The brain is among the most energetically costly organs in vertebrates,and thus trade-offs have been hypothesized to exert constraints on brain size evolution.The energy trade-off hypothesis(ETH) predicts that reducin...The brain is among the most energetically costly organs in vertebrates,and thus trade-offs have been hypothesized to exert constraints on brain size evolution.The energy trade-off hypothesis(ETH) predicts that reducing the energy consumption of reproduction or other costly tissues should compensate for the cost of a large brain.Egg production in birds requires a large proportion of the total energy budget,and a clutch mass in some bird species can outweigh the body mass of the female.To date,this hypothesis has mainly been tested in mammals and ectothermic animals such as anurans and fishes.We collated data on adult brain size,body mass and eggproduction traits such as clutch size,egg mass and annual broods from published studies,and conducted a phylogenetic comparative test of the interplay between egg-production investment and brain size evolution across bird species.After controlling for phylogenetic relationships and body size,we find a negative correlation between brain size and clutch size across 1395 species,which favored ETH.However,when egg mass was integrated in models,positive associations were detected between brain size and mass of eggs(via egg mass,clutch mass and annual total egg mass).Our results suggest that brain size trades off against egg-production only via certain aspects(e.g.,clutch size).By contrast,a positive relationship between brain size and total egg reproduction(e.g.,clutch mass and annual total egg mass) implied increased total energy budget outweighing energy allocation across bird species.Our study shows that there is no general energy trade-off between brain size and eggreproduction investment,and suggests that brain size evolution follows mixed strategies across bird species.展开更多
Oyster is one of the commercially important shellfish species in the world, and oyster cultivation has been one of the most prevalent shellfish aquaculture industries. Selective breeding researches and programs for se...Oyster is one of the commercially important shellfish species in the world, and oyster cultivation has been one of the most prevalent shellfish aquaculture industries. Selective breeding researches and programs for several commercial oyster species are briefly reviewed and the progress made from these programs is summarized in this paper. Particularly, the achievement of genetic improvement for growth, yield and disease resistance in some economically important oysters (the Pacific oyster, American oyster, European oyster and Sydney rock oyster et al.) is outlined accordingly here. So far, some fast growth lines and disease resistant strains have already been created. Two strategies, mass selection or family selection, were employed in these selective researches and programs. Both of them have been proved effective and fruitful. The estimations of heritability for live weight and whole size were in the range of 0.25-0.69 and of 0.2-0.5, respectively. All these efforts and results clearly showed that the regular breeding theories and techniques were applicable to oysters. Hopefully, the developments of regular breeding technology and that of molecular biology technology are expected to create a new era for oyster breeding science and practices in the future.展开更多
基金National Natural Science Foun-dation of China(Grant No.32170481 and Grant No.3221153042).
文摘The brain is among the most energetically costly organs in vertebrates,and thus trade-offs have been hypothesized to exert constraints on brain size evolution.The energy trade-off hypothesis(ETH) predicts that reducing the energy consumption of reproduction or other costly tissues should compensate for the cost of a large brain.Egg production in birds requires a large proportion of the total energy budget,and a clutch mass in some bird species can outweigh the body mass of the female.To date,this hypothesis has mainly been tested in mammals and ectothermic animals such as anurans and fishes.We collated data on adult brain size,body mass and eggproduction traits such as clutch size,egg mass and annual broods from published studies,and conducted a phylogenetic comparative test of the interplay between egg-production investment and brain size evolution across bird species.After controlling for phylogenetic relationships and body size,we find a negative correlation between brain size and clutch size across 1395 species,which favored ETH.However,when egg mass was integrated in models,positive associations were detected between brain size and mass of eggs(via egg mass,clutch mass and annual total egg mass).Our results suggest that brain size trades off against egg-production only via certain aspects(e.g.,clutch size).By contrast,a positive relationship between brain size and total egg reproduction(e.g.,clutch mass and annual total egg mass) implied increased total energy budget outweighing energy allocation across bird species.Our study shows that there is no general energy trade-off between brain size and eggreproduction investment,and suggests that brain size evolution follows mixed strategies across bird species.
文摘Oyster is one of the commercially important shellfish species in the world, and oyster cultivation has been one of the most prevalent shellfish aquaculture industries. Selective breeding researches and programs for several commercial oyster species are briefly reviewed and the progress made from these programs is summarized in this paper. Particularly, the achievement of genetic improvement for growth, yield and disease resistance in some economically important oysters (the Pacific oyster, American oyster, European oyster and Sydney rock oyster et al.) is outlined accordingly here. So far, some fast growth lines and disease resistant strains have already been created. Two strategies, mass selection or family selection, were employed in these selective researches and programs. Both of them have been proved effective and fruitful. The estimations of heritability for live weight and whole size were in the range of 0.25-0.69 and of 0.2-0.5, respectively. All these efforts and results clearly showed that the regular breeding theories and techniques were applicable to oysters. Hopefully, the developments of regular breeding technology and that of molecular biology technology are expected to create a new era for oyster breeding science and practices in the future.
