Association between protein feeding and reproductive efficiency in the dairy cow : specific emphasis on protein feeding in Finland

Selostus: Lypsylehmien valkuaisruokinnan ja hedelmällisyyden yhteys: kirjallisuustutkimus valkuaisruokinnan vaikutuksista Suomen olosuhteissa

The evolution and consequences of sex-specific reproductive variance.

Natural selection favors alleles that increase the number of offspring produced by their carriers. But in a world that is inherently uncertain within generations, selection also favors alleles that reduce the variance in the number of offspring produced. If previous studies have established this principle, they have largely ignored fundamental aspects of sexual reproduction and therefore how selection on sex-specific reproductive variance operates. To study the evolution and consequences of sex-specific reproductive variance, we present a population-genetic model of phenotypic evolution in a dioecious population that incorporates previously neglected components of reproductive variance. First, we derive the probability of fixation for mutations that affect male and/or female reproductive phenotypes under sex-specific selection. We find that even in the simplest scenarios, the direction of selection is altered when reproductive variance is taken into account. In particular, previously unaccounted for covariances between the reproductive outputs of different individuals are expected to play a significant role in determining the direction of selection. Then, the probability of fixation is used to develop a stochastic model of joint male and female phenotypic evolution. We find that sex-specific reproductive variance can be responsible for changes in the course of long-term evolution. Finally, the model is applied to an example of parental-care evolution. Overall, our model allows for the evolutionary analysis of social traits in finite and dioecious populations, where interactions can occur within and between sexes under a realistic scenario of reproduction.

Additive effects of ectoparasites over reproductive attempts in the long-lived Alpine swift

1. Parasitism is a non-negligible cost of reproduction in wild organisms, and hosts are selected to partition resources optimally between current and future reproduction. While parents can compensate for the cost of parasitism by increasing their current reproductive investment, such change in resource allocation is expected to carry-over costs on future reproduction. 2. Life history theory predicts that because long-lived organisms have a high residual reproductive value, they should be more reluctant to increase parental effort in response to parasites. Also, when rearing successive infested broods, the cost of parasitism can cumulate over the years and hence be exacerbated by past infestations. 3. We tested these two predictions in the alpine swift Apus melba, a long-lived colonial bird that is infested intensely by the nest-based blood sucking louse-fly Crataerina melbae. For this purpose, we manipulated ectoparasite load over 3 consecutive years and measured reproductive parameters in successive breeding attempts of adults assigned randomly to 'parasitized' and 'deparasitized' treatments. 4. In current reproduction, fathers of experimentally parasitized broods produced a similar number of offspring as fathers from the deparasitized treatment, but the rearing period was prolonged by 4 days. Fathers that were assigned to the parasitized treatment in year x produced significantly fewer fledglings the following year x + 1 than those of the deparasitized treatment. The number of young produced by fathers in year x + 1 was correlated negatively with the number of days they cared for their brood in the previous year x. We also found a significant interaction between treatments performed over 2 successive years, with fathers of parasitized broods suffering a larger fitness loss if in the past they had already cared for a parasitized brood rather than for a deparasitized one. Similar effects of parasitism, although partly non-significant (0.05 < P-values > 0.10), were found in mothers. 5. Altogether, our results show that parasites can modify resource allocation between current and future reproduction in long-lived hosts, and that the cost of parasitism can cumulate over the years. It emphasizes the fact that effects of parasites can depend on past infestations and become apparent in future reproduction only.

Hydrocarbon divergence and reproductive isolation in Timema stick insects.

BACKGROUND: Individuals commonly prefer certain trait values over others when choosing their mates. If such preferences diverge between populations, they can generate behavioral reproductive isolation and thereby contribute to speciation. Reproductive isolation in insects often involves chemical communication, and cuticular hydrocarbons, in particular, serve as mate recognition signals in many species. We combined data on female cuticular hydrocarbons, interspecific mating propensity, and phylogenetics to evaluate the role of cuticular hydrocarbons in diversification of Timema walking-sticks. RESULTS: Hydrocarbon profiles differed substantially among the nine analyzed species, as well as between partially reproductively-isolated T. cristinae populations adapted to different host plants. In no-choice trials, mating was more likely between species with similar than divergent hydrocarbon profiles, even after correcting for genetic divergences. The macroevolution of hydrocarbon profiles, along a Timema species phylogeny, fits best with a punctuated model of phenotypic change concentrated around speciation events, consistent with change driven by selection during the evolution of reproductive isolation. CONCLUSION: Altogether, our data indicate that cuticular hydrocarbon profiles vary among Timema species and populations, and that most evolutionary change in hydrocarbon profiles occurs in association with speciation events. Similarities in hydrocarbon profiles between species are correlated with interspecific mating propensities, suggesting a role for cuticular hydrocarbon profiles in mate choice and speciation in the genus Timema.

Reproductive bribing and policing as evolutionary mechanisms for the suppression of within-group selfishness.

We show that a new, simple, and robust general mechanism for the social suppression of within-group selfishness follows from Hamilton's rule applied in a multilevel selection approach to asymmetrical, two-person groups: If it pays a group member to behave selfishly (i.e., increase its share of the group's reproduction, at the expense of group productivity), then its partner will virtually always be favored to provide a reproductive "bribe" sufficient to remove the incentive for the selfish behavior. The magnitude of the bribe will vary directly with the number of offspring (or other close kin) potentially gained by the selfish individual and inversely with both the relatedness r between the interactants and the loss in group productivity because of selfishness. This bribe principle greatly extends the scope for cooperation within groups. Reproductive bribing is more likely to be favored over social policing for dominants rather than subordinates and as intragroup relatedness increases. Finally, analysis of the difference between the group optimum for an individual's behavior and the individual's inclusive fitness optimum reveals a paradoxical feedback loop by which bribing and policing, while nullifying particular selfish acts, automatically widen the separation of individual and group optima for other behaviors (i.e., resolution of one conflict intensifies others).

Temperament and reproductive performance in farmed sable

Selostus: Tarhatun soopelin luonne ja lisääntymiskyky

Gene by environment interaction: effects of a single-gene and social-environment on reproductive phenotypes of fire ant queens

1. The gene Pgm-3 (or a closely linked gene) influences the phenotype and reproductive success of queens in multiple-queen (polygynous) colonies but not single-queen (monogynous) colonies of the Fire Ant Solenopsis invicta. 2. We investigated the mechanisms of differential phenotypic expression of Pgm-3 in these alternate social forms. Mature winged queens with the homozygous genotype Pgm-3(a/a) averaged 26% heavier than queens with the genotypes Pgm-3(a/b) and Pgm 3(b/b) in the polygynous form. Heterozygotes were slightly heavier (2%) than Pgm-3(b/b) queens in this form, demonstrating that the allele Pgm-3(a) is not completely recessive in its effects on weight. 3. There was no significant difference in weight among queens of the three Pgm-3 genotypes in the monogynous form, with the mean weight of monogynous queens slightly greater than that of polygynous Pgm-3(a/a) queens. Differences in weight between queens of the two social forms and among queens of the three genotypes in the polygynous form are not evident at the pupal stage and thus appear to develop during sexual maturation of the adults. This suggests that some component of the social environment of polygynous colonies inhibits weight gains during queen maturation and that Pgm-(3a/a) queens are relatively less sensitive to this factor. 4. To test whether the high cumulative queen pheromone level characteristic of polygynous colonies is the factor responsible for the differential queen maturation, we compared phenotypes of winged queens reared in split colonies in which pheromone levels were manipulated by adjusting queen number. Queens produced in colony fragments made monogynous were heavier than those produced in polygynous fragments, a finding consistent with the hypothesis that pheromone level affects the reproductive development of queens. However, genotype-specific differences in weights of queens were similar between the two treatments, suggesting that pheromone level was not the key factor of the social environment responsible for the gene-environment interaction. 5. To test whether limited food availability to winged queens associated with the high brood/worker ratios in polygynous colonies is the factor responsible for this interaction, similar split-colony experiments were performed. Elevated brood/worker ratios decreased the weight of winged queens but there was no evidence that this treatment intensified differential weight gains among queens with different Pgm-3 genotypes. Manipulation of the amount of food provided to colonies had no effect on queen weight. 6. The combined data indicate that cumulative pheromone level and brood/worker ratio are two of the factors responsible for the differences in reproductive phenotypes between monogynous and polygynous winged queens but that these factors are not directly responsible for inducing the phenotypic effects of Pgm-3 in polygynous colonies.

Reproductive biology of Faidherbia albida (Del.) A. Chev.

Abstract

Reproductive characteristics of the predator Podisus nigrispinus fed with an insect resistant soybean variety

The objective of this research was to evaluate the effect of the insect resistant soybean genotype IAC 17 on reproductive characteristics of Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) females compared to the soybean insect susceptible genotype UFV 16. Treatments were: T1) females of P. nigrispinus fed on plants of the UFV 16 and Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae) caterpillars reared on leaves of this variety; T2) females of P. nigrispinus fed on plants of the IAC 17 and A. gemmatalis caterpillars reared on leaves of this variety. Longevity of females, pre-oviposition, oviposition and pos-oviposition periods, number of eggs and egg masses/female, egg weight, interval between egg mass laying, number of eggs/egg mass, percentage of nymphs, number of nymphs/female and total number of prey killed/female of P. nigrispinus were evaluated. Most of the characteristics evaluated showed similar results between treatments, but the oviposition period was longer for females reared on the resistant genotype than on the susceptible one and the percentage of total females that laid eggs was lower on the IAC 17. Also, the resistant genotype caused higher mortality of P. nigrispinus females at the beginning of its adult stage and egg production by females of this predator was better spread along its adult stage with this resistant genotype. On the other hand, results suggest no effect of the resistant genotype on the offspring of this predator.

Flight, feeding and reproductive behavior of Phyllophaga cuyabana (Moser) (Coleoptera: Melolonthidae) adults

Phyllophaga cuyabana is a univoltine species and its development occurs completely underground. Its control by conventional methods, such as chemical and biological insecticides, is difficult, so it is important to understand its dispersion, reproduction, and population behavior in order to determine best pest management strategies. The objective of this work was to study the behavior of adults of P. cuyabana. This study was carried out in the laboratory, greenhouse and field sites in Paraná State, Brazil (24º25' S and 52º48' W), during four seasons. The results obtained demonstrate that: a) P. cuyabana adults have a synchronized short-flight period when mating and reproduction occurs; b) adults tend to aggregate in specific sites for mating; c) the majority of adults left the soil on alternate nights; d) the choice of mating and oviposition sites was made by females before copulation, since after copulation adults did not fly from or bury themselves at nearby locations; e) females that fed on leaves after mating, oviposited more eggs than females that had not fed;f) plant species such as sunflower (Helianthus annuus) and the Crotalaria juncea are important food sources for adults.

Morphogenetic characteristics and management of Tanzania grass

The objective of this work was to evaluate the effect of grazing interval and period of evaluation over tissue turnover in Tanzania grass pastures (Panicum maximum cv. Tanzania) and to ascertain if herbage accumulation rate can be used as a criterion to establish a defoliation schedule for this grass in Southeast of Brazil. A randomized block design with a split-plot arrangement was used. The effect of three grazing intervals was evaluated within seven periods between October 1995 and September 1996. Responses monitored were leaf and stem elongation rates, leaf senescence rate, stem length, and tiller density. Net herbage accumulation rate was calculated using tissue turnover data. The grazing intervals for Tanzania grass should be around 38 days between October and April (spring and early autumn) and 28 days during the reproductive phase of the grass (April/May). Between May and September (late autumn and winter), grazing interval should be around 48 days. Herbage accumulation rate is not a good criterion to establish defoliation time for Tanzania grass. Studies on the effects of stem production in grazing efficiency, animal intake and forage quality are needed to improve Tanzania grass management.

Tiller size/density compensation in grazed Tifton 85 bermudagrass swards

The objective of this study was to evaluate the occurrence of the tiller size/density compensation mechanism in Tifton 85 bermudagrass swards grazed by sheep under continuous stocking. Treatments corresponded to four sward steady state conditions (5, 10, 15, and 20 cm of sward surface height), maintained by sheep grazing. The experimental design was a complete randomized block with four replicates. Pasture responses evaluated include: tiller population density, tiller mass, leaf mass and leaf area per tiller, and herbage mass. Tiller volume, leaf area index, tiller leaf/stem ratio, and tiller leaf area/volume ratio were calculated and simple regression analyses between tiller population density and tiller mass were performed. Measurements were made in December, 1998, and January, April, and July, 1999. The swards showed a tiller size/density compensation mechanism in which high tiller population densities were associated with small tillers and vice-versa, except in July, 1999. Regression analyses revealed that linear coefficients were steeper than the theoretical expectation of -3/2. Increments in herbage mass were attributable to increases in tiller mass in December and January. Leaf area/volume ratio values of Tifton 85 tillers were much lower than those commonly found for temperate grass species.

Statistically significant changes of antimüllerian hormone and inhibin levels during the physiologic menstrual cycle in reproductive age women.

OBJECTIVE: To define the dynamics of antimüllerian hormone (AMH) and inhibins during the physiologic menstrual cycle. DESIGN: Longitudinal study. SETTING: University hospital. PATIENT(S): 36 young, healthy, normal weight Caucasian women without medication. INTERVENTION(S): Normal ovulatory menstrual cycles were evaluated by regular blood sampling taken every other day and periovulatory every day. MAIN OUTCOME MEASURE(S): Serum concentrations of AMH, inhibin A and B, follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin, estradiol, progesterone, and free testosterone were measured in all blood samples. RESULT(S): Median AMH levels are statistically significantly higher in the late follicular compared with ovulation or the early luteal phase. There are statistically significant correlations between both AMH and FSH, and AMH and free testosterone in all cycle phases. Inhibin A increases strongly in the late follicular phase and peaks at day LH + 4. Inhibin B shows a broad midfollicular and a sharp early luteal peak, the difference being statistically significant between day LH + 4 and the earlier time points and between day LH + 2 and day LH. Although there is a negative association between inhibin A or B and the body mass index (BMI), there is no correlation between AMH and the BMI. CONCLUSION(S): Levels of AMH show a statistically significant change during the menstrual cycle and may influence the circulating gonadotropin and steroid hormone levels.