Krogh’s principle states, “For such a large number of problems there will be some animal of choice, or a few such animals, on which it can be most conveniently studied.” The downside of picking a question first and then finding an ideal organism on which to study it is that it will inevitably leave many organisms neglected. Here, we promote the inverse Krogh principle: all organisms are worthy of study. The inverse Krogh principle and the Krogh principle are not opposites. Rather, the inverse Krogh principle emphasizes a different starting point for research: start with a biological unit, such as an organism, clade, or specific organism trait, then seek or create tractable research questions. Even the hardest-to-study species have research questions that can be asked of them: Where does it fall within the tree of life? What resources does it need to survive and reproduce? How does it differ from close relatives? Does it have unique adaptations? The Krogh and inverse Krogh approaches are complementary, and many research programs naturally include both. Other considerations for picking a study species include extreme species, species informative for phylogenetic analyses, and the creation of models when a suitable species does not exist. The inverse Krogh principle also has pitfalls. A scientist that picks the organism first might choose a research question not really suited to the organism, and funding agencies rarely fund organism-centered grant proposals. The inverse Krogh principle does not call for all organisms to receive the same amount of research attention. As knowledge continues to accumulate, some organisms—models—will inevitably have more known about them than others. Rather, it urges a broader search across organismal diversity to find sources of inspiration for research questions and the motivation needed to pursue them.

中文翻译：

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逆克罗原理：所有生物都值得研究

Krogh 的原则指出，“对于如此大量的问题，将有一些动物可供选择，或者一些这样的动物，可以最方便地对其进行研究。” 首先选择一个问题然后找到一个理想的生物体来研究它的缺点是它不可避免地会忽略许多生物体。在这里，我们提倡逆 Krogh 原则：所有生物都值得研究。逆克罗原理和克罗原理不是对立的。相反，逆 Krogh 原则强调研究的不同起点：从一个生物单位开始，例如生物体、进化枝或特定的生物体特征，然后寻求或创造易于处理的研究问题。即使是最难研究的物种也有可以向它们提出的研究问题：它落在生命树的什么地方？它需要什么资源才能生存和繁殖？和近亲有什么区别？它有独特的适应性吗？Krogh 和反 Krogh 方法是互补的，许多研究项目自然包括两者。选择研究物种的其他考虑因素包括极端物种、为系统发育分析提供信息的物种，以及在不存在合适物种时创建模型。逆 Krogh 原理也有缺陷。首先选择生物体的科学家可能会选择一个并不真正适合该生物体的研究问题，资助机构很少资助以生物体为中心的资助提案。逆 Krogh 原则并不要求所有生物体都受到相同数量的研究关注。随着知识的不断积累，一些生物体——模型——将不可避免地比其他生物体更了解它们。相反，它敦促对生物多样性进行更广泛的搜索，以找到研究问题的灵感来源和追求这些问题所需的动机。