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Cerebral lateralization, an evolutionarily ancient and widespread phenomenon among vertebrates, is thought to bestow cognitive advantages. The advantages of lateralization at the individual-level do not necessarily require that the entire population share the same pattern of lateralization. In fact, directional bias in lateralization may lead to behavioural predictability and enhanced predator success or prey evasion. Recent theory has suggested that population-level lateralization may be favored if individuals are better able to perform coordinated behaviours, providing a distinct advantage in cooperative contexts. Here we test whether the highly social, cooperatively breeding cichlid fish Neolamprologus pulcher shows lateralized responses to a social stimulus. We found population-level biases in males; on average male N. pulcher use their right eye/left hemisphere to view their mirror image. Individual females had a preferred hemisphere, but these preferences appeared not to be directionally aligned among females. We discuss these results in the context of coordinated social behaviour and suggest future research directions.  相似文献   

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In highly social species, dominant individuals often monopolize reproduction, resulting in reproductive investment that is status dependent. Yet, for subordinates, who typically invest less in reproduction, social status can change and opportunities to ascend to dominant social positions are presented suddenly, requiring abrupt changes in behaviour and physiology. In this study, we examined male reproductive anatomy, physiology and behaviour following experimental manipulations of social status in the cooperatively breeding cichlid fish, Neolamprologus pulcher. This unusual fish species lives in permanent social groups composed of a dominant breeding pair and 1-20 subordinates that form a linear social dominance hierarchy. By removing male breeders, we created 18 breeding vacancies and thus provided an opportunity for subordinate males to ascend in status. Dominant females play an important role in regulating status change, as males successfully ascended to breeder status only when they were slightly larger than the female breeder in their social group. Ascending males rapidly assumed behavioural dominance, demonstrated elevated gonadal investment and androgen concentrations compared with males remaining socially subordinate. Interestingly, to increase gonadal investment ascending males appeared to temporarily restrain somatic growth. These results highlight the complex interactions between social status, reproductive physiology and group dynamics, and underscore a convergent pattern of reproductive investment among highly social, cooperative species.  相似文献   

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An investigation was made to evaluate the pharmacological importance of fruit peel extracts of Mangifera indica (MI), Citrullus vulgaris (CV) and Cucumis melo (CM) with respect to the possible regulation of tissue lipid peroxidation (LPO), thyroid dysfunctions, lipid and glucose metabolism. Pre-standardized doses (200 mg/kg of MI and 100 mg/kg both of CV and CM), based on the maximum inhibition in hepatic LPO, were administered to Wistar albino male rats for 10 consecutive days and the changes in tissue (heart, liver and kidney) LPO and in the concentrations of serum triiodothyronine (T3), thyroxin (T4), insulin, glucose, α-amylase and different lipids were examined. Administration of three test peel extracts significantly increased both the thyroid hormones (T3 and T4) with a concomitant decrease in tissue LPO, suggesting their thyroid stimulatory and antiperoxidative role. This thyroid stimulatory nature was also exhibited in propylthiouracil (PTU) induced hypothyroid animals. However, only minor influence was observed in serum lipid profile in which CM reduced the concentrations of total cholesterol and low-density lipoprotein-cholesterol (LDL-C), while CV decreased triglycerides and very low-density lipoprotein-cholesterol (VLDL-C). When the combined effects of either two (MI + CV) or three (MI + CV + CM) peel extracts were evaluated in euthyroid animals, serum T3 concentration was increased in response to MI + CV and MI + CV + CM treatments, while T4 level was elevated by the combinations of first two peels only. Interestingly, both the categories of combinations increased T4 levels, but not T3 in PTU treated hypothyroid animals. Moreover, a parallel increase in hepatic and renal LPO was observed in these animals, suggesting their unsafe nature in combination. In conclusion the three test peel extracts appear to be stimulatory to thyroid functions and inhibitory to tissue LPO but only when treated individually.  相似文献   

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The ultrastructure of septa and septum-associated septal pore caps are important taxonomic markers in the Agaricomycotina (Basidiomycota, Fungi). The septal pore caps covering the typical basidiomycetous dolipore septum are divided into three main phenotypically recognized morphotypes: vesicular-tubular (including the vesicular, sacculate, tubular, ampulliform, and globular morphotypes), imperforate, and perforate. Until recently, the septal pore cap-type reflected the higher-order relationships within the Agaricomycotina. However, the new classification of Fungi resulted in many changes including revision of existing and addition of new orders. Therefore, the septal pore cap ultrastructure of more than 325 species as reported in literature was related to this new classification. In addition, the septal pore cap ultrastructures of Rickenella fibula and Cantharellus formosus were examined by transmission electron microscopy. Both fungi have dolipore septa associated with perforate septal pore caps. These results combined with data from the literature show that the septal pore cap-type within orders of the Agaricomycotina is generally monomorphic, except for the Cantharellales and Hymenochaetales.It appears from the fungal phylogeny combined with the septal pore cap ultrastructure that the vesicular-tubular and the imperforate type both may have arisen from endoplasmic reticulum. Thereafter, the imperforate type eventually gave rise to the perforate septal pore cap-type.  相似文献   

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