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41.
Postcopulatory sexual selection, either in the form of sperm competition or cryptic female choice, is an important selective force that is thought to have generated the enormous variation in sperm morphology observed interspecifically. However, the evolutionary significance of intraspecific variation in sperm morphology, and the role that postcopulatory sexual selection plays in influencing this variation, remains poorly investigated in invertebrates. Here, we tested the hypothesis that postcopulatory sexual selection reduces variation in sperm morphology, both between and within males, in 27 species of eusocial ants and bees. These eusocial species offer an unusual opportunity to assess how selection acts on variance in sperm morphology, as haploid males produce clonal, haploid sperm that does not experience haploid-diploid conflict. We provide solid evidence that males of polyandrous ant and bee species indeed produce less-variable sperm, indicating that sperm competition selected for sperm of superior quality. Our results offer a mechanistic explanation for the evolution of high-quality sperm and provide comprehensive evidence that sperm morphology of social insects is influenced by sexual selection. 相似文献
42.
Aedes albopictus mosquito is an opportunistic blood feeder and has a broad host range. The feeding behavior and habits of this mosquito are liable to increase the transmission potential of arboviruses. The survival and fecundity in A. albopictus fed on different hosts and post-blood meal provision of sugar were investigated in a laboratory-reared colony. Adult survival of caged female A. albopictus that were fed on blood of two different hosts (double meal) was higher than the females fed only on one host (single meal) (mean survival: 70.2 ± 9.6 vs. 55.5 ± 5.5%, respectively) when held in the laboratory for 72 h after blood feeding. Mean survival of females provided 10% sucrose solution (in water) after a single or double blood meal was higher (90.5 ± 6.4% and 89.3 ± 6.5%, respectively) than in the respective groups receiving water only following blood feeding (double meal: 49.0 ± 9.6%; single meal: 45.3 ± 10.9%). Females receiving a double meal were more fecund on average (89.0 ± 6.6 eggs) than females provided a single meal (82.3 ± 8.2 eggs). 相似文献
43.
PAVEL B. KLIMOV EKATERINA A. SIDORCHUK 《Biological journal of the Linnean Society. Linnean Society of London》2011,102(3):661-668
It is generally assumed that male control over mating and a lack of precopulatory female choice are prevalent in many animals and in astigmatan mites in particular. We show that several morphological structures of females of some astigmatan mites are indicative of precopulatory female choice: (1) copulatory tubes acting like intromittent organs; (2) specialized structures assisting male–female attachment and possibly allowing indirect mate selection in immature females; and (3) a unique, pad‐like terminal opisthosomal organ used to cling to the male during copulation in Glaesacarus rhombeus (= Acarus rhombeus Koch et Berendt, 1854) belonging to an extinct family, Glaesacaridae, from the Upper Eocene Baltic amber. An exceptionally well‐preserved copulating pair from amber provides insight into the function of this organ and reproductive behaviour in this mite. Female control over mating may reduce the timing of insemination, harassment by males, and damage caused by copulation. As a consequence, this can lessen male–male aggression, select against precopulatory guarding, and reduce the risk of predation. By contrast to extant taxa, males of G. rhombeus do not have any apparent specialized structures aiding clinging to the female during copulation, suggesting that this mating system is either an earlier step in the evolution of the female‐dominated mating system and/or a remarkable example of imbalanced female counteradaptations against the male's reproductive interest that may occur during an arms race between the two sexes. We offer an approach that can falsify the hypothesis assuming precopulatory female choice and discuss an alternative hypothesis suggesting that these female structures evolved in response to the need to reduce damage associated with mating or precopulatory guarding. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 661–668. 相似文献
44.
Weinstock M 《Neurochemical research》2007,32(10):1730-1740
An increased incidence of anxiety, depression and attention deficits in children has been linked to psychological stress during
pregnancy. Subjection of a pregnant rat to stress at a time when the foetal limbic and hypothalamic pituitary adrenal (HPA)
axes develop results in anxiogenic and depressive behaviour and learning and attention deficits in the offspring, which depend
on its gender, intensity and timing of the maternal stress and behaviour being tested. Maternal stress increases corticosterone
levels in the foetal brain, decreases foetal testosterone and brain aromatase activity in males, and alters brain catecholamine
activity to that in females. Learning deficits, reductions in hippocampal neurogenesis, LTP and dendritic spine density in
the prefrontal cortex are more readily seen in prenatally-stressed males, while anxiety, depression and increased response
of the HPA axis to stress are more prevalent in females. Genders may differ in the sensitivity of developing brain areas to
stress hormones.
Special issue dedicated to Dr. Moussa Youdim. 相似文献
45.
46.
John Prenter Robert W. Elwood W. Ian Montgomery 《Evolution; international journal of organic evolution》1999,53(6):1987-1994
We investigate the association between female reproductive investment, absolute size, and sexual size dimorphism in spiders to test the predictions of the fecundity-advantage hypothesis. The relationships between absolute size and sexual size dimorphism and aspects of female reproductive output are examined in comparative analyses using phylogenetically independent contrasts. We provide support for the idea that allometry for sexual dimorphism is the result of variation in female size more so than male size. Regression analyses suggest selection for increased fecundity in females. We argue that fecundity selection provides the only general explanation for the evolution of sexual size dimorphism in spiders. 相似文献
47.
48.
49.
Joanna Kamińska Olga M. Koper Edyta Siedlecka-Czykier Joanna Matowicka-Karna Jerzy Bychowski Halina Kemona 《Saudi Journal of Biological Sciences》2018,25(7):1263-1271
Introduction
Thrombotic and inflammatory mechanisms are involved in the pathophysiology of acute coronary syndrome (ACS). The aim of the study was the evaluation of inflammation (white blood cells count/WBC, C-reactive protein/CRP, interleukin-6/IL-6) and platelet (platelet count/PLT, mean platelet volume/MPV, large platelet/LPLT, beta-thromboglobulin/β-TG) biomarkers in the groups of ACS patients depending on the severity of signs and symptoms and compared to controls without coronary artery disease.Materials and methods
The study group included 93 patients categorized into 3 subgroups depending on the severity of signs and symptoms of ACS. PLT, MPV, LPLT, and WBC were determined on hematological analyzer, IL-6 and β-TG were measured using the ELISA method.Results
In the whole group of ACS patients WBC, CRP, IL-6, MPV, and β-TG were significantly higher as compared to controls. Analyzing the inflammation and platelet biomarkers depending on the severity of signs and symptoms in comparison to controls, statistically significant differences for above-mentioned parameters were also found. There were no significant differences between the advancement of coronary artery changes and inflammation as well as platelet parameters, except for CRP concentrations. The AUCs for all inflammation parameters tested were similar, however the highest AUCs showed WBC and CRP. Among platelet parameters the highest AUC revealed β-TG.Conclusion
Markers of inflammation and platelet activation may be associated to myocardial ischemia and myocardial injury. WBC, CRP and IL-6 as inflammation parameters and MPV and β-TG as platelet biomarkers may be useful indicators of the presence of coronary artery disease. 相似文献50.
Although females are traditionally thought of as the choosy sex, there is increasing evidence in many species that males will preferentially court or mate with certain females over others when given a choice. In the fruit fly, Drosophila melanogaster, males discriminate between potential mating partners based on a number of female traits, including species, mating history, age, and condition. Interestingly, many of these male preferences are affected by the male''s previous sexual experiences, such that males increase courtship toward types of females that they have previously mated with and decrease courtship toward types of females that have previously rejected them. D. melanogaster males also show courtship and mating preferences for larger females over smaller females, likely because larger females have higher fecundity. It is unknown, however, whether this preference shows behavioral plasticity based on the male''s sexual history as we see for other male preferences. Here, we manipulate the sexual experience of D. melanogaster males and test whether this manipulation has any effect on the strength of male mate choice for large females. We find that sexually inexperienced males have a robust courtship preference for large females that is unaffected by previous experience mating with, or being rejected by, females of differing sizes. Given that female body size is one of the most common targets of male mate choice across insect species, our experiments with D. melanogaster may provide insight into how these preferences develop and evolve. 相似文献