We test the adaptive value of clutch size observed in a natural population of the chestnut weevil Curculio elephas. Clutch size is defined as the number of immatures per infested chestnut. In natural conditions, clutch size averages 1.7 eggs. By manipulating clutch size in the field, we demonstrate that deviations from the theoretical "Lack clutch size", estimated as eight immatures, are mainly due to proximate and delayed effects of clutch size on offspring performance. We show the existence of a trade-off between clutch size and larval weight. The latter, a key life-history trait, is highly correlated with fitness because it is a strong determinant of larval survival and potential fecundity of offspring females. The fitness of different potential oviposition strategies characterized by their clutch sizes, ranging from one to nine immatures, was calculated from field- estimated parameters. Chestnut weevil females obtain an evolutionary advantage by laying their eggs singly, since, for instance, fitness of single-egg clutches exceeds fitness of two-egg clutches and four-egg clutches by 8.0% and 15.1% respectively.
A morphometric study of the glomerular population in the olfactory bulb of the mouse has been carried out by using stereological methods. On the basis of the assumption that the glomerular population is a polydispersed system of spheres, glomerular profile distributions obtained from profile measurements were subjected to a mathematical unfolding procedure to obtain the actual glomerular size distribution. We used a distribution-free method to account for the combined effects of overprojection due to section thickness and truncation (two missing profile mechanisms). Results proved better than those obtained directly from profile measurements without stereological analysis. Several new findings were obtained. First, significant variations of the glomerulus sizes were found along the rostrocaudal axis. The glomeruli are larger in the middle region of the olfactory bulb, whereas their numerical density decreases in the same region. Moreover, the profile density is homogeneous along the rostrocaudal axis. In other words, the relative surface occupied by the periglomerular cells in the glomerular layer is invariant. As a consequence, it may be concluded that the variations in size and numerical density are inversely correlated. Thus, since the glomeruli are larger in the middle region, their number per unit volume is logically smaller in this same area. Finally, the computerization of all these data has led us to estimate the number of glomeruli (1,810 +/- 41) in the olfactory bulb of the mouse. In order to get a comparative idea of their advantages and disadvantages, other standard stereological methods were used in the present study to determine this number. Functional interpretations of the variations of the size and numerical density along the rostrocaudal axis of the olfactory bulb are discussed with respect to ontogenetic and morphofunctional data obtained elsewhere.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.