followed a fully factorial design. Incubations were 14 d and recorded the following life-history traits: number of moults, time to first batch of eggs, time to first clutch, size at first batch of eggs, size at first clutch, number of clutches per female, number of offspring per clutch, and total offspring per female. Both ammonia and microcystin were detrimental to most life-history traits. Interactive effects of the toxins occurred for five traits: the time to first batch of eggs appearing in the brood pouch, time to first clutch, size at first clutch, number of clutches, and total offspring per female. The interactive effects of ammonia and microcystin appeared to be synergistic on some parameters (e.g., time to first eggs) and antagonistic on others (e.g., total offspring per female). In conclusion, the released toxins during the degradation of Microcystis blooms would result, according to our data, in substantially negative effect on D. magna.

Acute and chronic toxicity of polychlorinated biphenyl 126 to Tigriopus japonicus: Effects on survival, growth, reproduction, and intrinsic rate of population growth

The harpacticoid copepod Tigriopus japonicus has a wide geographical distribution and is considered as a suitable model species for the assessment of toxicity of marine pollutants. The aim of the present study was to test the impacts of polychlorinated biphenyl (PCB) 126 (3,3',4,4',5-pentachlorobiphenyl) on the growth, development, and reproduction of T. japonicus in two successive generations. We first quantified the 96-h 50% lethal concentration (2.83 mg/L; all reported concentrations are nominal values), the no-observed-effect concentration (0.6 mg/L), and the lowest-observed-effect concentration (LOEC; 1.2 mg/L) of PCB126 in the nauplii. Nauplii were more sensitive than the adults, which still survived at the highest tested PCB126 concentration (8 mg/L). In the chronic toxicity testing, 10 life history traits were quantified for T. japonicus. No obvious effect on any of these traits was observed in the first generation (F0) at tested concentrations (<100 µg/L) lower than the LOEC. During the second generational life-cycle exposure (F1), however, PCB126 had an obvious toxic effect on the reproduction (>1 µg/L) and growth (>0.1 µg/L). Thus, copepods became more sensitive to PCB126 exposure as generations developed. Among the different traits tested, body size was the most sensitive parameter. Reproduction (fecundity, number of clutches, nauplii/clutch) and intrinsic population growth were also significantly impacted by PCB exposure. The survivorship, sex ratio, hatching time, and development were not affected. Environmental risk assessment of contaminants must therefore be based on a long-term multigenerational exposure to provide a realistic measurement of the influences of pollutants on aquatic life.

Larval development rate of the mosquitoes Culex quinquefasciatus and Aedes aegypti (Diptera: Culicidae) varies between clutches: implications for population ecology

AbstractEgg clutches from two mosquito species were incubated under controlled conditions and the larval development time was recorded. Both the egg raft‐laying mosquito Culex quinquefasciatus and the individual egg layer Aedes aegypti displayed significant intraspecific variation between clutches when it came to larval development at the same temperature. Furthermore, embryonic incubation temperature was found to influence subsequent larval growth rate in some cases. These hitherto undocumented phenomena are indicative of development rate plasticity that appears to be conserved across mosquito genera. The derived development rate data were used to calculate the minimum number of egg clutches required to give a representative mean day‐degrees value for a population of each species. These values were six and five clutches, respectively. A simple population simulation was given to illustrate the impact of different larval development rates when overlapping generations of problem mosquitoes breed. The implication of this work for mosquito population modelling is that the extent of developmental rate variation needs to be taken into account. Furthermore, such conserved variation in larval development rate illustrates the extent of selective pressures on this life history trait.

Reproductive output and ultrasonography of an endangered population of East Pacific green turtles

AbstractReproductive output is one of the most relevant aspects of life history. We analyzed the reproductive output of the endangered East Pacific green turtle (Chelonia mydas) nesting in Nombre de Jesús, Costa Rica. We supplemented beach patrols with ultrasonography to estimate clutch frequency. With ultrasound scans, we classified the stage of turtle ovaries as: early stage (2 or more clutches), late stage (1 clutch), and depleted ovaries (no clutches). We calculated mean (±SD) estimated clutch frequency (ECF) to be 3.7 ± 1.8 (n = 24) and an adjusted frequency considering individual stage (ECFU; ECF + number of clutches remaining as observed in the last ultrasound) as 5.1 ± 1.3. This is greater than previously described for East Pacific green turtles. Greater individual output could be representative of a healthier population; but could also indicate a decrease in the estimate population numbers previously reported. © 2011 The Wildlife Society.

Description of the individual growth of Daphnia magna (Crustacea: Cladocera) through the von Bertalanffy growth equation. Effect of photoperiod and temperature

Daphnia magna is a cladoceran used as a model organism in aquatic ecology and ecotoxicology studies. Because growth is a critical parameter to study the effect of environmental conditions on the development of zooplankters, the somatic growth of D. magna was measured here and described by the von Bertalanffy growth equation (VBGE), a mathematical model widely used in fisheries management. For this purpose, the effect of two temperatures (20 and 25°C) and two photoperiod conditions (12:12 and 16:8, light:dark) was assayed. Experiments began with neonate females and were finished when parthenogenetic females reached the age of 41 days; they were fed the microalga Ankistrodesmus falcatus (400,000 cell ml−1, 12 mg l−1, dry weight). According to the VBGE, maximal length (L max) was inversely correlated with the growth rate (K). The highest L max (6.45 mm) was for the females grown at 20°C with the 12:12 photoperiod, whereas the maximum growth rate (K = 0.182 ± 0.010) was for individuals grown at 25°C with the 12:12 photoperiod. The number of clutches during the studied period was significantly higher for females grown at 25°C, 12:12. Temperature affected the growth rate and the maximum size in D. magna; interaction of temperature with photoperiod was also noteworthy. The VBGE was a nifty way to assess the effects of the tested environmental factors.

Nesting Activity and Clutch Size of Batagur affinis edwardmolli from the Setiu River, Terengganu, Malaysia

Nesting activity of a depleted population of the eastern Malay Peninsula river terrapin, Batagur affinis edwardmolli, in the Setiu River, Terengganu, Malaysia, is documented for the first time over a 6-year period (2004–2009). The number of clutches deposited per year ranged from 17 to 30 with annual average clutch sizes ranging from 23 to 30 eggs per clutch. The nesting season is brief, beginning at the end of January and continuing through March.

Seasonality and Status of Nesting Hawksbill (Eretmochelys imbricata) and Green Turtles (Chelonia mydas) at D'Arros Island, Amirantes Group, Seychelles

Abstract We report on data collected during the first long-term turtle monitoring and conservation program conducted in the Amirantes Islands Group of Seychelles. Green turtle (Chelonia mydas) and hawksbill (Eretmochelys imbricata) nesting activity was recorded on a daily basis, year-round, over a period of 62 months between November 2004 and December 2009 at D'Arros Island, in the context of a community-based turtle monitoring and conservation program coordinated by the D'Arros Research Centre (DRC). Green turtle nesting occurred year-round with a distinct peak in late March but also evidence of a bimodal pattern with a dominant peak during February to April and a secondary peak in July and August. For hawksbills, nesting peaked in early December, with 94.0% of nesting emergences during the four-month interval from 1 October to 31 January. Along the 5-km nesting beach, the estimated average number of clutches laid annually was 95 for green turtles (range 65–120) and 300 (range 277–318) for hawksbills. As...

Reproduction and Age Composition of a Population of Woodland Salamanders (Plethodon albagula) After a Prescribed Burn in Southwestern Arkansas

We studied a population of Plethodon albagula inhabiting an abandoned mine in Garland County, Arkansas, to test whether variables such as fecundity, diameter of egg, total number of eggs produced, and total number of clutches were influenced by precipitation or prescribed burning. We also compared ratios of juveniles to adults during summer, a period when P. albagula sought refuge in the mine, to determine if prescribed burning influenced certain life stages more than others. Comparing years before and after burning and accounting for the influence of precipitation, we did not detect a significant effect of the prescribed burn on any reproductive variable. However, we did discover a decline in some reproductive variables 1.5 years post-burning. There also was no decline in the ratio of juveniles to adults before or after the burn. Prescribed burning in the inactive season did not affect reproduction or age composition of the population of P. albagula.

Performance of Sudanese native Dwarf and Bare Neck Chicken raised under improved traditional production system

A total of 300 indigenous pullets of various ecotypes were used for phenotypic characterization of the native chicken of Sudan. This study aimed at evaluating production performance, egg characteristics and clutch traits of dwarf (Betwil) and Bare Neck ecotypes. Laying rate, average egg weight and egg components weights (albumen, yolk and shell) were significantly lower (P<0.05) in dwarf (Betwil) than in Bare Neck. However yolk : albumen ratio and relative yolk weight were higher in dwarf (Betwil) than in Bare Neck. There were high and positive correlations between egg weight and egg components weights (albumen, yolk and shell) in both ecotypes, whereas the correlation between egg weight and shell thickness was low. The average number of egg per clutch, average clutch length and the number of clutch per year for dwarf (Betwil) were 9.89 eggs, 14.44 days and 5 clutches whereas the corresponding results for Bare Neck were 13.52 eggs, 20.04 days and 4 clutches. Hatchability from fertile eggs using natural incubation for dwarf (Betwil) and Bare Neck were 65.6 and 59.09 percent respectively. The observed oviposition patterns in both ecotypes seemed to be irregular with pauses ranging from 1-3 days and most of the eggs were laid during the day period from 10 am to 2 pm.

Talgoxens Parus major antal och häckningsbiologi – resultat av 25 års holkstudier

A nest-box population of Great Tits Parus major was followed in 1986–2010. Maximum number of breeding attempts was three times higher than the minimum number but there was no significant trend through 2005. The number of nest-boxes declined from 94 to 55 during the last five years making it difficult to interpret the recent trend but most likely there was an increase. 17% of the first breeding attempts failed and resulted in replacement clutches. The number of second clutches was 13% of the number of first clutches. There was no correlation between population size and winter temperature. There was no significant advancement of laying date in spite of the fact laying date was correlated with April temperature and that local April temperature showed a significant positive trend during the study period. Mean clutch size was 9.2 eggs. The number of fledglings was 4.65, which is low compared to other studies. Replacement and second clutches produced 4.37 fledglings. Both clutch size and number of fledglings declined during the study period.