Number Of Eggs In Females Research Articles

Evolutionary stable sex ratios with non‐facultative male‐eggs first sex allocation in fig wasps

Sex allocation theory has long generated insights into the nature of natural selection. Classical models have elucidated causal phenomena such as local mate competition and inbreeding on the degree of female bias exhibited by various invertebrates. Typically, these models assume mothers facultatively adjust sex allocation using predictive cues of future offspring mating conditions. Here we relax this assumption by developing a sex allocation model for haplodiploid mothers experiencing local mate competition that lay a fixed number of male eggs first. Female egg number is determined by remaining oviposition sites or remaining eggs of the mother, depending on which is exhausted first. Our model includes parameters for variation in foundress number, patch size, fecundity and offspring mortality that allow us to generate secondary sex ratio predictions based on specific parameterizations for natural populations. Simulations show that: 1) in line with classical models, factors that increase sib‐mating result in mothers laying relatively more female eggs; 2) high offspring mortality leads to relatively more males as fertilization insurance; 3) unlike classical model predictions, sub‐optimal predictions, such as more males than females are possible. In addition, our model provides the first quantitative predictions for the expected number of males and females in a patch where typically only one mother utilizes a given patch. We parameterized the model with data obtained from seven species of southern African fig wasps to predict expected means and variances for numbers of male and female offspring for typical numbers of mothers utilizing a patch. These predictions were compared to secondary sex ratio data from single foundress patches, the most commonly encountered situation for these species. Our predictions matched both the observed number and variance of male and female offspring with a high degree of accuracy suggesting that facultative adjustment is not required to produce evolutionary stable sex ratios.

Динамика структуры популяций двух видов бокоплавов рода Echinogammarus (Gammaridae, Amphipoda) из бухты Ласпи (Крым, Чёрное море)

Исследование популяционных характеристик массовых видов беспозвоночных зоны заплеска важно для оценки и прогнозирования состояния прибрежной экосистемы моря. В течение года исследовали популяционную структуру двух массовых видов амфипод: Echinogammarus karadagiensis (Grintsov, 2009) и Echinogammarus foxi (Schellenberg, 1928) зоны заплеска галечно-песчаного пляжа б. Ласпи. Выявлены важные особенности в изменении размерного состава, соотношения самцов и самок, соотношения взрослых особей и молоди, количества яиц у самок, размеров взрослых самцов и самок.

Does cestode infection affect reproduction of the endangered golden venus chub, Hemigrammocypris neglectus?

The effects of larval cestode (Neogryporhynchus cheilancristrotus) infection on the reproduction of golden venus chub Hemigrammocypris neglectus and their population growth were estimated by analysis of the relationships between the abundance of cestodes and the breeding behavior of male chubs, as well as the fecundity of female chubs. N. cheilancristrotus causes a prominent abdominal distention in H. neglectus because of a hypertrophied hepatopancreas. Cestode infection displayed no negative relationship to chasing behavior by males of females or to the number of prenatal eggs in females. Thus, we conclude that cestode infection has little effect on the population growth of the host fish through reproductive behavior/fecundity, despite the prominent pathological change in the hepatopancreas.

Quantifying fecundity in Macoma balthica using an enzyme-linked immunosorbent assay (ELISA)

Monoclonal antibodies specific to a heat shock protein 70-like protein expressed in the eggs of Macoma balthica (mb-HSP70) were employed to develop an enzyme-linked immunosorbent assay (ELISA) to quantify fecundity in females. The assay was specific to egg tissue, with no demon- strable reactivity with juvenile or male tissues. The concentration of mb-HSP70 increased as the female gonads matured, necessitating the determination of a calibration curve for future experi- ments. The number of eggs in females was positively correlated with body mass index (BMI), and clams with a BMI <1.4 did not produce eggs. The estimated number of eggs per clam during the fall spawning period was similar to that observed in eastern North Atlantic populations in clams of simi- lar size; clams with shell lengths from 16 to 18 mm had from 7000 to 60 000 eggs apiece. Larger clams had up to 450 000 eggs. This assay effectively quantifies eggs at any stage of gonadal development in which eggs can be distinguished microscopically and is easier and cheaper to perform than other techniques of comparable precision.

The Possible Influence of Male Worm Age on the Fecundity of Moniliformis moniliformis (Acanthocephala) in Laboratory Rats

During the course of a primary infection of Moniliformis moniliformis in rats, involving an experimentally structured population of worms derived from infective doses of 10 male and 10 female cystacanths per rat, the fecundity of the female worms appeared to be influenced by the age of the males. The experimental design ensured that all the female worms were 35 days old when fecundity was assessed. On average, the number of eggs in females recovered from rats containing 28-day-old males was 20,930 +/- 2,143, that from rats containing 35-day-old males was 7,434 +/- 937, and that from 42-day-old males was 14,396 +/- 1,704; these values were found to be significantly different (least significant difference, P less than or equal to 0.01). The results suggest that the variable age of the worms would be likely to favor fecundity in naturally occurring infections.

Fecundity ofCaenis(Ephemeroptera: Caenidae) in Elevated Water Temperatures

ABSTRACT The influence of elevated water temperatures on fecundity of Caenis sp. emerging from large outdoor channels was investigated during the summer of 1980. Four temperature levels were provided: Ambient (Tennessee River, U.S.A.), and approximately 3°, 6°, and 9° C above ambient. Number of eggs per female ranged between 212 and 1787 at all temperature levels. A median test indicated a significantly lower number of eggs in females from +9 channels than from the other temperature levels.

POPILLIA JAPONICA (COLEOPTERA: SCARABAEIDAE): A MATHEMATICAL MODEL OF OVIPOSITION IN HETEROGENEOUS AGROECOSYSTEMS

AbstractA mathematical model is developed which simulates the effect of the number of eggs in females, food source, and soil conditions, on ovogenesis and oviposition of Japanese beetle populations. The number of eggs in females is used as the state indicator, and simulated trends are compared to field data. Potential applications in pest management are discussed.