Influences of population density on reproductive output at food excess in the guppy, Poecilia reticulata (Peters).

Experiments were performed to examine the influence of population density on the fecundity and fertility in the guppy, Poecilia reticulata. The frequency of females with only ova or with different combinations of reproductive units and developmental stages in the ovary was significantly different between different densities but not between females with one and two gestations from the same population density. The ovarian width of females with one gestation from the lowest density was significantly larger than in the highest population density. Gonad length and height and ovarian volume of females with two gestation periods were larger in the lowest compared with the highest density. After one gestation, females at the lowest population level had greater ovarian length, height, gonad weight, width and volume compared with those from the higher density. Ovarian length, height and volume and gonad weight were also significantly greater among females of two gestation periods in the lowest than in the second lowest density. The average gonadosomatic ratio was highest in the lowest population density. A significant correlation was found between gonad volume and total body weight and between gonad volume and ovarian weight of females at every population level. This was also the case when ovarian weight vs. total body weight was examined in each population density. Only at the lowest population level was there a significant correlation between fecundity and total body length and between fertility and body length. A significant relationship was also found between gonad volume and total body length and between gonad weight and body length at the same population level. No significant difference of fecundity and ovum size was found between females of one and two gestation periods from the same density. Fecundity and fertility were significantly higher among females of one and two gestation periods from the lowest than from the highest density.

Experiments were performed to investigate the influences of dietary protein on fecundity in the guppy, Poecilia reticulata. No significant differences in total body length and standard length were found between females given food with different protein levels. A significantly higher total body weight was found both in females fed on 47% and 31% protein compared with females given 15% protein. The frequencies of females with only intrafollicular embryos or with only ova or both embryos and ova in the ovary were not significantly different between populations given different protein amounts. There was a significantly lower frequency of females without embryos and ova but with previtellogenic oocytes in the group given highest protein (47%) compared with the group fed on 31%. Significantly higher values of ovarian length, width and gonad weight were found among females given 47% protein compared with females fed on 15% protein. The ovarian height was significantly higher only in females given the highest protein amount when compared with the group fed on 31% protein. No significant difference of ovarian volume was found between groups given different protein contents. The average gonadosomatic ratio was highest in the groups fed on 47% protein. Significant correlations were found between gonad weight and total body weight of females in each group. Ovarian volume versus total body weight as well as versus gonad weight also yielded significant correlations in all groups. No significant differences of fecundity were found either between females given 47% and 31% protein or between females fed on 47% and 15% protein. A somewhat higher number of ova per individual fish was, however, observed among females given 31% when compared with females fed on 15% protein. The ovum size remained the same between groups given different protein contents. No significant correlation was found between fecundity and ovum diameter in the groups.

Feeding experiments were carried out to examine the effects of different amounts of dietary non-protein (carbohydrates and lipids) on fecundity and fertility in the guppy. Poecilia reticulate (Peters). There were no significant differences in total body length between females given different amounts of non-protein food, but females given 85% non-protein diet had a significantly higher standard length than females given 69 or 53% non-protein components. A significantly higher total body weight was also found in the groups fed on 85% non-protein diet than among females given 53% non-protein. The frequencies of females with only intrafollicular embryos or with both embryos and ova alternatively with only previtellogenic oocytes in the ovary were not significantly different between populations fed on different non-protein contents. In the group given 69% non-protein the frequency of females with only ova was significantly higher than among females fed on 53% non-protein. The ovarian width, ovarian volume and gonad weight were all significantly higher in females given 85% non-protein than in females fed on 53% non-protein. There were no significant differences of fecundity and fertility between any groups given different amounts of non-protein (85, 69 and 53%). This was also true for embryo size and ovum diameter.

To establish normal values for the volume and maximal diameter of ovaries and ovarian follicles and for the number of ovarian follicles in magnetic resonance imaging (MRI) based on menstrual cycle phase and age. We performed MRI of the pelvis on 100 healthy women. Volume of the ovaries and largest ovarian follicles and the number of ovarian follicles were determined by menstrual cycle phase and age. The mean volume of the ovaries significantly increased with age and reached its peak between 31 and 40 years, and subsequently decreased. The mean volume of the largest ovarian follicles also significantly increased with age to reach its peak at 41-50 years. The highest mean numbers of ovarian follicles were found at 20-40 years. When the volumes of ovaries and of the largest ovarian follicles, and the number of ovarian follicles were compared between the first and second phase of the menstrual cycle, no significant differences were found. The volume and maximal diameter of ovaries and ovarian follicles and the number of ovarian follicles differ significantly with age, but not between the two phases of the menstrual cycle. Knowledge of MRI-related normal values can be expected to aid the early identification of ovarian pathologies.

Introduction: Ovarian Reserve (OR) serves as an important indicator of a female’s reproductive potential and remaining reproductive lifespan. With the societal shift towards delayed marriages and increased career focus among women, there is a growing need to understand the impact of age on fertility and the role of assisted reproductive techniques. Aim: To evaluate the volume of both left and right ovaries in asymptomatic females using ultrasonographic measurement of various morphometric parameters. Materials and Methods: This cross-sectional observational study was conducted in the Department of Anatomy, in association with the Department of Obstetrics and Gynaecology and Department of Radiodiagnosis, King George’s Medical University, Uttar Pradesh, Lucknow, India, from September 2016 to June 2017. Total 100 non pregnant females aged 19-49 years were included in the study. Ultrasonography was used to measure the Longitudinal Length (LL), Transverse Diameter (TD), and Anteroposterior Diameter (APD) of both ovaries (right and left). The volume of each ovary was calculated using the formula: 0.523×LL×TD×APD. Statistical Package for the Social Sciences (SPSS) software version 24.0 was used to assess the maximum, minimum, and mean±Standard Deviation (SD) for all the morphometric parameters of the right and left ovaries. A paired t-test was used to compare these morphometric parameters, and a p-value <0.05 was considered statistically significant. Results: The mean±SD age of the study participants was 34.06±9.35 years. The mean±SD of LL, TD, APD, and volume for the right ovary were 3.12±0.29 cm, 2.37±0.24 cm, 1.76±0.19 cm, and 6.78±1.08 cm³, respectively. The mean±SD of LL, TD, APD, and volume for the left ovary were 3.08±0.45 cm, 2.32±0.25 cm, 1.76±0.18 cm, and 6.61±1.06 cm³, respectively. A comparison between these morphometric parameters of the right and left ovaries did not reveal any statistically significant differences. Conclusion: The use of sonography is rapidly increasing nowadays in the field of gynaecology and reproductive medicine, and ovarian parameters are of great importance in diagnosing ovarian abnormalities in adolescents, PCOS, and ovarian cancer. In the field of reproductive medicine, ultrasound is helpful in serial follicular monitoring of females on ovulogens to assess their ovarian reserve.

A critical need to evaluate methods to reduce production costs of Upland cotton (Gossypium hirsutum L.) to help maintain its. competitive market position, prompted experiments designed to evaluate the influence of row width and plant population on yield and fiber properties. Upland cotton was grown in 25.4‐, 50.8‐, 76.2‐, and 101.6‐cm‐spaced rows with population levels of 128,000 (low) and 256,000 (high) plants/ha at three locations in Georgia. Significant differences in yield due to test location and to row width were found, but differences in plant populations did not affect yield.Seeding with a modified grain drill produced 88% of the plants desired at the low population level and 82% at the high population level, but left much to be desired in uniformity of seed distribution, placement, and coverage.We found no difference in lint percentage and seed size except that due to location. Boll size was affected by plant population and location but not by row width. The only fiber characteristic affected by row width was fiber fineness. Earliness was influenced only by location. Significant interactions of row width × location were found for yield, number of plants, lint percentage, and fineness. The population × location interaction was significant for boll size and number of plants. The second order interaction of population × row width × location was significant for boll size. Results relative to yield were encouraging and indicated that the narrow‐row, high‐population system might provide partial solutions to some production problems.

The F1 and parents involved in a winter wheat cross (‘Reed’ Χ ‘Gaines’) were grown at five population levels under irigation for 3 years at Aberdeen, Idaho. The F2 was grown in the same experiment for 2 years and the F3 for 1 year.A slight amount of heterosis was expressed in plant height.Heterosis was expressed by the hybrid in grain yield. When means over all five population levels were compared, the F1 produced more grain than either parent in all 3 years. Differences were significant except for that between the F1 and Gaines in 1965. The F1 produced significantly more grain than the F2 in 1964 and 1965, and the F3 in 1965. There was no significant difference between the F2 and F3 in 1965.No heterosis was evident in number of spikes per plant. Gaines produced more spikes per plant than the hybrid each year. Some degree of heterosis was expressed in number of kernels per spike and in kernel size 2 years out of 3.Reed (tall variety) was used as border around all plots in two replications and Gaines (short variety) was used as border in two replications in 1963 and 1964. The only significant competition effects measured were on height in 1964 and on grains of grain per plot in 1963. Each entry in 1965 was bordered by itself.F1 and parent plants were slightly taller when grown at the higher plant densities.Population level had an effect on grain yield. In 2 out of 3 years highest yields were produced by the hybrid and by Gaines at level 3. In no year were the F1 means at population levels 3, 4, or 5 significantly different. The same was true for both parents. On the basis of this test a producer could cut his seeding rate to that of population level 3 (approximately one plant per 2.5 cm (1 inch) or 0.9 hectoliter per hectare (3‐¼ pecks per acre). This could be important if hybrid wheat seed becomes available and is relatively costly. More tests at different population levels should be conducted before a general recommendation can be made.Plants grown at low population levels produced more spikes and more kernels per spike than those grown at high levels. Seed size was little influenced by plant density, although there was a trend toward smaller seed at the high population levels.

Spatial confinement to a home range is theorized to be a more energetically efficient method of acquiring resources than random searching due to spatial memory. Intraspecific studies that have compared home range size at different population densities have found that home ranges shrink as population density increases. This negative trend could be due to increased conspecific competition via population density increase or due to correlations between resource density and population density. We use the 10-year population cycle of snowshoe hares (Lepus americanus) and individual-level food-add experiments as a case study to assess whether the mechanism of the relationship between home range size and population density is related to competition from increased conspecific density or confounds between population density and resource density. Over six winters (1 December-31 March) and a 50-fold change in population density, we estimated weekly home range sizes (n = 464; 90% minimum convex polygons) of 88 radio-collared hares, of which 26 were food-supplemented. We found a negative relationship between home range size and population density in controls; home ranges decreased by 2.5 ha as hare density increased from 0.24 to 1.2 hare/ha. Food-supplemented hares showed a more negative response to population density than controls (4.0 ± 0.56 ha decrease per 1 hare/ha increase). Our results suggest that the negative trend between home range size and population density is not due to confounds between population and resource density. Likely, there is a trade-off between resource acquisition and some other density-driven constraint when foraging at high densities, which we suggest is a reduction in resource sharing to minimize competition and maintain resource familiarity at high densities.

One of the problems related to population that still has to be faced by Simalungun is the problem of the imbalance in the distribution of the population. Incomplete division of the population brings problems to population density and population pressure in an area. This study uses data sources from the Central Statistics Agency (BPS) Simalungun. The data used in this study is data from 2015-2019 which consists of 32 Districts. Therefore, the researchers used the K-Means algorithm in clustering 32 sub-districts in Simalungun Regency. The data will be processed by clustering in 3 clusters, namely clusters with high population levels, clusters with moderate population levels and clusters with low population levels. The iteration process takes 5 times so that the results obtained are 4 sub-districts with high population level clusters (C1), 11 cluster sub-districts with moderate population level (C2) and 17 cluster sub-districts with low population level (C3)

During a long term study (10 years) of an increasing forest roe deer Capreolus capreolus (Linnaeus, 1758) population, the reliability of a kilometric index for monitoring population size was tested.Kilometric index was defined by the ratio "number of observed animals/number of kilometers" of standardized transect.Three indexes were constructed: one for each transect, one for a transect set and one for all transects performed during a year.Actual population size was estimated each year by capture -mark -recapture.A modification of Petersen -Lincoln Index allowing long-term use was applied as the reference method.The relationship between annual kilometric index and population size estimation was assessed by calibrating index using linear and logistic regression.Moreover, we looked for different population levels using analyses of variance applied on the different indexes.Although high correlation was obtained between annual kilometric index and reference method, calibration equation led to unreliable population schedule.This demonstrated differential sensitivity of kilometric index according to population levels.Three population levels were discriminated by analyses of variance: a low population level during the four first years, a transition level corresponding to the fifth year and a high population level during the five last years.Indexes defined on a transect set (called "photo") appeared as the more informative.Such a study showed that to look for differential population levels from abundance indexes (bioindicator conception) is more pertinent than to establish conversion equations (calibration conception) in order to monitor forest roe deer population.

Studying the change in population distribution and density can provide important basis for regional development and planning. The spatial patterns and driving factors of the change in population density in China were not clear yet. Therefore, using the population census data in 2000 and 2010, this study firstly analyzed the change of population density in China and divided the change in all 2353 counties into 4 types, consisting of rapid increase, slow increase, slow decrease and rapid decrease. Subsequently, based on the partial least square (PLS) regression method, we recognized the significant factors (among 11 natural and social-economic factors) impacting population density change for the whole country and counties with different types of population change. The results showed that: (1) compared to the population density in 2000, in 2010, the population density in most of the counties (over 60%) increased by 21 persons per km2 on average, while the population density in other counties decreased by 13 persons per km2. Of all the 2353 counties, 860 and 589 counties respectively showed rapid and slow increase in population density, while 458 and 446 counties showed slow and rapid decrease in population density, respectively. (2) Among the 11 factors, social-economic factors impacted population density change more significantly than natural factors. The higher economic development level, better medical condition and stronger communication capability were the main pull factors of population increase. The dense population density was the main push factor of population decrease. These conclusions clarified the spatial pattern of population change and its influencing factors in China over the past 10 years and could provide helpful reference for the future population planning.

Studies on reproduction of fish are important and essential requirements for improvement of fishery resources management and conservation. The fish samples were dissected to ascertain the relationship among fecundity with length and weight of fish and its ovary as well as GSI, ova diameter, for total proteins, glucose, lipids, cholesterol and DNA/RNA ratio during spawning seasons. The fecundity was ranged from 1695±524.44 to 3297±282.99eggs with total body length 22.52±2.84 to 27.90±1.88cm and total body weight 172.33±10.9 to 240.9±7.59g. The total proteins, RNA and total lipids contents were lower in pre-spawning season (37.8±4.1, 56.4±3.2 and 18.6±4.7mg/g respectively) and post spawning season 34.7±3.1, 58.4±4.4 and 14.4±2.2mg/g) than spawning season (83.9±3.8, 82.03±3.3 and 36.3±1.72mg/g). In contrast, the cholesterol and glucose levels were significantly higher in pre-spawning (59.8±2.5, 58.8±4.51mg/g) and post-spawning (70.2±1.84, 61.16±4.73mg/g) than spawning season (29.8±2.2, 28.1±1.70mg/g). The relationship of fecundity with total length, total weight of fish and ovary were found to be linear. It is concluded that by knowing the exact breeding season and relationship of fecundity with various parameters of Schizothorax plagiostomus, we could conserve this declining species in natural water bodies by artificial breeding.

Although different researches related to the population dynamics of orient fruit fly [Bactrocera dorsalis( Hendel) ]have already been conducted by many Chinese scholars,the systematic researches related to the population dynamics of B. dorsalis in different habitats have not yet been conducted. In order to reveal the effect of different habitats on the population dynamic of B. dorsalis,the population dynamics of B. dorsalis was monitored by using sex induction agents during 2008—2009 in each monitoring point in Fuzhou,Fujian,China. The study objects are displayed as follows. The first one is population dynamics and density of B. dorsalis in different orchards,including guava,carambola,grape,luffa, cucumber citrus,grapefuit and mixture orchard. The second one is population dynamics and density in orchard and its surroundings jungles. The third one is population dynamics and density in different geographical environment in orchard, including ridge and valley,along river and not. And the last one is population dynamics and density in city and countryside. The result shows,first,that the population of B. dorsalis reaches peak when the fruit ripening in each type of orchard. Second,the population density in mixed orchard is obviously higher than the orchards of single species. Third,the population density in orchard was higher than surrounding jungles during the fruit ripening while the case was contrary to former after the fruit ripening in the orchard. Forth,the population level in valley was higher than ridge while the number along river was higher than that not along river. Fifth,the population period in city subdivision is earlier than in countryside and the population density in city is also higher than in countryside. Last,some useful and effective methods for improving control of this pest were also proposed,and drawbacks of this study and the future researches were presented. Based on our results,we suggest,first,that trying to avoid mixed cultivation with all kind of fruits in the agricultural production because of the population density in the orchard of single species is much lower than mixed orchard. Second,the field microclimate should be taken into account in pest forecasting and prevention. Third,the population changing of B. dorsalis in city should be emphasized by government and quarantine department. Because the population period in city subdivision is earlier than in countryside and the former population density is also higher than later. Next,based on the limitations of this study,some suggestions for further research are presented. Insufficient number of monitoring points is the mainly limitation in this study. For example,space-time dynamic characteristic between city subdivision and countryside has not yet been reflected because of insufficient number of monitoring points. So the characteristic of space-time dynamics between city and countryside be done in future research. Moreover,the cause of the difference of B. dorsalis populations in different habitats will be revealed in future study,especially the reasons of the difference of B. dorsalis populations in different orchards,the causes of the population dynamics between orchard and its surrounding jungles and the reasons of population dynamics between city and countryside.

Animals can adjust reproductive strategies in favour of corporation or competition in response to local population size and density, the two key factors of social environments. However, previous studies usually focus on either population size or density but ignore their interactions. Using a haplodiploid spider mite, Tetranychus ludeni Zacher, we carried out a factorial experiment in the laboratory to examine how ovipositing females adjust their fecundity and offspring sex ratio during their early reproductive life under various population size and density. We reveal that females laid significantly more eggs with increasing population size and significantly fewer eggs with increasing population density. This suggests that large populations favour cooperation between individuals and dense populations increase competition. We demonstrate a significant negative interaction of population size and density that resulted in significantly fewer eggs laid in the large and dense populations. Furthermore, we show that females significantly skewed the offspring sex ratio towards female-biased in small populations to reduce the local mate competition among their sons. However, population density incurred no significant impact on offspring sex ratio, while the significant positive interaction of population size and density significantly increased the proportion of female offspring in the large and dense populations, which will minimise food or space competition as females usually disperse after mating at crowded conditions. These results also suggest that population density affecting sex allocation in T. ludeni is intercorrelated with population size. This study provides evidence that animals can manipulate their reproductive output and adjust offspring sex ratio in response to various social environments, and the interactions of different socio-environmental factors may play significant roles.

Studying the effect of oxygen availability and matrix structure on population density and inter-strain interactions of Listeria monocytogenes in different dairy model systems