Sexual selection by female mating preference for male nuptial coloration has been suggested as a driving force in the rapid speciation of Lake Victoria cichlid fish. This process could have been facilitated or acceler...Sexual selection by female mating preference for male nuptial coloration has been suggested as a driving force in the rapid speciation of Lake Victoria cichlid fish. This process could have been facilitated or accelerated by genetic associations between female preference loci and male coloration loci. Preferences, as well as coloration, are heritable traits and are probably determined by more than one gene. However, little is known about potential genetic associations between these traits. In turbid water, we found a population that is variable in male nuptial coloration from blue to yellow to red. Males at the extreme ends of the phenotype distribution resemble a reproductively isolated species pair in clear water that has diverged into one species with blue-grey males and one species with bright red males. Females of the turbid water population vary in mating preference coinciding with the male phenotype distribution. For the current study, these females were mated to blue males. We measured the coloration of the sires and male offspring. Parents-offspring regression showed that the sires did not affect male offspring coloration, which confirms earlier findings that the blue species breeds true. In contrast, male offspring coloration was determined by the identity of the dams, which suggests that there is heritable variation in male color genes between females. However, we found that mating preferences of the dams were not correlated with male offspring coloration. Thus, there is no evidence for strong genetic linkage between mating preference and the preferred trait in this population [Current Zoology 56 （1）： 57-64 2010].展开更多
The theory of ecological speciation suggests that assortative mating evolves most easily when mating preferences aredirectly linked to ecological traits that are subject to divergent selection. Sensory adaptation can ...The theory of ecological speciation suggests that assortative mating evolves most easily when mating preferences aredirectly linked to ecological traits that are subject to divergent selection. Sensory adaptation can play a major role in this process,because selective mating is often mediated by sexual signals: bright colours, complex song, pheromone blends and so on. Whendivergent sensory adaptation affects the perception of such signals, mating patterns may change as an immediate consequence.Alternatively, mating preferences can diverge as a result of indirect effects: assortative mating may be promoted by selectionagainst intermediate phenotypes that are maladapted to their (sensory) environment. For Lake Victoria cichlids, the visual environmentconstitutes an important selective force that is heterogeneous across geographical and water depth gradients. We investigatethe direct and indirect effects of this heterogeneity on the evolution of female preferences for alternative male nuptial colours(red and blue) in the genus Pundamilia. Here, we review the current evidence for divergent sensory drive in this system, extractgeneral principles, and discuss future perspectives [Current Zoology 56 (3): 285-299, 2010].展开更多
African indigenous vegetables have many nutritional and health benefits that have not been well researched and fully exploited. The objective of this study was to determine iron and protein contents of seven priority ...African indigenous vegetables have many nutritional and health benefits that have not been well researched and fully exploited. The objective of this study was to determine iron and protein contents of seven priority African indigenous vegetables found in Eastern Africa. The vegetables were planted at two sites, Maseno University, Maseno in western Kenya and Jomo Kenyatta University of Agriculture and Technology （JKUAT）, Juja in Central Kenya between 2006 and 2008. These vegetables were organically grown and edible parts of each of the vegetable harvested during vegetative growth stages just before onset of flowering and analysed for iron and protein contents. Nightshade and cowpea had high levels of both iron and protein. Pumpkin leaves and amaranths had high iron content while spiderplant and slenderleaf had high protein levels. Both iron and protein levels differed significantly between the seven vegetables at both sites. Nightshade and cowpea contained iron and protein levels that would provide 100% of the recommended daily allowance （RDA） iron and 50% of recommended daily allowance protein for optimal human growth and health. These results help to demonstrate the nutritional value of African indigenous vegetables and their potential use in nutrition intervention programs.展开更多
基金supported by the Netherlands Science Fotmdation (NWO-ALW 810.64.011)research grants from Leiden University Fundthe Schure-Beijerinck-Popping Foundation
文摘Sexual selection by female mating preference for male nuptial coloration has been suggested as a driving force in the rapid speciation of Lake Victoria cichlid fish. This process could have been facilitated or accelerated by genetic associations between female preference loci and male coloration loci. Preferences, as well as coloration, are heritable traits and are probably determined by more than one gene. However, little is known about potential genetic associations between these traits. In turbid water, we found a population that is variable in male nuptial coloration from blue to yellow to red. Males at the extreme ends of the phenotype distribution resemble a reproductively isolated species pair in clear water that has diverged into one species with blue-grey males and one species with bright red males. Females of the turbid water population vary in mating preference coinciding with the male phenotype distribution. For the current study, these females were mated to blue males. We measured the coloration of the sires and male offspring. Parents-offspring regression showed that the sires did not affect male offspring coloration, which confirms earlier findings that the blue species breeds true. In contrast, male offspring coloration was determined by the identity of the dams, which suggests that there is heritable variation in male color genes between females. However, we found that mating preferences of the dams were not correlated with male offspring coloration. Thus, there is no evidence for strong genetic linkage between mating preference and the preferred trait in this population [Current Zoology 56 （1）： 57-64 2010].
基金funded by the Swiss National Science Foundation (SNSF)the Netherlands Foundation for Scientific Research (NWO-ALW and NWO-WOTRO)
文摘The theory of ecological speciation suggests that assortative mating evolves most easily when mating preferences aredirectly linked to ecological traits that are subject to divergent selection. Sensory adaptation can play a major role in this process,because selective mating is often mediated by sexual signals: bright colours, complex song, pheromone blends and so on. Whendivergent sensory adaptation affects the perception of such signals, mating patterns may change as an immediate consequence.Alternatively, mating preferences can diverge as a result of indirect effects: assortative mating may be promoted by selectionagainst intermediate phenotypes that are maladapted to their (sensory) environment. For Lake Victoria cichlids, the visual environmentconstitutes an important selective force that is heterogeneous across geographical and water depth gradients. We investigatethe direct and indirect effects of this heterogeneity on the evolution of female preferences for alternative male nuptial colours(red and blue) in the genus Pundamilia. Here, we review the current evidence for divergent sensory drive in this system, extractgeneral principles, and discuss future perspectives [Current Zoology 56 (3): 285-299, 2010].
文摘African indigenous vegetables have many nutritional and health benefits that have not been well researched and fully exploited. The objective of this study was to determine iron and protein contents of seven priority African indigenous vegetables found in Eastern Africa. The vegetables were planted at two sites, Maseno University, Maseno in western Kenya and Jomo Kenyatta University of Agriculture and Technology （JKUAT）, Juja in Central Kenya between 2006 and 2008. These vegetables were organically grown and edible parts of each of the vegetable harvested during vegetative growth stages just before onset of flowering and analysed for iron and protein contents. Nightshade and cowpea had high levels of both iron and protein. Pumpkin leaves and amaranths had high iron content while spiderplant and slenderleaf had high protein levels. Both iron and protein levels differed significantly between the seven vegetables at both sites. Nightshade and cowpea contained iron and protein levels that would provide 100% of the recommended daily allowance （RDA） iron and 50% of recommended daily allowance protein for optimal human growth and health. These results help to demonstrate the nutritional value of African indigenous vegetables and their potential use in nutrition intervention programs.
