Mothers can epigenetically influence their progeny’s characteristics in response to environmental conditions they experience, thereby increasing offspring adaptation to anticipated future conditions. When resource shortage is anticipated, females are expected to produce larger offspring, as large body size often confers competitive and dispersal advantages. We tested this hypothesis using the polyembryonic parasitoid, Copidosoma koehleri. In this wasp, each egg proliferates into a clone of genetically identical individuals within its moth host, and body size correlates negatively with clone size. We expected females anticipating resource limitation to produce fewer and larger offspring per clone than females that anticipate abundant resources. Encounter rates of parasitoid females with hosts were manipulated to simulate varying levels of resource availability. High-encounter-rate females were introduced to ten hosts successively, while low-encounter-rate females encountered each of ten hosts at 8-h intervals. To control for female age at oviposition, we also introduced females at different ages to a single host. Contrary to our predictions, low-encounter-rate females produced larger offspring clones than high-encounter-rate females, and offspring body size did not differ between treatments. Low-encounter-rate females were shorter-lived than females that encountered hosts successively. Single-oviposition females resembled the high-encounter-rate females in longevity but produced as many offspring per clone as in the low-encounter-rate treatment. Female age, and number of previous host encounters, did not affect offspring clone size. These results suggest that offspring proliferation bears a cost to mothers, thus mothers that repeatedly induce high proliferation in their offspring pay an increased price. 相似文献
In this work, four major Lebanese rivers were investigated, the Damour, Ibrahim, Kadisha, and Orontes, which are located in South, Central, and North Lebanon and Bekaa Valley, respectively. Five sampling sites were considered from upstream to downstream, and 12 sampling campaigns over four seasons were conducted during 2010–2011. Thirty-seven physicochemical parameters and five microbial tests were evaluated. A principal component analysis (PCA) was used for data evaluation. The first PCA, applied to the matrix-containing data that was acquired on all four rivers, showed that each river was distinct in terms of trophic state and pollution sources. The Ibrahim River was more likely to be polluted with industrial and human discharges, while the Kadisha River was severely polluted with anthropogenic human wastes. The Orontes and Damour rivers seemed to have the lowest rates of water pollution, especially the Orontes, which had the best water quality. PCA was also performed on individual data matrices for each river. In all cases, the results showed that the springs of each river have good water quality and are free from severe contamination. The other monitoring sites on each river were likely exposed to human activities and showed important spatial evolution. Through this work, a spatiotemporal fingerprint was obtained for each studied river, defining a “water mass reference” for each one. This model could be used as a monitoring tool for subsequent water quality surveys to highlight any temporal evolution of water quality.
