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JASON K.M. HANNA 《Bioethics》2010,24(7):341-347
Many critics of commercial surrogate motherhood argue that it violates the rights of children. In this paper, I respond to several versions of this objection. The most common version claims that surrogacy involves child‐selling. I argue that while proponents of surrogacy have generally failed to provide an adequate response to this objection, it can be overcome. After showing that the two most prominent arguments for the child‐selling objection fail, I explain how the commissioning couple can acquire parental rights by paying the surrogate only for her reproductive labor. My explanation appeals to the idea that parental rights are acquired by those who have claims over the reproductive labor that produces the child, not necessarily by those who actually perform the labor. This account clarifies how commercial surrogacy differs from commercial adoption. In the final section of the paper, I consider and reject three further child‐based objections to commercial surrogacy: that it establishes a market in children's attributes, that it requires courts to stray from the best interests standard in determining custodial rights, and that it requires the surrogate to neglect her parental responsibilities. Since each of these objections fails, children's rights probably do not pose an obstacle to the acceptability of commercial surrogacy arrangements. 相似文献
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The evolutionary forces shaping within‐ and across‐species variation in the investment in male and female sex function are still incompletely understood. Despite earlier suggestions that in plants the evolution or cosexuality vs. dioecy, as well as sex allocation among cosexuals, is affected by seed and pollen dispersal, no formal model has explicitly used dispersal distances to address this problem. Here, we present a game‐theory model as well as a simulation study that fills in this gap. Our model predicts that dioecy should evolve if seeds and pollen disperse widely and that sex allocation among cosexuals should be biased towards whichever sex function produces more widely dispersing units. Dispersal limitations stabilize cosexuality by reinforcing competition between spatially clumped dispersal units from the same source, leading to saturating fitness returns that render sexual specialization unprofitable. However, limited pollen dispersal can also increase the risk of selfing, thus potentially selecting for dioecy as an outbreeding mechanism. Finally, we refute a recent claim that cosexuals should always invest equally in both sex functions. 相似文献
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The heat evolved by 1 mm-thick tissue slices of the appendixof the Sauromatum guttatum inflorescence was measured calorimetricallyduring development. From D5 (5 d before inflorescence-opening,designated as D-day) to D2 about 8 µW mg1fresh wt. was observed, and during D1 an increase inheat evolution to 14 µW mg1 fresh wt. was monitored.The heat was produced through oxidative metabolism, since replacingthe air in the microcalorimeter with nitrogen blocked heatproduction.Addition of salicylic acid to tissue slices of thermogenic organs(appendix, lowest part of the spadix and male flowers) and ofnon-thermogenic organs (female flowers, club-shaped organs andlower part of the spadix) of Sauromatum inflorescences revealedthat the acid boosted heat-production only in the thermogenicorgans. The effect of the acid manifested itself with no appreciablelag time, and it generated non-linearity in the rate of heat-productionby tissue slices of the appendix. In the appendices of the highlythermogenic Arum italicum and of the weakly thermogenic Amorphophallusrivieri, salicylic acid selectively boosted the rate of heat-productionin the appendix of A. italicum. A Q10 of 24 was found between15C to 25 C for 1 mm-thick slices of D4 appendicesof S guttatum. Addition of digitonin or deoxycholate to pre-D-daytissue slices of the appendix increased the rate of heat-production. Key words: Amorphophallus rivieri, Arum italicum, microcalorimetry, salicylic acid, Sauromatum guttatum 相似文献