Summary 1.Reproductive value is an integrated measure of survival and reproduction fundamental to understanding life-history evolution and population dynamics, but little is known about intraspecific variation in reproductive value and factors explaining such variation, if any. 2. By applying generalized additive mixed models to longitudinal individual-based data of the common tern Sterna hirundo, we estimated age-specific annual survival probability, breeding probability and reproductive performance, based on which we calculated age-specific reproductive values. We investigated effects of sex and recruitment age (RA) on each trait. 3. We found age effects on all traits, with survival and breeding probability declining with age, while reproductive performance first improved with age before levelling off. We only found a very small, marginally significant, sex effect on survival probability, but evidence for decreasing age-specific breeding probability and reproductive performance with RA. 4. As a result, males had slightly lower age-specific reproductive values than females, while birds of both sexes that recruited at the earliest ages of 2 and 3 years (i.e. 54% of the tern population) had somewhat higher fitness prospects than birds recruiting at later ages. While the RA effects on breeding probability and reproductive performance were statistically significant, these effects were not large enough to translate to significant effects on reproductive value. 5. Age-specific reproductive values provided evidence for senescence, which came with fitness costs in a range of 17-21% for the sex-RA groups. 6. Our study suggests that intraspecific variation in reproductive value may exist, but that, in the common tern, the differences are small.

Reaction mechanisms and multifragmentation processes have been studied for 64 Znϩ 58 Ni collisions at intermediate energies with the help of antisymmetrized molecular dynamics ͑AMD-V͒ model calculations. Experimental energy spectra, angular distributions, charge distributions, and isotope distributions, classified by their associated charged particle multiplicities, are compared with the results of the AMD-V calculations. In general the experimental results are reasonably well reproduced by the calculations. The multifragmentation observed experimentally at all incident energies is also reproduced by the AMD-V calculations. A detailed study of AMD-V events reveals that, in nucleon transport, the reaction shows some transparency, whereas in energy transport the reaction is much less transparent at all incident energies studied here. The transparency in the nucleon transport indicates that, even for central collisions, about 75% of the projectile nucleons appear in the forward direction. In energy transport about 80% of the initial kinetic energy of the projectile in the centerof-mass frame is dissipated. The detailed study of AMD-V events also elucidates the dynamics of the multifragmentation process. The study suggests that, at 35A MeV, the semitransparency and thermal expansion are the dominant mechanisms for the multifragmentation process, whereas at 49A MeV and higher incident energies a nuclear compression occurs at an early stage of the reaction and plays an important role in the multifragmentation process in addition to that of the thermal expansion and the semitransparency.

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Formation and decay of hot nuclei have been studied in 64 Zn 1 nat Ti collisions between 35 and 79 MeV͞nucleon. The mass and excitation energy of excited quasiprojectiles are reconstructed from the kinematical characteristics of their decay products. In central collisions, excitation energies larger than 10 MeV͞nucleon are reached. Comparisons with theoretical predictions indicate that a fraction of the excitation energy is associated with an isotropic radial flow. [S0031-9007(96)00539-X] PACS numbers: 25.70.Lm, 21.65.+f, 25.70.Mn, 25.70.Pq One of the presently most debated questions in heavyion physics at intermediate energies focuses on the properties of hot nuclear matter and, in particular, on the so-called multifragmentation process as well as on the search for a liquid-gas phase transition. A very often invoked scenario is the occurrence of a compressionexpansion phase at the beginning of the interaction between projectile and target. In the course of such a process, after an initial compression, the hot nuclear matter expands towards low density regions where it can break up into fragments [1][2][3][4]. An alternative to this scenario is the occurrence of an expansion just arising from the pressure induced by the thermal energy [5]. From the fragment kinetic energies, we expect to gain information about the magnitude of the collective radial flow resulting from the expansion phase. Indeed, recent results show evidence for a collective energy of a few MeV͞nucleon at bombarding energies lower than 100 MeV͞nucleon [6-11], and reaching even higher values (.10 MeV͞nucleon) at higher bombarding energies [11][12][13][14][15].This Letter reports on the properties of hot nuclei formed in the 64 Zn 1 nat Ti reaction, which was investigated at GANIL at several bombarding energies between 35 and 79 MeV͞nucleon [16]. Light charged particles (LCP's: Z 1 and 2) and intermediate mass fragments (IMF's: Z $ 3) were detected in two plastic multidetectors covering a total solid angle of 84% of 4p, between 3 ± and 150 ± [17,18]. Detection of LCP's and IMF's was achieved for energies above 2.5 MeV͞nucleon. Identification of IMF's was possible only above 15-20 MeV͞nucleon. Heavier fragments were detected and identified in an additional set of seven DE-E telescopes between 3 ± and 30 ± .The events were sorted according to the violence of the collision measured by the total transverse momentum, taken as the sum of the moduli of transverse momenta of all particles detected in an event. It was assumed that the transverse momentum is maximum for head-on collisions and is a decreasing function of the impact parameter. The experimental impact parameter b exp has been derived from the measured differential cross section [16]. Results of simulations exhibit a linear relationship between b exp and the true impact parameter with a standard deviation of 1-1.5 fm [19].The correlation between the total multiplicity of charged products detected in an event and the corresponding total parallel momentum displays two distinct regions [16]. Low...

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Hyperparasitism is a normal behavior of parasitoids, which often happens among species. Conspecific hyperparasitism, such as some kinds of heteronomous hyperparasitic behaviors, has been only reported in some species belonging to Aphelinidae. In this article, the conspecific hyperparasitism of Pachycrepoideus vindemmiae (Pteromalidae) is reported, with Drosophila puparia as hosts. Hosts were exposed to P. vindemmiae females twice to parasitism with nine, twelve, and fifteen day intervals between the two exposures. None of the infested hosts emerged more than one offspring, and emergence of parasitoid offspring occurred in two obvious events, synchronously with the exposure time intervals, which suggested that offspring emerging during the first and second events would come from the primary and secondary parasitoids, respectively, and the inference with the developmental duration of offspring also indicated this. With two P. vindemmiae strains that could be identified by a simple sequence repeat marker, the above speculation of the origin of those offspring emerging during the two events was confirmed. Dissection of hosts exposed twice revealed a cannibalism behavior of larvae from the secondary foundresses on the primary conspecific pupae. Our results suggested a conspecific hyperparasitism behavior of the secondary parasitoids on the primary conspecifics. Measures showed a reduced body size for the adults from the conspecific hyperparasitism. Foundresses from the conspecific hyperparasitism had less fitness variables than those from primary parasitism, with shorter longevity, less life time fecundity, lower values of infestation degree, and lower success rate of parasitism. However, when the parasitoids from the conspecific hyperparasitism met healthy Drosophila puparia, their offspring would recover to normal size. Frequency of the conspecific hyperparasitism behavior enhanced with the decreasing of proportion of healthy hosts in the oviposition patch. The conspecific hyperparasitism of P. vindemmiae on the primary conspecifics would be helpful to last the population when healthy hosts are absent in the oviposition patch.